HP E MSR Router Configuration Manual

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HPE FlexNetwork MSR Router Series

Comware 7 MPLS Configuration Guide

Part number: 5998-8833 Software version: CMW710-R0305 Document version: 6PW106-20160308

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rmation contained herein is subject to change without notice. The only warranties for Hewlett Packard Enterprise products and services are set forth in the express warranty statements acco mpanying such products and services. Nothing herein should be construe d as constituting an additional warranty. Hewlett Packard Enterprise shall not be liable for technical or editorial errors or omissions co ntained herein.

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Acknowledgments

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Configuring basic MPLS ················································································· 1

Basic concepts ··········································································································································· 1 MPLS network architecture ························································································································ 2 LSP establishment ····································································································································· 3 MPLS forwarding ········································································································································ 4 PHP ···························································································································································· 4

Protocols and standards ···························································································································· 5 Compatibility information ···································································································································· 5 MPLS configuration task list ······························································································································· 5 Enabling MPLS ·················································································································································· 6 Setting MPLS MTU ············································································································································ 6 Specifying the label type advertised by the egress ···························································································· 7 Configuring TTL propagation ····························································································································· 8 Enabling sending of MPLS TTL-expired messages ··························································································· 9 Enabling MPLS forwarding statistics ·················································································································· 9

Enabling FTN forwarding statistics ············································································································· 9

Enabling MPLS label forwarding statistics for LSPs ················································································ 10

Enabling MPLS label forwarding statistics for a VPN instance ································································ 10 Enabling split horizon for MPLS forwarding ····································································································· 10 Enabling SNMP notifications for MPLS ············································································································ 11 Displaying and maintaining MPLS ··················································································································· 11

Configuring a static LSP ··············································································· 13

Overview ·························································································································································· 13 Configuration prerequisites ······························································································································ 13 Configuration procedure ·································································································································· 13 Displaying static LSPs ····································································································································· 14 Static LSP configuration example ···················································································································· 14

Configuring LDP ···························································································· 17

Terminology ············································································································································· 17

LDP messages ········································································································································· 17

LDP operation ·········································································································································· 18

Label distribution and control ··················································································································· 19

LDP GR ···················································································································································· 21

LDP NSR ·················································································································································· 22

LDP-IGP synchronization ························································································································· 23

LDP FRR ·················································································································································· 23

LDP over MPLS TE ·································································································································· 24

Protocols ·················································································································································· 25 Compatibility information ·································································································································· 25 LDP configuration task list ······························································································································· 25 Enabling LDP ··················································································································································· 26

Enabling LDP globally ······························································································································ 26

Enabling LDP on an interface ·················································································································· 26 Configuring Hello parameters ·························································································································· 26 Configuring LDP session parameters ·············································································································· 27 Configuring LDP backoff ·································································································································· 29 Configuring LDP MD5 authentication ··············································································································· 29 Configuring LDP to redistribute BGP unicast routes ························································································ 30 Configuring an LSP generation policy ·············································································································· 30 Configuring the LDP label distribution control mode ························································································ 31 Configuring a label advertisement policy ········································································································· 31 Configuring a label acceptance policy ············································································································· 32 Configuring LDP loop detection ······················································································································· 33

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Configuring LDP session protection ················································································································· 34 Configuring LDP GR ········································································································································ 35 Configuring LDP NSR ······································································································································ 35 Configuring LDP-IGP synchronization ············································································································· 35

Configuring LDP-OSPF synchronization ·································································································· 36

Configuring LDP-ISIS synchronization ····································································································· 37 Configuring LDP FRR ······································································································································ 37 Setting a DSCP value for outgoing LDP packets ····························································································· 37 Resetting LDP sessions ··································································································································· 38 Enabling SNMP notifications for LDP ·············································································································· 38 Displaying and maintaining LDP ······················································································································ 38 IPv4 LDP configuration examples ···················································································································· 39

LDP LSP configuration example ·············································································································· 39

Label acceptance control configuration example ····················································································· 43

Label advertisement control configuration example ················································································· 47

LDP FRR configuration example ·············································································································· 52 IPv6 LDP configuration examples ···················································································································· 55

IPv6 LDP LSP configuration example ······································································································ 55

IPv6 label acceptance control configuration example ·············································································· 61

IPv6 label advertisement control configuration example ·········································································· 65

Configuring MPLS TE ··················································································· 71

TE and MPLS TE ····································································································································· 71

MPLS TE basic concepts ························································································································· 71

Static CRLSP establishment ···················································································································· 71

Dynamic CRLSP establishment ··············································································································· 71

CRLSP establishment using PCE path calculation ·················································································· 73

Traffic forwarding ····································································································································· 74

Make-before-break ··································································································································· 75

Route pinning ··········································································································································· 76

Tunnel reoptimization ······························································································································· 76

Automatic bandwidth adjustment ············································································································· 76

CRLSP backup ········································································································································· 77

FRR ·························································································································································· 77

DiffServ-aware TE ···································································································································· 78

Bidirectional MPLS TE tunnel ·················································································································· 80

Protocols and standards ·························································································································· 80 MPLS TE configuration task list ······················································································································· 81 Enabling MPLS TE ··········································································································································· 82 Configuring a tunnel interface ·························································································································· 83 Configuring DS-TE ··········································································································································· 83 Configuring an MPLS TE tunnel to use a static CRLSP ·················································································· 84 Configuring an MPLS TE tunnel to use a dynamic CRLSP ············································································· 85

Configuration task list ······························································································································· 85

Configuring MPLS TE attributes for a link ································································································ 85

Advertising link TE attributes by using IGP TE extension ········································································ 86

Configuring MPLS TE tunnel constraints ································································································· 87

Establishing an MPLS TE tunnel by using RSVP-TE ··············································································· 89

Controlling CRLSP path selection ············································································································ 89

Controlling MPLS TE tunnel setup ··········································································································· 91 Configuring an MPLS TE tunnel to use a CRLSP calculated by PCEs ··························································· 93

Configuring a PCE ··································································································································· 93

Discovering PCEs ···································································································································· 94

Establishing a CRLSP by using the path calculated by PCEs ································································· 94

Establishing a backup CRLSP by using the path calculated by PCEs ····················································· 94

Configuring PCEP session parameters ···································································································· 95 Configuring load sharing for an MPLS TE tunnel ····························································································· 95 Configuring traffic forwarding ··························································································································· 96

Configuring static routing to direct traffic to an MPLS TE tunnel or tunnel bundle ··································· 96

Configuring PBR to direct traffic to an MPLS TE tunnel or tunnel bundle ················································ 97

Configuring automatic route advertisement to direct traffic to an MPLS TE tunnel or tunnel bundle ······· 97

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Configuring a bidirectional MPLS TE tunnel ···································································································· 98 Configuring CRLSP backup ····························································································································· 99 Configuring MPLS TE FRR ···························································································································· 100

Enabling FRR ········································································································································· 100

Configuring a bypass tunnel on the PLR ································································································ 100

Configuring node fault detection ············································································································ 104

Configuring the optimal bypass tunnel selection interval ······································································· 105 Enabling SNMP notifications for MPLS TE ···································································································· 105 Displaying and maintaining MPLS TE ············································································································ 105 MPLS TE configuration examples ·················································································································· 106

Establishing an MPLS TE tunnel over a static CRLSP ·········································································· 106

Establishing an MPLS TE tunnel with RSVP-TE ···················································································· 111

Establishing an inter-AS MPLS TE tunnel with RSVP-TE ······································································ 117

Establishing an inter-area MPLS TE tunnel over a CRLSP calculated by PCEs ··································· 124

Bidirectional MPLS TE tunnel configuration example ············································································ 128

CRLSP backup configuration example ·································································································· 134

Manual bypass tunnel for FRR configuration example ·········································································· 138

Auto FRR configuration example ··········································································································· 144

IETF DS-TE configuration example ······································································································· 150 Troubleshooting MPLS TE ····························································································································· 157

No TE LSA generated ···························································································································· 157

Configuring a static CRLSP ········································································ 158

Overview ························································································································································ 158 Configuration procedure ································································································································ 158 Displaying static CRLSPs ······························································································································ 159 Static CRLSP configuration example ············································································································· 159

Configuring RSVP ······················································································· 165

RSVP messages ···································································································································· 165

CRLSP setup procedure ························································································································ 166

RSVP refresh mechanism ······················································································································ 166

RSVP authentication ······························································································································ 167

RSVP GR ··············································································································································· 167

Protocols and standards ························································································································ 168 RSVP configuration task list ··························································································································· 168 Enabling RSVP ·············································································································································· 168 Configuring RSVP refresh ······························································································································ 168 Configuring RSVP Srefresh and reliable RSVP message delivery ································································ 169 Configuring RSVP hello extension ················································································································· 169 Configuring RSVP authentication ·················································································································· 170 Setting a DSCP value for outgoing RSVP packets ························································································ 171 Configuring RSVP GR ··································································································································· 172 Enabling BFD for RSVP ································································································································· 172 Displaying and maintaining RSVP ················································································································· 172 RSVP configuration examples ······················································································································· 173

Establishing an MPLS TE tunnel with RSVP-TE ···················································································· 173

RSVP GR configuration example ··········································································································· 179

Configuring tunnel policies ·········································································· 182

Configuration guidelines ························································································································· 182

Configuration procedure ························································································································· 183 Displaying tunnel information ························································································································· 184 Tunnel policy configuration examples ············································································································ 184

Preferred tunnel configuration example ································································································· 184

Exclusive tunnel configuration example ································································································· 184

Tunnel selection order configuration example ······················································································· 185

Preferred tunnel and tunnel selection order configuration example ······················································· 186

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Configuring MPLS L3VPN ·········································································· 188

Basic MPLS L3VPN architecture ··········································································································· 188

MPLS L3VPN concepts ·························································································································· 188

MPLS L3VPN route advertisement ········································································································ 190

MPLS L3VPN packet forwarding ············································································································ 191

MPLS L3VPN networking schemes ······································································································· 192

Inter-AS VPN ·········································································································································· 194

Carrier's carrier ······································································································································ 198

Nested VPN ··········································································································································· 200

Multirole host ·········································································································································· 201

HoVPN ··················································································································································· 202

OSPF VPN extension ····························································································································· 204

BGP AS number substitution and SoO attribute ···················································································· 206

MPLS L3VPN FRR ································································································································· 207

Multi-VPN instance CE ··························································································································· 209

Protocols and standards ························································································································ 210 MPLS L3VPN configuration task list ·············································································································· 211 Configuring basic MPLS L3VPN ···················································································································· 211

Configuration prerequisites ···················································································································· 211

Configuring VPN instances ···················································································································· 211

Configuring routing between a PE and a CE ························································································· 213

Configuring routing between PEs ··········································································································· 218

Configuring BGP VPNv4 route control ··································································································· 219 Configuring inter-AS VPN ······························································································································ 220

Configuring inter-AS option A ················································································································· 220

Configuring inter-AS option B ················································································································· 221

Configuring inter-AS option C ················································································································ 222 Configuring nested VPN ································································································································ 224 Configuring multirole host ······························································································································ 225

Configuring and applying PBR ··············································································································· 226

Configuring a static route ······················································································································· 226 Configuring HoVPN ········································································································································ 226 Configuring an OSPF sham link ····················································································································· 227

Configuring a loopback interface ············································································································ 228

Redistributing the loopback interface address ······················································································· 228

Creating a sham link ······························································································································ 228 Configuring routing on an MCE ······················································································································ 229

Configuring routing between an MCE and a VPN site ··········································································· 229

Configuring routing between an MCE and a PE ···················································································· 234 Specifying the VPN label processing mode on the egress PE ······································································ 237 Configuring BGP AS number substitution and SoO attribute ········································································· 238 Configuring MPLS L3VPN FRR ····················································································································· 238 Enabling SNMP notifications for MPLS L3VPN ····························································································· 240 Displaying and maintaining MPLS L3VPN ····································································································· 240 MPLS L3VPN configuration examples ··········································································································· 242

Configuring basic MPLS L3VPN ············································································································ 242

Configuring MPLS L3VPN over a GRE tunnel ······················································································· 247

Configuring a hub-spoke network ·········································································································· 251

Configuring MPLS L3VPN inter-AS option A ························································································· 258

Configuring MPLS L3VPN inter-AS option B ························································································· 262

Configuring MPLS L3VPN inter-AS option C ························································································· 267

Configuring MPLS L3VPN carrier's carrier in the same AS ··································································· 274

Configuring MPLS L3VPN carrier's carrier in different ASs ··································································· 282

Configuring nested VPN ························································································································· 289

Configuring multirole host ······················································································································ 298

Configuring HoVPN ································································································································ 300

Configuring an OSPF sham link ············································································································· 307

Configuring MCE ···································································································································· 311

Configuring BGP AS number substitution ······························································································ 316

Configuring BGP AS number substitution and SoO attribute ································································· 320

Page 7

Configuring MPLS L3VPN FRR through VPNv4 route backup for a VPNv4 route ································ 323

Configuring MPLS L3VPN FRR through VPNv4 route backup for an IPv4 route ·································· 325

Configuring MPLS L3VPN FRR through IPv4 route backup for a VPNv4 route ···································· 327

Configuring IPv6 MPLS L3VPN ·································································· 330

IPv6 MPLS L3VPN packet forwarding ··································································································· 330

IPv6 MPLS L3VPN routing information advertisement ·········································································· 331

IPv6 MPLS L3VPN network schemes and functions ············································································· 331

Protocols and standards ························································································································ 332 IPv6 MPLS L3VPN configuration task list ······································································································ 332 Configuring basic IPv6 MPLS L3VPN ············································································································ 332

Configuring VPN instances ···················································································································· 332

Configuring routing between a PE and a CE ························································································· 335

Configuring routing between PEs ··········································································································· 340

Configuring BGP VPNv6 route control ··································································································· 341 Configuring inter-AS IPv6 VPN ······················································································································ 342

Configuring inter-AS IPv6 VPN option A ································································································ 343

Configuring inter-AS IPv6 VPN option C ································································································ 343 Configuring multirole host ······························································································································ 344

Configuring and applying IPv6 PBR ······································································································· 344

Configuring an IPv6 static route ············································································································· 345 Configuring an OSPFv3 sham link ················································································································· 345

Configuring a loopback interface ············································································································ 345

Redistributing the loopback interface address ······················································································· 345

Creating a sham link ······························································································································ 346 Configuring routing on an MCE ······················································································································ 346

Configuring routing between an MCE and a VPN site ··········································································· 346

Configuring routing between an MCE and a PE ···················································································· 351 Configuring BGP AS number substitution and SoO attribute ········································································· 355 Displaying and maintaining IPv6 MPLS L3VPN ····························································································· 355 IPv6 MPLS L3VPN configuration examples ··································································································· 356

Configuring IPv6 MPLS L3VPNs ············································································································ 356

Configuring an IPv6 MPLS L3VPN over a GRE tunnel ·········································································· 363

Configuring IPv6 MPLS L3VPN inter-AS option A ················································································· 366

Configuring IPv6 MPLS L3VPN inter-AS option C ················································································· 371

Configuring IPv6 MPLS L3VPN carrier's carrier in the same AS ··························································· 377

Configuring multirole host ······················································································································ 385

Configuring an OSPFv3 sham link ········································································································· 387

Configuring IPv6 MCE ···························································································································· 391

Configuring BGP AS number substitution ······························································································ 396

Configuring BGP AS number substitution and SoO attribute ································································· 401

Configuring MPLS L2VPN ·········································································· 404

Basic concepts of MPLS L2VPN ············································································································ 404

MPLS L2VPN network models ··············································································································· 405

Remote connection establishment ········································································································· 406

Local connection establishment ············································································································· 407

PW types ················································································································································ 407

Control word ··········································································································································· 409

MPLS L2VPN interworking ····················································································································· 409

PW redundancy ······································································································································ 410

Multi-segment PW ·································································································································· 410

VCCV ····················································································································································· 412 Compatibility information ································································································································ 412 MPLS L2VPN configuration task list ·············································································································· 412 Enabling L2VPN ············································································································································· 413 Configuring an AC ·········································································································································· 413

Configuring the interface with Ethernet or VLAN encapsulation ···························································· 414

Configuring the interface with PPP encapsulation ················································································· 414

Configuring the interface with HDLC encapsulation ··············································································· 414

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Configuring a cross-connect ·························································································································· 415 Configuring a PW ··········································································································································· 415

Configuring a PW class ·························································································································· 415

Configuring a static PW ·························································································································· 415

Configuring an LDP PW ························································································································· 416

Configuring a BGP PW ·························································································································· 416

Configuring a remote CCC connection ·································································································· 418 Binding an AC to a cross-connect ·················································································································· 419 Configuring PW redundancy ·························································································································· 419

Configuring static PW redundancy ········································································································· 420

Configuring LDP PW redundancy ·········································································································· 420 Configuring interworking for a cross-connect ································································································· 421 Enabling SNMP notifications for L2VPN PW ································································································· 422 Displaying and maintaining MPLS L2VPN ····································································································· 422 MPLS L2VPN configuration examples ··········································································································· 423

Configuring local MPLS L2VPN connections ························································································· 423

Configuring IP interworking over local MPLS L2VPN connections ························································ 424

Configuring a static PW ·························································································································· 426

Configuring an LDP PW ························································································································· 429

Configuring IP interworking over an LDP PW ························································································ 433

Configuring a BGP PW ·························································································································· 436

Configuring a remote CCC connection ·································································································· 440

Configuring an intra-domain multi-segment PW ···················································································· 444

Configuring an inter-domain multi-segment PW ···················································································· 447

Configuring VPLS ······················································································· 453

Basic VPLS architecture ························································································································ 453

VPLS implementation ····························································································································· 454

H-VPLS ·················································································································································· 456

Hub-spoke networking ··························································································································· 458 Compatibility information ································································································································ 458 VPLS configuration task list ··························································································································· 459 Enabling L2VPN ············································································································································· 459 Configuring an AC ·········································································································································· 460 Configuring a VSI ··········································································································································· 460 Configuring a PW ··········································································································································· 461

Configuring a PW class ·························································································································· 461

Configuring a static PW ·························································································································· 461

Configuring an LDP PW ························································································································· 462

Configuring a BGP PW ·························································································································· 462

Configuring a BGP auto-discovery LDP PW ·························································································· 464 Binding an AC to a VSI ·································································································································· 466 Configuring UPE dual homing ························································································································ 466

Configuring static PW redundancy ········································································································· 466

Configuring LDP PW redundancy ·········································································································· 467 Configuring MAC address learning ················································································································ 468 Enabling SNMP notifications for L2VPN PW ································································································· 468 Displaying and maintaining VPLS ·················································································································· 468 VPLS configuration examples ························································································································ 470

Static PW configuration example ··········································································································· 470

LDP PW configuration example ············································································································· 474

BGP PW configuration example ············································································································· 476

BGP auto-discovery LDP PW configuration example ············································································ 480

H-VPLS using MPLS access configuration example ············································································· 485

Hub-spoke VPLS configuration example ······························································································· 489

H-VPLS UPE dual homing configuration example ················································································· 492

Configuring L2VPN access to L3VPN or IP backbone ································ 498

Conventional L2VPN access to L3VPN or IP backbone ········································································ 498

Improved L2VPN access to L3VPN or IP backbone ·············································································· 499

Page 9

Configuring conventional L2VPN access to L3VPN or IP backbone ····························································· 500 Configuring improved L2VPN access to L3VPN or IP backbone ··································································· 500

Configuring an L2VE interface ··············································································································· 501

Configuring an L3VE interface ··············································································································· 501 Displaying and maintaining L2VPN access to L3VPN or IP backbone ·························································· 502 Improved L2VPN access to L3VPN or IP backbone configuration examples ················································ 502

Access to MPLS L3VPN through an LDP MPLS L2VPN ······································································· 502

Access to IP backbone through an LDP VPLS ······················································································ 508

Configuring MPLS OAM ·············································································· 513

MPLS ping ·············································································································································· 513

MPLS tracert ·········································································································································· 513

BFD for MPLS ········································································································································ 513

Periodic MPLS tracert ···························································································································· 514 Protocols and standards ································································································································ 514 Configuring MPLS OAM for LSP tunnels ······································································································· 514

Configuring MPLS ping for LSPs ··········································································································· 514

Configuring MPLS tracert for LSPs ········································································································ 515

Configuring BFD for LSPs ······················································································································ 515

Configuring periodic MPLS tracert for LSPs ·························································································· 516 Configuring MPLS OAM for MPLS TE tunnels ······························································································ 516

Configuring MPLS ping for MPLS TE tunnels ························································································ 516

Configuring MPLS tracert for MPLS TE tunnels ····················································································· 516

Configuring BFD for MPLS TE tunnels ·································································································· 517 Configuring MPLS OAM for a PW ·················································································································· 517

Configuring MPLS ping for a PW ··········································································································· 518

Configuring BFD for a PW ······················································································································ 518 Displaying MPLS OAM ·································································································································· 521 BFD for LSP configuration example ··············································································································· 522

Configuring MPLS protection switching ······················································ 525

Protection switching triggering modes ··································································································· 525

Protection switching modes ··················································································································· 525

Path switching modes ···························································································································· 526 Protocols and standards ································································································································ 526 Compatibility information ································································································································ 526 MPLS protection switching configuration task list ·························································································· 527 Enabling MPLS protection switching ·············································································································· 527 Creating a protection group ··························································································································· 527 Configuring PS attributes for the protection group ························································································· 529 Configuring command switching for the protection group ·············································································· 530 Configuring the PSC message sending interval ···························································································· 530 Displaying and maintaining MPLS protection switching ················································································· 530 MPLS protection switching configuration example························································································· 531

Network requirements ···························································································································· 531

Configuration procedure ························································································································· 532

Verifying the configuration ······················································································································ 534

Document conventions and icons ······························································· 535

Conventions ··················································································································································· 535 Network topology icons ·································································································································· 536

Support and other resources ······································································ 537

Accessing Hewlett Packard Enterprise Support ···························································································· 537 Accessing updates ········································································································································· 537

Websites ················································································································································ 538

Customer self repair ······························································································································· 538

Remote support ······································································································································ 538

Documentation feedback ······················································································································· 538

vii

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Index ··········································································································· 540

viii

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Configuring basic MPLS

Multiprotocol Label Switching (MPLS) provides connection-oriented label switching over connectionless IP backbone networks. It integrates both the flexibility of IP routing and the simplicity of Layer 2 switching.

Overview

MPLS has the following features:

• High speed and efficiency—MPLS uses short- and fixed-length labels to forward packets, avoiding complicated routing table lookups.

• Multiprotocol support—MPLS resides between the link layer and the network layer. It can work over various link layer protocols (for example, PPP, ATM, frame relay, and Ethernet) to provide connection-oriented services for various network layer protocols (for example, IPv4, IPv6, and IPX).

• Good scalability—The connection-oriented switching and multilayer label stack features enable MPLS to deliver various extended services, such as VPN, traffic engineering, and QoS.

Basic concepts

FEC

MPLS groups packets with the same characteristics (such as packets with the same destination or service class) into a forwarding equivalence class (FEC). Packets of the same FEC are handled in the same way on an MPLS network.

Label

A label uniquely identifies an FEC and has local significance.

Figure 1 Format of a label

A label is encapsulated betwee n the Layer 2 heade r and Layer 3 header of a packet. It is four bytes long and consists of the following fields:

• Label—20-bit label value.

• TC—3-bit traffic class, used for QoS. It is also called Exp.

• S—1-bit bottom of stack flag. A label stack can contain multiple labels. The label nearest to the

Layer 2 header is called the top label, and the label nearest to the Layer 3 header is called the bottom label. The S field is set to 1 if the label is the bottom label and set to 0 if not.

• TTL—8-bit time to live field used for MPLS loop prevention.

LSR

A router that performs MPLS forwarding is a label switching router (LSR).

Page 12

LSP

LFIB

A label switched path (LSP) is the path along which packets of an FEC travel through an MPLS network.

An LSP is a unidirectional packet forwarding path. Two neighboring LSRs are called the upstream LSR and downstream LSR along the direction of an LSP. As shown in Figure 2, LSR B downstream LSR of LSR A, and LSR A is the upstream LSR of LSR B.

Figure 2 Label switched path

The Label Forwarding Information Base (LFIB) on an MPLS network functions like the Forwarding Information Base (FIB) on an IP network. When an LSR receives a labeled packet, it searches the LFIB to obtain information for forwarding the packet. The information includes the label operation type, the outgoing label value, and the next hop.

is the

Control plane and forwarding plane

An MPLS node consists of a control plane and a forwarding plane.

• Control plane—Assigns labels, distributes FEC-label mappings to neighbor LSRs, creates the LFIB, and establishes and removes LSPs.

• Forwarding plane—Forwards packets according to the LFIB.

MPLS network architecture

Figure 3 MPLS network architecture

An MPLS network has the following types of LSRs:

• Ingress LSR—Ingress LSR of packets. It labels packets entering into the MPLS network.

• Transit LSR—Intermediate LSRs in the MPLS network. The transit LSRs on an LSP forward

packets to the egress LSR according to labels.

Page 13

• Egress LSR—Egress LSR of packets. It removes labels from packets and forwards the packets to their destination networks.

LSP establishment

LSPs include static and dynamic LSPs.

• Static LSP—To establish a static LSP, you must configure an LFIB entry on each LSR along the LSP. Establishing static LSPs consumes fewer resources than establishing dynamic LSPs, but static LSPs cannot automatically adapt to network topology changes. Therefore, static LSPs are suitable for small-scale networks with simple, stable topologies.

• Dynamic LSP—Established by a label distribution protocol (also called an MPLS signaling protocol). A label distribution protocol classifies FECs, distributes FEC-label mappings, and establishes and maintains LSPs. Label distribution protocols include protocols designed specifically for label distribution, such as the Label Distribution Protocol (LDP), and protocols extended to support label distribution, such as MP-BGP and RSVP-TE.

In this document, the term "label distribution protocols" refers to all protocols for label distribution. The term "LDP" refers to the RFC 5036 LDP.

A dynamic LSP is established in the following steps:

1. A downstream LSR classifies FECs according to destination addresses.

2. The downstream LSR assigns a label for each FEC, and distributes the FEC-label binding to its

upstream LSR.

3. The upstream LSR establishes an LFIB entry for the FEC according to the binding inform ation.

After all LSRs along the LSP establish an LFIB entry for the FEC, a dynamic LSP is established for the packets of this FEC.

Figure 4 Dynamic LSP establishment

Page 14

MPLS forwarding

Figure 5 MPLS forwarding

10.1.0.0

Router A

FIB table

NexthopDest Out intOut label

Router C

IP:10.1.1.1

GE2/0/1 GE2/0/2

GE2/0/240

In label

Router B

Ingress

Oper

Swap

GE2/0/1

LFIB table Out label

Router C

Router F

Nexthop

Router D

GE2/0/2

In label

Out int GE2/0/2

GE2/0/1

Oper

Router D

Egress

MPLS network

Pop

Out label

IP:10.1.1.140 IP:10.1.1.1 50 IP:10.1.1.1

GE2/0/2

LFIB table

Nexthop

Router E

Out int

GE2/0/2

As shown in Figure 5, a packet is forwarded over the MPLS network as follows:

1. Router B (the ingress LSR) receives a packet with no label. Then, it performs the following operations:

a. Identifies the FIB entry that matches the destination address of the packet. b. Adds the outgoing la bel (40, in this example) to the packet. c. Forwards the labeled packet out of the interface GigabitEthernet 2/0/2 to the next hop LSR

Router C.

2. When receiving the labeled packet, Router C processes the packet as follows: a. Identifies the LFIB entry that has an incoming label of 40. b. Uses the outgoing label 5 0 of the entry to replace label 40 in the packet. c. Forwards the labeled packet out of the outgoing interface GigabitEthernet 2/0/2 to the next

hop LSR Router D.

3. When receiving the labeled packet, Router D (the egress LSR) processes the packet as follows: a. Identifies the LFIB entry that has an incoming label of 50. b. Removes the label from th e packet. c. Forwards the packet out of the outgoing interface GigabitEthernet 2/0/2 to the next hop LSR

Router E.

If the LFIB entry records no outgoing interface or next hop information, Router D performs the following operations:

a. Identifies the FIB entry by the IP header. b. Forwards the packet according to the FIB entry.

PHP

An egress node must perform two forwarding table lookups to forward a packet:

• Two LFIB lookup s (if the packet has more than one label).

Page 15

• One LFIB lookup and one FIB lookup (if the packet has only one label).

The penultimate hop popping (PHP) feature can pop the label at the penultimate node, so the egress node only performs one table lookup.

A PHP-capable egress node sends the penultimate node an implicit null label of 3. This label never appears in the label stack of packets. If an incoming packet matches an LFIB entry containing the implicit null label, the penultimate node pops the top label and forwards the packet to the egress node. The egress node directly forwards the packet.

Sometimes, the egress node must use the TC field in the label to perform QoS. To keep the TC information, you can configure the egress node to send the penultimate node an explicit null label of

0. If an incoming packet matches an LFIB entry containing the explicit null label, the penultimate hop

replaces the top label value with value 0, and forwards the packet to the egress node. The egress node gets the TC information, pops the label of the packet, and forwards the packet.

Protocols and standards

• RFC 3031, Multiprotocol Label Switching Architecture

• RFC 3032, MPLS Label Stack Encoding

• RFC 5462, Multiprotocol Label Switching (MPLS) Label Stack Entry: "EXP" Field Renamed to

"T raffic Class" Field

Compatibility information

Commands and descriptions for centralized devices apply to the followin g routers:

• MSR1002-4/1003-8S.

• MSR2003.

• MSR2004-24/2004-48.

• MSR3012/3024/3044/3064.

Commands and descriptions for distributed devices apply to MSR4060 and MSR4080 routers.

MPLS configuration task list

Tasks at a glance

(Required.) Enabling MPLS (Optional.) Setting MPLS MTU (Optional.) Specifying the label type advertised by the egress (Optional.) Configuring TTL propagation (Optional.) Enabling sending of MPLS TTL-expired messages (Optional.) Enabling MPLS forwarding statistics (Optional.) Enabling split horizon for MPLS forwarding (Optional.) Enabling SNMP notifications for MPLS

Page 16

Enabling MPLS

Before you enable MPLS, perform the following tasks:

• Configure link layer protocols to ensure connectivity at the link layer.

• Configure IP addresses for interfaces to ensure IP conne ctivity between neighboring nodes.

• Configure static routes or an IGP protocol to ensure IP connectivity among LSRs.

To enable MPLS:

Step Command Remarks

1. Enter system view.

2. Configure an LSR ID for the

local node.

3. Enter the view of the interface that needs to perform MPLS forwarding.

system-view

mpls lsr-id

interface

interface-number

lsr-id

interface-type

N/A By default, no LSR ID is configured.

An LSR ID must be unique in an MPLS network and in IP address format. As a best practice, use the IP address of a loopback interface as an LSR ID.

N/A

4. Enable MPLS on the interface.

Setting MPLS MTU

MPLS adds the label stack between the link layer header and network layer header of each packet. T o ma ke sure the size of MPLS labeled packets i s smaller than the MTU of an interface, configure a n MPLS MTU on the interface.

MPLS compares each MPLS packet against the interface MPLS MTU. When the packet exceeds the MPLS MTU:

• If fragmentation is allowed, MPLS performs the following operations: a. Removes the label stack from the packet. b. Fragments the IP packet. The length of a fragment is the MPLS MTU minus the length of the

label stack.

c. Adds the label stack to each fragment, and forwards the fragments.

• If fragmentation is not allowed, the LSR drops the packet.

To set an MPLS MTU for an interface:

Step Command Remarks

1. Enter system view.

mpls enable

system-view

By default, MPLS is disabled on the interface.

N/A

2. Enter interface view.

3. Set an MPLS MTU for the

interface.

interface

interface-number

mpls mtu

interface-type

value

The following applies when an interface handles MPLS packets:

N/A

By default, no MPLS MTU is set on an interface.

Page 17

• MPLS packets carrying L2VPN or IPv6 packets are always forwarded by an interface, even if the length of the MPLS packets exceeds the MPLS MTU of the interface. Whether the forwarding can succeed depends on the actual forwarding capacity of the interface.

• If the MPLS MTU of an interface is greater than the MTU of the interface, data forwarding might fail on the interface.

• If you do not configure the MPLS MTU of an interface, fragmentation of MPLS packets is based on the MTU of the interface without considering MPLS labels. An MPLS fragment might be larger than the interface MTU and be dropped.

Specifying the label type advertised by the egress

In an MPLS network, an egress can advertise the following types of labels:

• Implicit null label with a value of 3.

• Explicit null label with a value of 0.

• Non-null label.

For LSPs established by a label distribution protocol, the label advertised by the egress determines how the penultimate hop processes a labeled packet.

• If the egress advertises an implicit null label, the penultimate hop directly pops the top label of a matching packet.

• If the egress advertises an explicit null label, the penultimate hop swaps the top label value of a matching packet with the explicit null label.

• If the egress advertises a non-null label, the penultimate hop swaps the top label of a matching packet with the label assigned by the egress.

Configuration guidelines

As a best practice, configure the egress to advertise an implicit null label to the penultimate hop if the penultimate hop supports PHP. If you want to simplify packet forwarding on the egress but keep labels to determine QoS policies, configure the egress to advertise an explicit null label to the penultimate hop. Use non-null labels only in particular scenarios. For example, when OAM is configured on the egress, the egress can get the OAM function entity status only through non-null labels.

As a penultimate hop, the device accepts the implicit null label, explicit null label, or normal label advertised by the egress device.

For LDP LSPs, the mpls label advertise command triggers LDP to delete the LSPs established before the command is executed and re-establishes new LSPs.

For BGP LSPs, the mpls label advertise command takes effect only on the BGP LSPs estab lished after the command is executed. To apply the new setting to BGP LSPs established before the command is executed, delete the routes corresponding to the BGP LSPs, and then redistribute the routes.

Configuration procedure

To specify the type of label that the egress node will advertise to the penultimate hop:

Step Command Remarks

1. Enter system view.

2. Specify the label type

advertised by the egress to the penultimate hop.

system-view mpls label advertise

explicit-null

{

non-null

}

implicit-null

N/A

By default, an egress advertises an implicit null label to the penultimate hop.

Page 18

Configuring TTL propagation

When TTL propagation is enabl ed, the ingress node copi es the TTL value of an IP packet to the TTL field of the label. Each LSR on the LSP decreases the label TTL value by 1. The LSR that pops the label copies the remaining label TTL value back to the IP TTL of the packet. The IP TTL value can reflect how many hops the packet has traversed in the MPLS network. The IP tracert facility can show the real path along which the packet has traveled.

Figure 6 TTL propagation

When TTL propagation is disabl ed, the ingress node sets the label TTL to 255. Each LSR on the LSP decreases the label TTL value by 1. The LSR that pops the label does not change the IP TTL value when popping the label. Therefore, the MPLS backbone nodes are invisible to user networks, and the IP tracert facility cannot show the real path in the MPLS network.

Figure 7 Without TTL propagation

Follow these guidelines when you configure TTL propagation:

• As a best practice, set the same TTL processing mode on all LSRs of an LSP.

• To enable TTL propagation for a VPN, you must enable it on all PE devices in the VPN. Then,

you can get the same traceroute result (hop count) from those PEs.

To enable TTL propagation:

Step Command Remarks

1. Enter system view.

system-view

N/A

Page 19

Step Command Remarks

By default, TTL propagation is enabled only for public-network packets.

2. Enable TTL propagation.

mpls ttl propagate vpn

}

public

{

This command affects only the propagation between IP TTL and label TTL. Within an MPLS network, TTL is always copied between the labels of an MPLS packet.

Enabling sending of MPLS TTL-expired messages

This feature enables an LSR to generate an ICMP TTL-expired message upon receiving an MPLS packet with a TTL of 1. If the MPLS packet has only one label, the LSR sends the ICMP TTL-expired message back to the source through IP routing. If the MPLS packet has multiple labels, the LSR sends it along the LSP to the egress, which then sends the message back to the sou rce.

To enable sending of MPLS TTL-expired messages:

Step Command Remarks

1. Enter system view.

2. Enable sending of MPLS

TTL-expired messages.

system-view

mpls ttl expiration enable

N/A By default, this function is

enabled.

Enabling MPLS forwarding statistics

Enabling FTN forwarding statistics

FEC-to-NHLFE map (FTN) entries are FIB entries that contain outgoing labels used for FTN forwarding. When an LSR receives an unlabeled packet, it searches for the corresponding FTN entry based on the destination IP address. If a match is found, the LSR adds the outgoing label i n the FTN entry to the packet and forwards the labeled packet.

To enable FTN forwarding statistics:

Step Command Remarks

1. Enter system view.

2. Enter RIB view.

3. Create a RIB IPv4 address

family and enter RIB IPv4 address family view.

4. Enable the device to maintain FTN entries in the RIB.

5. Enable FTN forwarding statistics for a destination network.

system-view rib

address-family ipv4

ftn enable

mpls-forwarding statistics prefix-list

prefix-list-name

N/A N/A

By default, no RIB IPv4 address family is created.

By default, the device does not maintain FTN entries in the RIB.

By default, FTN forwarding statistics is disabled for all destination networks.

Page 20

Enabling MPLS label forwarding statistics for LSPs

MPLS label forwarding for LSPs forwards a labeled packet based on its incoming label. Perform this task to enable MPLS label forwarding statistics for LSPs and MPLS statistics reading.

Then, you can use the display mpls lsp verbose command to view MPLS label statistics. To enable MPLS label forwarding statistics:

Step Command Remarks

1. Enter system view.

system-view

N/A

2. Enable MPLS label forwarding statistics for the specified LSPs.

3. Enable MPLS label statistics reading, and set the reading interval.

mpls statistics

vpn-instance-name ] { ipv4-destination mask-length | ipv6-destination prefix-length } |

static

mpls statistics interval

all

vpn-instance

{

| [

ipv4

ipv6

ingress-lsr-id tunnel-id }

interval

By default, MPLS label forwarding statistics are disabled for all LSPs.

By default, MPLS label statistics reading is disabled.

Enabling MPLS label forwarding statistics for a VPN instance

MPLS label forwarding for a VPN instance performs the following operations:

• Forwards a labeled packet for the VPN instance based on its incoming label.

• Adds a label to an unlabeled packet received by the VPN instance and forwards the labeled

packet.

Perform this task to enable MPLS label forwarding statistics for a VPN instance and MPLS st atistics reading. Then, you can use the display ip vpn-instance mpls statistics command to view MPLS label statistics.

To enable MPLS label forwarding statistics:

Step Command Remarks

1. Enter system view.

2. Enter VPN instance view.

3. Enable MPLS label

forwarding statistics for the VPN instance.

4. Enable MPLS label statistics reading, and set the reading interval.

system-view ip vpn-instance

mpls statistics enable

mpls statistics interval

vpn-instance-name N/A

interval

N/A

By default, MPLS label forwarding statistics are disabled for all VPN instances.

By default, MPLS label statistics reading is disabled.

Enabling split horizon for MPLS forwarding

This feature prevents MPLS packets received from an interface from being forwarded back to that interface to provide loop-free forwarding.

To enable split horizon for MPLS forwarding:

Step Command Remarks

1. Enter system view.

system-view

N/A

Page 21

Step Command Remarks

2. Enable split horizon for

MPLS forwarding.

mpls forwarding split-horizon

By default, split horizon is disabled for MPLS forwarding.

Enabling SNMP notifications for MPLS

This feature enables MPLS to generate SNMP notifications. The generated SNMP notifications are sent to the SNMP module.

For more information about SNMP notifications, see Network Management and Monitoring Configuration Guide.

To enable SNMP notifications for MPLS:

Step Command Remarks

1. Enter system view.

2. Enable SNMP

notifications for MPLS.

system-view

snmp-agent trap enable mpls

N/A By default, SNMP notifications for

MPLS are enabled.

Displaying and maintaining MPLS

Execute display commands in any view and reset commands in user view.

Task Command

Display MPLS interface information. Display usage information for MPLS

labels.

Display LSP information.

Display MPLS Nexthop Information Base (NIB) information.

Display usage information for NIDs. Display LSP statistics. Display MPLS summary information. Display MPLS label forwarding statistics

for VPN instances. Display ILM entries (centralized devices

in standalone mode).

display mpls interface

display mpls label

display mpls lsp outgoing-interface

bgp

ldp

{

vpn-instance

[

ipv6

display mpls nib

display mpls nid display mpls lsp statistics display mpls summary display ip vpn-instance mpls statistics

vpn-instance-name ]

display mpls forwarding ilm

local

vpn-instance-name ] [ ipv4-dest mask-length |

[ ipv6-dest prefix-length ] ] [

[ interface-type interface-number ]

{ label-value1 [

egress

[

[ nib-id ]

[ nid-value1 [ to nid-value2 ] ]

interface-type interface-number |

rsvp-te

in-label

static

[ label ]

label-value2 ] |

label-value |

static-cr

verbose

ingress

transit

} |

]

instance-name

[

all }

protocol

]

Display ILM entries (distributed devices in standalone mode/centralized devices in IRF mode).

Display ILM entries (distributed devices in IRF mode).

Display NHLFE entries (centralized

display mpls forwarding ilm

display mpls forwarding ilm slot

slot-number ]

display mpls forwarding nhlfe

[ label ] [

[ nid ]

slot

slot-number ]

chassis

chassis-number

Page 22

Task Command

devices in standalone mode).

Display NHLFE entries (distributed devices in standalone mode/centralized devices in IRF mode).

display mpls forwarding nhlfe

[ nid ] [

slot

slot-number ]

Display NHLFE entries (distributed devices in IRF mode).

Clear MPLS forwarding statistics for the specified LSPs.

Clear MPLS forwarding statistics for VPN instances.

display mpls forwarding nhlfe slot

slot-number ]

reset mpls statistics

ipv4

{

ipv4-destination mask-length |

prefix-length } |

all

{

static

| te ingress-lsr-id tunnel-id }

[ nid ] [

vpn-instance

| [

reset ip vpn-instance mpls statistics

vpn-instance-name ]

chassis

chassis-number

vpn-instance-name ]

ipv6

ipv6-destination

instance-name

[

Page 23

Configuring a static LSP

Overview

A static label switched path (LSP) is established by manually specifying the incoming label and outgoing label on each node (ingress, transit, or egress node) of the forwarding path.

Static LSPs consume fewer resources, but they cannot automatically adapt to network topology changes. Therefore, static LSPs are suitable for small and stable n etworks with simple topologies.

Follow these guidelines to establish a static LSP:

• The ingress node performs the following operations: a. Determines an FEC for a packet according to the destination address. b. Adds the label for that FEC into the packet. c. Forwards the packet to the next hop or out of the outgoing interface.

Therefore, on the ingress node, you must specify the outgoing label for the destination address (the FEC) and the next hop or the outgoing interface.

• A transit node swaps the label carried in a received p acket with a label, and forwards the packet to the next hop or out of the outgoing interface. Therefore, on each transit node, you must specify the incoming label, the outgoing label, and the next hop or the outgoing interface.

• If PHP is not configured, an egress node pops the incoming label of a packet, and performs label forwarding according to the inner label or IP forwarding. Therefore, on the e gre ss node, you only need to specify the incoming label.

• The outgoing label specified on an LSR must be the same as the incoming label specified on the directly connected downstream LSR.

Configuration prerequisites

Before you configure a static LSP, perform the following tasks:

1. Identify the ingress node, transit nodes, and egress node of the LSP.

2. Enable MPLS on all interfaces that participate in MPLS forwarding. For more information, see

"Configuring basic MPLS."

3. Make

sure the ingress node has a route to the destination address of the LSP. This is not

required on transit and egress nodes.

Configuration procedure

To configure a static LSP:

Step Command Remarks

1. Enter system view.

2. Configure the ingress

node of the static LSP.

3. Configure the transit node of the static LSP.

system-view static-lsp ingress

destination

mask-length } {

outgoing-interface

interface-number }

static-lsp transit

in-label {

dest-addr { mask |

nexthop

lsp-name

nexthop

lsp-name

interface-type

out-label

next-hop-addr |

out-label

in-label

N/A

If you specify a next hop for the static LSP, make sure the ingress node has an active route to the specified next hop address.

If you specify a next hop for the static LSP, make sure the transit

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Step Command Remarks

outgoing-interface

interface-number }

interface-type

out-label

node has an active route to the specified next hop address.

4. Configure the egress node of the static LSP.

static-lsp egress

in-label

lsp-name

in-label

Displaying static LSPs

Execute display commands in any view .

Task Command

Display static LSP information.

display mpls static-lsp

Static LSP configuration example

Network requirements

Router A, Router B, and Router C all support MPLS. Establish static LSPs between Router A and Router C, so that subnets 11.1.1.0/24 and 21.1.1.0/24

can access each other over MPLS.

Figure 8 Network diagram

You do not need to configure this command if the outgoing label configured on the penultimate hop of the static LSP is 0 or 3.

lsp-name

[

lsp-name ]

Configuration restrictions and guidelines

• For an LSP, the outgoing label specified on an LSR must be identical with the incoming label specified on the downstream LSR.

• LSPs are unidirectional. You must configure an LSP for each direction of the data forwarding path.

• A route to the destination address of the LSP must be available on the ingress and egress nodes, but it is not needed on transit nodes. Therefore, you do not need to configure a routing protocol to ensure IP connectivity among all routers.

Configuration procedure

1. Configure IP addresses for all interfaces, including the loopback interfaces, as shown in Figure

8. (Details not shown.)

2. Configure a static route to the destination address of each LSP: # On Router A, configure a static route to network 21.1.1.0/24.

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<RouterA> system-view [RouterA] ip route-static 21.1.1.0 24 10.1.1.2

# On Router C, configure a static route to network 11.1.1.0/24.

<RouterC> system-view [RouterC] ip route-static 11.1.1.0 255.255.255.0 20.1.1.1

3. Configure basic MPLS on the routers: # Configure Router A.

[RouterA] mpls lsr-id 1.1.1.9 [RouterA] interface serial 2/1/0 [RouterA-Serial2/1/0] mpls enable [RouterA-Serial2/1/0] quit

# Configure Router B.

[RouterB] mpls lsr-id 2.2.2.9 [RouterB] interface serial 2/1/0 [RouterB-Serial2/1/0] mpls enable [RouterB-Serial2/1/0] quit [RouterB] interface serial 2/1/1 [RouterB-Serial2/1/1] mpls enable [RouterB-Serial2/1/1] quit

# Configure Router C.

[RouterC] mpls lsr-id 3.3.3.9 [RouterC] interface serial 2/1/0 [RouterC-Serial2/1/0] mpls enable [RouterC-Serial2/1/0] quit

4. Configure a static LSP from Router A to Router C: # Configure the LSP ingress node, Router A.

[RouterA] static-lsp ingress AtoC destination 21.1.1.0 24 nexthop 10.1.1.2 out-label 30

# Configure the LSP transit node, Router B.

[RouterB] static-lsp transit AtoC in-label 30 nexthop 20.1.1.2 out-label 50

# Configure the LSP egress node, Router C.

[RouterC] static-lsp egress AtoC in-label 50

5. Create a static LSP from Router C to Router A: # Configure the LSP ingress node, Router C.

[RouterC] static-lsp ingress CtoA destination 11.1.1.0 24 nexthop 20.1.1.1 out-label 40

# Configure the LSP transit node, Router B.

[RouterB] static-lsp transit CtoA in-label 40 nexthop 10.1.1.1 out-label 70

# Configure the LSP egress node, Router A.

[RouterA] static-lsp egress CtoA in-label 70

Verifying the configuration

# Display static LSP information on routers, for example, on Router A.

[RouterA] display mpls static-lsp Total: 2 Name FEC In/Out Label Nexthop/Out Interface State AtoC 21.1.1.0/24 NULL/30 10.1.1.2 Up CtoA -/- 70/NULL - Up

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# Test the connectivity of the LSP from Router A to Router C.

[RouterA] ping mpls -a 11.1.1.1 ipv4 21.1.1.0 24 MPLS Ping FEC: 21.1.1.0/24 : 100 data bytes 100 bytes from 20.1.1.2: Sequence=1 time=4 ms 100 bytes from 20.1.1.2: Sequence=2 time=1 ms 100 bytes from 20.1.1.2: Sequence=3 time=1 ms 100 bytes from 20.1.1.2: Sequence=4 time=1 ms 100 bytes from 20.1.1.2: Sequence=5 time=1 ms

--- FEC: 21.1.1.0/24 ping statistics ---

5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max = 1/1/4 ms

# Test the connectivity of the LSP from Router C to Router A.

[RouterC] ping mpls -a 21.1.1.1 ipv4 11.1.1.0 24 MPLS Ping FEC: 11.1.1.0/24 : 100 data bytes 100 bytes from 10.1.1.1: Sequence=1 time=5 ms 100 bytes from 10.1.1.1: Sequence=2 time=1 ms 100 bytes from 10.1.1.1: Sequence=3 time=1 ms 100 bytes from 10.1.1.1: Sequence=4 time=1 ms 100 bytes from 10.1.1.1: Sequence=5 time=1 ms

--- FEC: 11.1.1.0/24 ping statistics ---

5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max = 1/1/5 ms

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Configuring LDP

Overview

The Label Distribution Protocol (LDP) dynamically distributes FEC-label mapping information between LSRs to establish LSPs.

Terminology

LDP session

Two LSRs establish a TCP-based LDP session to exchange FEC-label mappings.

LDP peer

Two LSRs that use L DP to exchange FEC-label mappings are LSR peers.

Label spaces and LDP identifiers

Label spaces include the following types:

• Per-interface label space—Each interface uses a single, independent label space. Different interfaces can use the same label values.

• Per-platform label space—Each LSR uses a single label space. The device only supports the per-platform label space.

A six-byte LDP Identifier (LDP ID) identifies a label space on an LSR. It is in the format of <LSR ID>:<label space number>, where:

• The LSR ID takes four bytes to identity the LSR.

• The label space number takes two bytes to identify a label space within the LSR.

A label space number of 0 indicates that the label spa ce is a per-platform label sp ace. A label space number other than 0 indicates a per-interface label space.

LDP uses the same LDP ID format on IPv4 and IPv6 networks. An LDP ID must be globally unique.

FECs and FEC-label mappings

MPLS groups packets with the same characteristics (such as the same destination or service class) into a class, called an FEC. The packets of the same FEC are handled in the same way on an MPLS network.

LDP can classify FECs by destination IP address and by PW. This document describes FEC classification by destination IP address. For information about FEC classification by PW, see "Configuring MPLS L2VPN" and "Configuring VPLS."

An LSR assig its peers in a Label Mapping message.

ns a label for an FEC and advertises the FEC-label mapping, or FEC-label binding, to

LDP messages

LDP mainly uses the following types of messages:

• Discovery messages—Declare and maintain the presence of LS Rs, such as Hello me ssages.

• Session messages—Establish, maintain, and terminate sessions between LDP peers, such

as Initialization messages used for parameter negotiation and Keepalive messages used to maintain sessions.

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• Advertisement messages—Create, alter , and remove FEC-label mappings, such as Label Mapping messages used to advertise FEC-label mappings.

• Notification messages—Provide advisory information and notify errors, such as Notification messages.

LDP uses UDP to transport discovery messages for efficiency, and uses TCP to transport session, advertisement, and notification messages for reliability.

LDP operation

LDP can operate on an IPv4 or IPv6 network, or a network where IPv4 coexists with IPv6. LDP operates similarly on IPv4 and IPv6 networks.

LDP operates in the following phases:

Discovering and maintaining LDP peers

LDP discovers peers in the following ways:

• Basic Discovery—Discovers directly connected LSRs.

{ On an IPv4 network, an LSR sends IPv4 Link Hello messages to multicast address

224.0.0.2. All directly connected LSRs can discover the LSR and establish an IPv4 Link Hello adjacency.

{ On an IPv6 network, an LSR sends IPv6 Link Hello messages to FF02:0:0:0:0:0:0:2. All

directly connected LSRs can discover the LSR and establish an IPv6 Link Hello adjacency.

{ On a network where IPv4 and IPv6 coexist, an LSR sends both IPv4 and IPv6 Link Hello

messages to each directly connected LSR and keeps both the IPv4 and IPv6 Link Hello adjacencies with a neighbor.

• Extended Discovery—Sends LDP IPv4 Targeted Hello messages to an IPv4 address or LDP IPv6 Targeted Hello messages to an IPv6 address. The destination LSR can discover the LSR and establish a hello adjacency. This mechanism is typically used i n LDP session protection, LDP over MPLS TE, MPLS L2VPN, and VPLS. For more information about MPLS L2VPN and VPLS, see "Configuring MPLS L2VPN," and "Configuring VPLS."

can establish two hello adjacencies with a directly connected neighbor through both discovery

LDP mechanisms. It sends Hello messages at the hello interval to maintain a hello adjacency. If LDP receives no Hello message from a hello adjacency before the hello hold timer expires, it removes the hello adjacency.

Establishing and maintaining LDP sessions

LDP establishes a session to a peer in the following steps:

1. Establishes a TCP connection with the neighbor. On a network where IPv4 and IPv6 coexist, LDP establishes an IPv6 TCP connection. If LDP

fails to establish the IPv6 TCP connection, LDP tries to establish an IPv4 TCP connection.

2. Negotiates session parameters such as LDP version, label distribution method, and Keepalive timer, and establishes an LDP session to the neighbor if the negotiation succeeds.

After a session is established, LDP sends LDP PDUs (an LDP PDU carries one or more LDP messages) to maintain the session. If no information is exchanged between the LDP peers within th e Keepalive interval, LDP sends Keepalive messages at the Keepali ve interval to maintain the session. If LDP receives no LDP PDU from a neighbor before the keep alive hold timer expires, or the last hello adjacency with the neighbor is removed, LDP terminates the session.

LDP can also send a Shutdown message to a neighbor to terminate the LDP session. An LSR can establish only one LDP session to a neighbor. The session can be used to exchange

IPv4 and IPv6 FEC-label mappings at the same time.

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Establishing LSPs

LDP classifies FECs according to destination IP addresses in IP routing entries, creates FEC-label mappings, and advertises the mappings to LDP peers through LDP sessions. After an LDP peer receives an FEC-label mapping, it uses the received label and the label locally assigne d to that FEC to create an LFIB entry for that FEC. When all LSRs (from the Ingress to the Egress) establish an LFIB entry for the FEC, an LSP is established exclusively for the FEC.

Figure 9 Dynamically establishing an LSP

Label distribution and control

Label advertisement modes

Figure 10 Label advertisement modes

LDP advertises label-FEC mappings in one of the following way s:

• Downstream Unsolicited (DU) mode—Distributes FEC-label mappings to the upstre am LSR, without waiting for label requests. The device supports only the DU mode.

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• Downstream on Demand (DoD) mode—Sends a label request for an FEC to the downstream LSR. After receiving the label reque st, the downstre am LSR distrib utes the FEC-label mapping for that FEC to the upstream LSR.

NOTE:

pair of upstream and downstream LSRs must use the same label advertisement mode. Otherwise,

the LSP cannot be established.

Label distribution control

LDP controls label distribution in one of the following ways:

• Independent label distribution—Distributes an FEC-label mapping to an upstream LSR at any time. An LSR might distribute a mapping for an FEC to its upstream LSR before it receives a label mapping for that FEC from its downstream LSR. As shown in Figure 11, in DU mode, each LSR di label-switch the FEC. The LSRs do not need to wait for a label mapping for the FEC from its downstream LSR. In DoD mode, an LSR distributes a label mapping for an FEC to its upstream LSR after it receives a label request for the FEC. The LSR does not need to wait for a label mapping for the FEC from its downstream LSR.

Figure 11 Independent label distribution control mode

stributes a label mapping for an FEC to its upstream LSR whenever it is ready to

• Ordered label distribution—Distributes a label mapping for an FEC to its upstream LSR only after it receives a label mapping for that FEC from its downstream LSR unless the local node is the egress node of the FEC. As shown in Figure 10, in DU mo

de, an LSR distributes a label mapping for an FEC to its upstream LSR only if it receiv es a label mappin g for the FEC from its downstream LSR. In DoD mode, when an LSR (Transit) receives a label request for an FEC from its upstream LSR (Ingress), it continues to send a label request for the FEC to its downstream LSR (Egress). After the transit LSR receives a label m apping for the FEC from the egress LSR, it distributes a label mapping for the FEC to the ingress LSR.

Label retention mode

The label retention mode specifies whether an LSR maintains a label mapping for an FEC learned from a neighbor that is not its next hop.

• Liberal label retention—Retains a received label mapping for an FEC regardless of whether the advertising LSR is the next hop of the FEC. This mechanism allows for quicke r adaptation to topology changes, but it wastes system resources because LDP has to keep us eless labels. The device only supports liberal label retention.

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• Conservative label retention—Retains a received label mapping for an FEC only when the

LDP GR

LDP Graceful Restart (GR) preserves label forwarding information when the signaling protocol or control plane fails, so that LSRs can still forward packets according to forwarding entries.

Figure 12 LDP GR

advertising LSR is the next hop of the FEC. This mechanism saves label resour ces, but it cannot quickly adapt to topology changes.

As shown in Figure 12, GR defines the following roles:

• GR restarter—An LSR that performs GR. It must be GR-capable.

• GR helper—A neighbor LSR that helps the GR restarter to co mplete GR.

The device can act as a GR restarter or a GR helper.

Figure 13 LDP GR operation

GR restarter

Protocol

restarts

MPLS

forwarding state

holding time

Set up an LDP session, and identify that

they are LDP GR capable

Re-establish the LDP session

Send label mappings

GR helper

Reconnect time

LDP recovery time

As shown in Figure 13, LDP GR operates as follows:

1. LSRs establish an LDP session. The L flag of the Fault Tolerance TLV in their Initialization messages is set to 1 to indicate that they support LDP GR.

2. When LDP restarts, the GR restarter starts the MPLS Forwarding State Holding timer, and marks the MPLS forwarding entries as stale. When the GR helper de tects that the LDP session to the GR restarter goes down, it performs the following operations:

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a. Marks the FEC-label mappings learned from the session as stale. b. Starts the Reconnect timer received from the GR restarter.

3. After LDP completes restart, the GR restarter re-establishes an LDP se ssi on to t he GR h elpe r.

{ If the LDP session is not set up before the Reconnect timer expires, the GR helper deletes

the stale FEC-label mappings and the corresponding MPLS forwarding entri es.

{ If the LDP session is successfully set up before the Reconnect timer expires, the GR

restarter sends the remaining time of the MPLS Forwarding State Holding timer to the GR helper.

The remaining time is sent as the LDP Recovery time.

4. After the LDP session is re-established, the GR helper starts the LDP Recovery timer.

5. The GR restarter and the GR helper exchange label mappings and update their MPLS

forwarding tables. The GR restarter compares each received label mapping against stale MPLS forwarding

entries. If a match is found, the restarter deletes the stale mark for the matching entry. Otherwise, it adds a new entry for the label mapping.

The GR helper compares each received label mapping against stale FEC-label mappings. If a match is found, the helper deletes the stale mark for the mat chin g mappin g. Otherwi se, it add s the received FEC-label mapping and a new MPLS forwarding entry for the mapping.

6. When the MPLS Forwarding State Holding timer expires, the GR restarter deletes all stale MPLS forwarding entries.

7. When the LDP Recovery timer expires, the GR helper deletes all stale FEC-label mappings.

LDP NSR

LDP nonstop routing (NSR) backs up protocol states and data (including LDP session and LSP information) from the active process to the standby process. When the LDP primary process fails , the backup process seamlessly takes over primary processi ng. The LDP peers a re not notified of the LDP interruption. The LDP peers keep the LDP session in Operational state, and the forwarding is not interrupted.

The LDP primary process fails when one of the following situations occurs:

• The primary process restarts.

• The MPU where the primary process resides fails.

• The MPU where the primary process resides performs an ISSU.

• The LDP process' position determined by the process placement function is different from the

position where the LDP process is operating.

Choose LDP NSR or LDP GR to ensure continuous traffic forwarding.

• Device requirements

{ To use LDP NSR, the device must have two or more MPUs, and the primary and backup

{ To use LDP GR, the device can have only one MPU on the device.

• LDP peer requirements

{ With LDP NSR, LDP pee rs of the local device are not notified of any switchover event on the

{ With LDP GR, the LDP peer must be able to identify the GR capability flag (in the

processes for LDP reside on different MPUs.

local device. The local device does not require help from a peer to restore the MPLS forwarding information.

Initialization message) of the GR restarter. The LDP peer acts as a GR helper to help the GR restarter to restore MPLS forwarding information.

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LDP-IGP synchronization

Basic operating mechanism

LDP establishes LSPs based on the IGP optimal route. If LDP is not synchronized with IGP, MPLS traffic forwarding might be interrupted.

LDP is not synchronized with IGP when one of the following situations occurs:

• A link is up, and IGP advertises and uses this link. However, LDP LSPs on this link have not been established.

• An LDP session on a link is down, and LDP LSPs on the link have be en removed. However , IGP still uses this link.

• The Ordered label distribution control mode is used. IGP use d the link before the local device received the label mappings from the downstream LSR to establish LDP LSPs.

After LDP-IGP synchronization is enabled, IGP advertises the actual cost of a link only when LDP convergence on the link is completed. Before LDP convergence is completed, IGP advertises the maximum cost of the link. In this way, the link is visible on the IGP topology, but IGP does not select this link as the optimal route when other links are available. Therefore, the device can avoid discarding MPLS packets when there is not an LDP LSP established on the optimal route.

LDP convergence on a link is completed when both the following situations occur:

• The local device establishes an LDP session to at least one peer, and the LDP session is already in Operational state.

• The local device has distributed the label mappings to at least one peer.

Notification delay for LDP convergence completion

By default, LDP immediately sends a notification to IGP that LDP convergence has completed. However, immediate notifications might cause MPLS traffic forwarding interruptions in one of the following scenarios:

• LDP peers use the Ordered label distribution control mode. The de vice has not received a label mapping from downstream at the time LDP notifies IGP that LDP convergence has completed.

• A large numb er of label ma ppings a re distributed from downstream. Label a dvertisement is not completed when LDP notifies IGP that LDP convergence has completed.

To avoid traffic forwarding interruptions in these scenarios, configure the notification delay. When LDP convergence on a link is completed, LDP waits before notifying IGP.

Notification delay for LDP restart or active/standby switchover

When an LDP restart or an active/standby switchover occurs, LDP takes time to converge, and LDP notifies IGP of the LDP-IGP synchronization status a s follows:

• If a notification delay is not configured, LDP immediately notifies IGP of the current synchronization states during convergence, and then updates the states after LDP convergence. This could impact IGP processing.

• If a notification delay is configured, LDP notifies IGP of the LDP-IGP synchronization states in bulk when one of the following events occurs:

{ LDP recovers to the state before the restart or switchover. { The maximum delay timer expires.

LDP FRR

A link or router failure on a path can cau se packet loss until LDP establishes a new LSP on the new path. LDP FRR enables fast rerouting to minimize the failover time. LDP FRR is based on IP FRR and is enabled automatically after IP FRR is enabled.

Page 34

You can use one of the following methods to enable IP FRR:

• Configure an IGP to automatically calculate a backup next hop.

• Configure an IGP to specify a backup next hop by using a routing policy.

Figure 14 Network diagram for LDP FRR

As shown in Figure 14, configure IP FRR on LSR A. The IGP automatically calculates a backup next hop or it specifies a backup next hop through a routing policy. LDP creates a primary LSP and a backup LSP according to the primary route and the backup route calculated by IGP. When the primary LSP operates correctly, it forwards the MPLS packets. When the primary LSP fails, LDP directs packets to the backup LSP.

When packets are forwarded through the backup LSP, IGP calculates the optimal path based on the new network topology. When IGP route convergence occurs, LDP establishe s a new LSP according to the optimal path. If a new LSP is not established after IGP route convergence, traffic forwarding might be interrupted. As a best practice, enable LDP-IGP synchronization to work with LDP FRR to reduce traffic interruption.

LDP over MPLS TE

Figure 15 LDP over MPLS TE

As shown in Figure 15, in a layered network, MPLS TE is deployed in the core layer, and the distribution layer uses LDP as the label distribution protocol. To set up an LDP LSP across the core layer, you can establi sh the LDP LSP over the existing MPLS TE tunnel to simplify configuration. You only need to enable LDP on the tunnel interfaces of the ingress and egress nodes for the MPLS TE tunnel. An LDP session will be established between the tunnel ingress and egress. Label Mapping messages are advertised through the session and an LDP LSP is established. The LDP LSP is

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carried on the MPLS TE LSP, creating a hierarchical LSP. For more information about MPLS TE tunnels, see "Configuring MPLS TE."

Protocols

• RFC 5036, LDP Specification

• draft-ietf-mpls-ldp-ipv6-09.txt

Compatibility information

Commands and descriptions for centralized devices apply to the followin g routers:

• MSR1002-4/1003-8S.

• MSR2003.

• MSR2004-24/2004-48.

• MSR3012/3024/3044/3064.

Commands and descriptions for distributed devices apply to MSR4060 and MSR4080 routers.

LDP configuration task list

Tasks at a glance

Enable LDP:

1. (Required.) Enabling LDP globally

2. (Req

(Optional.) Configuring Hello parameters (Optional.) Configuring LDP session parameters (Optional.) Configuring LDP backoff (Optional.) Configuring LDP MD5 authentication (Optional.) Configuring LDP to redistribute BGP unicast routes (Optional.) Configuring an LSP generation policy (Optional.) Configuring the LDP label distribution control mode (Optional.) Configuring a label advertisement policy (Optional.) Configuring a label acceptance policy (Optional.) Configuring LDP loop detection (Optional.) Configuring LDP session protection (Optional.) Configuring LDP GR (Optional.) Configuring LDP NSR

uired.) Enabling LDP on an interface

(Optional.) Configuring LDP-IGP synchronization (Optional.) Configuring LDP FRR (Optional.) Setting a DSCP value for outgoing LDP packets (Optional.) Resetting LDP sessions (Optional.) Enabling SNMP notifications for LDP

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Enabling LDP

To enable LDP, you must first enable LDP globally. Then, enable LDP on relevant interfaces or configure IGP to automatically enable LDP on those interfaces.

Enabling LDP globally

Step Command Remarks

1. Enter system view.

2. Enable LDP for the local

node or for a VPN.

system-view

• Enable LDP for the local node and enter LDP view:

mpls ldp

• Enable LDP for a VPN and enter LDP-VPN instance view:

a. mpls ldp b. vpn-instance

vpn-instance-name

N/A

By default, LDP is disabled.

3. Configure an LDP LSR ID.

lsr-id

Enabling LDP on an interface

Step Command Remarks

1. Enter system view.

2. Enter interface view.

3. Enable IPv4 LDP on the

interface.

4. Enable IPv6 LDP on the interface.

system-view

interface

interface-number

mpls ldp enable

mpls ldp ipv6 enable

interface-type

Configuring Hello parameters

Perform this task to set the following hello timers:

• Link Hello hold time and Link Hello interval. If an interface is enabled with both IPv4 LDP and IPv6 LDP, the parameters configured on the

interface can be used for both IPv4 and IPv6 Link Hello messages.

• Targeted Hello hold time and Targeted Hello interval for a peer.

By default, the LDP LSR ID is the same as the MPLS LSR ID.

N/A If the interface is bound to a VPN

instance, you must enable LDP for the VPN instance by using

vpn-instance

the LDP view.

By default, IPv4 LDP is disabled on an interface.

By default, IPv6 LDP is disabled on an interface.

command in

Setting Link Hello timers

Step Command Remarks

1. Enter system view.

system-view

N/A

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Step Command Remarks

2. Enter the view of the

interface where you want to establish an LDP session.

interface

interface-number

interface-type

N/A

3. Set the Link Hello hold time.

4. Set the Link Hello interval.

mpls ldp timer hello-hold

timeout

mpls ldp timer hello-interval

interval

Setting Targeted Hello timers for an LDP peer

Step Command Remarks

1. Enter system view.

2. Enter LDP view.

3. Specify an LDP peer and enter

LDP peer view. The device will send unsolicited Targeted Hellos to the peer and can respond to the Targeted Hellos sent from the peer.

4. Set the Targeted Hell o hold time.

5. Set the Target Hello interval.

system-view mpls ldp

targeted-peer

ipv6-address }

mpls ldp timer hello-hold

timeout

mpls ldp timer hello-interval

interval

{ ip-address |

By default, the Link Hello hold time is 15 seconds.

By default, the Link Hello interval is 5 seconds.

N/A N/A

By default, the device does not send Targeted Hellos to or receive Targeted Hellos from any peer.

By default, the Targeted Hello hold time is 45 seconds.

By default, the Targeted Hello interval is 15 seconds.

Configuring LDP session parameters

This task configures the following LDP session parameters:

• Keepalive hold time and Keepalive interval.

• LDP transport address—IP address for establishing TCP connections.

LDP uses Basic Discovery and Extended Discovery mechanisms to discovery LDP peers and establish LDP sessions with them.

When you configure LDP session parameters, follow these guid elines:

• The configured LDP transport address m ust be the IP address of an up interface on the device . Otherwise, no LDP session can be established.

• Make sure the LDP transport addresses of the local and peer LSRs can reach each other . Otherwise, no TCP connection can be establish ed.

Configuring LDP sessions parameters for Basic Discovery mechanism

Step Command Remarks

1. Enter system view.

2. Enter interface view.

3. Set the Keepalive hold time.

system-view interface

interface-number

mpls ldp timer keepalive-hold

timeout

interface-type

N/A

By default, the Keepalive hold time is 45 seconds.

4. Set the Keepalive interval.

mpls ldp timer keepalive-interval

interval

By default, the Keepalive interval is 15 seconds.

Page 38

Step Command Remarks

By default, the LDP transport address is the LSR ID of the local device if the interface where you want to establish an LDP session belongs to the public network. If the interface belongs to a VPN, the LDP transport address is the primary IP address of the interface.

If the interface where you want to establish an LDP session is bound to a VPN instance, the interface with the IP address specified with this command must be bound to the same VPN instance.

5. Configure the LDP transport address.

mpls ldp transport-address

{ ip-address | ipv6-address |

interface

}

Configuring LDP IPv4 sessions parameters for Extended Discovery mechanism

Step Command Remarks

1. Enter system view.

system-view

N/A

2. Enter LDP view.

3. Specify an LDP peer and enter

LDP peer view. The device will send unsolicited Targeted Hellos to the peer and can respond to Targeted Hellos sent from the targeted peer.

4. Set the Keepalive hold time.

5. Set the Keepalive interval.

6. Configure the LDP transport

address.

mpls ldp

targeted-peer

mpls ldp timer keepalive-hold

timeout

mpls ldp timer keepalive-interval

mpls ldp transport-address

ip-address

interval

N/A

By default, the device does not send Targeted Hellos to or receive Targeted Hellos from any peer.

By default, the Keepalive hold time is 45 seconds.

By default, the Keepalive interval is 15 seconds.

By default, the LDP transport address is the LSR ID of the local device.

Configuring LDP IPv6 sessions parameters for Extended Discovery mechanism

Step Command Remarks

1. Enter system view.

2. Enter LDP view.

3. Specify an LDP peer and enter

LDP peer view. The device will send unsolicited Targeted Hellos to the peer and can respond to Targeted Hellos sent from the targeted peer.

system-view mpls ldp

targeted-peer

ipv6-address

N/A N/A

By default, the device does not send Targeted Hellos to or receive Targeted Hellos from any peer.

4. Set the Keepalive hold time.

5. Set the Keepalive interval.

6. Configure the LDP transport

mpls ldp timer keepalive-hold

timeout

mpls ldp timer keepalive-interval

mpls ldp transport-address

interval

By default, the LDP IPv6

By default, the Keepalive hold time is 45 seconds.

By default, the Keepalive interval is 15 seconds.

Page 39

Step Command Remarks

address.

ipv6-address

Configuring LDP backoff

If LDP session parameters (for example, the label advertisement mode) are incompatible, two LDP peers cannot establish a session, and they will keep negotiating with each other.

The LDP backoff mechanism can mitigat e this problem by using an initial delay timer and a ma ximum delay timer. After failing to establish a session to a peer LSR fo r the first time, LDP does not start an attempt until the initial delay timer expires. If the session setup fails again, LDP waits for two times the initial delay before the next attempt, and so forth until the maximum delay time is reached. After that, the maximum delay time will always take effect.

To configure LDP backoff:

Step Command Remarks

1. Enter system view.

2. Enter LDP view or enter

LDP-VPN instance view.

system-view

• Enter LDP view:

mpls ldp

• Enter LDP-VPN instance view:

a. mpls ldp b. vpn-instance

vpn-instance-name

transport address is not

configured.

N/A

3. Set the initial delay time and maximum delay time.

backoff initial maximum

maximum-time

initial-time

By default, the initial delay time is 15 seconds, and the maximum delay time is 120 seconds.

Configuring LDP MD5 authentication

To improve security for LDP sessions, you can configure MD5 authentication for the underlying TCP connections to check the integrity of LDP messages.

For two LDP peers to establish an LDP sessi on successfully , make sure the LDP MD5 authentication configurations on the LDP peers are consistent.

To configure LDP MD5 authentication:

Step Command Remarks

1. Enter system view.

2. Enter LDP view or enter

LDP-VPN instance view.

3. Enable LDP MD5 authentication.

system-view

• Enter LDP view:

mpls ldp

• Enter LDP-VPN instance view:

a. mpls ldp b. vpn-instance

vpn-instance-name

md5-authentication plain

} password

peer-lsr-id {

cipher

N/A

By default, LDP MD5 authentication is disabled.

Page 40

Configuring LDP to redistribute BGP unicast routes

By default, LDP automatically redistributes IGP routes, including the BGP routes that have been redistributed into IGP. Then, LDP assigns labels to the IGP routes and labeled BGP routes, if these routes are permitted by an LSP generation policy. LDP does not automatically redistribute BGP unicast routes if the routes are not redistributed into the IGP.

For example, on a carrier's carrier network where IGP is not configured between a PE of a Level 1 carrier and a CE of a Level 2 carrier, LDP cannot redistribute BGP unicast routes to assign labels to them. For this network to operate correctly , you can enable LDP to redistribute BGP unicast routes. If the routes are permitted by an LSP generation policy, LDP assigns labels to them to establish LSPs. For more information about carrier's carrier, see "Configuring MPLS L3VPN".

o configure LDP to redistribute BGP unicast routes:

Step Command Remarks

1. Enter system view.

2. Enter LDP view or enter

LDP-VPN instance view.

system-view

• Enter LDP view:

mpls ldp

• Enter LDP-VPN instance view:

a. mpls ldp b. vpn-instance

vpn-instance-name

N/A

3. Enable LDP to redistribute BGP IPv4 unicast routes.

4. Enable LDP to redistribute BGP IPv6 unicast routes.

import bgp

ipv6 import bgp

By default, LDP does not redistribute BGP IPv4 unicast routes.

By default, LDP does not redistribute BGP IPv6 unicast routes.

Configuring an LSP generation policy

LDP assigns labels to the routes that have been redistributed into LDP to generate LSPs. An LSP generation policy specifies which redistributed routes can be used by LDP to generate LSPs to control the number of LSPs, as follows:

• Use all routes to establish LSPs.

• Use the routes permitted by an IP prefix list to establish LSPs. For information about IP prefix

list configuration, see Layer 3—IP Routing Configuration Guid e.

• Use only IPv4 host routes with a 32-bit mask or IPv6 host routes with a 128-bit mask to establish LSPs.

By default, LDP uses only IPv4 host routes with a 32-bit mask or IPv6 host routes with a 128-bit mask to establish LSPs. The other two methods can result in more LSPs than the default policy. To change the policy, make sure the system resources and bandwidth resources are sufficient.

To configure an LSP generation policy:

Step Command Remarks

1. Enter system view.

2. Enter LDP view or enter

system-view

• Enter LDP view:

N/A N/A

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Step Command Remarks

LDP-VPN instance view.

mpls ldp

• Enter LDP-VPN instance view:

a. mpls ldp b. vpn-instance

vpn-instance-name

3. Configure an IPv4 LSP

generation policy.

4. Configure an IPv6 LSP generation policy.

lsp-trigger

prefix-list-name }

ipv6 lsp-trigger

prefix-list-name }

{

all

prefix-list

all

{

prefix-list

By default, LDP uses only the redistributed IPv4 routes with a 32-bit mask to establish LSPs.

By default, LDP uses only the redistributed IPv6 routes with a 128-bit mask to establish LSPs.

Configuring the LDP label distribution control mode

Step Command Remarks

1. Enter system view.

2. Enter LDP view or enter

LDP-VPN instance view.

3. Configure the label distribution control mode.

system-view

• Enter LDP view:

mpls ldp

• Enter LDP-VPN instance view:

a. mpls ldp b. vpn-instance

vpn-instance-name

label-distribution ordered }

independent

{

N/A

By default, the Ordered label distribution mode is used.

Configuring a label advertisement policy

A label advertisement policy uses IP prefix lists to control the FEC-label mappings advertised to peers.

As shown in Figure 16, LSR A B. It advertises label mappings for FECs permitted by IP prefix list C to LSR C.

advertises label mappings for FECs permitted by IP prefix list B to LSR

Page 42

Figure 16 Label advertisement control diagram

A label advertisement policy on an LSR and a label acceptance policy on its upstream LSR can achieve the same purpose. As a best practice, use label advertisement policies to reduce network load if downstream LSRs support label advertisement control.

Before you configure an LDP label advertisement policy, create an IP prefix list. For information about IP prefix list configuration, see Layer 3—IP Routing Configuration Guide.

To configure a label advertisement policy:

Step Command Remarks

1. Enter system view.

2. Enter LDP view or enter

LDP-VPN instance view.

3. Configure an IPv4 label advertisement policy.

4. Configure an IPv6 label advertisement policy.

system-view

• Enter LDP view:

mpls ldp

• Enter LDP-VPN instance view:

a. mpls ldp b. vpn-instance

vpn-instance-name

advertise-label prefix-list

prefix-list-name [ peer-prefix-list-name ]

ipv6 advertise-label prefix-list

prefix-list-name [ peer-prefix-list-name ]

peer

N/A

By default, LDP advertises all IPv4 FEC-label mappings permitted by the LSP generation policy to all peers.

By default, LDP advertises all IPv6 FEC-label mappings permitted by the LSP generation policy to all peers.

Configuring a label acceptance policy

A label accept ance policy uses an IP prefix list to control the label mappings received from a peer. As shown in Figure 17, LSR A

uses an IP prefix list to filter label mappings from LSR B, and it does

not filter label mappings from LSR C.

Page 43

Figure 17 Label acceptance control diagram

A label advertisement policy on an LSR and a label acceptance policy on its upstream LSR can achieve the same purpose. As a be st practice, use the label advertisement poli cy to reduce network load.

You must create an IP prefix list before you configure a label acceptance policy. For information about IP prefix list configuration, see Layer 3—IP Routing Configuration Guide.

To configure a label acceptance policy:

Step Command Remarks

1. Enter system view.

2. Enter LDP view or enter

LDP-VPN instance view.

3. Configure an IPv4 label acceptance policy.

4. Configure an IPv6 label acceptance policy.

system-view

• Enter LDP view:

mpls ldp

• Enter LDP-VPN instance view:

a. mpls ldp b. vpn-instance

vpn-instance-name

accept-label peer

prefix-list-name

ipv6 accept-label peer prefix-list

prefix-list-name

peer-lsr-id

prefix-list

peer-lsr-id

Configuring LDP loop detection

LDP detects and terminates LSP loops in the followin g ways:

• Maximum hop count—LDP adds a hop count in a label request or label mapping message. The hop count value increments by 1 on each LSR. When the maximum hop count is reached, LDP considers that a loop has occurred and terminate s the esta blishment of the LSP.

• Path vector—LDP adds L SR ID information in a label request or label mapping message. Each LSR checks whether its LSR ID is contained in the message. If it is not, the LSR adds its own LSR ID into the message. If it is, the LSR considers that a loop has occurred and terminates LSP establishment. In addition, when the number of LSR IDs in the messag e rea che s the path vector limit, LDP also considers that a loop has occurred and terminates LSP establishment.

N/A

By default, LDP accepts all IPv4 FEC-label mappings.

By default, LDP accepts all IPv6 FEC-label mappings.

To configure LDP loop detection:

Page 44

Step Command Remarks

1. Enter system view.

2. Enter LDP view or enter

LDP-VPN instance view.

3. Enable loop detection.

4. Set the maximum hop

count.

system-view

• Enter LDP view:

mpls ldp

• Enter LDP-VPN instance view:

a. mpls ldp b. vpn-instance

vpn-instance-name

loop-detect

maxhops

hop-number

N/A

By default, loop detection is disabled.

After loop detection is enabled, the device uses both the maximum hop count and the path vector methods to detect loops.

By default, the maximum hop count is 32.

5. Set the path vector limit.

NOTE:

pv-limit

pv-number

The LDP loop detection feature is applicable only in networks comprised of devices that do not support TTL mechanism, such as ATM switches. Do not use LDP loop detection on other networks because it only results in extra LDP overhead.

Configuring LDP session protection

If two LDP peers have both a direct link and an indirect link in between, you can configure this feature to protect their LDP session when the direct link fails.

LDP establishes both a Link Hello adjacency over the direct link and a Targeted Hello adjacency over the indirect link with the peer. When the direct link fails, LDP deletes the Link Hello adjacency but still maintains the Targeted Hello adjacency. In this way, the LDP session between the two peers is kept available, and the FEC-label mappings based on this session are not deleted. When the direct link recovers, the LDP peers do not need to re-establish the LDP session or re-learn the FEC-label mappings.

When you enable the session protection function, you can also specify the session protection duration. If the Link Hello adjacency does not recover within the duration, LDP deletes the Targeted Hello adjacency and the LDP session. If you do not specify the session protection duration, the two peers will always maintain the LDP session over the Targeted Hello adjacency.

By default, the path vector limit is 32.

LDP session protection is applicable only to IPv4 networks. To configure LDP session protection:

Step Command Remarks

1. Enter system view.

2. Enter LDP view.

3. Enable the session

protection function.

system-view mpls ldp session protection

peer

time ] [

peer-prefix-list-name ]

duration

[

N/A N/A By default, session protection is

disabled.

Page 45

Configuring LDP GR

Before you configure LDP GR, enable LDP on the GR restarte r and GR helpers. To configure LDP GR:

Step Command Remarks

1. Enter system view.

2. Enter LDP view.

3. Enable LDP GR.

4. Set the Reconnect timer

for LDP GR.

5. Set the MPLS Forwarding State Holding timer for LDP GR.

system-view mpls ldp graceful-restart graceful-restart timer reconnect

reconnect-time

graceful-restart timer forwarding-hold

Configuring LDP NSR

N/A

By default, LDP GR is disabled. By default, the Reconnect time is

hold-time

120 seconds. By default, the MPLS Forwarding

State Holding time is 180 seconds.

The following matrix shows the feature and hardware compatibility:

Hardware LDP NSR compatibility

MSR954(JH296A/JH297A/JH298A/JH299A) Yes

MSR1002-4/1003-8S

MSR2003

MSR2004-24/2004-48

MSR3012/3024/3044/3064

MSR4060/4080 Yes

To configure LDP NSR:

• In standalone mode: No

• In IRF mode: Yes

• In standalone mode: No

• In IRF mode: Yes

• In standalone mode: No

• In IRF mode: Yes

• In standalone mode: No

• In IRF mode: Yes

Step Command Remarks

1. Enter system view.

2. Enter LDP view.

3. Enable LDP NSR.

system-view mpls ldp non-stop-routing

N/A

By default, LDP NSR is disabled.

Configuring LDP-IGP synchronization

After you enable LDP-IGP synchronization for an OSPF process, OSPF area, or an IS-IS process, LDP-IGP synchronization is enabled on the OSPF process inte rfaces or the IS-IS process interfaces.

You can execute the mpls ldp igp sync disable command to disable LDP-IGP synchronization on interfaces where LDP-IGP synchronization is not required.

Page 46

LDP-IGP synchronization protection is only applicable to an IPv4 network.

Configuring LDP-OSPF synchronization

LDP-IGP synchronization is not supported for an OSPF process and its OSPF areas if the OSPF process belongs to a VPN instance.

To configure LDP-OSPF synchronization for an OSPF process:

Step Command Remarks

1. Enter system view.

system-view

N/A

ospf [

2. Enter OSPF view.

3. Enable LDP-OSPF

synchronization.

4. Return to system view.

5. Enter interface view.

6. (Optional.) Disable LDP-IGP

synchronization on the interface.

7. Return to system view.

8. Enter LDP view.

9. (Optional.) Set the delay for

LDP to notify IGP of the LDP convergence.

10. (Optional.) Set the maximum delay for LDP to notify IGP of the LDP-IGP synchronization status after an LDP restart or active/standby switchover.

To configure LDP-OSPF synchronization for an OSPF area:

process-id |

router-id ] *

mpls ldp sync

quit interface

interface-number

mpls ldp igp sync disable

quit mpls ldp

igp sync delay

igp sync delay on-restart

interface-type

router-id

time

N/A

By default, LDP-OSPF synchronization is disabled.

N/A

By default, LDP-IGP synchronization is not disabled on an interface.

N/A N/A By default, LDP immediately

notifies IGP of the LDP convergence completion.

By default, the maximum notification delay is 90 seconds.

Step Command Remarks

1. Enter system view.

2. Enter OSPF view.

3. Enter area view.

4. Enable LDP-OSPF

synchronization.

5. Return to system view.

6. Enter interface view.

7. (Optional.) Disable LDP-IGP

synchronization on the interface.

8. Return to system view.

9. Enter LDP view.

system-view ospf

[ process-id |

area

area-id

mpls ldp sync

quit interface

interface-number

mpls ldp igp sync disable

quit mpls ldp

interface-type

router-id

router-id ]

N/A

N/A By default, LDP-OSPF

synchronization is disabled. N/A

N/A

By default, LDP-IGP synchronization is not disabled on an interface.

N/A N/A

Page 47

Step Command Remarks

10. (Optional.) Set the delay for

LDP to notify IGP of the LDP convergence.

11. (Optional.) Set the maximum delay for LDP to notify IGP of the LDP-IGP synchronization status after an LDP restart or active/standby switchover.

igp sync delay

igp sync delay on-restart

time

Configuring LDP-ISIS synchronization

LDP-IGP synchronization is not supported for an IS-IS process that belongs to a VPN instance. To configure LDP-ISIS synchronization for an IS-IS process:

Step Command Remarks

1. Enter system view.

2. Enter IS-IS view.

3. Enable LDP-ISIS

synchronization.

4. Return to system view.

system-view isis

[ process-id ]

mpls ldp sync

quit

level-1

[

level-2 ]

time

By default, LDP immediately notifies IGP of the LDP convergence completion.

By default, the maximum notification delay is 90 seconds.

N/A N/A By default, LDP-ISIS

synchronization is disabled. N/A

5. Enter interface view.

6. (Optional.) Disable LDP-IGP

synchronization on the interface.

7. Return to system view.

8. Enter LDP view.

9. (Optional.) Set the delay for

LDP to notify IGP of the LDP convergence completion.

10. (Optional.) Set the maximum delay for LDP to notify IGP of the LDP-IGP synchronization status after an LDP restart or an active/standby switchover occurs.

interface

interface-number

mpls ldp igp sync disable

quit mpls ldp

igp sync delay

igp sync delay on-restart

Configuring LDP FRR

LDP FRR is based on IP FRR, and is enabled auto matically after IP FRR is enabled. For information about configuring IP FRR, see Layer 3—IP Routing Configuration Guide.

interface-type

time

N/A

By default, LDP-IGP synchronization is not disabled on an interface.

N/A N/A By default, LDP immediately

notifies IGP of the LDP convergence completion.

By default, the maximum notification delay is 90 seconds.

Setting a DSCP value for outgoing LDP packets

To control the transmission preference of outgoing LDP packets, specify a DSCP value for outgoing LDP packets.

Page 48

To set a DSCP value for outgoing LDP packets:

Step Command Remarks

1. Enter system view.

2. Enter LDP view.

3. Set a DSCP value for outgoing

LDP packets.

system-view mpls ldp

dscp

dscp-value

Resetting LDP sessions

Changes to LDP session parameters take ef fect only on new LDP sessi ons. To apply the changes to an existing LDP session, you must reset all LDP sessions by executing the reset mpls ldp command.

Execute the reset mpls ldp command in user view.

Task Command Remarks

Reset LDP sessions.

reset mpls ldp [ vpn-instance

vpn-instance-name ] [

peer

peer-id ]

N/A N/A By default, the DSCP value for

outgoing LDP packets is 48.

If you specify the command resets the LDP session to the specified peer without validating the session parameter changes.

peer

keyword, this

Enabling SNMP notifications for LDP

This feature enables generating SNMP notifications for LDP upo n LDP sessi on changes, as defined in RFC 3815. The generated SNMP notifications are sent to the SNMP module.

To enable SNMP notifications for LDP:

Step Command Remarks

1. Enter system view.

2. Enable SNMP

notifications for LDP.

system-view

snmp-agent trap enable ldp

N/A By default, SNMP notifications for

LDP are enabled.

For more information about SNMP notifications, see Network Management and Monitoring Configuration Guide.

Displaying and maintaining LDP

Execute display commands in any view .

Task Command

Display LDP discovery information (centralized devices in standalone mode).

display mpls ldp discovery

interface

[ [ [

ipv6

interface-type interface-number |

targeted-peer

] | [

vpn-instance

[

{ ip-address | ipv6-address } ] ] [

vpn-instance-name ]

peer

peer-lsr-id ]

verbose

]

Display LDP discovery information (distributed devices in standalone mode/centralized devices in IRF mode).

display mpls ldp discovery

interface

[ [

ipv6

[

standby slot

[

interface-type interface-number |

targeted-peer

] | [

slot-number ]

vpn-instance

[

{ ip-address | ipv6-address } ] ] [

vpn-instance-name ]

peer

peer-lsr-id ]

verbose

]

Page 49

Task Command

Display LDP discovery information (distributed devices in IRF mode).

display mpls ldp discovery

interface

[ [

ipv6

[

standby chassis

[

interface-type interface-number |

targeted-peer

] | [

chassis-number

vpn-instance

[

{ ip-address | ipv6-address } ] ] [

slot

vpn-instance-name ]

peer

peer-lsr-id ]

slot-number ]

verbose

]

Display LDP FEC-label mapping information (centralized devices in standalone mode).

Display LDP FEC-label mapping information (distributed devices in standalone mode/centralized devices in IRF mode).

Display LDP FEC-label mapping information (distributed devices in IRF mode).

Display LDP-IGP synchronization information.

Display LDP interface information.

Display LDP LSP information.

Display LDP running parameters. Display LDP peer and session

information (centralized devices in standalone mode).

Display LDP peer and session information (distributed devices in standalone mode/centralized devices in IRF mode).

display mpls ldp fec

[ ip-address mask-length | ipv6-address prefix-length | [

summary

[

display mpls ldp fec

[ ip-address mask-length | ipv6-address prefix-length | [

summary

[

display mpls ldp fec

[ ip-address mask-length | ipv6-address prefix-length | [

summary

[ slot-number ]

display mpls ldp igp sync

interface-number ]

display mpls ldp interface

[ interface-type interface-number ] [

display mpls ldp lsp

[ ip-address mask-length | ipv6-address prefix-length |

display mpls ldp parameter [ vpn-instance

display mpls ldp peer

[ peer-lsr-id ] [

display mpls ldp peer

[ peer-lsr-id ] [

] ]

standby slot

] ] [

standby chassis

] ] [

verbose ]

verbose

vpn-instance

[

vpn-instance

[

vpn-instance

[

vpn-instance

[

vpn-instance

[

vpn-instance

[

] [

vpn-instance-name ]

slot-number ]

vpn-instance-name ]

chassis-number

interface

[

vpn-instance

[

ipv6 ]

vpn-instance-name ]

standby slot

slot

interface-type

vpn-instance-name ]

slot-number ]

ipv6

ipv6 ]

]

Display LDP peer and session information (distributed devices in IRF mode).

Display LDP summary information (centralized devices in standalone mode).

Display LDP summary information (distributed devices in standalone mode/centralized devices in IRF mode).

Display LDP summary information (distributed devices in IRF mode).

display mpls ldp peer

[ peer-lsr-id ] [ slot-number ]

display mpls ldp summary

vpn-instance-name ]

display mpls ldp summary

vpn-instance-name ] [

display mpls ldp summary

vpn-instance-name ] [ slot-number ]

verbose

vpn-instance

[

standby chassis

] [

standby slot

standby chassis

IPv4 LDP configuration examples

LDP LSP configuration example

Network requirements

Router A, Router B, and Router C all support MPLS.

all

[

all

[

all

[

vpn-instance-name ]

chassis-number

vpn-instance

slot-number ]

vpn-instance

chassis-number

slot

Page 50

Configure LDP to establish LSPs between Router A and Router C, so subnets 11.1.1.0/24 and

21.1.1.0/24 can reach each other over MPLS. Configure LDP to establish LSPs only for destinations 1.1.1.9/32, 2.2.2.9/32, 3.3.3.9/32, 11.1.1.0/24,

and 21.1.1.0/24 on Router A, Router B, and Router C.

Figure 18 Network diagram

Requirements analysis

• To ensure that the LSRs establish IPv4 LSPs automatically, enable IPv4 LDP on each LSR.

• To establish IPv4 LDP LSPs, configure an IPv4 routing protocol to ensure IP connectivity

between the LSRs. This example uses OSPF.

• To control the number of IPv4 LSPs, configure an IPv4 LSP generation policy on each LSR.

Configuration procedure

1. Configure IP addresses and masks for interfaces, including the loopback interfaces, as shown

in Figure 18. (Detail

2. Configure OSPF on each router to ensure IP connectivity between them: # Configure Router A.

<RouterA> system-view [RouterA] ospf [RouterA-ospf-1] area 0 [RouterA-ospf-1-area-0.0.0.0] network 1.1.1.9 0.0.0.0 [RouterA-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255 [RouterA-ospf-1-area-0.0.0.0] network 11.1.1.0 0.0.0.255 [RouterA-ospf-1-area-0.0.0.0] quit [RouterA-ospf-1] quit

# Configure Router B.

<RouterB> system-view [RouterB] ospf [RouterB-ospf-1] area 0 [RouterB-ospf-1-area-0.0.0.0] network 2.2.2.9 0.0.0.0 [RouterB-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255 [RouterB-ospf-1-area-0.0.0.0] network 20.1.1.0 0.0.0.255 [RouterB-ospf-1-area-0.0.0.0] quit [RouterB-ospf-1] quit

# Configure Router C.

<RouterC> system-view [RouterC] ospf [RouterC-ospf-1] area 0

s not shown.)

Page 51

[RouterC-ospf-1-area-0.0.0.0] network 3.3.3.9 0.0.0.0 [RouterC-ospf-1-area-0.0.0.0] network 20.1.1.0 0.0.0.255 [RouterC-ospf-1-area-0.0.0.0] network 21.1.1.0 0.0.0.255 [RouterC-ospf-1-area-0.0.0.0] quit [RouterC-ospf-1] quit

# Verify that the routers have learned the routes to each other. This example uses Router A.

[RouterA] display ip routing-table

Destinations : 21 Routes : 21

Destination/Mask Proto Pre Cost NextHop Interface

0.0.0.0/32 Direct 0 0 127.0.0.1 InLoop0

1.1.1.9/32 Direct 0 0 127.0.0.1 InLoop0

2.2.2.9/32 O_INTRA 10 1 10.1.1.2 Ser2/1/0

3.3.3.9/32 O_INTRA 10 2 10.1.1.2 Ser2/1/0

10.1.1.0/24 Direct 0 0 10.1.1.1 Ser2/1/0

10.1.1.0/32 Direct 0 0 10.1.1.1 Ser2/1/0

10.1.1.1/32 Direct 0 0 127.0.0.1 InLoop0

10.1.1.255/32 Direct 0 0 10.1.1.1 Ser2/1/0

11.1.1.0/24 Direct 0 0 11.1.1.1 GE2/0/1

11.1.1.0/32 Direct 0 0 11.1.1.1 GE2/0/1

11.1.1.1/32 Direct 0 0 127.0.0.1 InLoop0

11.1.1.255/32 Direct 0 0 11.1.1.1 GE2/0/1

20.1.1.0/24 O_INTRA 10 2 10.1.1.2 Ser2/1/0

21.1.1.0/24 O_INTRA 10 3 10.1.1.2 Ser2/1/0

127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0

127.0.0.0/32 Direct 0 0 127.0.0.1 InLoop0

127.0.0.1/32 Direct 0 0 127.0.0.1 InLoop0

127.255.255.255/32 Direct 0 0 127.0.0.1 InLoop0

224.0.0.0/4 Direct 0 0 0.0.0.0 NULL0

224.0.0.0/24 Direct 0 0 0.0.0.0 NULL0

255.255.255.255/32 Direct 0 0 127.0.0.1 InLoop0

3. Enable MPLS and IPv4 LDP: # Configure Router A.

[RouterA] mpls lsr-id 1.1.1.9 [RouterA] mpls ldp [RouterA-ldp] quit [RouterA] interface serial 2/1/0 [RouterA-Serial2/1/0] mpls enable [RouterA-Serial2/1/0] mpls ldp enable [RouterA-Serial2/1/0] quit

# Configure Router B.

[RouterB] mpls lsr-id 2.2.2.9 [RouterB] mpls ldp [RouterB-ldp] quit [RouterB] interface serial 2/1/0 [RouterB-Serial2/1/0] mpls enable [RouterB-Serial2/1/0] mpls ldp enable

Page 52

[RouterB-Serial2/1/0] quit [RouterB] interface serial 2/1/1 [RouterB-Serial2/1/1] mpls enable [RouterB-Serial2/1/1] mpls ldp enable [RouterB-Serial2/1/1] quit

# Configure Router C.

[RouterC] mpls lsr-id 3.3.3.9 [RouterC] mpls ldp [RouterC-ldp] quit [RouterC] interface serial 2/1/0 [RouterC-Serial2/1/0] mpls enable [RouterC-Serial2/1/0] mpls ldp enable [RouterC-Serial2/1/0] quit

4. Configure IPv4 LSP generation policies: # On Router A, create IP prefix list routera, and configure LDP to use only the routes permitted

by the prefix list to establish LSPs.

[RouterA] ip prefix-list routera index 10 permit 1.1.1.9 32 [RouterA] ip prefix-list routera index 20 permit 2.2.2.9 32 [RouterA] ip prefix-list routera index 30 permit 3.3.3.9 32 [RouterA] ip prefix-list routera index 40 permit 11.1.1.0 24 [RouterA] ip prefix-list routera index 50 permit 21.1.1.0 24 [RouterA] mpls ldp [RouterA-ldp] lsp-trigger prefix-list routera [RouterA-ldp] quit

# On Router B, create IP prefix list routerb, and configure LDP to use only the routes permitted by the prefix list to establish LSPs.

[RouterB] ip prefix-list routerb index 10 permit 1.1.1.9 32 [RouterB] ip prefix-list routerb index 20 permit 2.2.2.9 32 [RouterB] ip prefix-list routerb index 30 permit 3.3.3.9 32 [RouterB] ip prefix-list routerb index 40 permit 11.1.1.0 24 [RouterB] ip prefix-list routerb index 50 permit 21.1.1.0 24 [RouterB] mpls ldp [RouterB-ldp] lsp-trigger prefix-list routerb [RouterB-ldp] quit

# On Router C, create IP prefix list routerc, and configure LDP to use only the routes permitted by the prefix list to establish LSPs.

[RouterC] ip prefix-list routerc index 10 permit 1.1.1.9 32 [RouterC] ip prefix-list routerc index 20 permit 2.2.2.9 32 [RouterC] ip prefix-list routerc index 30 permit 3.3.3.9 32 [RouterC] ip prefix-list routerc index 40 permit 11.1.1.0 24 [RouterC] ip prefix-list routerc index 50 permit 21.1.1.0 24 [RouterC] mpls ldp [RouterC-ldp] lsp-trigger prefix-list routerc [RouterC-ldp] quit

Verifying the configuration

# Display LDP LSP information on the routers, for example, on Router A.

[RouterA] display mpls ldp lsp Status Flags: * - stale, L - liberal, B - backup

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FECs: 5 Ingress: 3 Transit: 3 Egress: 2

FEC In/Out Label Nexthop OutInterface

1.1.1.9/32 3/-

-/1279(L)

2.2.2.9/32 -/3 10.1.1.2 Ser2/1/0

1279/3 10.1.1.2 Ser2/1/0

3.3.3.9/32 -/1278 10.1.1.2 Ser2/1/0

1278/1278 10.1.1.2 Ser2/1/0

11.1.1.0/24 1277/-

-/1277(L)

21.1.1.0/24 -/1276 10.1.1.2 Ser2/1/0

1276/1276 10.1.1.2 Ser2/1/0

# Test the connectivity of the LDP LSP from Router A to Router C.

[RouterA] ping mpls -a 11.1.1.1 ipv4 21.1.1.0 24 MPLS Ping FEC: 21.1.1.0/24 : 100 data bytes 100 bytes from 20.1.1.2: Sequence=1 time=1 ms 100 bytes from 20.1.1.2: Sequence=2 time=1 ms 100 bytes from 20.1.1.2: Sequence=3 time=8 ms 100 bytes from 20.1.1.2: Sequence=4 time=2 ms 100 bytes from 20.1.1.2: Sequence=5 time=1 ms

--- FEC: 21.1.1.0/24 ping statistics ---

5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max = 1/2/8 ms

# Test the connectivity of the LDP LSP from Router C to Router A.

[RouterC] ping mpls -a 21.1.1.1 ipv4 11.1.1.0 24 MPLS Ping FEC: 11.1.1.0/24 : 100 data bytes 100 bytes from 10.1.1.1: Sequence=1 time=1 ms 100 bytes from 10.1.1.1: Sequence=2 time=1 ms 100 bytes from 10.1.1.1: Sequence=3 time=1 ms 100 bytes from 10.1.1.1: Sequence=4 time=1 ms 100 bytes from 10.1.1.1: Sequence=5 time=1 ms

--- FEC: 11.1.1.0/24 ping statistics ---

5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max = 1/1/1 ms

Label acceptance control configuration example

Network requirements

Two links, Router A—Router B—Router C and Router A—Router D—Router C, exist between subnets 11.1.1.0/24 and 21.1.1.0/24.

Configure LDP to establish LSPs only for routes to subnets 11.1.1.0/24 and 21.1.1.0/24. Configure LDP to establish LSPs only on the link Router A—Router B—Router C to forward traffic

between subnets 11.1.1.0/24 and 21.1.1.0/24.

Page 54

Figure 19 Network diagram

Loop0

2.2.2.9/32

GE2/0/1

11.1.1.1/24

11.1.1.0/24 21.1.1.0/24

Requirements analysis

• To ensure that the LSRs establish IPv4 LSPs automatically, enable IPv4 LDP on each LSR.

• To establish IPv4 LDP LSPs, configure an IPv4 routing protocol to ensure IP connectivity

between the LSRs. This example uses OSPF.

• To ensure that LDP establishes IPv4 LSPs only for the routes 11.1.1.0/24 and 2 1.1.1.0/24, configure IPv4 LSP generation policies on each LSR.

• To ensure that LDP establishes IPv4 LSPs only over the link Router A—Router B—Router C, configure IPv4 label acceptance policies as follows:

{ Router A accepts only the label mapping for FEC 21.1.1.0/24 received from Router B.

Router A denies the label mapping for FEC 21.1.1.0/24 received from Router D.

{ Router C accepts only the label mapping for FEC 11.1.1.0/24 received from Router B.

Router C denies the label mapping for FEC 11.1.1.0/24 received from Router D.

Loop0

1.1.1.9/32

Router A

10.1.1.2/24

Ser2/1/0

10.1.1.1/24 Ser2/1/1

30.1.1.1/24

30.1.1.2/24

Ser2/1/0

Router B

Loop0

4.4.4.9/32

Router D

Ser2/1/1

20.1.1.1/24

20.1.1.2/24

40.1.1.2/24

Ser2/1/1

40.1.1.1/24

Ser2/1/0

Ser2/1/1

Loop0

3.3.3.9/32

GE2/0/1

21.1.1.1/24

Router C

Configuration procedure

1. Configure IP addresses and masks for interfaces, including the loopback interfaces, as shown

in Figure 19. (Detail

2. Configure OSPF on each router to ensure IP connectivity between them. (Details not shown.)

3. Enable MPLS and IPv4 LDP:

# Configure Router A.

<RouterA> system-view [RouterA] mpls lsr-id 1.1.1.9 [RouterA] mpls ldp [RouterA-ldp] quit [RouterA] interface serial 2/1/0 [RouterA-Serial2/1/0] mpls enable [RouterA-Serial2/1/0] mpls ldp enable [RouterA-Serial2/1/0] quit [RouterA] interface serial 2/1/1 [RouterA-Serial2/1/1] mpls enable [RouterA-Serial2/1/1] mpls ldp enable [RouterA-Serial2/1/1] quit

s not shown.)

Page 55

# Configure Router B.

<RouterB> system-view [RouterB] mpls lsr-id 2.2.2.9 [RouterB] mpls ldp [RouterB-ldp] quit [RouterB] interface serial 2/1/0 [RouterB-Serial2/1/0] mpls enable [RouterB-Serial2/1/0] mpls ldp enable [RouterB-Serial2/1/0] quit [RouterB] interface serial 2/1/1 [RouterB-Serial2/1/1] mpls enable [RouterB-Serial2/1/1] mpls ldp enable [RouterB-Serial2/1/1] quit

# Configure Router C.

<RouterC> system-view [RouterC] mpls lsr-id 3.3.3.9 [RouterC] mpls ldp [RouterC-ldp] quit [RouterC] interface serial 2/1/0 [RouterC-Serial2/1/0] mpls enable [RouterC-Serial2/1/0] mpls ldp enable [RouterC-Serial2/1/0] quit [RouterC] interface serial 2/1/1 [RouterC-Serial2/1/1] mpls enable [RouterC-Serial2/1/1] mpls ldp enable [RouterC-Serial2/1/1] quit

# Configure Router D.

<RouterD> system-view [RouterD] mpls lsr-id 4.4.4.9 [RouterD] mpls ldp [RouterD-ldp] quit [RouterD] interface serial 2/1/0 [RouterD-Serial2/1/0] mpls enable [RouterD-Serial2/1/0] mpls ldp enable [RouterD-Serial2/1/0] quit [RouterD] interface serial 2/1/1 [RouterD-Serial2/1/1] mpls enable [RouterD-Serial2/1/1] mpls ldp enable [RouterD-Serial2/1/1] quit

4. Configure IPv4 LSP generation policies: # On Router A, create IP prefix list routera, and configure LDP to use only the routes permitted

by the prefix list to establish LSPs.

[RouterA] ip prefix-list routera index 10 permit 11.1.1.0 24 [RouterA] ip prefix-list routera index 20 permit 21.1.1.0 24 [RouterA] mpls ldp [RouterA-ldp] lsp-trigger prefix-list routera [RouterA-ldp] quit

Page 56

# On Router B, create IP prefix list routerb, and configure LDP to use only the routes permitted by the prefix list to establish LSPs.

[RouterB] ip prefix-list routerb index 10 permit 11.1.1.0 24 [RouterB] ip prefix-list routerb index 20 permit 21.1.1.0 24 [RouterB] mpls ldp [RouterB-ldp] lsp-trigger prefix-list routerb [RouterB-ldp] quit

# On Router C, create IP prefix list routerc, and configure LDP to use only the routes permitted by the prefix list to establish LSPs.

[RouterC] ip prefix-list routerc index 10 permit 11.1.1.0 24 [RouterC] ip prefix-list routerc index 20 permit 21.1.1.0 24 [RouterC] mpls ldp [RouterC-ldp] lsp-trigger prefix-list routerc [RouterC-ldp] quit

# On Router D, create IP prefix list routerd, and configure LDP to use only the routes permitted by the prefix list to establish LSPs.

[RouterD] ip prefix-list routerd index 10 permit 11.1.1.0 24 [RouterD] ip prefix-list routerd index 20 permit 21.1.1.0 24 [RouterD] mpls ldp [RouterD-ldp] lsp-trigger prefix-list routerd [RouterD-ldp] quit

5. Configure IPv4 label acceptance policies: # On Router A, create an IP prefix list prefix-from-b that permits subnet 21.1.1.0/24. Router A

uses this list to filter FEC-label mappings received from Router B.

[RouterA] ip prefix-list prefix-from-b index 10 permit 21.1.1.0 24

# On Router A, create an IP prefix list prefix-from-d that denies subnet 21.1.1.0/24. Router A uses this list to filter FEC-label mappings received from Router D.

[RouterA] ip prefix-list prefix-from-d index 10 deny 21.1.1.0 24

# On Router A, configure label acceptance policies to filter FEC-label mappings received from Router B and Router D.

[RouterA] mpls ldp [RouterA-ldp] accept-label peer 2.2.2.9 prefix-list prefix-from-b [RouterA-ldp] accept-label peer 4.4.4.9 prefix-list prefix-from-d [RouterA-ldp] quit

# On Router C, create an IP prefix list prefix-from-b that permits subnet 11.1.1.0/24. Router C uses this list to filter FEC-label mappings received from Router B.

[RouterC] ip prefix-list prefix-from-b index 10 permit 11.1.1.0 24

# On Router C, create an IP prefix list prefix-from-d that denies subnet 11.1.1.0/24. Router A uses this list to filter FEC-label mappings received from Router D.

[RouterC] ip prefix-list prefix-from-d index 10 deny 11.1.1.0 24

# On Router C, configure label acceptance policies to filter FEC-label mappings received from Router B and Router D.

[RouterC] mpls ldp [RouterC-ldp] accept-label peer 2.2.2.9 prefix-list prefix-from-b [RouterC-ldp] accept-label peer 4.4.4.9 prefix-list prefix-from-d [RouterC-ldp] quit

Verifying the configuration

# Display LDP LSP information on the routers, for example, on Router A.

[RouterA] display mpls ldp lsp

Page 57

Status Flags: * - stale, L - liberal, B - backup FECs: 2 Ingress: 1 Transit 1 Egress: 1

FEC In/Out Label Nexthop OutInterface

11.1.1.0/24 1277/-

-/1148(L)

21.1.1.0/24 -/1276 10.1.1.2 Ser2/1/0

1276/1276 10.1.1.2 Ser2/1/0

The output shows that the next hop of the LSP for FEC 21.1.1.0/24 is Router B (10.1.1.2). The LSP has been established over the link Router A—Router B—Router C, not over the link Router A—Router D—Router C.

# Test the connectivity of the LDP LSP from Router A to Router C.

--- FEC: 21.1.1.0/24 ping statistics ---

5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max = 1/2/8 ms

# Test the connectivity of the LDP LSP from Router C to Router A.

--- FEC: 11.1.1.0/24 ping statistics ---

5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max = 1/1/1 ms

Label advertisement control configuration example

Network requirements

Two links, Router A—Router B—Router C and Router A—Router D—Router C, exist between subnets 11.1.1.0/24 and 21.1.1.0/24.

Configure LDP to establish LSPs only for routes to subnets 11.1.1.0/24 and 21.1.1.0/24. Configure LDP to establish LSPs only on the link Router A—Router B—Router C to forward traffic

between subnets 11.1.1.0/24 and 21.1.1.0/24.

Page 58

Figure 20 Network diagram

Loop0

2.2.2.9/32

GE2/0/1

11.1.1.1/24

11.1.1.0/24 21.1.1.0/24

Requirements analysis

• To ensure that the LSRs establish IPv4 LSPs automatically, enable IPv4 LDP on each LSR.

• To establish IPv4 LDP LSPs, configure an IPv4 routing protocol to ensure IP connectivity

between the LSRs. This example uses OSPF.

• To ensure that LDP establishes IPv4 LSPs only for the routes 11.1.1.0/24 and 2 1.1.1.0/24, configure IPv4 LSP generation policies on each LSR.

• To ensure that LDP establishes IPv4 LSPs only over the link Router A—Router B—Router C, configure IPv4 label advertisement policies as follows:

{ Router A advertises only the label mapping for FEC 11.1.1.0/24 to Router B. { Router C advertises only the label mapping for FEC 21.1.1.0/24 to Router B. { Router D does not advertise label mapping for FEC 21.1.1.0/24 to Router A. Router D does

not advertise label mapping for FEC 11.1.1.0/24 to Router C.

Loop0

1.1.1.9/32

Router A

10.1.1.2/24

Ser2/1/0

10.1.1.1/24 Ser2/1/1

30.1.1.1/24

30.1.1.2/24

Ser2/1/0

Router B

Loop0

4.4.4.9/32

Router D

Ser2/1/1

20.1.1.1/24

20.1.1.2/24

40.1.1.2/24

Ser2/1/1

40.1.1.1/24

Ser2/1/0

Ser2/1/1

Loop0

3.3.3.9/32

GE2/0/1

21.1.1.1/24

Router C

Configuration procedure

1. Configure IP addresses and masks for interfaces, including the loopback interfaces, as shown

in Figure 20. (Detail

2. Configure OSPF on each router to ensure IP connectivity between them. (Details not shown.)

3. Enable MPLS and IPv4 LDP:

# Configure Router A.

s not shown.)

Page 59

# Configure Router B.

# Configure Router C.

# Configure Router D.

4. Configure IPv4 LSP generation policies: # On Router A, create IP prefix list routera, and configure LDP to use only the routes permitted

by the prefix list to establish LSPs.

Page 60

# On Router B, create IP prefix list routerb, and configure LDP to use only the routes permitted by the prefix list to establish LSPs.

# On Router C, create IP prefix list routerc, and configure LDP to use only the routes permitted by the prefix list to establish LSPs.

# On Router D, create IP prefix list routerd, and configure LDP to use only the routes permitted by the prefix list to establish LSPs.

5. Configure IPv4 label advertisement policies: # On Router A, create an IP prefix list prefix-to-b that permits subnet 11.1.1.0/24. Router A

uses this list to filter FEC-label mappings advertised to Router B.

[RouterA] ip prefix-list prefix-to-b index 10 permit 11.1.1.0 24

# On Router A, create an IP prefix list peer-b that permits 2.2.2.9/32. Router A uses this list to filter peers.

[RouterA] ip prefix-list peer-b index 10 permit 2.2.2.9 32

# On Router A, configure a label advertisement policy to advertise only the label mapping for FEC 11.1.1.0/24 to Router B.

[RouterA] mpls ldp [RouterA-ldp] advertise-label prefix-list prefix-to-b peer peer-b [RouterA-ldp] quit

# On Router C, create an IP prefix list prefix-to-b that permits subnet 21.1.1.0/24. Router C uses this list to filter FEC-label mappings advertised to Router B.

[RouterC] ip prefix-list prefix-to-b index 10 permit 21.1.1.0 24

# On Router C, create an IP prefix list peer-b that permits 2.2.2.9/32. Router C uses this list to filter peers.

[RouterC] ip prefix-list peer-b index 10 permit 2.2.2.9 32

# On Router C, configure a label advertisement policy to advertise only the label mapping for FEC 21.1.1.0/24 to Router B.

[RouterC] mpls ldp [RouterC-ldp] advertise-label prefix-list prefix-to-b peer peer-b [RouterC-ldp] quit

# On Router D, create an IP prefix list prefix-to-a that denies subnet 21.1.1.0/24. Router D uses this list to filter FEC-label mappings to be advertised to Router A.

[RouterD] ip prefix-list prefix-to-a index 10 deny 21.1.1.0 24 [RouterD] ip prefix-list prefix-to-a index 20 permit 0.0.0.0 0 less-equal 32

Page 61

# On Router D, create an IP prefix list peer-a that permits 1.1.1.9/32. Router D uses this list to filter peers.

[RouterD] ip prefix-list peer-a index 10 permit 1.1.1.9 32

# On Router D, create an IP prefix list prefix-to-c that denies subnet 11.1.1.0/24. Router D uses this list to filter FEC-label mappings to be advertised to Router C.

[RouterD] ip prefix-list prefix-to-c index 10 deny 11.1.1.0 24 [RouterD] ip prefix-list prefix-to-c index 20 permit 0.0.0.0 0 less-equal 32

# On Router D, create an IP prefix list peer-c that permits subnet 3.3.3.9/32. Router D uses this list to filter peers.

[RouterD] ip prefix-list peer-c index 10 permit 3.3.3.9 32

# On Router D, configure a label advertisement policy. This policy ensures that Router D does not advertise label mappings for FEC 21.1.1.0/24 to Router A, and does not advertise label mappings for FEC 11.1.1.0/24 to Router C.

[RouterD] mpls ldp [RouterD-ldp] advertise-label prefix-list prefix-to-a peer peer-a [RouterD-ldp] advertise-label prefix-list prefix-to-c peer peer-c [RouterD-ldp] quit

Verifying the configuration

# Display LDP LSP information on each router.

[RouterA] display mpls ldp lsp Status Flags: * - stale, L - liberal, B - backup FECs: 2 Ingress: 1 Transit: 1 Egress: 1

FEC In/Out Label Nexthop OutInterface

11.1.1.0/24 1277/-

-/1151(L)

-/1277(L)

21.1.1.0/24 -/1276 10.1.1.2 Ser2/1/0

1276/1276 10.1.1.2 Ser2/1/0 [RouterB] display mpls ldp lsp Status Flags: * - stale, L - liberal, B - backup FECs: 2 Ingress: 2 Transit: 2 Egress: 0

FEC In/Out Label Nexthop OutInterface

11.1.1.0/24 -/1277 10.1.1.1 Ser2/1/0

1277/1277 10.1.1.1 Ser2/1/0

21.1.1.0/24 -/1149 20.1.1.2 Ser2/1/1

1276/1149 20.1.1.2 Ser2/1/1 [RouterC] display mpls ldp lsp Status Flags: * - stale, L - liberal, B - backup FECs: 2 Ingress: 1 Transit: 1 Egress: 1

FEC In/Out Label Nexthop OutInterface

11.1.1.0/24 -/1277 20.1.1.1 Ser2/1/0

1148/1277 20.1.1.1 Ser2/1/0

21.1.1.0/24 1149/-

-/1276(L)

-/1150(L)

Page 62

[RouterD] display mpls ldp lsp Status Flags: * - stale, L - liberal, B - backup FECs: 2 Ingress: 0 Transit: 0 Egress: 2

FEC In/Out Label Nexthop OutInterface

11.1.1.0/24 1151/-

-/1277(L)

21.1.1.0/24 1150/-

The output shows that Router A and Router C have received FEC-label mappings only from Rou ter B. Router B has received FEC-label mappings from both Router A and Router C. Router D does not receive FEC-label mappings from Router A or Router C. LDP has established an LSP only over the link Router A—Router B—Router C.

# Test the connectivity of the LDP LSP from Router A to Router C.

--- FEC: 21.1.1.0/24 ping statistics ---

5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max = 1/2/8 ms

# Test the connectivity of the LDP LSP from Router C to Router A.

--- FEC: 11.1.1.0/24 ping statistics ---

5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max = 1/1/1 ms

LDP FRR configuration example

Network requirements

Router S, Router A, and Router D reside in the same OSPF domain. Configure OSPF FRR so LDP can establish a primary LSP and a backup LSP on the Router S—Router D and the Router S—Router A—Router D links, respectively.

When the primary LSP operates correctly, traffic between subnets 11.1.1.0/24 and 21.1.1.0/24 is forwarded through the LSP.

When the primary LSP fails, traffic between the two subnets can be immediately switched to the backup LSP.

Page 63

Figure 21 Network diagram

Loop0

1.1.1.1/32

Router S

11.1.1.0/24 21.1.1.0/24

Requirements analysis

• To ensure that the LSRs establish IPv4 LSPs automatically, enable IPv4 LDP on each LSR.

• To establish IPv4 LDP LSPs, configure an IPv4 routing protocol to ensure IP connectivity

between the LSRs. This example uses OSPF.

• To ensure that LDP establishes IPv4 LSPs only for the routes 11.1.1.0/24 and 2 1.1.1.0/24, configure IPv4 LSP generation policies on each LSR.

• To allow LDP to establish backup LSRs, configure OSPF FRR on Router S and Router D.

GE2/0/2

13.13.13.1/24

Loop0

2.2.2.2/32

Router A

Backup LSP

Primary LSP

GE2/0/2

13.13.13.2/24

Router D

Loop0

3.3.3.3/32

Configuration procedure

1. Configure IP addresses and masks for interfaces, including the loopback interfaces, as shown

in Figure 21. (Detail

2. Configure OSPF on each router to ensure IP connectivity between them. (Details not shown.)

3. Configure OSPF FRR by using one of the following methods:

{ (Method 1.) Enable OSPF FRR to calculate a backup next hop by using the LFA algorithm:

# Configure Router S.

<RouterS> system-view [RouterS] bfd echo-source-ip 10.10.10.10 [RouterS] ospf 1 [RouterS-ospf-1] fast-reroute lfa [RouterS-ospf-1] quit

# Configure Router D.

<RouterD> system-view [RouterD] bfd echo-source-ip 11.11.11.11 [RouterD] ospf 1 [RouterD-ospf-1] fast-reroute lfa [RouterD-ospf-1] quit

{ (Method 2.) Enable OSPF FRR to specify a backup next hop by using a routing policy:

# Configure Router S.

<RouterS> system-view [RouterS] bfd echo-source-ip 10.10.10.10 [RouterS] ip prefix-list abc index 10 permit 21.1.1.0 24 [RouterS] route-policy frr permit node 10 [RouterS-route-policy] if-match ip address prefix-list abc

s not shown.)

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[RouterS-route-policy] apply fast-reroute backup-interface gigabitethernet 2/0/1 backup-nexthop 12.12.12.2

[RouterS-route-policy] quit [RouterS] ospf 1 [RouterS-ospf-1] fast-reroute route-policy frr [RouterS-ospf-1] quit

# Configure Router D.

<RouterD> system-view [RouterD] bfd echo-source-ip 10.10.10.10 [RouterD] ip prefix-list abc index 10 permit 11.1.1.0 24 [RouterD] route-policy frr permit node 10 [RouterD-route-policy] if-match ip address prefix-list abc [RouterD-route-policy] apply fast-reroute backup-interface gigabitethernet 2/0/1

backup-nexthop 24.24.24.2 [RouterD-route-policy] quit [RouterD] ospf 1 [RouterD-ospf-1] fast-reroute route-policy frr [RouterD-ospf-1] quit

4. Enable MPLS and IPv4 LDP: # Configure Router S.

[RouterS] mpls lsr-id 1.1.1.1 [RouterS] mpls ldp [RouterS-mpls-ldp] quit [RouterS] interface gigabitethernet 2/0/1 [RouterS-GigabitEthernet2/0/1] mpls enable [RouterS-GigabitEthernet2/0/1] mpls ldp enable [RouterS-GigabitEthernet2/0/1] quit [RouterS] interface gigabitethernet 2/0/2 [RouterS-GigabitEthernet2/0/2] mpls enable [RouterS-GigabitEthernet2/0/2] mpls ldp enable [RouterS-GigabitEthernet2/0/2] quit

# Configure Router D.

[RouterD] mpls lsr-id 3.3.3.3 [RouterD] mpls ldp [RouterD-mpls-ldp] quit [RouterD] interface gigabitethernet 2/0/1 [RouterD-GigabitEthernet2/0/1] mpls enable [RouterD-GigabitEthernet2/0/1] mpls ldp enable [RouterD-GigabitEthernet2/0/1] quit [RouterD] interface gigabitethernet 2/0/2 [RouterD-GigabitEthernet2/0/2] mpls enable [RouterD-GigabitEthernet2/0/2] mpls ldp enable [RouterD-GigabitEthernet2/0/2] quit

# Configure Router A.

[RouterA] mpls lsr-id 2.2.2.2 [RouterA] mpls ldp [RouterA-mpls-ldp] quit [RouterA] interface gigabitethernet 2/0/1

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[RouterA-GigabitEthernet2/0/1] mpls enable [RouterA-GigabitEthernet2/0/1] mpls ldp enable [RouterA-GigabitEthernet2/0/1] quit [RouterA] interface gigabitethernet 2/0/2 [RouterA-GigabitEthernet2/0/2] mpls enable [RouterA-GigabitEthernet2/0/2] mpls ldp enable [RouterA-GigabitEthernet2/0/2] quit

5. Configure IPv4 LSP generation policies so LDP uses all static routes and IGP routes to establish LSPs:

# Configure Router S.

[RouterS] mpls ldp [RouterS-ldp] lsp-trigger all [RouterS-ldp] quit

# Configure Router D.

[RouterD] mpls ldp [RouterD-ldp] lsp-trigger all [RouterD-ldp] quit

# Configure Router A.

[RouterA] mpls ldp [RouterA-ldp] lsp-trigger all [RouterA-ldp] quit

Verifying the configuration

# Verify that primary and backup LSPs have been established.

[RouterS] display mpls ldp lsp 21.1.1.0 24 Status Flags: * - stale, L - liberal, B - backup FECs: 1 Ingress: 2 Transit: 2 Egress: 0

FEC In/Out Label Nexthop OutInterface

21.1.1.0/24 -/1276 13.13.13.2 GE2/0/2

2174/1276 13.13.13.2 GE2/0/2

-/1276(B) 12.12.12.2 GE2/0/1

2174/1276(B) 12.12.12.2 GE2/0/1

IPv6 LDP configuration examples

IPv6 LDP LSP configuration example

Network requirements

Router A, Router B, and Router C all support MPLS. Configure LDP to establish IPv6 LSPs between Router A and Router C, so subnets 11::0/64 and

21::0/64 can reach each other over MPLS. Configure LDP to establish LSPs only for destinations 100::1/128, 100::2/128, 100::3/128, 11::0/64,

and 21::0/64 on Router A, Router B, and Router C.

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Figure 22 Network diagram

Loop0

1.1.1.9/32

100::1/128

Loop0

2.2.2.9/32

100::2/128

Loop0

3.3.3.9/32

100::3/128

GE2/0/1

11::1/64

Router A Router B Router C

11::0/64 21::0/64

Requirements analysis

• To ensure that the LSRs establish IPv6 LSPs automatically, enable IPv6 LDP on each LSR.

• To establish IPv6 LDP LSPs, configure an IPv6 routing protocol to ensure IP connectivity

between the LSRs. This example uses OSPFv3.

• To control the number of IPv6 LSPs, configure an IPv6 LSP generation policy on each LSR.

Configuration procedure

1. Configure IPv6 addresses and masks for interfaces, including the loopback interfaces, as

shown in Figure 22. (Detai

2. Configure OSPFv3 on each router to ensure IP connectivity between them: # Configure Router A.

<RouterA> system-view [RouterA] ospfv3 [RouterA-ospfv3-1] router-id 1.1.1.9 [RouterA-ospfv3-1] area 0 [RouterA-ospfv3-1-area-0.0.0.0] quit [RouterA-ospfv3-1] quit [RouterA] interface loopback 0 [RouterA-LoopBack0] ospfv3 1 area 0.0.0.0 [RouterA-LoopBack0] quit [RouterA] interface gigabitethernet 2/0/1 [RouterA-GigabitEthernet2/0/1] ospfv3 1 area 0.0.0.0 [RouterA-GigabitEthernet2/0/1] quit [RouterA] interface serial 2/1/0 [RouterA-Serial2/1/0] ospfv3 1 area 0.0.0.0 [RouterA-Serial2/1/0] quit

# Configure Router B.

<RouterB> system-view [RouterB] ospfv3 [RouterB-ospfv3-1] router-id 2.2.2.9 [RouterB-ospfv3-1] area 0 [RouterB-ospfv3-1-area-0.0.0.0] quit [RouterB-ospfv3-1] quit [RouterB] interface loopback 0 [RouterB-LoopBack0] ospfv3 1 area 0.0.0.0 [RouterB-LoopBack0] quit

Ser2/1/0 10::1/64

Ser2/1/0

10::2/64

ls not shown.)

Ser2/1/1 20::1/64

Ser2/1/0

20::2/64

GE2/0/1 21::1/64

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[RouterB] interface serial 2/1/0 [RouterB-Serial2/1/0] ospfv3 1 area 0.0.0.0 [RouterB-Serial2/1/0] quit [RouterB] interface serial 2/1/1 [RouterB-Serial2/1/1] ospfv3 1 area 0.0.0.0 [RouterB-Serial2/1/1] quit

# Configure Router C.

<RouterC> system-view [RouterC] ospfv3 [RouterC-ospfv3-1] router-id 3.3.3.9 [RouterC-ospfv3-1] area 0 [RouterC-ospfv3-1-area-0.0.0.0] quit [RouterC-ospfv3-1] quit [RouterC] interface loopback 0 [RouterC-LoopBack0] ospfv3 1 area 0.0.0.0 [RouterC-LoopBack0] quit [RouterC] interface gigabitethernet 2/0/1 [RouterC-GigabitEthernet2/0/1] ospfv3 1 area 0.0.0.0 [RouterC-GigabitEthernet2/0/1] quit [RouterC] interface serial 2/1/0 [RouterC-Serial2/1/0] ospfv3 1 area 0.0.0.0 [RouterC-Serial2/1/0] quit

# Verify that the routers have learned the routes to each other. This example uses Router A.

[RouterA] display ipv6 routing-table

Destinations : 12 Routes : 12

Destination: ::1/128 Protocol : Direct NextHop : ::1 Preference: 0 Interface : InLoop0 Cost : 0

Destination: 10::/64 Protocol : Direct NextHop : :: Preference: 0 Interface : Ser2/1/0 Cost : 0

Destination: 10::1/128 Protocol : Direct NextHop : ::1 Preference: 0 Interface : InLoop0 Cost : 0

Destination: 11::/64 Protocol : Direct NextHop : :: Preference: 0 Interface : GE2/0/1 Cost : 0

Destination: 11::1/128 Protocol : Direct NextHop : ::1 Preference: 0 Interface : InLoop0 Cost : 0

Destination: 20::/64 Protocol : O_INTRA

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NextHop : FE80::20C:29FF:FE9D:EAC0 Preference: 10 Interface : Ser2/1/0 Cost : 2

Destination: 21::/64 Protocol : O_INTRA NextHop : FE80::20C:29FF:FE9D:EAC0 Preference: 10 Interface : Ser2/1/0 Cost : 3

Destination: 100::1/128 Protocol : Direct NextHop : ::1 Preference: 0 Interface : InLoop0 Cost : 0

Destination: 100::2/128 Protocol : O_INTRA NextHop : FE80::20C:29FF:FE9D:EAC0 Preference: 10 Interface : Ser2/1/0 Cost : 1

Destination: 100::3/128 Protocol : O_INTRA NextHop : FE80::20C:29FF:FE9D:EAC0 Preference: 10 Interface : Ser2/1/0 Cost : 2

Destination: FE80::/10 Protocol : Direct NextHop : :: Preference: 0 Interface : InLoop0 Cost : 0

Destination: FF00::/8 Protocol : Direct NextHop : :: Preference: 0 Interface : NULL0 Cost : 0

3. Enable MPLS and IPv6 LDP: # Configure Router A.

[RouterA] mpls lsr-id 1.1.1.9 [RouterA] mpls ldp [RouterA-ldp] quit [RouterA] interface serial 2/1/0 [RouterA-Serial2/1/0] mpls enable [RouterA-Serial2/1/0] mpls ldp ipv6 enable [RouterA-Serial2/1/0] mpls ldp transport-address 10::1 [RouterA-Serial2/1/0] quit

# Configure Router B.

[RouterB] mpls lsr-id 2.2.2.9 [RouterB] mpls ldp [RouterB-ldp] quit [RouterB] interface serial 2/1/0 [RouterB-Serial2/1/0] mpls enable [RouterB-Serial2/1/0] mpls ldp ipv6 enable [RouterB-Serial2/1/0] mpls ldp transport-address 10::2 [RouterB-Serial2/1/0] quit [RouterB] interface serial 2/1/1 [RouterB-Serial2/1/1] mpls enable [RouterB-Serial2/1/1] mpls ldp ipv6 enable

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[RouterB-Serial2/1/1] mpls ldp transport-address 20::1 [RouterB-Serial2/1/1] quit

# Configure Router C.

[RouterC] mpls lsr-id 3.3.3.9 [RouterC] mpls ldp [RouterC-ldp] quit [RouterC] interface serial 2/1/0 [RouterC-Serial2/1/0] mpls enable [RouterC-Serial2/1/0] mpls ldp ipv6 enable [RouterC-Serial2/1/0] mpls ldp transport-address 20::2 [RouterC-Serial2/1/0] quit

4. Configure IPv6 LSP generation policies: # On Router A, create IPv6 prefix list routera, and configure LDP to use only the routes

permitted by the prefix list to establish IPv6 LSPs.

[RouterA] ipv6 prefix-list routera index 10 permit 100::1 128 [RouterA] ipv6 prefix-list routera index 20 permit 100::2 128 [RouterA] ipv6 prefix-list routera index 30 permit 100::3 128 [RouterA] ipv6 prefix-list routera index 40 permit 11::0 64 [RouterA] ipv6 prefix-list routera index 50 permit 21::0 64 [RouterA] mpls ldp [RouterA-ldp] ipv6 lsp-trigger prefix-list routera [RouterA-ldp] quit

# On Router B, create IPv6 prefix list routerb, and configure LDP to use only the routes permitted by the prefix list to establish IPv6 LSPs.

[RouterB] ipv6 prefix-list routerb index 10 permit 100::1 128 [RouterB] ipv6 prefix-list routerb index 20 permit 100::2 128 [RouterB] ipv6 prefix-list routerb index 30 permit 100::3 128 [RouterB] ipv6 prefix-list routerb index 40 permit 11::0 64 [RouterB] ipv6 prefix-list routerb index 50 permit 21::0 64 [RouterB] mpls ldp [RouterB-ldp] ipv6 lsp-trigger prefix-list routerb [RouterB-ldp] quit

# On Router C, create IPv6 prefix list routerc, and configure LDP to use only the routes permitted by the prefix list to establish IPv6 LSPs.

[RouterC] ipv6 prefix-list routerc index 10 permit 100::1 128 [RouterC] ipv6 prefix-list routerc index 20 permit 100::2 128 [RouterC] ipv6 prefix-list routerc index 30 permit 100::3 128 [RouterC] ipv6 prefix-list routerc index 40 permit 11::0 64 [RouterC] ipv6 prefix-list routerc index 50 permit 21::0 64 [RouterC] mpls ldp [RouterC-ldp] ipv6 lsp-trigger prefix-list routerc [RouterC-ldp] quit

Verifying the configuration

# Display IPv6 LDP LSP information on the routers, for example, on Router A.

[RouterA] display mpls ldp lsp ipv6 Status Flags: * - stale, L - liberal, B - backup FECs: 5 Ingress: 3 Transit: 3 Egress: 2

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FEC: 11::/64 In/Out Label: 2426/- OutInterface : Nexthop : In/Out Label: -/2424(L) OutInterface : Nexthop : -

FEC: 21::/64 In/Out Label: -/2425 OutInterface : Ser2/1/0 Nexthop : FE80::20C:29FF:FE9D:EAC0 In/Out Label: 2423/2425 OutInterface : Ser2/1/0 Nexthop : FE80::20C:29FF:FE9D:EAC0

FEC: 100::1/128 In/Out Label: 1040377/- OutInterface : Nexthop : In/Out Label: -/2426(L) OutInterface : Nexthop : -

FEC: 100::2/128 In/Out Label: -/1040379 OutInterface : Ser2/1/0 Nexthop : FE80::20C:29FF:FE9D:EAC0 In/Out Label: 2425/1040379 OutInterface : Ser2/1/0 Nexthop : FE80::20C:29FF:FE9D:EAC0

FEC: 100::3/128 In/Out Label: -/2427 OutInterface : Ser2/1/0 Nexthop : FE80::20C:29FF:FE9D:EAC0 In/Out Label: 2424/2427 OutInterface : Ser2/1/0 Nexthop : FE80::20C:29FF:FE9D:EAC0

# Test the connectivity of the IPv6 LDP LSP from Router A to Router C.

[RouterA] ping ipv6 -a 11::1 21::1 Ping6(56 data bytes) 11::1 --> 21::1, press CTRL_C to break 56 bytes from 21::1, icmp_seq=0 hlim=63 time=2.000 ms 56 bytes from 21::1, icmp_seq=1 hlim=63 time=1.000 ms 56 bytes from 21::1, icmp_seq=2 hlim=63 time=3.000 ms 56 bytes from 21::1, icmp_seq=3 hlim=63 time=3.000 ms 56 bytes from 21::1, icmp_seq=4 hlim=63 time=2.000 ms

--- Ping6 statistics for 21::1 ---

5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max/std-dev = 1.000/2.200/3.000/0.748 ms

# Test the connectivity of the IPv6 LDP LSP from Router C to Router A.

[RouterC] ping ipv6 -a 21::1 11::1 Ping6(56 data bytes) 21::1 --> 11::1, press CTRL_C to break 56 bytes from 11::1, icmp_seq=0 hlim=63 time=2.000 ms 56 bytes from 11::1, icmp_seq=1 hlim=63 time=1.000 ms 56 bytes from 11::1, icmp_seq=2 hlim=63 time=1.000 ms 56 bytes from 11::1, icmp_seq=3 hlim=63 time=1.000 ms

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56 bytes from 11::1, icmp_seq=4 hlim=63 time=1.000 ms

--- Ping6 statistics for 11::1 ---

5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max/std-dev = 1.000/1.200/2.000/0.400 ms

IPv6 label acceptance control configuration example

Network requirements

Two links, Router A—Router B—Router C and Router A—Router D—Router C, exist between subnets 11::0/64 and 21::0/64.

Configure LDP to establish LSPs only for routes to subnets 11::0/64 and 21::0/64. Configure LDP to establish LSPs only on the link Router A—Router B—Router C to forward traffic

between subnets 11::0/64 and 21::0/64.

Figure 23 Network diagram

Requirements analysis

• To ensure that the LSRs establish IPv6 LSPs automatically, enable IPv6 LDP on each LSR.

• To establish IPv6 LDP LSPs, configure an IPv6 routing protocol to ensure IP connectivity

between the LSRs. This example uses OSPFv3.

• To ensure that LDP establishes IPv6 LSPs only for the routes 11::0/64 and 21::0/64, configure IPv6 LSP generation policies on each LSR.

• To ensure that LDP establishes IPv6 LSPs only over the link Router A—Router B—Router C, configure IPv6 label acceptance policies as follows:

{ Router A accepts only the label mapping for FEC 21::0/64 re ceived from Router B. Router A

denies the label mapping for FEC 21::0/64 received from Router D.

{ Router C accepts only the label mapping for FEC 1 1::0/64 received from Router B. Router C

denies the label mapping for FEC 11::0/64 received from Router D.

Configuration procedure

1. Configure IPv6 addresses and masks for interfaces, including the loopback interfaces, as

shown in Figure 23. (Detai

ls not shown.)

Page 72

2. Configure OSPFv3 on each router to ensure IP connectivity between them. (Details not shown.)

3. Enable MPLS and IPv6 LDP:

# Configure Router A.

<RouterA> system-view [RouterA] mpls lsr-id 1.1.1.9 [RouterA] mpls ldp [RouterA-ldp] quit [RouterA] interface serial 2/1/0 [RouterA-Serial2/1/0] mpls enable [RouterA-Serial2/1/0] mpls ldp ipv6 enable [RouterA-Serial2/1/0] mpls ldp transport-address 10::1 [RouterA-Serial2/1/0] quit [RouterA] interface serial 2/1/1 [RouterA-Serial2/1/1] mpls enable [RouterA-Serial2/1/1] mpls ldp ipv6 enable [RouterA-Serial2/1/1] mpls ldp transport-address 30::1 [RouterA-Serial2/1/1] quit

# Configure Router B.

<RouterB> system-view [RouterB] mpls lsr-id 2.2.2.9 [RouterB] mpls ldp [RouterB-ldp] quit [RouterB] interface serial 2/1/0 [RouterB-Serial2/1/0] mpls enable [RouterB-Serial2/1/0] mpls ldp ipv6 enable [RouterB-Serial2/1/0] mpls ldp transport-address 10::2 [RouterB-Serial2/1/0] quit [RouterB] interface serial 2/1/1 [RouterB-Serial2/1/1] mpls enable [RouterB-Serial2/1/1] mpls ldp ipv6 enable [RouterB-Serial2/1/1] mpls ldp transport-address 20::1 [RouterB-Serial2/1/1] quit

# Configure Router C.

<RouterC> system-view [RouterC] mpls lsr-id 3.3.3.9 [RouterC] mpls ldp [RouterC-ldp] quit [RouterC] interface serial 2/1/0 [RouterC-Serial2/1/0] mpls enable [RouterC-Serial2/1/0] mpls ldp ipv6 enable [RouterC-Serial2/1/0] mpls ldp transport-address 20::2 [RouterC-Serial2/1/0] quit [RouterC] interface serial 2/1/1 [RouterC-Serial2/1/1] mpls enable [RouterC-Serial2/1/1] mpls ldp ipv6 enable [RouterC-Serial2/1/1] mpls ldp transport-address 40::2 [RouterC-Serial2/1/1] quit

# Configure Router D.

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<RouterD> system-view [RouterD] mpls lsr-id 4.4.4.9 [RouterD] mpls ldp [RouterD-ldp] quit [RouterD] interface serial 2/1/0 [RouterD-Serial2/1/0] mpls enable [RouterD-Serial2/1/0] mpls ldp ipv6 enable [RouterD-Serial2/1/0] mpls ldp transport-address 30::2 [RouterD-Serial2/1/0] quit [RouterD] interface serial 2/1/1 [RouterD-Serial2/1/1] mpls enable [RouterD-Serial2/1/1] mpls ldp ipv6 enable [RouterD-Serial2/1/1] mpls ldp transport-address 40::1 [RouterD-Serial2/1/1] quit

4. Configure IPv6 LSP generation policies: # On Router A, create IPv6 prefix list routera, and configure LDP to use only the routes

permitted by the prefix list to establish IPv6 LSPs.

[RouterA] ipv6 prefix-list routera index 10 permit 11::0 64 [RouterA] ipv6 prefix-list routera index 20 permit 21::0 64 [RouterA] mpls ldp [RouterA-ldp] ipv6 lsp-trigger prefix-list routera [RouterA-ldp] quit

# On Router B, create IPv6 prefix list routerb, and configure LDP to use only the routes permitted by the prefix list to establish IPv6 LSPs.

[RouterB] ipv6 prefix-list routerb index 10 permit 11::0 64 [RouterB] ipv6 prefix-list routerb index 20 permit 21::0 64 [RouterB] mpls ldp [RouterB-ldp] ipv6 lsp-trigger prefix-list routerb [RouterB-ldp] quit

# On Router C, create IPv6 prefix list routerc, and configure LDP to use only the routes permitted by the prefix list to establish IPv6 LSPs.

[RouterC] ipv6 prefix-list routerc index 10 permit 11::0 64 [RouterC] ipv6 prefix-list routerc index 20 permit 21::0 64 [RouterC] mpls ldp [RouterC-ldp] ipv6 lsp-trigger prefix-list routerc [RouterC-ldp] quit

# On Router D, create IPv6 prefix list routerd, and configure LDP to use only the routes permitted by the prefix list to establish IPv6 LSPs.

[RouterD] ipv6 prefix-list routerd index 10 permit 11::0 64 [RouterD] ipv6 prefix-list routerd index 20 permit 21::0 64 [RouterD] mpls ldp [RouterD-ldp] ipv6 lsp-trigger prefix-list routerd [RouterD-ldp] quit

5. Configure IPv6 label acceptance policies: # On Router A, create an IPv6 prefix list prefix-from-b that permits subnet 21::0/64. Router A

uses this list to filter FEC-label mappings received from Router B.

[RouterA] ipv6 prefix-list prefix-from-b index 10 permit 21::0 64

# On Router A, create an IPv6 prefix list prefix-from-d that denies subnet 21::0/64. Router A uses this list to filter FEC-label mappings received from Router D.

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[RouterA] ipv6 prefix-list prefix-from-d index 10 deny 21::0 64

# On Router A, configure IPv6 label acceptance policies to filter FEC-label mappings received from Router B and Router D.

[RouterA] mpls ldp [RouterA-ldp] ipv6 accept-label peer 2.2.2.9 prefix-list prefix-from-b [RouterA-ldp] ipv6 accept-label peer 4.4.4.9 prefix-list prefix-from-d [RouterA-ldp] quit

# On Router C, create an IPv6 prefix list prefix-from-b that permits subnet 11::0/64. Router C uses this list to filter FEC-label mappings received from Router B.

[RouterC] ipv6 prefix-list prefix-from-b index 10 permit 11::0 64

# On Router C, create an IPv6 prefix list prefix-from-d that denies subnet 11::0/64. Router A uses this list to filter FEC-label mappings received from Router D.

[RouterC] ipv6 prefix-list prefix-from-d index 10 deny 11::0 64

# On Router C, configure IPv6 label acceptance policies to filter FEC-label mappings received from Router B and Router D.

[RouterC] mpls ldp [RouterC-ldp] ipv6 accept-label peer 2.2.2.9 prefix-list prefix-from-b [RouterC-ldp] ipv6 accept-label peer 4.4.4.9 prefix-list prefix-from-d [RouterC-ldp] quit

Verifying the configuration

# Display IPv6 LDP LSP information on the routers, for example, on Router A.

[RouterA] display mpls ldp lsp ipv6 Status Flags: * - stale, L - liberal, B - backup FECs: 2 Ingress: 1 Transit 1 Egress: 1

FEC: 11::/64 In/Out Label: 2417/- OutInterface : Nexthop : -

FEC: 21::/64 In/Out Label: -/2416 OutInterface : Ser2/1/0 Nexthop : FE80::20C:29FF:FE9D:EAC0 In/Out Label: 2415/2416 OutInterface : Ser2/1/0 Nexthop : FE80::20C:29FF:FE9D:EAC0

The output shows that the next hop of the IPv6 LSP for FEC 21::0/64 is Router B (FE80::20C:29FF:FE9D:EAC0). The IPv6 LSP has been established over the link Router A—Router B—Router C, not over the link Router A—Router D—Router C.

# Test the connectivity of the IPv6 LDP LSP from Router A to Router C.

[RouterA] ping ipv6 -a 11::1 21::1 Ping6(56 data bytes) 11::1 --> 21::1, press CTRL_C to break 56 bytes from 21::1, icmp_seq=0 hlim=63 time=4.000 ms 56 bytes from 21::1, icmp_seq=1 hlim=63 time=3.000 ms 56 bytes from 21::1, icmp_seq=2 hlim=63 time=3.000 ms 56 bytes from 21::1, icmp_seq=3 hlim=63 time=2.000 ms 56 bytes from 21::1, icmp_seq=4 hlim=63 time=1.000 ms

--- Ping6 statistics for 21::1 ---

5 packets transmitted, 5 packets received, 0.0% packet loss

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round-trip min/avg/max/std-dev = 1.000/2.600/4.000/1.020 ms

# Test the connectivity of the IPv6 LDP LSP from Router C to Router A.

[RouterC] ping ipv6 -a 21::1 11::1 Ping6(56 data bytes) 21::1 --> 11::1, press CTRL_C to break 56 bytes from 11::1, icmp_seq=0 hlim=63 time=1.000 ms 56 bytes from 11::1, icmp_seq=1 hlim=63 time=2.000 ms 56 bytes from 11::1, icmp_seq=2 hlim=63 time=1.000 ms 56 bytes from 11::1, icmp_seq=3 hlim=63 time=2.000 ms 56 bytes from 11::1, icmp_seq=4 hlim=63 time=1.000 ms

--- Ping6 statistics for 11::1 ---

5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max/std-dev = 1.000/1.400/2.000/0.490 ms

IPv6 label advertisement control configuration example

Network requirements

Two links, Router A—Router B—Router C and Router A—Router D—Router C, exist between subnets 11::0/64 and 21::0/64.

Configure LDP to establish LSPs only for routes to subnets 11::0/64 and 21::0/64. Configure LDP to establish LSPs only on the link Router A—Router B—Router C to forward traffic

between subnets 11::0/64 and 21::0/64.

Figure 24 Network diagram

Requirements analysis

• To ensure that the LSRs establish IPv6 LSPs automatically, enable IPv6 LDP on each LSR.

• To establish IPv6 LDP LSPs, configure an IPv6 routing protocol to ensure IP connectivity

between the LSRs. This example uses OSPFv3.

• To ensure that LDP establishes IPv6 LSPs only for the routes 11::0/64 and 21::0/64, configure IPv6 LSP generation policies on each LSR.

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• To ensure that LDP establishes IPv6 LSPs only over the link Router A—Router B—Router C, configure IPv6 label advertisement policies as follows:

{ Router A advertises only the label mapping for FEC 11::0/64 to Router B. { Router C advertises only the label mapping for FEC 21::0/64 to Router B. { Router D does not advertise label mapping for FEC 21::0/64 to Router A. Router D does not

advertise label mapping for FEC 11::0/64 to Router C.

Configuration procedure

1. Configure IPv6 addresses and masks for interfaces, including the loopback interfaces, as

shown in Figure 24. (Detai

2. Configure OSPFv3 on each router to ensure IP connectivity between them. (Details not shown.)

3. Enable MPLS and IPv6 LDP:

# Configure Router A.

<RouterA> system-view [RouterA] mpls lsr-id 1.1.1.9 [RouterA] mpls ldp [RouterA-ldp] quit [RouterA] interface serial 2/1/0 [RouterA-Serial2/1/0] mpls enable [RouterA-Serial2/1/0] mpls ldp ipv6 enable [RouterA-Serial2/1/0] mpls ldp transport-address 10::1 [RouterA-Serial2/1/0] quit [RouterA] interface serial 2/1/1 [RouterA-Serial2/1/1] mpls enable [RouterA-Serial2/1/1] mpls ldp ipv6 enable [RouterA-Serial2/1/1] mpls ldp transport-address 30::1 [RouterA-Serial2/1/1] quit

# Configure Router B.

<RouterB> system-view [RouterB] mpls lsr-id 2.2.2.9 [RouterB] mpls ldp [RouterB-ldp] quit [RouterB] interface serial 2/1/0 [RouterB-Serial2/1/0] mpls enable [RouterB-Serial2/1/0] mpls ldp ipv6 enable [RouterB-Serial2/1/0] mpls ldp transport-address 10::2 [RouterB-Serial2/1/0] quit [RouterB] interface serial 2/1/1 [RouterB-Serial2/1/1] mpls enable [RouterB-Serial2/1/1] mpls ldp ipv6 enable [RouterB-Serial2/1/1] mpls ldp transport-address 20::1 [RouterB-Serial2/1/1] quit

# Configure Router C.

<RouterC> system-view [RouterC] mpls lsr-id 3.3.3.9 [RouterC] mpls ldp [RouterC-ldp] quit [RouterC] interface serial 2/1/0 [RouterC-Serial2/1/0] mpls enable

ls not shown.)

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[RouterC-Serial2/1/0] mpls ldp ipv6 enable [RouterC-Serial2/1/0] mpls ldp transport-address 20::2 [RouterC-Serial2/1/0] quit [RouterC] interface serial 2/1/1 [RouterC-Serial2/1/1] mpls enable [RouterC-Serial2/1/1] mpls ldp ipv6 enable [RouterC-Serial2/1/1] mpls ldp transport-address 40::2 [RouterC-Serial2/1/1] quit

# Configure Router D.

<RouterD> system-view [RouterD] mpls lsr-id 4.4.4.9 [RouterD] mpls ldp [RouterD-ldp] quit [RouterD] interface serial 2/1/0 [RouterD-Serial2/1/0] mpls enable [RouterD-Serial2/1/0] mpls ldp ipv6 enable [RouterD-Serial2/1/0] mpls ldp transport-address 30::2 [RouterD-Serial2/1/0] quit [RouterD] interface serial 2/1/1 [RouterD-Serial2/1/1] mpls enable [RouterD-Serial2/1/1] mpls ldp ipv6 enable [RouterD-Serial2/1/1] mpls ldp transport-address 40::1 [RouterD-Serial2/1/1] quit

4. Configure IPv6 LSP generation policies: # On Router A, create IPv6 prefix list routera, and configure LDP to use only the routes

permitted by the prefix list to establish IPv6 LSPs.

# On Router B, create IPv6 prefix list routerb, and configure LDP to use only the routes permitted by the prefix list to establish IPv6 LSPs.

# On Router C, create IPv6 prefix list routerc, and configure LDP to use only the routes permitted by the prefix list to establish IPv6 LSPs.

# On Router D, create IPv6 prefix list routerd, and configure LDP to use only the routes permitted by the prefix list to establish IPv6 LSPs.

[RouterD] ipv6 prefix-list routerd index 10 permit 11::0 64 [RouterD] ipv6 prefix-list routerd index 20 permit 21::0 64

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[RouterD] mpls ldp [RouterD-ldp] ipv6 lsp-trigger prefix-list routerd [RouterD-ldp] quit

5. Configure IPv6 label advertisement policies: # On Router A, create an IPv6 prefix list prefix-to-b that permits subnet 11::0/64. Router A uses

this list to filter FEC-label mappings advertised to Router B.

[RouterA] ipv6 prefix-list prefix-to-b index 10 permit 11::0 64

# On Router A, create an IP prefix list peer-b that permits 2.2.2.9/32. Router A uses this list to filter peers.

[RouterA] ip prefix-list peer-b index 10 permit 2.2.2.9 32

# On Router A, configure an IPv6 label advertisement policy to advertise only the label mapping for FEC 11::0/64 to Router B.

[RouterA] mpls ldp [RouterA-ldp] ipv6 advertise-label prefix-list prefix-to-b peer peer-b [RouterA-ldp] quit

# On Router C, create an IPv6 prefix list prefix-to-b that permits subnet 21::0/64. Router C uses this list to filter FEC-label mappings advertised to Router B.

[RouterC] ipv6 prefix-list prefix-to-b index 10 permit 21::0 64

# On Router C, create an IP prefix list peer-b that permits 2.2.2.9/32. Router C uses this list to filter peers.

[RouterC] ip prefix-list peer-b index 10 permit 2.2.2.9 32

# On Router C, configure an IPv6 label advertisement policy to advertise only the label mapping for FEC 21::0/64 to Router B.

[RouterC] mpls ldp [RouterC-ldp] ipv6 advertise-label prefix-list prefix-to-b peer peer-b [RouterC-ldp] quit

# On Router D, create an IPv6 prefix list prefix-to-a that denies subnet 21::0/64. Router D uses this list to filter FEC-label mappings to be advertised to Router A.

[RouterD] ipv6 prefix-list prefix-to-a index 10 deny 21::0 64 [RouterD] ipv6 prefix-list prefix-to-a index 20 permit 0::0 0 less-equal 128

# On Router D, create an IP prefix list peer-a that permits 1.1.1.9/32. Router D uses this list to filter peers.

[RouterD] ip prefix-list peer-a index 10 permit 1.1.1.9 32

# On Router D, create an IPv6 prefix list prefix-to-c that denies subnet 11::0/64. Router D uses this list to filter FEC-label mappings to be advertised to Router C.

[RouterD] ipv6 prefix-list prefix-to-c index 10 deny 11::0 64 [RouterD] ipv6 prefix-list prefix-to-c index 20 permit 0::0 0 less-equal 128

# On Router D, create an IP prefix list peer-c that permits subnet 3.3.3.9/32. Router D uses this list to filter peers.

[RouterD] ip prefix-list peer-c index 10 permit 3.3.3.9 32

# On Router D, configure an IPv6 label advertisement policy. This policy ensures that Router D does not advertise label mappings for FEC 21::0/64 to Router A, and does not advertise label mappings for FEC 11::0/64 to Router C.

[RouterD] mpls ldp [RouterD-ldp] ipv6 advertise-label prefix-list prefix-to-a peer peer-a [RouterD-ldp] ipv6 advertise-label prefix-list prefix-to-c peer peer-c [RouterD-ldp] quit

Verifying the configuration

# Display LDP LSP information on the routers, for example, on Router A.

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[RouterA] display mpls ldp lsp ipv6 Status Flags: * - stale, L - liberal, B - backup FECs: 2 Ingress: 1 Transit: 1 Egress: 1

FEC: 11::/64 In/Out Label: 2417/- OutInterface : Nexthop : In/Out Label: -/1098(L) OutInterface : Nexthop : In/Out Label: -/2418(L) OutInterface : Nexthop : -

FEC: 21::/64 In/Out Label: -/2416 OutInterface : Ser2/1/0 Nexthop : FE80::20C:29FF:FE9D:EAC0 In/Out Label: 2415/2416 OutInterface : Ser2/1/0 Nexthop : FE80::20C:29FF:FE9D:EAC0 [RouterB] display mpls ldp lsp ipv6 Status Flags: * - stale, L - liberal, B - backup FECs: 2 Ingress: 2 Transit: 2 Egress: 0

FEC: 11::/64 In/Out Label: -/2417 OutInterface : Ser2/1/0 Nexthop : FE80::20C:29FF:FE9D:EA8E In/Out Label: 2418/2417 OutInterface : Ser2/1/0 Nexthop : FE80::20C:29FF:FE9D:EA8E

FEC: 21::/64 In/Out Label: -/1099 OutInterface : Ser2/1/1 Nexthop : FE80::20C:29FF:FE05:1C01 In/Out Label: 2416/1099 OutInterface : Ser2/1/1 Nexthop : FE80::20C:29FF:FE05:1C01 [RouterC] display mpls ldp lsp ipv6 Status Flags: * - stale, L - liberal, B - backup FECs: 2 Ingress: 1 Transit: 1 Egress: 1

FEC: 11::/64 In/Out Label: -/2418 OutInterface : Ser2/1/0 Nexthop : FE80::20C:29FF:FE9D:EAA2 In/Out Label: 1098/2418 OutInterface : Ser2/1/0 Nexthop : FE80::20C:29FF:FE9D:EAA2

FEC: 21::/64 In/Out Label: 1099/- OutInterface : Nexthop : In/Out Label: -/2416(L) OutInterface : Nexthop : In/Out Label: -/1097(L) OutInterface : -

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Nexthop : [RouterD] display mpls ldp lsp ipv6 Status Flags: * - stale, L - liberal, B - backup FECs: 2 Ingress: 0 Transit: 0 Egress: 2

FEC: 11::/64 In/Out Label: 1098/- OutInterface : Nexthop : -

FEC: 21::/64 In/Out Label: 1097/- OutInterface : Nexthop : -

The output shows that Router A and Router C have received FEC-label mappings only from Rou ter B. Router B has received FEC-label mappings from both Router A and Router C. Router D does not receive FEC-label mappings from Router A or Route r C. LDP has established an IPv6 LSP only over the link Router A—Router B—Route r C.

# Test the connectivity of the IPv6 LDP LSP from Router A to Router C.

--- Ping6 statistics for 21::1 ---

5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max/std-dev = 1.000/2.600/4.000/1.020 ms

# Test the connectivity of the IPv6 LDP LSP from Router C to Router A.

--- Ping6 statistics for 11::1 ---

5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max/std-dev = 1.000/1.400/2.000/0.490 ms

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Configuring MPLS TE

Overview

TE and MPLS TE

Network congestion can degrade the network backbone performance. It might occur when network resources are inadequate or when load distribution is unbalanced. Traffic engineering (TE) is intended to avoid the latter situation where partial congestion might occur because of improper resource allocation.

TE can make the best use of network resources and avoid uneven load distribution by using the following functionalities:

• Real-time monitoring of traffic and traffic load on network elements.

• Dynamic tuning of traffic management attributes, routing parameters, and resource s

constraints.

MPLS TE combines the MPLS technology and traffic engineering. It reserves resources by establishing LSP tunnels along the specified paths, allowing traffic to bypass congested nodes to achieve appropriate load distribution.

With MPLS TE, a service provider can deploy traffic engineering on the existing MPLS backbone to provide various services and optimize network resources management.

MPLS TE basic concepts

• CRLSP—Constraint-based Routed Label Switched Path. To establish a CRLSP, you must configure routing, and specify constrains, such as the bandwidth and explicit paths.

• MPLS TE tunnel—A virtual point-to-point connection from the in gress node to the egress node. Typically, an MPLS TE tunnel consists of one CRLSP. To deploy CRLSP backup or transmit traffic over multiple paths, you need to establish multiple CRLSPs for one class of traffic. In this case, an MPLS TE tunnel consists of a set of CRLSPs. An MPLS TE tunnel is identified by an MPLS TE tunnel interface on the ingress node. When the outgoing interface of a traffic flow is an MPLS TE tunnel interface, the traffic flow is forwarded through the CRLSP of the MPLS TE tunnel.

Static CRLSP establishment

A static CRLSP is established by manually specifying the incoming label, outgoing label, and other constraints on each hop along the path that the traffic travels. Static CRLSPs feature simple configuration, but they cannot automatically adapt to network changes.

For more information about static CRLSPs, see "Configuring a static CRLSP."

Dynamic CRLSP establishment

Dynamic CRLSPs are dynamically established as follows:

1. An IGP advertises TE attributes for links.

2. MPLS TE uses the CSPF algorithm to calculate the shortest path to the tunnel destination.

The path must meet constraints such as bandwidth and explicit routing.

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3. A label distribution protocol (such as RSVP-TE) advertises labels to establish CRLSPs and reserves bandwidth resources on each node along the calculated path.

Dynamic CRLSPs adapt to network changes and support CRLSP backup and fast reroute, but they require complicated configurations.

Advertising TE attributes

MPLS TE uses extended link state IGPs, such as OSPF and IS-IS, to advertise TE attributes for links.

TE attributes include the maximum bandwidth, maximum reservable bandwidth, non-reserved bandwidth for each priority , and the link attribute. The IGP floods TE attributes on the network. Each node collects the TE attributes of all links on all routers within the local area or at the same level to build up a TE database (TEDB).

Calculating paths

Based on the TEDB, MPLS TE uses the Constraint-based Shortest Path First (CSPF) algorithm, an improved SPF algorithm, to calculate the shortest, TE constraints-compliant path to the tunnel destination.

CSPF first prunes TE constraints-incompliant links from the TEDB, and then it performs SPF calculation to identify the shortest path (a set of LSR addresses) to an egress. CSPF calculation is usually performed on the ingress node of an MPLS TE tunnel.

TE constraints include the bandwidth, affinity, setup and holding priorities, and explicit path. They are configured on the ingress node of an MPLS TE tunnel.

• Bandwidth Bandwidth constraints specify the class of service and the required bandwidth for the traffic to

be forwarded along the MPLS TE tunnel. A link complies with the bandwidth constraints when the reservable bandwidth for the class type is greate r than or equal to the bandwidth required b y the class type.

• Affinity Affinity determines which links a tunnel can use. The affinity attribute and its mask, and the link

attribute are all 32-bit long. A link is available for a tunnel if the link attribute meets the following requirements:

{ The link attribute bits corresponding to the affinity attribute's 1 bits whose mask bits are 1

must have a minimum of one bit set to 1.

{ The link attribute bits corresponding to the affinity attribute's 0 bits whose mask bits are 1

must have no bit set to 1. The link attribute bits corresponding to the 0 bits in the affinity mask are not checked. For example, if the affinity attribute is 0xFFFFFFF0 and its mask is 0x0000FFFF, a link is

available for the tunnel when its link attribute bits meet the following requirements:

{ The highest 16 bits each can be 0 or 1 (no requirements). { The 17 { The lowest four bits must be 0.

• Setup priority and holding priority If MPLS TE cannot find a qualified path to set up an MPLS TE tunnel, it removes an existing

MPLS TE tunnel and preempts its bandwidth. MPLS TE uses the setup priority and holding priority to make preemption decisions. For a new

MPLS TE tunnel to preempt an existing MPLS TE tunnel, the setup priority of the new tunnel must be higher than the holding priority of the existing tunnel. Both setup and holding priorities are in the range of 0 to 7. A smaller value represents a higher priority.

To avoid flapping caused by improper preemptions, the setup priority value of a tunnel must be equal to or greater than the holding priority value.

• Explicit path

through 28th bits must have a minimum of one bit whose value is 1.

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Explicit path specifies the nodes to pass and the nodes to not pass for a tunnel. Explicit paths include the following types:

{ Strict explicit path—Among the nodes that the path must traverse, a node and its previous

hop must be directly connected. Strict explicit path precisely specifies the path that an MPLS TE tunnel must traverse.

{ Loose explicit path—Among the nodes that the path must traverse, a node and its

previous hop can be indirectly connected. Loose explicit path vaguely specifies the path that an MPLS TE tunnel must traverse.

Strict explicit path and loose explicit path can be used together to specify that some nodes are directly connected and some nodes have other nodes in between.

Setting up a CRLSP through RSVP-TE

After calculating a path by using CSPF, MPLS TE uses a label distribution protocol to set up the CRLSP and reserves resources on each node of the path.

The device supports the label distribution protocol of RSVP-TE for MPLS TE. Resource Reservation Protocol (RSVP) reserves resources on each node along a path. Extended RSVP can support MPLS label distribution and allow resource reservation information to be transmitted with label bindings. This extended RSVP is called RSVP-TE.

For more information about RSVP, see "Configuring RSVP."

CRLSP establishment using PCE path calculation

On an MPLS TE network, a Path Computation Client (PCC), usually an LSR, uses the path calculated by Path Computation Elements (PCEs) to establish a CRLSP through RSVP-TE.

Basic concepts

• PCE—An entity that can calculate a path based on the TEDB, bandwidth, and other MPLS TE tunnel constraints. A PCE can provide intra-area or inter-area path calculation. A PCE can be manually specified on a PCC or automatically discovered through the PCE information advertised by OSPF TE.

• PCC—A PCC sends a re quest to PCEs for path calculation and uses the path information returned by PCEs to establish a CRLSP.

• PCEP—Path Computation Element Communication Protocol. PCEP runs between a PCC and a PCE, or between PCEs. It is used to establish PCEP sessions to exchange PCEP message s over TCP connections.

PCE path calculation

PCE path calculation has the following types:

• EPC—External Path Computation. EPC path calculation is performed by one PCE. It is applicable to intra-area path calculation.

• BRPC—Backward-Recursive PCE-Based Computation. BRPC path calculation is performed by multiple PCEs. It is applicable to inter-area path calculation.

As shown in Figure 25, P ABR that can calculate paths in Area 1 and Area 2. The CRLSP that PCC uses to reach a destination in Area 2 is established as follows:

1. PCC sends a path calculation request to PCE 1 to request the path to the CRLSP destination.

2. PCE 1 forwards the request to PCE 2.

PCE 1 cannot calculate paths in Area 2, so it forwards the request to PCE 2, the PCE responsible for Area 2 that contains the CRLSP destination.

3. After receiving the request from PCE 1, PCE 2 calculates potential paths to the CRLSP destination and sends the path information back to PCE 1 in a reply.

CE 1 is the ABR that can calculate paths in Area 0 and Area 1. PCE 2 is the

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4. PCE 1 uses the local and received path information to select an end-to-end path for the PCC to reach the CRLSP destination, and sends the path to PCC as a reply.

5. PCC uses the path calculated by PCEs to establish the CRLSP through RSVP-TE.

Figure 25 BRPC path calculation

Traffic forwarding

After an MPLS TE tunnel is established, traffic is not forwarded on the tunnel automatically . You must direct the traffic to the tunnel by using one of the following methods:

Static routing

You can direct traffic to an MPLS TE tunnel by creating a static route that reaches the destination through the tunnel interface. This is the easiest way to implement MPLS TE tunnel forwarding. Whe n traffic to multiple networks is to be forwarded through the MPLS TE tunnel, you must configure multiple static routes, which are complicated to configure and difficult to maintain.

For more information about static routing, see Layer 3—IP Routing Configuration Guide.

Policy-based routing

You can configure PBR on the ingress interface of traffic to direct the traffic that matches an ACL to the MPLS TE tunnel interface.

PBR can match the traffic to be forwarded on the tunnel not only by destination IP address, but also by source IP address, protocol type, and other criteria. Compared with static routing, PBR is more flexible but requires more complicated configuration.

For more information about policy-based routing, see Layer 3—IP Routing Configuration Guide.

Automatic route advertisement

Y ou ca n also configure automatic route advertiseme nt to forward traf fic through an MPLS TE tunnel. Automatic route advertisement distributes the MPLS TE tunnel to the IGP (OSPF or IS-IS), so the MPLS TE tunnel can participate in IGP routing calculation. Automatic route advertisement is easy to configure and maintain.

Automatic route advertisement can be implemented by using the following methods:

• IGP shortcut—Also known as AutoRoute Announce. It consi ders the MPLS TE tunnel as a link that directly connects the tunnel ingress node and the egress node. Only the ingress node uses the MPLS TE tunnel during IGP route calculation.

• Forwarding adjacency—Considers the MPLS TE tunnel as a link that directly connects the tunnel ingress node and the egress node, and advertises the link to the network through an IGP. Every node in the network uses the MPLS TE tunnel during IGP route calculation.

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Figure 26 IGP shortcut and forwarding adjacency diagram

As shown in Figure 26, an MPLS TE tunnel exists from Router D to Router C. IGP shortcut enables only the ingress node Router D to use the MPLS TE tunnel in the IGP route calculation. Router A cannot use this tunnel to reach Router C. With forwarding adjacency enabled, Router A can also know the existence of the MPLS TE tunnel. Router A can use this tunnel to transfer traf fic to Router C by forwarding the traffic to Router D.

Make-before-break

Make-before-break is a mechanism to change an MPLS TE tunnel with minimum data loss and without using extra bandwidth.

In cases of tunnel reoptimization and automatic bandwidth adjustment, traffic forwarding is interrupted if the existing CRLSP is removed before a new CRLSP is established. The make-before-break mechanism ensures that the existing CRLSP is removed after the new CRLS P is established and the traffic is switched to the new CRLSP. However, this wastes bandwidth resources if some links on the old and new CRLSPs are the same. This is because you need to reserve bandwidth on these links for the old and new CRLSPs separately. The make-before-break mechanism uses the SE resource reservation style to address this problem.

The resource reservation style refers to the style in which RSVP-TE reserves bandwidth resources during CRLSP establishment. The resource reservation style used by an MPLS TE tunnel is determined by the ingress node, and is advertised to other nodes through RSVP.

The device supports the following resource reservation styles:

• FF—Fixed-filter, where resources are reserved for individual senders and cannot be sha red among senders on the same session.

• SE—Shared-explicit, where resources are reserved for senders on the same session and shared among them. SE is mainly used for make-before-break.

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Figure 27 Diagram for make-before-break

As shown in Figure 27, a CRLSP with 30 M reserved bandwidth has been set up from Router A to Router D through the path Router A—Router B—Router C—Router D.

To increase the reserved bandwidth to 40 M, a new CRLSP must be set up through the path Router A——Router E—Router C—Router D. To achieve this purpose, RSVP-TE needs to res erve 30 M bandwidth for the old CRLSP and 40 M bandwidth for the new CRLSP on the link Router C—Router D. However, there is not enough bandwidth.

After the make-before-break mechanism is used, the new CRLSP can share the b andwidth reserved for the old CRLSP. After the new CRLSP is set up, traffic is switched to the new CRLSP without service interruption, and then the old CRLSP is removed.

Route pinning

Route pinning enables CRLSPs to always use the original optimal path even if a new optimal route has been learned.

On a network where route changes frequently occur, you can use route pinning to avoid re-establishing CRLSPs upon route changes.

Tunnel reoptimization

Tunnel reoptimization allows you to ma nually or dynamically trigger the ingress node to recalculate a path. If the ingress node recalculates a better path, it creates a new CRLSP, switches traffic from the old CRLSP to the new, and then deletes the old CRLSP.

MPLS TE uses the tunnel reoptimization function to implement dynamic CRLSP optimization. For example, if a link on the optimal path does not have enough reservable bandwidth , MPLS TE sets up the tunnel on another path. When the link has enough bandwidth, the tunnel optimization function can switch the MPLS TE tunnel to the optimal path.

Automatic bandwidth adjustment

Because users cannot estimate accurately how much traffic they need to transmit through a service provider network, the service provider should be able to perform the following operations:

• Create MPLS TE tunnels with the bandwidth initially requested by the users.

• Automatically tune the bandwidth resources when user traffic incre ases.

MPLS TE uses the automatic bandwidth adjustment function to meet this requirement. After the automatic bandwidth adjustment is enabled, the device periodically samples the output rate of the tunnel and computes the average output rate within the sampling interval. When t he auto bandwidth adjustment frequency timer expires, MPLS TE resizes the tunnel bandwidth to the maximum average output rate sampled during the adjustment time for new CRLSP establishment. If the new

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CRLSP is set up successfully, MPLS TE switches traffic to the new CRLSP and clears the old CRLSP.

You can use a command to limit the maximum and minimum bandwidth. If the tunnel bandwidth calculated by auto bandwidth adjustment is greater than the maximum bandwidth, MPLS TE uses the maximum bandwidth to set up the new CRLSP. If it is smaller than the minimum bandwidth, MPLS TE uses the minimum bandwidth to set up the new CRLSP.

CRLSP backup

CRLSP backup uses a CRLSP to back up a primary CRLSP. When the ingress detects that the primary CRLSP fails, it switches traffic to the backup CRLSP. When the primary CRLSP recovers, the ingress switches traffic back.

CRLSP backup has the following modes:

• Hot standby—A backup CRLSP is created immediately after a primary CRLSP is created.

• Ordinary—A backup CRLSP is created after the primary CRLSP fails.

FRR

Fast reroute (FRR) protects CRLSPs from link and node failures. FRR can implement 50-millisecond CRLSP failover.

After FRR is enabled for an MPLS TE tunnel, once a link or node fails on the primary CRLSP, FRR reroutes the traffic to a bypass tunnel. The ingress node attempts to set up a new CRLSP. After the new CRLSP is set up, traffic is forwarded on the new CRLSP.

CRLSP backup provides end-to-end path protection for a CRLSP without time limitation. FRR provides quick but temporary protection for a link or node on a CRLSP.

Basic concepts

• Primary CRLSP—Protected CRLSP.

• Bypass tunnel—An MPLS TE tunnel used to protect a link or node of the primary CRLSP.

• Point of local repair—A PLR is the ingress node of the bypa ss tunnel. It must be located on

the primary CRLSP but must not be the egress node of the primary CRLSP.

• Merge point—An MP is the egress node of the bypass tunnel. It must be located on the primary CRLSP but must not be the ingress node of the primary CRLSP.

Protection modes

FRR provides the following protection modes:

• Link protection—The PLR and the MP are connected through a di rect link and the primary CRLSP traverses this link. When the link fails, traffic is swit ched to the bypass tunnel. As shown in Figure 28, the p tunnel is Router B—Router F—Router C. This mode is also called next-hop (NHOP) protection.

rimary CRLSP is Router A—Route r B—Router C—Router D, and the bypass

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Figure 28 FRR link protection

• Node protection—The PLR and the MP are connected through a device and the primary CRLSP traverses this device. When the device fails, traf fic is swit ched to the bypass tunn el. As shown in Figure 29, the pri

mary CRLSP is Router A—Router B—Router C—Rout er D—Router E, and the bypass tunnel is Router B—Router F—Router D. Router C is the protected device. This mode is also called next-next-hop (NNHOP) protection.

Figure 29 FRR node protection

DiffServ-aware TE

DiffServ is a model that provides differentiated QoS guarantees based on class of service. MPLS TE is a traffic engineering solution that focuses on optimizing network resources allocation.

DiffServ-aware TE (DS-TE) combines Dif fServ and TE to optimize network resources allocation on a per-service class basis. DS-TE defines different bandwidth co nstrai nts for class types. It maps each traffic class type to the CRLSP that is constraint-compliant for the class type.

The device supports these DS-TE modes:

• Prestandard mode—Hewlett Packard Enterprise proprietary DS-TE.

• IETF mode—Complies with RFC 4124, RFC 4125, and RFC 4127.

Basic concepts

• CT—Class Type. DS-TE allocates link bandwidth, implements con straint-based routing, and performs admission control on a per-class type basis. A given traffic flow belongs to the same CT on all links.

• BC—Bandwidth Constraint. BC restricts the bandwidth for one or more CTs.

• Bandwidth constraint model—Algorithm for implementing bandwidth constraint s on different

CTs. A BC model comp rises two factors, the maximum number of BCs (MaxBC) and the mappings between BCs and CTs. DS-TE supports two BC models, Russian Dolls Model (RDM) and Maximum Allocation Model (MAM).

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• TE class—Defines a CT and a priority. The setup priority or holding priority of an MPLS TE tunnel for a CT must be the same as the priority of the TE class.

The prestandard and IETF modes of DS-TE have the following differences:

• The prestandard mode supports two CTs (CT 0 and CT 1), eight priorities, and a maximum of 16 TE classes. The IETF mode supports four CTs (CT 0 through CT 3), eight priorities, and a maximum of eight TE classes.

• The prestandard mode does not allow you to configure TE classes. The IETF mode allows for TE class configuration.

• The prestandard mode supports only RDM. The IETF mode supports both RDM and MAM.

• A device ope rating in prestandard mode cannot comm unicate with devices from some vendors.

A device operating in IETF mode can communicate with devices from other vendors.

How DS-TE operates

A device takes the followi ng steps to establish an MPLS TE tunnel for a CT:

1. Determines the CT. A device classifies traffic according to your configuration:

{ When configuring a dynamic MPLS TE tunnel, you can use the mpls te bandwidth

command on the tunnel interface to specify a CT for the traf fic to be forwarded by the tunnel.

{ When configuring a static MPLS TE tunnel, you can use the bandwidth keyword to specify

a CT for the traffic to be forwarded along the tunnel.

2. Checks whether bandwidth is enough for the CT. You can use the mpls te max-reservable-bandwidth command on an interface to configure

the bandwidth constraints of the interface. The device determines whether the bandwidth is enough to establish an MPLS TE tunnel for the CT.

The relation between BCs and CTs varies by BC model.

{ In RDM model, a BC constrains the total bandwidth of multiple CTs, as shown in Figure 30:

− BC 2 is for CT 2. The total bandwidth for CT 2 cannot exceed BC 2.

− BC 1 is for CT 2 and CT 1. The total ban dwidth fo r CT 2 and CT 1 cannot exceed BC 1.

− BC 0 is for CT 2, CT 1, and CT 0. The total bandwidth for CT 2, CT 1, and CT 0 cannot

exceed BC 0. In this model, BC 0 equals the maximum reservable bandwidth of the link.

In cooperation with priority preemption, the RDM model can also implement bandwidth isolation between CTs. RDM is suitable for networks where traffic is unstable and traffic bursts might occur.

Figure 30 RDM bandwidth constraints model

{ In MAM model, a BC constrains the bandwidth for only one CT. This ensures bandwidth

isolation among CTs no matter whether preemption is used or not. Compared with RDM, MAM is easier to configure. MAM is suitable for networks where traffic of each CT is stable and no traffic bursts occur. Figure 31 sho

ws an example:

− BC 0 is for CT 0. The bandwidth occupied by the traffic of CT 0 cannot exceed BC 0.

− BC 1 is for CT 1. The bandwidth occupied by the traffic of CT 1 cannot exceed BC 1.

− BC 2 is for CT 2. The bandwidth occupied by the traffic of CT 2 cannot exceed BC 2.

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− The total bandwidth occupied by CT 0, CT 1, and CT 2 cannot exceed the maximum reservable bandwidth.

Figure 31 MAM bandwidth constraints model

CT 0

BC 0

CT 1

BC 1

CT 2

BC 2

CT 0 CT 1 CT 2

Max reservable BW

3. Checks whether the CT and the LSP setup/holding priority match an existing TE class. An MPLS TE tunnel can be established for the CT only when the following conditions are met:

{ Every node along the tunnel has a TE class that matches the CT and the LSP setup priority. { Every node along the tunnel has a TE class that matches the CT and the LSP holding

priority.

Bidirectional MPLS TE tunnel

MPLS Transport Profile (MPLS-TP) uses bidirectional MPLS TE tunnels to implement 1:1 and 1+1 protection switching, and to support in-band detection tools and signaling protocols such as OAM and PSC.

A bidirectional MPLS TE tunnel includes a pair of CRLSPs in opposite directions. It can be established in the following modes:

• Co-routed mode—Uses the extended RSVP-TE protocol to establish a bidirectional MPLS TE tunnel. RSVP-TE uses a Path message to advertise the labels assigned by the upstream LSR to the downstream LSR. RSVP-TE uses a Resv message to advertise the labels assigned by the downstream LSR to the upstream LSR. During the delivery of the path message, a CRLSP in one direction is established. During the delivery of the Resv message, a CRLSP in the other direction is established. The CRLSPs of a bidirectional MPLS TE tunnel established in co-routed mode use the same path.

• Associated mode—In this mode, you establish a bidirectional MPLS TE tunnel by binding two unidirectional CRLSPs in opposite directions. The two CRLSPs can be established in different modes and use different paths. For example, one CRLSP is established staticall y and the other CRLSP is established dynamically by RSVP-TE.

For more information about establishing MPLS TE tunnel through RSVP-TE, the Path message, and the Resv message, see "Configuring RSVP."

Protocols and standards

• RFC 2702, Requirements for Traffic Engineering Over MPLS

• RFC 3564, Requirements for Support of Differentiated Service-aware MPLS Traffic

Engineering

• RFC 3812, Multiprotocol Label Switching (MPLS) Traffic Engineering (TE) Management Information Base (MIB)

• RFC 4124, Protocol Extensions for Support of Diffserv-aware MPLS Traffic Engineering

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• RFC 4125, Maximum Allocation Bandwidth Constraints Model for Diffserv-aware MPLS Traffic Engineering

• RFC 4127, Russian Dolls Bandwidth Constraints Model for Diffserv-aware MPLS Traffic Engineering

• ITU-T Recommendation Y.1720, Protection switching for MPLS networks

• RFC 4655, A Path Computation Element (PCE)-Based Architecture

• RFC 5088, OSPF Protocol Extensions for Path Computation Element Discovery

• RFC 5440, Path Computation Element (PCE) Communication Protocol (PCEP)

• RFC 5441, A Backwa rd-R e cur si ve PCE -B ased Com p utation (BRPC) Procedure to Compute

Shortest Constrained Inter-Domain Traffic Engineering LSP

• RFC 5455, Diffserv-Aware Class-Type Object for the Path Computation Element Communication Protocol

• RFC 5521, Extensions to the Path Computation Element Communication Protocol (PCEP) for Route Exclusions

• RFC 5886, A Set of Monitoring Tools for Path Computation Element (PCE)-Based Architecture

• draft-ietf-pce-stateful-pce-07

MPLS TE configuration task list

To configure an MPLS TE tunnel to use a static CRLSP, perform the following tasks:

1. Enable MPLS TE on each node and interface that the MPLS TE tunnel traverses.

2. Create a tunnel interface on the ingress node of the MPLS TE tunnel, and specify the tunnel

destination address—the address of the egress node.

3. Create a static CRLSP on each node that the MPLS TE tunnel traverses. For information about creating a static CRLSP, see "Configuring a static CRLSP."

4. On the ingress nod created static CRLSP.

5. On the ingress node of the MPLS TE tunnel, configure static routing, PBR, or automatic route advertisement to direct traffic to the MPLS TE tunnel.

To configure an MPLS TE tunnel to use a CRLSP dynamically established by RSVP-TE, perform the following tasks:

1. Enable MPLS TE and RSVP on each node and interface that the MPLS TE tunnel traverses. For information about enabling RSVP, see "Configuring RSVP."

2. Cre

3. Configure the link TE attributes (such as the maximum link bandwidth and link attribute) on

4. Configure an IGP on each node that the MPLS TE tunnel traverses, and configure the IGP to

5. On the ingress node of the MPLS TE tunnel, configure RSVP-TE to establish a CRLSP based

6. On the ingress node of the MPLS TE tunnel, configure static routing, PBR, or automatic route

ate a tunnel interface on the ingress node of the MPLS TE tunnel. On the tunnel interface, specify the tunnel destination address (the egress node IP address), and configure MPLS TE tunnel constraints (such as the tunnel bandwidth constraints and affinity).

each interface that the MPLS TE tunnel traverses.

support MPLS TE. Then, the nodes can advertise the link TE attributes through the IGP.

on the tunnel constraints and link TE attributes.

advertisement to direct traffic to the MPLS TE tunnel.

e of the MPLS TE tunnel, configure the tunnel interface to reference the

To configure an MPLS TE tunnel to use a PCE-calculated path to establish a CRLSP, perform the following tasks:

1. Enable MPLS TE and RSVP on each node and interface that the MPLS TE tunnel traverses.

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For information about enabling RSVP, see "Configuring RSVP."

2. Specify an LSR as a PCE and configure an IP address for the PCE.

3. Create a tunnel interface on the ingress node of the MPLS TE tunnel. On the tunnel interface,

specify the tunnel destination address (the egress node IP address), and configure MPLS TE tunnel constraints (such as the tunnel bandwidth constraints and affinity).

4. Configure link TE attributes (such as the maximum link bandwidth and link attribute) on each interface that the MPLS TE tunnel traverses.

5. Configure an IGP on each node that the MPLS TE tunnel traverses, and configure the IGP to support MPLS TE. Then, the nodes can advertise the link TE attributes through the IGP.

6. Configure the ingress node of the MPLS TE tunnel to use the path calculated by the PCE. Manually specify the PCE or configure OSPF TE to dynamically discover the PCE on the ingress node (PCC).

7. On the ingress node of the MPLS TE tunnel, configure RSVP-TE to establish a CRLSP based on the path calculated by the PCE.

8. On the ingress node of the MPLS TE tunnel, configure static routing, PBR, or automatic route advertisement to direct traffic to the MPLS TE tunnel.

You can also configure other MPLS TE functions such as the DS-TE, automatic bandwidth adjustment, and FRR as needed.

To configure MPLS TE, perform the following tasks:

Tasks at a glance

(Required.) Enabling MPLS TE (Required.) Configuring a tunnel interface (Optional.) Configuring DS-TE (Required.) Perform one of the following tasks to configure an MPLS TE tunnel:

• Configuring an MPLS TE tunnel to use a static CRLSP

• Configuring an MPLS TE tunnel to use a dynamic CRLSP

• Configuring an MPLS TE tunnel to use a CRLSP calculated by PCEs

(Optional.) Configuring load sharing for an MPLS TE tunnel (Required.) Configuring traffic forwarding:

• Configuring static routing to direct traffic to an MPLS TE tunnel or tunnel bundle

• Configuring PBR to direct traffic to an MPLS TE tunnel or tunnel bundle

• Configuring automatic route advertisement to direct traf

(Optional.) Configuring a bidirectional MPLS TE tunnel (Optional.) Configuring CRLSP backup

Only MPLS TE tunnels established by RSVP-TE support this configuration. (Optional.) Configuring MPLS TE FRR

Only MPLS TE tunnels established by RSVP-TE support this configuration. (Optional.) Enabling SNMP notifications for MPLS TE

fic to an MPLS TE tunnel or tunnel bundle

Enabling MPLS TE

Enable MPLS TE on each node and interface that the MPLS TE tunnel traverse s. Before you enable MPLS TE, perform the following tasks:

• Configure static routing or IGP to ensure that all LSRs can reach each other.

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• Enable MPLS. For information about enabling MPLS, see "Configuring basic MPLS."

To enable MPLS TE:

Step Command Remarks

1. Enter system view.

system-view

N/A

2. Enter MPLS TE view.

3. Return to system view.

4. Enter interface view.

5. Enable MPLS TE for the

interface.

mpls te

quit interface

interface-number

mpls te enable

interface-type

Configuring a tunnel interface

To configure an MPLS TE tunnel, you must create an MPLS TE tunnel interface and enter tunnel interface view. All MPLS TE tunnel attributes are configured in tunnel interface view. For more information about tunnel interfaces, see Layer 3—IP Servi ce s Conf iguration Guide.

Perform this task on the ingress node of the MPLS TE tunnel. To configure a tunnel interface:

Step Command Remarks

1. Enter system view.

2. Create an MPLS TE tunnel

interface and enter tunnel interface view.

3. Configure an IP address for the tunnel interface.

4. Specify the tunnel destination address.

system-view

interface tunnel mode mpls-te

ip address

{ mask-length | mask }

destination

tunnel-number

ip-address

By default, MPLS TE is disabled.

N/A

By default, MPLS TE is disabled on an interface.

N/A By default, no tunnel interface is

created. By default, a tunnel interface does

not have an IP address. By default, no tunnel destination

address is specified.

Configuring DS-TE

DS-TE is configurable on any node that an MPLS TE tunnel traverses. To configure DS-TE:

Step Command Remarks

1. Enter system view.

2. Enter MPLS TE view.

3. (Optional.) Configure the DS-TE

mode as IETF.

4. (Optional.) Configure the BC model of IETF DS-TE as MAM.

5. Configure a TE class.

system-view mpls te

ds-te mode ietf

ds-te bc-model mam

ds-te te-class class-type

te-class-index

N/A N/A By default, the DS-TE mode is

prestandard

By default, the BC model of IETF DS-TE is RDM.

The default TE classes for IETF mode are shown in Table 1.

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Step Command Remarks

class-type-number pri-number

priority

In prestandard mode, you cannot configure TE classes.

Table 1 Default TE classes in IETF mode

TE Class CT Priority

0 0 7 1 1 7 2 2 7 3 3 7 4 0 0 5 1 0 6 2 0 7 3 0

Configuring an MPLS TE tunnel to use a static CRLSP

To configure an MPLS TE tunnel to use a static CRLSP, perform the following tasks:

• Establish the static CRLSP.

• Specify the MPLS TE tunnel establishment mode as static.

• Configure the MPLS TE tunnel to reference the static CRLSP.

Other configurations, such as tunnel constraints and IGP extension, are not needed. To configure an MPLS TE tunnel to use a static CRLSP:

Step Command Remarks

1. Enter system view.

2. Create a static CRLSP.

3. Enter MPLS TE tunnel

interface view.

4. Specify the MPLS TE tunnel establishment mode as static.

5. Apply the static CRLSP to the tunnel interface.

system-view

See "Configuring a static CRLSP."

interface tunnel

mode mpls-te

[

mpls te signaling static

mpls te static-cr-lsp

tunnel-number

]

lsp-name

N/A N/A Execute this command on the

ingress node. By default, MPLS TE uses

RSVP-TE to establish a tunnel. By default, a tunnel does not

reference any static CRLSP.

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Configuring an MPLS TE tunnel to use a dynamic CRLSP

To configure an MPLS TE tunnel to use a CRLSP dynamically established by RSVP-TE, perform the following tasks:

• Configure MPLS TE attributes for the links.

• Configure IGP TE extension to advertise link TE attributes, so as to generate a TEDB on each

node.

• Configure tunnel constraints.

• Establish the CRLSP by using the signaling protocol RSVP-TE.

You must configure the IGP TE extension to form a TEDB. Otherwise, the path is created based on IGP routing rather than computed by CSPF.

Configuration task list

To establish an MPLS TE tunnel by using a dynamic CRLSP:

Tasks at a glance

(Required.) Configuring MPLS TE attributes for a link (Required.) Advertising link TE attributes by using IGP TE extension (Required.) Configuring MPLS TE tunnel constraints (Required.) Establishing an MPLS TE tunnel by using RSVP-TE (Optional.) Controlling CRLSP path selection (Optional.) Controlling MPLS TE tunnel setup

Configuring MPLS TE attributes for a link

MPLS TE attributes for a link include the maximum link bandwidth, the maximum reservable bandwidth, and the link attribute.

Perform this task on each interface that the MPLS TE tunnel traverses. To configure the link TE attributes:

Step Command Remarks

1. Enter system view.

2. Enter interface view.

3. Set the maximum link

bandwidth for MPLS TE traffic.

system-view interface

mpls te max-link-bandwidth

bandwidth-value

interface-type interface-number N/A

N/A

By default, the maximum link bandwidth for MPLS TE traffic is 0.

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Step Command Remarks

• Configure the maximum reservable bandwidth of the link (BC 0) and BC 1 in RDM model of the prestandard DS-TE:

mpls te max-reservable-bandwidth

4. Set the maximum

reservable bandwidth.

bandwidth-value [ bc1 bc1-bandwidth ]

• Configure the maximum reservable bandwidth of the link and the BCs in MAM model of the IETF DS-TE:

mpls te max-reservable-bandwidth mam bandwidth-value { bc0 bc0-bandwidth | bc1 bc1-bandwidth | bc2 bc2-bandwidth | bc3

bc3-bandwidth } *

• Configure the maximum reservable bandwidth of the link and the BCs in RDM model of the IETF DS-TE:

mpls te max-reservable-bandwidth rdm bandwidth-value [ bc1

bc1-bandwidth ] [ bc2 bc2-bandwidth ] [ bc3 bc3-bandwidth ]

Use one command according to the DS-TE mode and BC model configured in "Configuring DS-TE."

By default, the maximum reservable bandwidth of a link is 0 kbps and each BC is 0 kbps.

In RDM model, BC 0 is the maximum reservable bandwidth of a link.

5. Set the link attribute.

mpls te link-attribute

attribute-value

By default, the link attribute value is 0x00000000.

Advertising link TE attributes by using IGP TE extension

Both OSPF and IS-IS are extended to advertise link TE attributes. The extensions are called OSPF TE and IS-IS TE. If both OSPF TE and IS-IS TE are available, OSPF TE takes precedence.

Configuring OSPF TE

OSPF TE uses Type-10 opaque LSAs to carry the TE attributes for a link. Before you configure OSPF TE, you must enable opaque LSA advertisement and reception by using the opaque-capability enable command. For more information about opaque LSA advertisement and reception, see Layer 3—IP Routing Configuration Guide.

MPLS TE cannot reserve resources and distribute labels for an OSPF virtual link, and cannot establish a CRLSP through an OSPF virtual link. Therefore, make sure no virtual link exists in an OSPF area before you configure MPLS TE.

To configure OSPF TE:

Step Command Remarks

1. Enter system view.

2. Enter OSPF view.

system-view ospf

[ process-id ] N/A

N/A

3. Enable opaque LSA advertisement and reception.

4. Enter area view.

5. Enable MPLS TE for the

OSPF area.

By default, opaque LSA advertisement and reception are

opaque-capability enable

area

area-id N/A

mpls te enable

enabled. For more information about this

command, see Layer 3—IP Routing Command Reference.

By default, an OSPF area does not support MPLS TE.

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Configuring IS-IS TE

IS-IS TE uses a sub-TLV of the extended IS reachability TLV (type 22) to carry TE attributes. Because the extended IS reachability TLV carries wide metrics, specify a wide metric-compatible metric style for the IS-IS process before enabling IS-IS TE. Available metric styles for IS-IS TE include wide, compatible, or wide-compatible. For more information about IS-IS, see Layer 3—IP Routing Configuration Guide.

Because of the following conditions, specify an MTU that is equal to or greater than 512 bytes on each IS-IS enabled interface for IS-IS LSPs to be flooded on the network:

• The length of the extended IS reachability TLV might reach the maximum of 255 bytes.

• The LSP header takes 27 bytes and the TLV header takes two bytes.

• The LSP might also carry the authentication information.

To configure IS-IS TE:

Step Command Remarks

1. Enter system view.

2. Create an IS-IS process

and enter IS-IS view.

system-view

isis

[ process-id ] By default, no IS-IS process exists.

N/A

3. Specify a metric style.

4. Enable MPLS TE for the

IS-IS process.

5. Specify the types of the sub-TLVs for carrying DS-TE parameters.

cost-style wide-compatible

narrow-compatible

relax-spf-limit

[

mpls te enable Level-2

te-subtlv unreserved-subpool-bw

narrow

{

] }

Level-1

[

]

bw-constraint

{

wide

compatible

| {

}

value |

value }

Configuring MPLS TE tunnel constraints

Perform this task on the ingress node of the MPLS TE tunnel.

Configuring bandwidth constraints for an MPLS TE tunnel

Step Command Remarks

1. Enter system view.

2. Enter MPLS TE tunnel

interface view.

3. Configure bandwidth required for the tunnel, and specify a CT for the tunnel's traffic.

system-view interface tunnel

mode mpls-te

[

mpls te bandwidth ct2 | ct3

] bandwidth

tunnel-number

]

ct0

ct1 |

[

By default, only narrow metric style packets can be received and sent.

For more information about this command, see Layer 3—IP Routing Command Reference.

By default, an IS-IS process does not support MPLS TE.

By default, the parameter is carried in sub-TLV 252, and the

unreserved-bw-sub-pool

parameter is carried in sub-TLV

251.

N/A

By default, no bandwidth is assigned, and the class type is CT

bw-constraint

Configuring the affinity attribute for an MPLS TE tunnel

The associations between the link attribute and the af finity attribute might vary by vendor. To ensure the successful establishment of a tunnel between two devices from different vendors, correctly configure their respective link attribute and affinity attribute.

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To configure the affinity attribute for an MPLS TE tunnel:

Step Command Remarks

1. Enter system view.

2. Enter MPLS TE tunnel

interface view.

system-view interface tunnel

mode mpls-te

[

tunnel-number

]

N/A

3. Set an affinity for the MPLS TE tunnel.

mpls te affinity-attribute

attribute-value [ mask-value ]

mask

By default, the affinity is 0x00000000, and the mask is 0x00000000. The default affinity matches all link attributes.

Configuring a setup priority and a holding priority for an MPLS TE tunnel

Step Command Remarks

1. Enter system view.

2. Enter MPLS TE tunnel

interface view.

3. Set a setup priority and a holding priority for the MPLS TE tunnel.

system-view interface tunnel

mode mpls-te

[

mpls te priority

[ hold-priority ]

tunnel-number

]

setup-priority

N/A

By default, the setup priority and the holding priority are both 7 for an MPLS TE tunnel.

Configuring an explicit path for an MPLS TE tunnel

An explicit path is a set of nodes. The relationship between any two neighboring nodes on an explicit path can be either strict or loose.

• Strict—The two nodes must be directly connected.

• Loose—The two nodes can have devices in between.

When establishing an MPLS TE tunnel between areas or ASs, you must do the following:

• Use a loose explicit path.

• Specify the ABR or ASBR as the next hop of the path.

• Make sure the tunnel's ingress node and the ABR or ASBR can reach each other.

To configure an explicit path for a MPLS TE tunnel:

Step Command Remarks

1. Enter system view.

2. Create an explicit path and

enter its view.

3. Enable the explicit path.

4. Add or modify a node in the

explicit path.

5. Return to system view.

6. Enter MPLS TE tunnel

interface view.

system-view

explicit-path

undo disable

nexthop

ip-address [

loose

[

quit

interface tunnel

[

index

strict

path-name

exclude

] ]

index-number ]

include

tunnel-number

N/A By default, no explicit path exists

on the device. By default, an explicit path is

enabled. By default, an explicit path does

not include any node. You can specify the

keyword to have the CRLSP traverse the specified node or the

exclude

CRLSP bypass the specified node.

N/A

keyword to have the

include

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Step Command Remarks

mode mpls-te

7. Configure the MPLS TE

tunnel interface to use the explicit path, and specify a preference value for the explicit path.

[

mpls te path preference explicit-path

no-cspf

[

path-name

]

value

By default, MPLS TE uses the calculated path to establish a CRLSP.

Establishing an MPLS TE tunnel by using RSVP-TE

Before you configure this task, you must use the rsvp command and the rsvp enable command to enable RSVP on all nodes and interfaces that the MPLS TE tunnel traverses.

Perform this task on the ingress node of the MPLS TE tunnel. To configure RSVP-TE to establish an MPLS TE tunnel:

Step Command Remarks

1. Enter system view.

2. Enter MPLS TE tunnel

interface view.

3. Configure MPLS TE to use RSVP-TE to establish the tunnel.

4. Specify an explicit path for the MPLS TE tunnel, and specify the path preference value.

system-view interface tunnel

mode mpls-te

[

mpls te signaling rsvp-te

mpls te path preference

dynamic | explicit-path

{ path-name } [

tunnel-number

]

no-cspf ]

value

N/A

By default, MPLS TE uses RSVP-TE to establish a tunnel.

By default, MPLS TE uses the calculated path to establish a CRLSP.

Controlling CRLSP path selection

Before performing the configuration tasks in this section, be aware of each configuration objective and its impact on your device.

MPLS TE uses CSPF to calculate a path according to the TEDB and constraints and sets up the CRLSP through RSVP-TE. MPLS TE provides measures that affect the CSPF calculation. You can use these measures to tune the path selection for CRLSP.

Configuring the metric type for path selection

Each MPLS TE link has two metrics: IGP metric and TE metric. By planning the two metrics, you can select different tunnels for dif ferent classes of traf fic. For exam ple, use the IGP metric to rep resent a link delay (a smaller IGP metric value indicates a lower link delay), and use the TE metric to represent a link bandwidth value (a smaller TE metric value indicates a bigger link bandwidth val ue).

You can establish two MPLS TE tunnels: Tunnel 1 for voice traffic and Tunnel 2 for video traffic. Configure Tunnel 1 to use IGP metrics for path selection, and configure Tunnel 2 to use TE metrics for path selection. As a result, the video service (with larger traffic) travels through the path that has larger bandwidth, and the voice traffic travels through the path that has lower delay.

To configure the metric type for tunnel path selection:

Step Command Remarks

1. Enter system view.

2. Enter MPLS TE view.

system-view mpls te

N/A N/A

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Step Command Remarks

3. Specify the metric type to

use when no metric type is explicitly configured for a tunnel.

path-metric-type

{

igp

| te }

By default, a tunnel uses the TE metric for path selection.

Execute this command on the ingress node of an MPLS TE tunnel.

4. Return to system view.

5. Enter MPLS TE tunnel

interface view.

6. Specify the metric type for path selection.

7. Return to system view.

8. Enter interface view.

9. Assign a TE metric to the

link.

Configuring route pinning

When route pinning is enabled, MPLS TE tunnel reoptimization and automatic bandwidth adjustment are not available.

Perform this task on the ingress node of an MPLS TE tunnel.

quit interface tunnel

mode mpls-te

[

mpls te path-metric-type te

}

quit interface

interface-number

mpls te metric

interface-type

tunnel-number

]

value

{

igp

N/A

By default, no link metric type is specified and the one specified in MPLS TE view is used.

Execute this command on the ingress node of an MPLS TE tunnel.

N/A

By default, the link uses its IGP metric as the TE metric.

This command is available on every interface that the MPLS TE tunnel traverses.

To configure route pinning:

Step Command Remarks

1. Enter system view.

2. Enter MPLS TE tunnel

interface view.

3. Enable route pinning.

Configuring tunnel reoptimization

Tunnel reoptimization allows you to ma nually or dynamically trigger the ingress node to recalculate a path. If the ingress node recalculates a better path, it creates a new CRLSP, switches the traffic from the old CRLSP to the new CRLSP, and then deletes the old CRLSP.

Perform this task on the ingress node of an MPLS TE tunnel. To configure tunnel reoptimization:

Step Command Remarks

1. Enter system view.

2. Enter MPLS TE tunnel

interface view.

system-view interface tunnel

mode mpls-te

[

mpls te route-pinning

system-view interface tunnel

mode mpls-te

[

tunnel-number

]

tunnel-number

]

N/A

By default, route pinning is disabled.

N/A

HP E MSR Router Configuration Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Contents

Configuring basic MPLS

Overview

Basic concepts

Label

LFIB

Control plane and forwarding plane

MPLS network architecture

LSP establishment

MPLS forwarding

Protocols and standards

Compatibility information

MPLS configuration task list

Enabling MPLS

Setting MPLS MTU

Specifying the label type advertised by the egress

Configuration guidelines

Configuration procedure

Configuring TTL propagation

Enabling sending of MPLS TTL-expired messages

Enabling MPLS forwarding statistics

Enabling FTN forwarding statistics

Enabling MPLS label forwarding statistics for LSPs

Enabling MPLS label forwarding statistics for a VPN instance

Enabling split horizon for MPLS forwarding

Enabling SNMP notifications for MPLS

Displaying and maintaining MPLS

Configuring a static LSP

Overview

Configuration prerequisites

Configuration procedure

Displaying static LSPs

Static LSP configuration example

Network requirements

Configuration restrictions and guidelines

Configuration procedure

Verifying the configuration

Configuring LDP

Overview

Terminology

LDP session

LDP peer

Label spaces and LDP identifiers

FECs and FEC-label mappings

LDP messages

LDP operation

Discovering and maintaining LDP peers

Establishing and maintaining LDP sessions

Establishing LSPs

Label distribution and control

Label advertisement modes

Label distribution control

Label retention mode

LDP GR

LDP NSR

LDP-IGP synchronization

Basic operating mechanism

Notification delay for LDP convergence completion

Notification delay for LDP restart or active/standby switchover

LDP FRR

LDP over MPLS TE

Protocols

Compatibility information

LDP configuration task list

Enabling LDP

Enabling LDP globally

Enabling LDP on an interface

Configuring Hello parameters

Setting Link Hello timers

Setting Targeted Hello timers for an LDP peer

Configuring LDP session parameters

Configuring LDP sessions parameters for Basic Discovery mechanism

Configuring LDP IPv4 sessions parameters for Extended Discovery mechanism

Configuring LDP IPv6 sessions parameters for Extended Discovery mechanism

Configuring LDP backoff

Configuring LDP MD5 authentication