HP 6125XLG Layer 3—IP Routing Configuration Guide

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HP 6125XLG Blade Switch

Layer 3—IP Routing Configuration Guide

Part number: 5998-3719

Software version: Rlease 2306

Document version: 6W100-20130912

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Contents

IP routing basics ··························································································································································· 1

Routing table ······································································································································································ 1 Dynamic routing protocols ··············································································································································· 2 Route preference ······························································································································································· 2 Load sharing ······································································································································································ 3 Route backup ····································································································································································· 3 Route recursion ·································································································································································· 3 Route redistribution ··························································································································································· 3 Configuring the maximum number of ECMP routes ······································································································ 4 Displaying and maintaining a routing table ·················································································································· 4

Configuring static routing ············································································································································ 6

Configuring a static route ················································································································································· 6 Configuring BFD for static routes ····································································································································· 7

Bidirectional control mode ······································································································································ 7 Single-hop echo mode ············································································································································· 8

Configuring static route FRR ············································································································································· 9

Configuration guidelines ········································································································································· 9

Configuration procedure ········································································································································· 9 Displaying and maintaining static routes ···················································································································· 10 Static route configuration examples ····························································································································· 10

Basic static route configuration example ············································································································ 10

BFD for static routes configuration example (direct next hop) ·········································································· 12

BFD for static routes configuration example (indirect next hop) ······································································· 14

Static route FRR configuration example ·············································································································· 17

Configuring a default route ······································································································································· 19

Configuring RIP ·························································································································································· 20

RIP route entries ····················································································································································· 20

Routing loop prevention ········································································································································ 20

RIP operation ·························································································································································· 20

RIP versions ···························································································································································· 21

Protocols and standards ······································································································································· 21 RIP configuration task list ··············································································································································· 21 Configuring basic RIP ···················································································································································· 22

Enabling RIP ··························································································································································· 22

Controlling RIP reception and advertisement on interfaces ·············································································· 23

Configuring a RIP version ····································································································································· 23 Configuring RIP route control ········································································································································ 24

Configuring an additional routing metric ··········································································································· 24

Configuring RIPv2 route summarization·············································································································· 25

Disabling host route reception ····························································································································· 26

Advertising a default route ··································································································································· 26

Configuring received/redistributed route filtering ····························································································· 27

Configuring a preference for RIP ························································································································· 27

Configuring RIP route redistribution ····················································································································· 27 Tuning and optimizing RIP networks ···························································································································· 28

Configuration prerequisites ·································································································································· 28

Configuring RIP timers ··········································································································································· 28

Configuring split horizon and poison reverse ···································································································· 29

Configuring the maximum number of ECMP routes ·························································································· 29

Enabling zero field check on incoming RIPv1 messages ·················································································· 30

Enabling source IP address check on incoming RIP updates ············································································ 30

Configuring RIPv2 message authentication ········································································································ 31

Configuring the RIP packet sending rate ············································································································ 31 Configuring RIP GR ························································································································································ 31 Configuring BFD for RIP ················································································································································· 32 Configuring RIP FRR ······················································································································································· 32 Displaying and maintaining RIP ··································································································································· 33 RIP configuration examples ··········································································································································· 34

Configuring basic RIP ··········································································································································· 34

Configuring an additional metric for a RIP interface ························································································· 38

Configuring RIP to advertise a summary route ··································································································· 40

Configuring BFD for RIP (single-hop echo detection) ························································································· 42

Configuring RIP FRR ·············································································································································· 45

Configuring OSPF ······················································································································································ 48

OSPF packets ························································································································································· 48

LSA types ································································································································································ 49

OSPF areas ···························································································································································· 49

Router types ···························································································································································· 51

Route types ····························································································································································· 52

Route calculation ··················································································································································· 53

OSPF network types ·············································································································································· 53

DR and BDR ··························································································································································· 53

Protocols and standards ······································································································································· 54 OSPF configuration task list ·········································································································································· 55 Enabling OSPF ······························································································································································· 56

Configuration procedure ······································································································································ 57 Configuring OSPF areas ··············································································································································· 57

Configuring a stub area ······································································································································· 58

Configuring an NSSA area ·································································································································· 58

Configuring a virtual link ······································································································································ 59 Configuring OSPF network types ································································································································· 59

Configuring the broadcast network type for an interface ················································································· 60

Configuring the NBMA network type for an interface ······················································································ 60

Configuring the P2MP network type for an interface ························································································ 61

Configuring the P2P network type for an interface ··························································································· 62 Configuring OSPF route control ··································································································································· 62

Configuring OSPF route summarization ············································································································· 62

Configuring inbound OSPF route filtering ·········································································································· 63

Configuring Type-3 LSA filtering ·························································································································· 64

Configuring an OSPF cost for an interface ········································································································ 64

Configuring the maximum number of ECMP routes ·························································································· 65

Configuring OSPF preference ······························································································································ 65

Configuring OSPF route redistribution ················································································································ 66

Advertising a host route ········································································································································ 67

iii

Tuning and optimizing OSPF networks ························································································································ 67

Configuring OSPF timers ······································································································································ 68

Specifying LSA transmission delay ······················································································································ 68

Specifying SPF calculation interval ······················································································································ 69

Specifying the LSA arrival interval ······················································································································· 69

Specifying the LSA generation interval ··············································································································· 70

Disabling interfaces from receiving and sending OSPF packets ······································································ 70

Configuring stub routers ······································································································································· 71

Configuring OSPF authentication ························································································································ 71

Adding the interface MTU into DD packets ········································································································ 72

Configuring the maximum number of external LSAs in LSDB ··········································································· 72

Configuring OSPF exit overflow interval ············································································································· 73

Enabling compatibility with RFC 1583 ··············································································································· 73

Logging neighbor state changes ·························································································································· 73

Configuring OSPF network management ··········································································································· 74

Configuring the LSU transmit rate ························································································································ 74

Enabling OSPF ISPF ·············································································································································· 75 Configuring OSPF GR ··················································································································································· 75

Configuring the OSPF GR Restarter ····················································································································· 75

Configuring OSPF GR Helper ······························································································································ 76

Triggering OSPF GR ············································································································································· 77 Configuring BFD for OSPF ············································································································································ 77

Configuring bidirectional control detection ········································································································ 77

Configuring single-hop echo detection ··············································································································· 78 Configuring OSPF FRR ··················································································································································· 78

Configuring OSPF FRR to calculate a backup next hop using the LFA algorithm ·········································· 79

Configuring OSPF FRR to specify a backup next hop using a routing policy ················································· 79 Displaying and maintaining OSPF ······························································································································· 80 OSPF configuration examples ······································································································································ 81

Configuring basic OSPF ······································································································································· 81

Configuring OSPF route redistribution ················································································································ 84

Configuring OSPF to advertise a summary route ······························································································· 85

Configuring an OSPF stub area··························································································································· 88

Configuring an OSPF NSSA area ······················································································································· 91

Configuring OSPF DR election ····························································································································· 93

Configuring OSPF virtual links ····························································································································· 97

Configuring OSPF GR ··········································································································································· 99

Configuring BFD for OSPF ································································································································· 101

Configuring OSPF FRR ········································································································································ 104 Troubleshooting OSPF configuration ························································································································· 106

No OSPF neighbor relationship established ···································································································· 106

Incorrect routing information ······························································································································ 107

Configuring IS-IS ····················································································································································· 108

Terminology ························································································································································· 108

IS-IS address format ············································································································································· 108

NET ······································································································································································· 109

IS-IS area ······························································································································································ 110

IS-IS network types ·············································································································································· 112

IS-IS PDUs ····························································································································································· 113

IS-IS configuration task list ··········································································································································· 115 Configuring basic IS-IS ················································································································································ 116

Enabling IS-IS ······················································································································································· 116

Configuring the IS level and circuit level ·········································································································· 116

Configuring P2P network type for an interface ································································································ 117 Configuring IS-IS route control ···································································································································· 117

Configuring IS-IS link cost ··································································································································· 118

Specifying a preference for IS-IS ······················································································································· 119

Configuring the maximum number of ECMP routes ························································································ 119

Configuring IS-IS route summarization ·············································································································· 120

Configuring IS-IS route redistribution ················································································································ 121

Configuring IS-IS route filtering ·························································································································· 121

Configuring IS-IS route leaking ·························································································································· 122 Tuning and optimizing IS-IS networks ························································································································ 122

Specifying intervals for sending IS-IS hello and CSNP packets ····································································· 123

Specifying the IS-IS hello multiplier ···················································································································· 123

Configuring a DIS priority for an interface ······································································································· 123

Disabling an interface from sending/receiving IS-IS packets ········································································· 124

Enabling an interface to send small hello packets ··························································································· 124

Configuring LSP parameters ······························································································································· 124

Controlling SPF calculation interval ··················································································································· 127

Configuring convergence priorities for specific routes ···················································································· 127

Setting the LSDB overload bit ····························································································································· 128

Configuring system ID to host name mappings ································································································ 128

Enabling the logging of neighbor state changes ····························································································· 129

Enabling IS-IS ISPF ··············································································································································· 130 Enhancing IS-IS network security ································································································································ 130

Configuring neighbor relationship authentication ··························································································· 130

Configuring area authentication ························································································································ 131

Configuring routing domain authentication ······································································································ 131 Configuring IS-IS GR ···················································································································································· 132 Configuring BFD for IS-IS············································································································································· 133 Configuring IS-IS FRR ··················································································································································· 133

Configuring IS-IS FRR to automatically calculate a backup next hop ···························································· 134

Configuring IS-IS FRR using a routing policy ···································································································· 134 Displaying and maintaining IS-IS ······························································································································· 135 IS-IS configuration examples ······································································································································· 135

Basic IS-IS configuration example ····················································································································· 135

DIS election configuration example ··················································································································· 140

IS-IS route redistribution configuration example ······························································································ 144

IS-IS authentication configuration example······································································································· 147

IS-IS GR configuration example ························································································································· 150

BFD for IS-IS configuration example ·················································································································· 151

IS-IS FRR configuration example ························································································································ 154

Configuring BGP ····················································································································································· 158

BGP speaker and BGP peer ······························································································································· 158

BGP message types ············································································································································· 158

BGP path attributes ············································································································································· 159

BGP route selection ············································································································································· 163

BGP route advertisement rules ··························································································································· 163

BGP load balancing ············································································································································ 163

Settlements for problems in large-scale BGP networks ···················································································· 164

MP-BGP ································································································································································· 167

BGP configuration views ···································································································································· 168

Protocols and standards ····································································································································· 169 BGP configuration task list ·········································································································································· 169 Configuring basic BGP ················································································································································ 172

Enabling BGP ······················································································································································· 172

Configuring a BGP peer ····································································································································· 173

Configuring a BGP peer group ·························································································································· 174

Specifying the source interface for TCP connections ······················································································· 179 Generating BGP routes ················································································································································ 180

Injecting a local network ···································································································································· 181

Redistributing IGP routes····································································································································· 181 Controlling route distribution and reception ············································································································· 182

Configuring BGP route summarization ············································································································· 183

Advertising optimal routes in the IP routing table ···························································································· 184

Advertising a default route to a peer or peer group ······················································································· 184

Limiting routes received from a peer or peer group ························································································ 185

Configuring BGP route filtering policies ··········································································································· 186

Configuring BGP route dampening ··················································································································· 191 Controlling BGP path selection ··································································································································· 192

Specifying a preferred value for routes received ····························································································· 192

Configuring preferences for BGP routes ··········································································································· 193

Configuring the default local preference ·········································································································· 194

Configuring the MED attribute ··························································································································· 195

Configuring the NEXT_HOP attribute ················································································································ 199

Configuring the AS_PATH attribute ··················································································································· 201 Tuning and optimizing BGP networks ························································································································ 206

Configuring the keepalive interval and hold time ···························································································· 206

Configuring the interval for sending updates for the same route ··································································· 207

Enabling BGP to establish an EBGP session over multiple hops ···································································· 208

Enabling immediate reestablishment of direct EBGP connections upon link failure····································· 209

Enabling 4-byte AS number suppression ·········································································································· 209

Configuring MD5 authentication for BGP ········································································································ 210

Configuring BGP load balancing ······················································································································ 211

Disabling BGP to establish a session to a peer or peer group ······································································ 212

Configuring BGP soft-reset·································································································································· 212

Protecting an EBGP peer when memory usage reaches level 2 threshold ···················································· 216 Configuring a large-scale BGP network ···················································································································· 217

Configuring BGP community ······························································································································ 217

Configuring a BGP route reflector ····················································································································· 219

Configuring a BGP confederation ····················································································································· 219 Configuring BGP GR ··················································································································································· 220 Enabling trap ································································································································································ 221 Enabling logging of session state changes ··············································································································· 222 Configuring BFD for BGP ············································································································································ 222 Displaying and maintaining BGP ······························································································································· 223 IPv4 BGP configuration examples ······························································································································ 226

Basic BGP configuration example ····················································································································· 226

BGP and IGP route redistribution configuration example ··············································································· 230

BGP route summarization configuration example ··························································································· 233

BGP load balancing configuration example ···································································································· 236

BGP community configuration example ············································································································ 239

BGP route reflector configuration example······································································································· 242

BGP confederation configuration example ······································································································· 244

BGP path selection configuration example······································································································· 248

BGP GR configuration example ························································································································· 252

BFD for BGP configuration example ················································································································· 253 IPv6 BGP configuration examples ······························································································································ 257

IPv6 BGP basic configuration example ············································································································· 257

IPv6 BGP route reflector configuration example ······························································································ 260

BFD for IPv6 BGP configuration example ········································································································· 263 Troubleshooting BGP ··················································································································································· 267

Symptom ······························································································································································· 267

Analysis ································································································································································ 267

Solution ································································································································································· 267

Configuring PBR ······················································································································································ 268

Introduction to PBR ······················································································································································· 268

Policy ···································································································································································· 268

PBR and Track ······················································································································································ 269 PBR configuration task list ··········································································································································· 269 Configuring a policy ···················································································································································· 269

Creating a node ·················································································································································· 269

Configuring match criteria for a node ·············································································································· 269

Configuring actions for a node ·························································································································· 270 Configuring PBR ··························································································································································· 270 Displaying and maintaining PBR ································································································································ 270 Packet type-based interface PBR configuration example ························································································· 271

Network requirements ········································································································································· 271

Verifying the configuration ································································································································· 272

Configuring IPv6 static routing ······························································································································· 274

Configuring an IPv6 static route ································································································································· 274 Configuring BFD for IPv6 static routes ······················································································································· 275

Single-hop echo mode ········································································································································ 276 Displaying and maintaining IPv6 static routes ·········································································································· 277 IPv6 static routing configuration examples ················································································································ 277

Basic IPv6 static route configuration example ·································································································· 277

BFD for IPv6 static routes configuration example (direct next hop) ······························································· 279

BFD for IPv6 static routes configuration example (indirect next hop) ···························································· 281

Configuring an IPv6 default route ·························································································································· 285

Configuring RIPng ··················································································································································· 286

RIPng route entries ··············································································································································· 286

RIPng packets ······················································································································································· 286

Protocols and standards ····································································································································· 287 RIPng configuration task list ········································································································································ 287 Configuring basic RIPng ·············································································································································· 287 Configuring RIPng route control ································································································································· 288

Configuring an additional routing metric ········································································································· 288

vii

Configuring RIPng route summarization ··········································································································· 288

Configuring received/redistributed route filtering ··························································································· 289

Configuring a preference for RIPng ··················································································································· 289

Configuring RIPng route redistribution ·············································································································· 290 Tuning and optimizing the RIPng network ················································································································· 290

Configuring RIPng timers ···································································································································· 290

Configuring split horizon and poison reverse ·································································································· 291

Configuring zero field check on RIPng packets ······························································································· 291

Configuring the maximum number of ECMP routes ························································································ 292 Configuring RIPng GR·················································································································································· 292 Displaying and maintaining RIPng ····························································································································· 293 RIPng configuration examples····································································································································· 293

Basic RIPng configuration example ··················································································································· 293

RIPng route redistribution configuration example ···························································································· 296

Configuring OSPFv3 ··············································································································································· 299

OSPFv3 overview ························································································································································· 299

OSPFv3 packets··················································································································································· 299

OSPFv3 LSA types ··············································································································································· 299

Protocols and standards ····································································································································· 300 OSPFv3 configuration task list ···································································································································· 300 Enabling OSPFv3 ························································································································································· 301 Configuring OSPFv3 area parameters ······················································································································ 302

Configuring an OSPFv3 virtual link ··················································································································· 302 Configuring OSPFv3 network types ··························································································································· 303

Configuring the OSPFv3 network type for an interface ·················································································· 303

Configuring an NBMA or P2MP neighbor ······································································································· 304 Configuring OSPFv3 route control ····························································································································· 304

Configuring OSPFv3 route summarization ······································································································· 304

Configuring OSPFv3 received route filtering ···································································································· 305

Configuring Inter-Area-Prefix LSA filtering ········································································································ 305

Configuring an OSPFv3 cost for an interface ·································································································· 305

Configuring the maximum number of OSPFv3 ECMP routes ········································································· 306

Configuring a preference for OSPFv3 ·············································································································· 306

Configuring OSPFv3 route redistribution ·········································································································· 307 Tuning and optimizing OSPFv3 networks ················································································································· 307

Configuring OSPFv3 timers ································································································································ 308

Specifying LSA transmission delay ···················································································································· 308

Specifying SPF calculation interval ···················································································································· 308

Specifying the LSA generation interval ············································································································· 309

Configuring a DR priority for an interface ········································································································ 309

Ignoring MTU check for DD packets ················································································································· 310

Disabling interfaces from receiving and sending OSPFv3 packets ······························································· 310

Enabling the logging of neighbor state changes ····························································································· 311 Configuring OSPFv3 GR ············································································································································· 311

Configuring GR Restarter ···································································································································· 311

Configuring GR Helper ······································································································································· 312 Configuring BFD for OSPFv3 ······································································································································ 312 Displaying and maintaining OSPFv3 ························································································································· 313

viii

OSPFv3 configuration examples ································································································································ 313

Configuring OSPFv3 areas ································································································································ 313

Configuring OSPFv3 DR election ······················································································································· 317

Configuring OSPFv3 route redistribution ·········································································································· 320

Configuring OSPFv3 GR ···································································································································· 323

Configuring BFD for OSPFv3 ····························································································································· 325

Configuring IPv6 IS-IS ············································································································································· 328

Overview ······································································································································································· 328 Configuring basic IPv6 IS-IS ········································································································································ 328 Configuring IPv6 IS-IS route control ··························································································································· 329 Configuring BFD for IPv6 IS-IS ···································································································································· 330 Displaying and maintaining IPv6 IS-IS ······················································································································· 330 IPv6 IS-IS configuration examples ······························································································································ 331

IPv6 IS-IS basic configuration example ············································································································· 331

BFD for IPv6 IS-IS configuration example ········································································································· 335

Configuring IPv6 PBR ·············································································································································· 338

Introduction to IPv6 PBR ··············································································································································· 338

PBR and Track ······················································································································································ 339 IPv6 PBR configuration task list ··································································································································· 339 Configuring an IPv6 policy ········································································································································· 339

Creating an IPv6 node ········································································································································ 339

Configuring match criteria for an IPv6 node ···································································································· 339

Configuring actions for an IPv6 node ··············································································································· 340 Configuring IPv6 PBR ··················································································································································· 340 Displaying and maintaining IPv6 PBR ························································································································ 340 Packet type-based IPv6 interface PBR configuration example ················································································· 341

Configuring routing policies ··································································································································· 344

Filters ····································································································································································· 344

Routing policy ······················································································································································ 345 Configuring filters ························································································································································· 345

Configuring an IP prefix list ································································································································ 345

Configuring an AS path list ································································································································ 346

Configuring a community list ····························································································································· 346

Configuring an extended community list ·········································································································· 347 Configuring a routing policy ······································································································································· 347

Creating a routing policy ··································································································································· 347

Configuring if-match clauses ······························································································································ 348

Configuring apply clauses ·································································································································· 349

Configuring a continue clause ··························································································································· 350 Displaying and maintaining the routing policy ········································································································· 351 Routing policy configuration examples ······················································································································ 351

Applying a routing policy to IPv4 route redistribution ····················································································· 351

Applying a routing policy to IPv6 route redistribution ····················································································· 354

Support and other resources ·································································································································· 357

Contacting HP ······························································································································································ 357

Subscription service ············································································································································ 357 Related information ······················································································································································ 357

Documents ···························································································································································· 357

Websites ······························································································································································· 357 Conventions ·································································································································································· 358

Index ········································································································································································ 360

IP routing basics

IP routing directs IP packet forwarding on routers based on a routing table. This chapter focuses on unicast routing protocols. For more information about multicast routing protocols, see IP Multicast Configuration Guide.

Routing table

A router maintains at least two routing tables: a global routing table and a FIB. The FIB table contains only the optimal routes, and the global routing table contains all routes. The router uses the FIB table to forward packets. For more information about the FIB table, see Layer 3—IP Services Configuration Guide.

Table 1 c

ategorizes routes by different criteria.

Table 1 Route categories

Criterion Categories

Destination

• Network route—The destination is a network. The subnet mask is less than 32 bits.

• Host route—The destination is a host. The subnet mask is 32 bits.

Whether the destination is directly connected

• Direct route—The destination is directly connected.

• Indirect route—The destination is indirectly connected.

Origin

• Direct route—A direct route is discovered by the data link protocol on an interface,

and is also called an "interface route."

• Static route—A static route is manually configured by an administrator.

• Dynamic route—A dynamic route is dynamically discovered by a routing protocol.

To view brief information about a routing table, use the display ip routing-table command:

<Sysname> display ip routing-table

Destinations : 19 Routes : 19

Destination/Mask Proto Pre Cost NextHop Interface

0.0.0.0/32 Direct 0 0 127.0.0.1 InLoop0

1.1.1.0/24 Direct 0 0 1.1.1.1 Vlan1

1.1.1.0/32 Direct 0 0 1.1.1.1 Vlan1

1.1.1.1/32 Direct 0 0 127.0.0.1 InLoop0

1.1.1.255/32 Direct 0 0 1.1.1.1 Vlan1

2.2.2.0/24 Static 60 0 12.2.2.2 Vlan2

80.1.1.0/24 OSPF 10 2 80.1.1.1 Vlan3 ...

A route entry includes the following key items:

• Destination—IP address of the destination host or network.

• Mask—Mask length of the IP address.

• Pre—Preference of the route. Among routes to the same destination, the route with the highest

preference is optimal.

• Cost—If multiple routes to a destination have the same preference, the one with the smallest cost is

the optimal route.

• NextHop—Next hop.

• Interface—Output interface.

Dynamic routing protocols

Static routes work well in small, stable networks. They are easy to configure and require fewer system resources. However, in networks where topology changes occur frequently, a typical practice is to configure a dynamic routing protocol. Compared with static routing, a dynamic routing protocol is complicated to configure, requires more routers resources, and consumes more network resources.

Dynamic routing protocols dynamically collect and report reachability information to adapt to topology changes. They are suitable for large networks.

Dynamic routing protocols can be classified by different criteria, as shown in Table 2.

Table 2 Categories of

dynamic routing protocols

Criterion Categories

Operation scope

• IGPs—Work within an AS. Examples include RIP, OSPF, and IS-IS.

• EGPs—Work between ASs. The most popular EGP is BGP.

Routing algorithm

• Distance-vector protocols—Examples include RIP and BGP. BGP is also considered

a path-vector protocol.

• Link-state protocols—Examples include OSPF and IS-IS.

Destination address type

• Unicast routing protocols—Examples include RIP, OSPF, BGP, and IS-IS.

• Multicast routing protocols—Examples include PIM-SM and PIM-DM.

IP version

• IPv4 routing protocols—Examples include RIP, OSPF, BGP, and IS-IS.

• IPv6 routing protocols—Examples include RIPng, OSPFv3, IPv6 BGP, and IPv6 IS-IS.

An AS refers to a group of routers that use the same routing policy and work under the same administration.

Route preference

Routing protocols, including static and direct routing, each by default have a preference. If they find multiple routes to the same destination, the router selects the route with the highest preference as the optimal route.

The preference of a direct route is always 0 and cannot be changed. You can configure a preference for each static route and each dynamic routing protocol. The following table lists the route types and default preferences. The smaller the value, the higher the preference.

Table 3 Route types and default route preferences

Route type Preference

Direct route

Route type Preference

Multicast static route 1

OSPF 10

IS-IS 15

Unicast static route 60

RIP 100

OSPF ASE 150

OSPF NSSA 150

IBGP 255

EBGP 255

Unknown (route from an untrusted source) 256

Load sharing

A routing protocol may find multiple optimal equal-cost routes to the same destination. You can use these routes to implement equal-cost multi-path (ECMP) load sharing.

Static routing, IPv6 static routing, RIP, RIPng, OSPF, OSPFv3, BGP, IPv6 BGP, IS-IS, and IPv6 IS-IS support ECMP load sharing.

Route backup

Route backup can improve network availability. Among multiple routes to the same destination, the route with the highest priority is the primary route and others are secondary routes.

The router forwards matching packets through the primary route. When the primary route fails, the route with the highest preference among the secondary routes is selected to forward packets. When the primary route recovers, the router uses it to forward packets.

Route recursion

To use a route that has an indirectly connected next hop, a router must perform route recursion to find the outgoing interface to reach the next hop.

Route redistribution

Route redistribution enables routing protocols to learn route information from each other. A dynamic routing protocol can redistribute routes from other routing protocols, including direct and static routing. For more information, see the respective chapters on those routing protocols in this configuration guide.

Configuring the maximum number of ECMP routes

This configuration takes effect at next reboot. Make sure the reboot does not impact your network.

To configure the maximum number of ECMP routes:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Configure the maximum

number of ECMP routes.

max-ecmp-num number

By default, the maximum number of ECMP routes is 8.

3. (Optional.) Display the

maximum number of ECMP routes.

display max-ecmp-num

You can execute the display command in any view.

Displaying and maintaining a routing table

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

Task Command

Display routing table information.

display ip routing-table [ vpn-instance vpn-instance-name ] [ verbose ]

Display information about routes permitted by an IPv4 basic ACL.

display ip routing-table [ vpn-instance vpn-instance-name ] acl acl-number [ verbose ]

Display information about routes to a specific destination address.

display ip routing-table [ vpn-instance vpn-instance-name ] ip-address [ mask | mask-length ] [ longer-match ] [ verbose ]

Display information about routes to a range of destination addresses.

display ip routing-table [ vpn-instance vpn-instance-name ] ip-address1 to ip-address2 [ verbose ]

Display information about routes permitted by an IP prefix list.

display ip routing-table [ vpn-instance vpn-instance-name ] prefix-list prefix-list-name [ verbose ]

Display information about routes installed by a protocol.

display ip routing-table [ vpn-instance vpn-instance-name ] protocol protocol [ inactive | verbose ]

Display IPv4 route statistics. display ip routing-table [ vpn-instance vpn-instance-name ] statistics

Clear IPv4 route statistics.

reset ip routing-table statistics protocol [ vpn-instance vpn-instance-name ] { protocol | all }

Display IPv6 routing table information.

display ipv6 routing-table [ vpn-instance vpn-instance-name ] [ verbose ]

Display information about routes to an IPv6 destination address.

display ipv6 routing-table [ vpn-instance vpn-instance-name ] ipv6-address [ prefix-length ] [ longer-match ] [ verbose ]

Display information about routes permitted by an IPv6 basic ACL.

display ipv6 routing-table [ vpn-instance vpn-instance-name ] acl acl6-number [ verbose ]

Display information about routes to a range of IPv6 destination addresses.

display ipv6 routing-table [ vpn-instance vpn-instance-name ] ipv6-address1 to ipv6-address2 [ verbose ]

Display information about routes permitted by an IPv6 prefix list.

display ipv6 routing-table [ vpn-instance vpn-instance-name ] prefix-list prefix-list-name [ verbose ]

Task Command

Display information about routes installed by an IPv6 protocol.

display ipv6 routing-table [ vpn-instance vpn-instance-name ] protocol protocol [ inactive | verbose ]

Display IPv6 route statistics.

display ipv6 routing-table [ vpn-instance vpn-instance-name ] statistics

Clear IPv6 route statistics.

reset ipv6 routing-table statistics protocol [ vpn-instance vpn-instance-name ] { protocol | all }

Configuring static routing

Static routes are manually configured. If a network's topology i s simple, you only need to con figure static routes for the network to work properly.

Static routes cannot adapt to network topology changes. If a fault or a topological change occurs in the network, the network administrator must modify the static routes manually.

Configuring a static route

Before you configure a static route, complete the following tasks:

• Configure the physical parameters for related interfaces.

• Configure the link-layer attributes for related interfaces.

• Configure the IP addresses for related interfaces.

You can associate track with a static route to monitor the reachability of the next hops. For more information about track, see High Availability Configuration Guide.

To configure a static route:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Configure a static

route.

• Method 1:

ip route-static dest-address { mask |

mask-length } { next-hop-address [ track track-entry-number ] | interface-type interface-number [ next-hop-address ] | vpn-instance d-vpn-instance-name next-hop-address [ track track-entry-number ] }

[ permanent ] [ preference preference-value ] [ tag tag-value ] [ description description-text ]

• Method 2:

ip route-static vpn-instance

s-vpn-instance-name dest-address { mask | mask-length } { next-hop-address [ public ] [ track track-entry-number ] | interface-type interface-number [ next-hop-address ] | vpn-instance d-vpn-instance-name next-hop-address [ track track-entry-number ] }

[ permanent ] [ preference preference-value ] [ tag tag-value ] [ description description-text ]

Use either method.

By default, no static route is configured.

3. (Optional.)

Configure the default preference for static routes.

ip route-static default-preference

default-preference-value

The default setting is 60.

Step Command

Remarks

4. (Optional.) Delete all

static routes, including the default route.

delete [ vpn-instance vpn-instance-name ] static-routes all

To delete one static route, use the undo ip route-static command.

Configuring BFD for static routes

IMPORTANT:

Enabling BFD for a flapping route could worsen the situation.

BFD provides a general-purpose, standard, medium-, and protocol-independent fast failure detection mechanism. It can uniformly and quickly detect the failures of the bidirectional forwarding paths between two routers for protocols, such as routing protocols.

For more information about BFD, see High Availability Configuration Guide.

Bidirectional control mode

To use BFD bidirectional control detection between two devices, enable BFD control mode for each device's static route destined to the peer.

To configure a static route and enable BFD control mode for it, specify an output interface and a direct next hop, or specify an indirect next hop and a specific BFD packet source address for the static route.

To configure BFD control mode for a static route (direct next hop):

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Configure BFD

control mode for a static route.

• Method 1:

ip route-static dest-address { mask | mask-length } interface-type interface-number next-hop-address

bfd control-packet [ preference preference-value ] [ tag tag-value ] [ description description-text ]

• Method 2:

ip route-static vpn-instance s-vpn-instance-name dest-address { mask | mask-length } interface-type interface-number next-hop-address bfd control-packet [ preference preference-value ] [ tag tag-value ] [ description description-text ]

Use either method.

By default, BFD control mode for a static route is not configured.

To configure BFD control mode for a static route (indirect next hop):

Step Command

Remarks

1. Enter system view.

system-view N/A

Step Command

Remarks

2. Configure BFD

control mode for a static route.

• Method 1:

ip route-static dest-address { mask | mask-length } { next-hop-address bfd control-packet bfd-source

ip-address | vpn-instance d-vpn-instance-name next-hop-address bfd control-packet bfd-source ip-address } [ preference preference-value ] [ tag tag-value ] [ description description-text ]

• Method 2:

ip route-static vpn-instance s-vpn-instance-name dest-address { mask | mask-length } { next-hop-address bfd control-packet bfd-source ip-address | vpn-instance d-vpn-instance-name next-hop-address bfd control-packet bfd-source ip-address } [ preference preference-value ] [ tag tag-value ] [ description description-text ]

Use either method.

By default, BFD control mode for a static route is not configured.

Single-hop echo mode

With BFD echo mode enabled for a static route, the output interface sends BFD echo packets to the destination device, which loops the packets back to test the link reachability.

IMPORTANT:

Do not use BFD for a static route with the output interface in spoofing state.

To configure BFD echo mode for a static route:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Configure the source

address of echo packets.

bfd echo-source-ip ip-address

By default, the source address of echo packets is not configured.

For more information about this command, see High

Availability Command Reference.

3. Configure BFD echo

mode for a static route.

• Method 1:

ip route-static dest-address { mask | mask-length } interface-type interface-number next-hop-address bfd echo-packet [ preference preference-value ] [ tag tag-value ] [ description description-text ]

• Method 2:

ip route-static vpn-instance

s-vpn-instance-name dest-address { mask | mask-length } interface-type interface-number next-hop-address bfd echo-packet [ preference preference-value ] [ tag tag-value ] [ description description-text ]

Use either method.

By default, BFD echo mode for a static route is not configured.

Configuring static route FRR

A link or router failure on a path can cause packet loss and even routing loop. Static route fast reroute (FRR) enables fast rerouting to minimize the impact of link or node failures.

Figure 1 Network diagram

As shown in Figure 1, upon a link failure, FRR specifies a backup next hop by using a routing policy for routes matching the specified criteria. Packets are directed to the backup next hop to avoid traffic interruption.

Configuration guidelines

• Do not use static route FRR and BFD (for a static route) at the same time.

• Static route does not take effect when the backup output interface is unavailable.

• Equal-cost routes do not support FRR.

• The backup output interface and next hop cannot be modified directly or the same as the primary

output interface and next hop.

Configuration procedure

To configure static route FRR:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Configure the source

address of BFD echo packets.

bfd echo-source-ip ip-address

By default, the source address of BFD echo packets is not configured.

For more information about this command, see High

Availability Command Reference.

Step Command

Remarks

3. Configure static route

FRR.

• Method 1:

ip route-static dest-address { mask | mask-length } interface-type interface-number [ next-hop-address [ backup-interface interface-type interface-number [ backup-nexthop backup-nexthop-address ] ] ] [ permanent ]

• Method 2:

ip route-static vpn-instance

s-vpn-instance-name dest-address { mask | mask-length } interface-type interface-number [ next-hop-address [ backup-interface interface-type interface-number [ backup-nexthop backup-nexthop-address ] ] ] [ permanent ]

Use either method.

By default, static route FRR is not configured.

Displaying and maintaining static routes

Execute the display command in any view.

Task Command

Display static route information. display ip routing-table protocol static [ inactive | verbose ]

Static route configuration examples

Basic static route configuration example

Network requirements

Configure static routes on the switches in Figure 2 for interconnections between any two hosts.

Figure 2 Network diagram

Configuration procedure

1. Configure IP addresses for interfaces. (Details not shown.)

2. Configure static routes:

# Configure a default route on Switch A.

<SwitchA> system-view [SwitchA] ip route-static 0.0.0.0 0.0.0.0 1.1.4.2

# Configure two static routes on Switch B.

<SwitchB> system-view [SwitchB] ip route-static 1.1.2.0 255.255.255.0 1.1.4.1 [SwitchB] ip route-static 1.1.3.0 255.255.255.0 1.1.5.6

# Configure a default route on Switch C.

<SwitchC> system-view [SwitchC] ip route-static 0.0.0.0 0.0.0.0 1.1.5.5

3. Configure the default gateways of Host A, Host B, and Host C as 1.1.2.3, 1.1.6.1, and 1.1.3.1.

(Details not shown.)

Verifying the configuration

# Display static routes on Switch A.

[SwitchA] display ip routing-table protocol static

Summary Count : 1

Static Routing table Status : <Active> Summary Count : 1

Destination/Mask Proto Pre Cost NextHop Interface

0.0.0.0/0 Static 60 0 1.1.4.2 Vlan500

Static Routing table Status : <Inactive> Summary Count : 0

# Display static routes on Switch B.

[SwitchB] display ip routing-table protocol static

Summary Count : 2

Static Routing table Status : <Active> Summary Count : 2

Destination/Mask Proto Pre Cost NextHop Interface

1.1.2.0/24 Static 60 0 1.1.4.1 Vlan500

Static Routing table Status : <Inactive> Summary Count : 0

# Use the ping com mand on Host B to test the rea chability of Host A (Windows XP run s on the t wo hosts).

C:\Documents and Settings\Administrator>ping 1.1.2.2

Pinging 1.1.2.2 with 32 bytes of data:

Reply from 1.1.2.2: bytes=32 time=1ms TTL=126 Reply from 1.1.2.2: bytes=32 time=1ms TTL=126 Reply from 1.1.2.2: bytes=32 time=1ms TTL=126 Reply from 1.1.2.2: bytes=32 time=1ms TTL=126

Ping statistics for 1.1.2.2: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 1ms, Maximum = 1ms, Average = 1ms

# Use the tracert command on Host B to test the reachability of Host A.

C:\Documents and Settings\Administrator>tracert 1.1.2.2

Tracing route to 1.1.2.2 over a maximum of 30 hops

1 <1 ms <1 ms <1 ms 1.1.6.1 2 <1 ms <1 ms <1 ms 1.1.4.1 3 1 ms <1 ms <1 ms 1.1.2.2

Trace complete.

BFD for static routes configuration example (direct next hop)

Network requirements

In Figure 3, configure a static route to subnet 120.1.1.0/24 on Switch A, and configure a static route to s u b n e t 121.1.1. 0 / 2 4 o n S w i t c h B . E n a b l e B F D fo r both routes. Configure a static route to subnet

120.1.1.0/24 and a static route to subnet 121.1.1.0/24 on Switch C. When the link between Switch A and Switch B through the Layer 2 switch fails, BFD can detect the failure immediately and inform Switch A and Switch B to communicate through Switch C.

Figure 3 Network diagram

Device Interface IP address

Device

Interface

IP address

Switch A Vlan-int10 12.1.1.1/24

Switch B

Vlan-int10 12.1.1.2/24 Vlan-int11 10.1.1.102/24 Vlan-int13 13.1.1.1/24 Switch C Vlan-int11 10.1.1.100/24 Vlan-int13 13.1.1.2/24

Configuration procedure

1. Configure IP addresses for the interfaces. (Details not shown.)

2. Configure static routes and BFD:

# Configure static routes on Switch A and enable BFD control mode for the static route that traverses the Layer 2 switch.

<SwitchA> system-view [SwitchA] interface vlan-interface 10 [SwitchA-vlan-interface10] bfd min-transmit-interval 500 [SwitchA-vlan-interface10] bfd min-receive-interval 500 [SwitchA-vlan-interface10] bfd detect-multiplier 9 [SwitchA-vlan-interface10] quit [SwitchA] ip route-static 120.1.1.0 24 vlan-interface 10 12.1.1.2 bfd control-packet [SwitchA] ip route-static 120.1.1.0 24 vlan-interface 11 10.1.1.100 preference 65 [SwitchA] quit

# Configure static routes on Switch B and enable BFD control mode for the static route that traverses the Layer 2 switch.

<SwitchB> system-view [SwitchB] interface vlan-interface 10 [SwitchB-vlan-interface10] bfd min-transmit-interval 500 [SwitchB-vlan-interface10] bfd min-receive-interval 500 [SwitchB-vlan-interface10] bfd detect-multiplier 9 [SwitchB-vlan-interface10] quit [SwitchB] ip route-static 121.1.1.0 24 vlan-interface 10 12.1.1.1 bfd control-packet [SwitchB] ip route-static 121.1.1.0 24 vlan-interface 13 13.1.1.2 preference 65 [SwitchB] quit

# Configure static routes on Switch C.

<SwitchC> system-view [SwitchC] ip route-static 120.1.1.0 24 13.1.1.1 [SwitchC] ip route-static 121.1.1.0 24 10.1.1.102

Verifying the configuration

# Display BFD sessions on Switch A.

<SwitchA> display bfd session

Total Session Num: 1 Up Session Num: 1 Init Mode: Active

IPv4 Session Working Under Ctrl Mode:

LD/RD SourceAddr DestAddr State Holdtime Interface 4/7 12.1.1.1 12.1.1.2 Up 2000ms Vlan10

The output shows that the BFD session has been created.

# Display the static routes on Switch A.

<SwitchA> display ip routing-table protocol static

Summary Count : 1

Static Routing table Status : <Active>

Summary Count : 1

Destination/Mask Proto Pre Cost NextHop Interface

120.1.1.0/24 Static 60 0 12.1.1.2 Vlan10

Static Routing table Status : <Inactive> Summary Count : 0

The output shows that Switch A communicates with Switch B through VLAN-interface 10. Then the link over VLAN-interface 10 fails.

# Display static routes on Switch A.

<SwitchA> display ip routing-table protocol static

Summary Count : 1

Static Routing table Status : <Active> Summary Count : 1

Destination/Mask Proto Pre Cost NextHop Interface

120.1.1.0/24 Static 65 0 10.1.1.100 Vlan11

Static Routing table Status : <Inactive> Summary Count : 0

The output shows that Switch A communicates with Switch B through VLAN-interface 11.

BFD for static routes configuration example (indirect next hop)

Network requirements

In Figure 4, Switch A has a route to interface Loopback 1 (2.2.2.9/32) on Switch B, with the output interface VLAN-interface 10. Switch B has a route to interface Loopback 1 (1.1.1.9/32) on Switch A, with the output interface VLAN-interface 12. Switch D has a route to 1.1.1.9/32, with the output interface VLAN-interface 10, and a route to 2.2.2.9/32, with the output interface VLAN-interface 12.

Configure a static route to subnet 120.1.1.0/24 on Switch A, and configure a static route to subnet

121.1.1.0 / 24 on Sw it ch B. E na bl e BF D f or b ot h r ou te s . Co nf ig ur e a s t at ic ro ut e to su b n et 120 .1.1.0 /2 4 an d a static route to subnet 121.1.1.0/24 on both Switch C and Switch D. When the link between Switch A and Switch B through Switch D fails, BFD can detect the failure immediately and inform Switch A and Switch B to communicate through Switch C.

Figure 4 Network diagram

Configuration procedure

1. Configure IP addresses for interfaces. (Details not shown.)

2. Configure static routes and BFD:

# Configure static routes on Switch A and enable BFD control mode for the static route that traverses Switch D.

<SwitchA> system-view [SwitchA] bfd multi-hop min-transmit-interval 500 [SwitchA] bfd multi-hop min-receive-interval 500 [SwitchA] bfd multi-hop detect-multiplier 9 [SwitchA] ip route-static 120.1.1.0 24 2.2.2.9 bfd control-packet bfd-source 1.1.1.9 [SwitchA] ip route-static 120.1.1.0 24 vlan-interface 11 10.1.1.100 preference 65 [SwitchA] quit

# Configure static routes on Switch B and enable BFD control mode for the static route that traverses Switch D.

<SwitchB> system-view [SwitchB] bfd multi-hop min-transmit-interval 500 [SwitchB] bfd multi-hop min-receive-interval 500 [SwitchB] bfd multi-hop detect-multiplier 9 [SwitchB] ip route-static 121.1.1.0 24 1.1.1.9 bfd control-packet bfd-source 2.2.2.9 [SwitchB] ip route-static 121.1.1.0 24 vlan-interface 13 13.1.1.2 preference 65 [SwitchB] quit

# Configure static routes on Switch C.

<SwitchC> system-view [SwitchC] ip route-static 120.1.1.0 24 13.1.1.1 [SwitchC] ip route-static 121.1.1.0 24 10.1.1.102

# Configure static routes on Switch D.

<SwitchD> system-view [SwitchD] ip route-static 120.1.1.0 24 11.1.1.1 [SwitchD] ip route-static 121.1.1.0 24 12.1.1.1

Verifying the configuration

# Display BFD sessions on Switch A.

<SwitchA> display bfd session

Total Session Num: 1 Up Session Num: 1 Init Mode: Active

IPv4 Session Working Under Ctrl Mode:

LD/RD SourceAddr DestAddr State Holdtime Interface 4/7 1.1.1.9 2.2.2.9 Up 2000ms Loop1

The output shows that the BFD session has been created.

# Display the static routes on Switch A.

<SwitchA> display ip routing-table protocol static

Summary Count : 1

Static Routing table Status : <Active> Summary Count : 1

Destination/Mask Proto Pre Cost NextHop Interface

120.1.1.0/24 Static 60 0 12.1.1.2 Vlan10

Static Routing table Status : <Inactive> Summary Count : 0

The output shows that Switch A communicates with Switch B through VLAN-interface 10. Then the link over VLAN-interface 10 fails.

# Display static routes on Switch A.

<SwitchA> display ip routing-table protocol static

Summary Count : 1

Static Routing table Status : <Active> Summary Count : 1

Destination/Mask Proto Pre Cost NextHop Interface

120.1.1.0/24 Static 65 0 10.1.1.100 Vlan11

Static Routing table Status : <Inactive> Summary Count : 0

The output shows that Switch A communicates with Switch B through VLAN-interface 11.

Static route FRR configuration example

Network requirements

As shown in Figure 5, configure static routes on Switch S, Switch A, and Switch D, and configure static route FRR so when Link A becomes unidirectional, traffic can be switched to Link B immediately.

Figure 5 Network diagram

Configuration procedure

1. Configure IP addresses for interfaces. (Details not shown.)

2. Configure static routes FRR on link A:

# Configure a static route on Switch S, and specify VLAN-interface 100 as the backup output interface and 12.12.12.2 as the backup next hop.

<SwitchS> system-view [SwitchS] bfd echo-source-ip 4.4.4.4 [SwitchS] ip route-static 4.4.4.4 32 vlan-interface 200 13.13.13.2 backup-interface

vlan-interface 100 backup-nexthop 12.12.12.2

# Configure a static route on Switch D, and specify VLAN-interface 101 as the backup output interface and 24.24.24.2 as the backup next hop.

<SwitchD> system-view [SwitchD] bfd echo-source-ip 1.1.1.1 [SwitchD] ip route-static 1.1.1.1 32 vlan-interface 200 13.13.13.1 backup-interface

vlan-interface 101 backup-nexthop 24.24.24.2

3. Configure static routes on Switch A.

<SwitchA> system-view [SwitchA] ip route-static 4.4.4.4 32 vlan-interface 101 24.24.24.4 [SwitchA] ip route-static 1.1.1.1 32 vlan-interface 100 12.12.12.1

Verifying the configuration

# Display route 4.4.4.4/32 on Switch S to view the backup next hop information.

[SwitchS] display ip routing-table 4.4.4.4 verbose

Summary Count : 1

Destination: 4.4.4.4/32 Protocol: Static Process ID: 0 SubProtID: 0x0 Age: 04h20m37s Cost: 0 Preference: 60 Tag: 0 State: Active Adv

OrigTblID: 0x0 OrigVrf: default-vrf TableID: 0x2 OrigAs: 0 NBRID: 0x26000002 LastAs: 0 AttrID: 0xffffffff Neighbor: 0.0.0.0 Flags: 0x1008c OrigNextHop: 13.13.13.2 Label: NULL RealNextHop: 13.13.13.2 BkLabel: NULL BkNextHop: 12.12.12.2 Tunnel ID: Invalid Interface: Vlan-interface200 BkTunnel ID: Invalid BkInterface: Vlan-interface100

# Display route 1.1.1.1/32 on Switch D to view the backup next hop information.

[SwitchD] display ip routing-table 1.1.1.1 verbose

Summary Count : 1

Destination: 1.1.1.1/32 Protocol: Static Process ID: 0 SubProtID: 0x0 Age: 04h20m37s Cost: 0 Preference: 60 Tag: 0 State: Active Adv OrigTblID: 0x0 OrigVrf: default-vrf TableID: 0x2 OrigAs: 0 NBRID: 0x26000002 LastAs: 0 AttrID: 0xffffffff Neighbor: 0.0.0.0 Flags: 0x1008c OrigNextHop: 13.13.13.1 Label: NULL RealNextHop: 13.13.13.1 BkLabel: NULL BkNextHop: 24.24.24.2 Tunnel ID: Invalid Interface: Vlan-interface200 BkTunnel ID: Invalid BkInterface: Vlan-interface101

Configuring a default route

A default route is used to forward packets that do not match any specific routing entry in the routing table. Without a default route, packets that do not match any routing entries are discarded.

A default route can be configured in either of the following ways:

• The network administrator can configure a default route with both destination and mask being

0.0.0.0. For more information, see "Configuring a static route."

• S

ome dynamic routing protocols, such as OSPF, RIP, and IS-IS, can generate a default route. For example, an upstream router running OSPF can generate a default route and advertise it to other routers, which install the default route with the next hop being the upstream router. For more information, see the respective chapters on these routing protocols in this configuration guide.

Configuring RIP

Routing Information Protocol (RIP) is a distance-vector IGP suited to small-sized networks. It employs UDP to exchange route information through port 520.

Overview

RIP uses a hop count to measure the distance to a destination. The hop count from a router to a directly connected network is 0. The hop count from a router to a directly connected router is 1. To limit convergence time, RIP restricts the metric range from 0 to 15. A destination with a metric value of 16 (or greater) is considered unreachable. For this reason, RIP is not suitable for large-sized networks.

RIP route entries

RIP stores routing entries in a database. Each routing entry contains the following elements:

• Destination address—IP address of a destination host or a network.

• Next hop—IP address of the next hop.

• Egress interface—Egress interface of the route.

• Metric—Cost from the local router to the destination.

• Route time—Time elapsed since the last update. The time is reset to 0 when the routing entry is

updated.

• Route tag—Used for route control. For more information, see "Configuring routing policies."

Routing loop prevention

RIP uses the following mechanisms to prevent routing loops:

• Counting to infinity—A destination with a metric value of 16 is considered unreachable. When a

routing loop occurs, the metric value of a route will increment to 16 to avoid endless looping.

• Triggered updates—RIP immediately advertises triggered updates for topology changes to reduce

the possibility of routing loops and to speed up convergence.

• Split horizon—Disables RIP from sending routing information on the interface from which the

information was learned to prevent routing loops and save bandwidth.

• Poison reverse—Enables RIP to set the metric of routes received from a neighbor to 16 and sends

these routes back to the neighbor so the neighbor can delete such information from its routing table to prevent routing loops.

RIP operation

RIP works as follows:

1. RIP sends request messages to neighboring routers. Neighboring routers return response

messages that contain their routing tables.

2. RIP uses the received responses to update the local routing table and sends triggered update

messages to its neighbors. All RIP routers on the network do this to learn latest routing information.

3. RIP periodically sends the local routing table to its neighbors. After a RIP neighbor receives the

message, it updates its routing table, selects optimal routes, and sends an update to other neighbors. RIP ages routes to keep only valid routes.

RIP versions

There are two RIP versions, RIPv1 and RIPv2.

RIPv1 is a classful routing protocol. It advertises messages through broadcast only. RIPv1 messages do not carr y mask information, so RI Pv1 can only reco gnize natural networks su ch as Class A, B, and C. For this reason, RIPv1 does not support discontiguous subnets.

RIPv2 is a classless routing protocol. It has the following advantages over RIPv1:

• Supports route tags to implement flexible route control through routing policies.

• Supports masks, route summarization, and CIDR.

• Supports designated next hops to select the best ones on broadcast networks.

• Supports multicasting route updates so only RIPv2 routers can receive these updates to reduce

resource consumption.

• Supports plain text authentication and MD5 authentication to enhance security.

RIPv2 supports two transmission modes: broadcast and multicast. Multicast is the default mode using

224.0.0.9 as the multicast address. An interface operating in RIPv2 broadcast mode can also receive RIPv1 messages.

Protocols and standards

• RFC 1058, Routing Information Protocol

• RFC 1723, RIP Version 2 - Carrying Additional Information

• RFC 1721, RIP Version 2 Protocol Analysis

• RFC 1722, RIP Version 2 Protocol Applicability Statement

• RFC 1724, RIP Version 2 MIB Extension

• RFC 2082, RIPv2 MD5 Authentication

• RFC 2091, Triggered Extensions to RIP to Support Demand Circuits

• RFC 2453, RIP Version 2

RIP configuration task list

Tasks at a glance

Configuring basic RIP:

• (Required.) Enabling RIP

• (Optional.) Controlling RIP reception and advertisement on interfaces

• (Optional.) Configuring a RIP version

Tasks at a glance

(Optional.) Configuring RIP route control:

• Configuring an additional routing metric

• Configuring RIPv2 route summarization

• Disabling host route reception

• Advertising a default route

• Configuring received/redistributed route filtering

• Configuring a preference for RIP

• Configuring RIP route redistribution

(Optional.) Tuning and optimizing RIP networks:

• Configuring RIP timers

• Configuring split horizon and poison reverse

• Configuring the maximum number of ECMP routes

• Enabling zero field check on incoming RIPv1 messages

• Enabling source IP address check on incoming RIP updates

• Configuring RIPv2 message authentication

• Configuring the RIP packet sending rate

(Optional.) Configuring RIP GR

(Optional.) Configuring BFD for RIP

(Optional.) Configuring RIP FRR

Configuring basic RIP

Before you configure basic RIP settings, complete the following tasks:

• Configure the link layer protocol.

• Configure IP addresses for interfaces to ensure IP connectivity between neighboring routers.

Enabling RIP

Perform this task to create a RIP process and enable the RIP process on the interface attached to the specified network. An interface that is not on the specified network does not run RIP.

To enable multiple RIP processes on a router, you must specify an ID for each process. A RIP process ID has only local significance. Two RIP routers having different process IDs can also exchange RIP packets.

If you configure RIP settings in interface view before enabling RIP, the settings do not take effect until RIP is enabled. If a physical interface is attached to multiple networks, you cannot advertise these networks in different RIP processes.

To enable RIP:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Create a RIP process and

enter RIP view.

rip [ process-id ] [ vpn-instance vpn-instance-name ]

By default, no RIP process is enabled.

Step Command

Remarks

3. Enable the RIP process on the

interface attached to the specified network.

network network-address

By default, RIP is disabled on an interface.

The network 0.0.0.0 command can enable RIP on all interfaces in a single process, but does not apply to multiple RIP processes.

Controlling RIP reception and advertisement on interfaces

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter RIP view.

rip [ process-id ] [ vpn-instance

vpn-instance-name ]

N/A

3. Disable a specified interface

from sending RIP messages.

silent-interface { interface-type interface-number | all }

By default, all RIP-enabled interfaces can send RIP messages.

The disabled interface can still receive RIP messages and respond to unicast requests containing unknown ports.

4. Return to system view.

quit N/A

5. Enter interface view.

interface interface-type interface-number

N/A

6. Enable an interface to receive

RIP messages.

rip input

By default, a RIP-enabled interface can receive RIP messages.

7. Enable an interface to send

RIP messages.

rip output

By default, a RIP-enabled interface can send RIP messages.

Configuring a RIP version

You can configure a global RIP version in RIP view or an interface-specific RIP version in interface view.

An interface preferentially uses the interface-specific RIP version. If no interface-specific version is specified, the interface uses the global RIP version. If neither global nor interface-specific RIP version is configured, the interface sends RIPv1 broadcasts, and can receive RIPv1 broadcasts and unicasts, and RIPv2 broadcasts, multicasts, and unicasts.

To configure a RIP version:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter RIP view.

rip [ process-id ] [ vpn-instance

vpn-instance-name ]

N/A

Step Command

Remarks

3. Specify a global RIP version.

version { 1 | 2 }

By default, no global version is specified, and an interface sends RIPv1 broadcasts, and can receive RIPv1 broadcasts and unicasts, and RIPv2 broadcasts, multicasts, and unicasts.

4. Return to system view.

quit N/A

5. Enter interface view.

interface interface-type

interface-number

N/A

6. Specify a RIP version for the

interface.

rip version { 1 | 2 [ broadcast | multicast ] }

By default, no interface-specific RIP version is specified, and the interface sends RIPv1 broadcasts, and can receive RIPv1 broadcasts and unicasts, and RIPv2 broadcasts, multicasts, and unicasts.

Configuring RIP route control

Before you configure RIP route control, complete the following tasks:

• Configure IP addresses for interfaces to ensure IP connectivity between neighboring routers.

• Configure basic RIP.

Configuring an additional routing metric

An additional routing metric (hop count) can be added to the metric of an inbound or outbound RIP route.

An outbound additional metric is added to the metric of a sent route, and it does not change the route's metric in the routing table.

An inbound additional metric is added to the metric of a received route before the route is added into the routing table, and the route's metric is changed. If the sum of the additional metric and the original metric is greater than 16, the metric of the route is 16.

To configure additional routing metrics:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter interface view.

interface interface-type

interface-number

N/A

3. Specify an inbound

additional routing metric.

rip metricin [ route-policy route-policy-name ] value

The default setting is 0.

4. Specify an outbound

additional routing metric.

rip metricout [ route-policy route-policy-name ] value

The default setting is 1.

Configuring RIPv2 route summarization

Perform this task to summarize contiguous subnets into a summary network and sends the network to neighbors. The smallest metric among all summarized routes is used as the metric of the summary route.

Enabling RIPv2 automatic route summarization

Automatic summarization enables RIPv2 to generate a natural network for contiguous subnets. For example, suppose there are three subnet routes 10.1.1.0/24, 10.1.2.0/24, and 10.1.3.0/24. Automatic summarization automatically creates and advertises a summary route 10.0.0.0/8 instead of the more specific routes.

To enable RIPv2 automatic route summarization:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter RIP view.

rip [ process-id ] [ vpn-instance

vpn-instance-name ]

N/A

3. (Optional.) Enable RIPv2

automatic route summarization.

summary

By default, RIPv2 automatic route summarization is enabled.

If subnets in the routing table are not contiguous, disable automatic route summarization to advertise more specific routes.

Advertising a summary route

Perform this task to manually configure a summary route.

For example, suppose contiguous subnets routes 10.1.1.0/24, 10.1.2.0/24, and 10.1.3.0/24 exist in the routing table. You can create a summary route 10.1.0.0/16 on VLAN-interface 1 to advertise the summary route instead of the more specific routes.

To configure a summary route:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter RIP view.

rip [ process-id ] [ vpn-instance

vpn-instance-name ]

N/A

3. Disable RIPv2 automatic route

summarization.

undo summary

By default, RIPv2 automatic route summarization is enabled.

4. Return to system view.

quit N/A

5. Enter interface view.

interface interface-type interface-number

N/A

6. Configure a summary route.

rip summary-address ip-address

{ mask | mask-length }

By default, no summary route is configured.

Disabling host route reception

Perform this task to disable RIPv2 from receiving host routes from the same network to save network resources. This feature does not apply to RIPv1.

To disable RIP from receiving host routes:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter RIP view.

rip [ process-id ] [ vpn-instance

vpn-instance-name ]

N/A

3. Disable RIP from receiving

host routes.

undo host-route By default, RIP receives host routes.

Advertising a default route

You can advertise a default route on all RIP interfaces in RIP view or on a specific RIP interface in interface view. The interface view setting takes precedence over the RIP view settings.

To disable an interface from advertising a default route, use the rip default-route no-originate command on the interface.

To configure RIP to advertise a default route:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter RIP view.

rip [ process-id ] [ vpn-instance

vpn-instance-name ]

N/A

3. Enable RIP to advertise a

default route.

default-route { only | originate } [ cost cost ]

By default, RIP does not advertise a default route.

4. Return to system view.

quit N/A

5. Enter interface view.

interface interface-type interface-number

N/A

6. Configure the RIP interface to

advertise a default route.

rip default-route { { only | originate } [ cost cost ] | no-originate }

By default, a RIP interface can advertise a default route if the RIP process is enabled to advertise a default route.

NOTE:

The router enabled to advertise a default route does not accept default routes from RIP neighbors.

Configuring received/redistributed route filtering

Perform this task to filter received and redistributed routes by using an IP prefix list. You can also configure RIP to receive routes only from a specified neighbor.

To configure route filtering:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter RIP view.

rip [ process-id ] [ vpn-instance

vpn-instance-name ]

N/A

3. Configure the filtering of

received routes.

filter-policy { acl-number | gateway prefix-list-name | prefix-list prefix-list-name [ gateway prefix-list-name ] } import

[ interface-type interface-number ]

By default, the filtering of received routes is not configured.

This command filters received routes. Filtered routes are not installed into the routing table or advertised to neighbors.

4. Configure the filtering of

redistributed routes.

filter-policy { acl-number | prefix-list prefix-list-name } export [ protocol [ process-id ] | interface-type interface-number ]

By default, the filtering of redistributed routes is not configured.

This command filters redistributed routes, including routes redistributed with the import-route command.

Configuring a preference for RIP

If multiple IGPs fin d routes to the same destination, the route found by th e IGP that has the highest priority is selected as the optimal route. Perform this task to assign a preference to RIP. The smaller the preference value, the higher the priority.

To configure a preference for RIP:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter RIP view.

rip [ process-id ] [ vpn-instance

vpn-instance-name ]

N/A

3. Configure a preference for

RIP.

preference [ route-policy route-policy-name ] value

The default setting is 100.

Configuring RIP route redistribution

Perform this task to configure RIP to redistribute routes from other routing protocols, including OSPF, IS-IS, BGP, static, and direct.

To configure RIP route redistribution:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter RIP view.

rip [ process-id ] [ vpn-instance

vpn-instance-name ]

N/A

3. Redistribute routes from

another routing protocol.

import-route protocol [ process-id | all-processes | allow-ibgp ] [ cost

cost | route-policy route-policy-name | tag tag ] *

By default, RIP route redistribution is disabled.

This command can redistribute only active routes. To view active routes, use the display ip

routing-table protocol command.

4. (Optional.) Configure a

default cost for redistributed routes.

default cost value The default setting is 0.

Tuning and optimizing RIP networks

Configuration prerequisites

Before you tune and optimize RIP networks, complete the following tasks:

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

• Configure basic RIP.

Configuring RIP timers

You can change the RIP network convergence speed by adjusting the following RIP timers:

• Update timer—Specifies the interval between route updates.

• Timeout timer—Specifies the route aging time. If no update for a route is received within the aging

time, the metric of the route is set to 16.

• Suppress timer—Specifies how long a RIP route stays in suppressed state. When the metric of a

route is 16, the route enters the suppressed state. A suppressed route can be replaced by an updated route that is received from the same neighbor before the suppress timer expires and has a metric less than 16.

• Garbage-collect timer—Specifies the interval from when the metric of a route becomes 16 to when

it is deleted from the routing table. RIP advertises the route with a metric of 16. If no update is announced for that route before the garbage-collect timer expires, the route is deleted from the routing table.

IMPORTANT:

To avoid unnecessary traffic or route flapping, configure identical RIP timer settings on RIP routers.

To configure RIP timers:

Step Command

Remarks

1. Enter system view.

system-view N/A

Step Command

Remarks

2. Enter RIP view.

rip [ process-id ] [ vpn-instance

vpn-instance-name ]

N/A

3. Configure RIP timers.

timers { garbage-collect

garbage-collect-value | suppress suppress-value | timeout timeout-value | update update-value } *

By default:

• The garbage-collect timer is 120

seconds.

• The suppress timer is 120 seconds.

• The timeout timer is 180 seconds.

• The update timer is 30 seconds.

Configuring split horizon and poison reverse

The split horizon and poison reverse functions can prevent routing loops.

If both split horizon and poison reverse are configured, only the poison reverse function takes effect.

Enabling split horizon

Split horizon disables RIP from sending routes through the interface where the routes were learned to prevent routing loops between adjacent routers.

To enable split horizon:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter interface view.

interface interface-type

interface-number

N/A

3. Enable split horizon.

rip split-horizon By default, split horizon is enabled.

Enabling poison reverse

Poison reverse allows RIP to send routes through the interface where the routes were learned, but the metric of these routes is always set to 16 (unreachable) to avoid routing loops between neighbors.

To enable poison reverse:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter interface view.

interface interface-type

interface-number

N/A

3. Enable poison reverse.

rip poison-reverse

By default, poison reverse is disabled.

Configuring the maximum number of ECMP routes

Perform this task to implement load sharing over ECMP routes.

To configure the maximum number of ECMP routes:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter RIP view.

rip [ process-id ] [ vpn-instance

vpn-instance-name ]

N/A

3. Configure the maximum

number of ECMP routes.

maximum load-balancing number

By default, the maximum number of ECMP routes is the same as that configured in the max-ecmp-num command. For more information about the max-ecmp-num command, see IP Routing Command Reference.

Enabling zero field check on incoming RIPv1 messages

Some fields in the RIPv1 message must be set to zero. These fields are called "zero fields." You can enable zero field check on incoming RIPv1 messages. If a zero field of a message contains a non-zero value, RIP does not process the message. If you are certain that all messages are trustworthy, disable zero field check to save CPU resources.

This feature does not apply to RIPv2 packets, because they have no zero fields.

To enable zero field check on incoming RIPv1 messages:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter RIP view.

rip [ process-id ] [ vpn-instance

vpn-instance-name ]

N/A

3. Enable zero field check on

incoming RIPv1 messages.

checkzero

The default setting is enabled.

Enabling source IP address check on incoming RIP updates

Perform this task to enable source IP address check on incoming RIP updates.

Upon receiving a message on an Ethernet interface, RIP compares the source IP address of the message with the IP address of the interface. If they are not in the same network segment, RIP discards the message.

Upon receiving a message on a serial interface, RIP checks whether the source address of the message is the IP address of the peer interface. If not, RIP discards the message.

To enable source IP address check on incoming RIP updates:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter RIP view.

rip [ process-id ] [ vpn-instance

vpn-instance-name ]

N/A

Step Command

Remarks

3. Enable source IP address

check on incoming RIP messages.

validate-source-address By default, this function is enabled.

Configuring RIPv2 message authentication

Perform this task to enable authentication on RIPv2 messages. This feature does not apply to RIPv1 because RIPv1 does not support authentication. Although you can specify an authentication mode for RIPv1 in interface view, the configuration does not take effect.

RIPv2 supports two authentication modes: simple authentication and MD5 authentication.

To configure RIPv2 message authentication:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter interface view.

interface interface-type interface-number N/A

3. Configure RIPv2

authentication.

rip authentication-mode { md5 { rfc2082 { cipher cipher-string | plain plain-string } key-id | rfc2453 { cipher cipher-string | plain

plain-string } } | simple { cipher cipher-string | plain plain-string } }

By default, RIPv2 authentication is not configured.

Configuring the RIP packet sending rate

Perform this task to specify the interval for sending RIP packets and the maximum number of RIP packets that can be sent at each interval. This feature can avoid excessive RIP packets from affecting system performance and consuming too much bandwidth.

To configure the RIP packet sending rate:

Step Command…

Remarks

1. Enter system view.

system-view N/A

2. Enter RIP view.

rip [ process-id ] [ vpn-instance

vpn-instance-name ]

N/A

3. Specify the interval for

sending RIP packets and the maximum number of RIP packets that can be sent at each interval.

output-delay time count count

By default, an interface sends up to three RIP packets every 20 milliseconds.

Configuring RIP GR

GR ensures forwarding continuity when a routing protocol restarts or an active/standby switchover occurs.

Two routers are required to complete a GR process. The following are router roles in a GR process.

• GR Restarter—Graceful restarting router. It must have GR capability.

• GR Helper—A neighbor of the GR Restarter. It helps the GR Restarter to complete the GR process.

After RIP restarts on a router, the router must learn RIP routes again and update its FIB table, which causes network disconnections and route reconvergence.

With the GR feature, the restarting router (known as the "GR Restarter") can notify the event to its GR capable neighbors. GR capable neighbors (known as "GR Helpers") keep their adjacencies with the router within a GR interval. During this process, the FIB table of the router does not change. After the restart, the router contacts its neighbors to retrieve its FIB.

By default, a RIP-enabled device acts as the GR Helper. Perform this task on the GR Restarter.

To configure GR on the GR Restarter:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enable RIP and enter RIP

view.

rip [ process-id ] [ vpn-instance vpn-instance-name ]

N/A

3. Enable GR for RIP.

graceful-restart By default, RIP GR is disabled.

Configuring BFD for RIP

RIP detects route failures by periodically sending requests. If it receives no response for a route within a certain time, RIP considers the route unreachable. This detection mechanism is not fast enough. To speed up convergence, perform this task to enable BFD for RIP. For more information about BFD, see High Availability Configuration Guide.

BFD provides only single-hop echo detection mode for directly connected RIP neighbors. In this mode, a BFD session is established only when the neighbor has route information to send.

To enable BFD for RIP (single-hop echo detection):

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Configure the source IP

address of BFD echo packets.

bfd echo-source-ip ip-address

By default, the source IP address of BFD echo packets is not configured.

3. Enter interface view.

interface interface-type interface-number

N/A

4. Enable BFD for RIP.

rip bfd enable By default, BFD for RIP is disabled.

Configuring RIP FRR

A link or router failure on a path can cause packet loss and even routing loop until RIP completes routing convergence based on the new network topology. FRR uses BFD to detect failures and enables fast rerouting to minimize the impact of link or node failures.

Figure 6 Network diagram for RIP FRR

In Figure 6, configure FRR on Router B by using a routing policy to specify a backup next hop. When the primary link fails, RIP directs packets to the backup next hop. At the same time, RIP calculates the shortest path based on the new network topology, and forwards packets over that path after network convergence.

Configuration restrictions and guidelines

• RIP FRR takes effect only for RIP routes learned from directly connected neighbors.

• Do not use RIP FRR and BFD for RIP at the same time. Otherwise, FRR might fail to work.

• RIP FRR is available only when the state of primary link (with Layer 3 interfaces staying up) changes

from bidirectional to unidirectional or when the primary link fails.

Configuration prerequisites

You must specify a next hop by using the apply fast-reroute backup-interface command in a routing policy and reference the routing policy for FRR. For more information about routing policy configuration, see "Configuring routing policies."

Configuration procedure

To configure RIP FRR:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Configure the source address

of echo packets.

bfd echo-source-ip ip-address

By default, the source address of echo packets is not configured.

3. Enter RIP view.

rip [ process-id ] [ vpn-instance

vpn-instance-name ]

N/A

4. Configure RIP FRR.

fast-reroute route-policy

route-policy-name

By default, RIP FRR is disabled.

Displaying and maintaining RIP

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

Task Command

Display RIP current status and configuration information.

display rip [ process-id ]

Display all active routes in RIP database. display rip process-id database

Task Command

Display RIP interface information.

display rip process-id interface [ interface-type interface-number ]

Display routing information about a specified RIP process.

display rip process-id route [ ip-address { mask | mask-length } | peer ip-address | statistics ]

Reset a RIP process. reset rip process-id process

Clear statistics for a RIP process. reset rip process-id statistics

RIP configuration examples

Configuring basic RIP

Network requirements

As shown in Figure 7, enable RIPv2 on all interfaces on Switch A and Switch B. Configure Switch B to not advertise route 10.2.1.0/24 to Switch A, and to accept only route 2.1.1.0/24 from Switch A.

Figure 7 Network diagram

Configuration procedure

1. Configure IP addresses for interfaces. (Details not shown.)

2. Configure basic RIP:

# Configure Switch A.

<SwitchA> system-view [SwitchA] rip [SwitchA-rip-1] network 192.168.1.0 [SwitchA-rip-1] network 172.16.0.0 [SwitchA-rip-1] network 172.17.0.0 [SwitchA-rip-1] quit

# Configure Switch B.

<SwitchB> system-view [SwitchB] rip [SwitchB-rip-1] network 192.168.1.0 [SwitchB-rip-1] network 10.0.0.0 [SwitchB-rip-1] quit

# Display the RIP routing table of Switch A.

[SwitchA] display rip 1 route Route Flags: R - RIP A - Aging, S - Suppressed, G - Garbage-collect

--------------------------------------------------------------------------- Peer 192.168.1.2 on Vlan-interface100 Destination/Mask Nexthop Cost Tag Flags Sec

10.0.0.0/8 192.168.1.2 1 0 RA 11

The output shows that RIPv1 uses a natural mask.

3. Configure a RIP version:

# Configure RIPv2 on Switch A.

[SwitchA] rip [SwitchA-rip-1] version 2 [SwitchA-rip-1] undo summary [SwitchA-rip-1] quit

# Configure RIPv2 on Switch B.

[SwitchB] rip [SwitchB-rip-1] version 2 [SwitchB-rip-1] undo summary [SwitchB-rip-1] quit

# Display the RIP routing table on Switch A.

[SwitchA] display rip 1 route Route Flags: R - RIP A - Aging, S - Suppressed, G - Garbage-collect

----------------------------------------------------------------------------

Peer 192.168.1.2 on Vlan-interface100 Destination/Mask Nexthop Cost Tag Flags Sec

10.0.0.0/8 192.168.1.2 1 0 RA 50

10.2.1.0/24 192.168.1.2 1 0 RA 16

10.1.1.0/24 192.168.1.2 1 0 RA 16

The output shows that RIPv2 uses classless subnet masks.

NOTE:

fter RIPv2 is configured, RIPv1 routes might still exist in the routing table until they are aged out.

# Display the RIP routing table on Switch B.

[SwitchB] display rip 1 route Route Flags: R - RIP A - Aging, S - Suppressed, G - Garbage-collect

--------------------------------------------------------------------------- Peer 192.168.1.3 on Vlan-interface100 Destination/Mask Nexthop Cost Tag Flags Sec

172.16.1.0/24 192.168.1.3 1 0 RA 19

172.17.1.0/24 192.168.1.3 1 0 RA 19

4. Configure route filtering:

# Reference IP prefix lists on Switch B to filter received and redistributed routes.

[SwitchB] ip prefix-list aaa index 10 permit 172.16.1.0 24 [SwitchB] ip prefix-list bbb index 10 permit 10.1.1.0 24 [SwitchB] rip 1 [SwitchB-rip-1] filter-policy prefix-list aaa import

[SwitchB-rip-1] filter-policy prefix-list bbb export [SwitchB-rip-1] quit

# Display the RIP routing table on Switch A.

[SwitchA] display rip 100 route Route Flags: R - RIP A - Aging, S - Suppressed, G - Garbage-collect

--------------------------------------------------------------------------- Peer 192.168.1.2 on Vlan-interface100 Destination/Mask Nexthop Cost Tag Flags Sec

10.1.1.0/24 192.168.1.2 1 0 RA 19

# Display the RIP routing table on Switch B.

[SwitchB] display rip 1 route Route Flags: R - RIP A - Aging, S - Suppressed, G - Garbage-collect

--------------------------------------------------------------------------- Peer 192.168.1.3 on Vlan-interface100 Destination/Mask Nexthop Cost Tag Flags Sec

172.16.1.0/24 192.168.1.3 1 0 RA 19

Configuring RIP route redistribution

Network requirements

As shown in Figure 8, Switch B communicates with Switch A through RIP 100 and with Switch C through RIP 200.

Configure RIP 200 to redistribute direct routes and routes from RIP 100 on Switch B so Switch C can learn routes destined for 10.2.1.0/24 and 11.1.1.0 / 24 . Sw i t c h A c a n n o t l e a r n r o u t e s d e s t i n e d f o r 12. 3 .1. 0 / 24 and 16.4.1.0/24.

Figure 8 Network diagram

Configuration procedure

1. Configure IP addresses for interfaces. (Details not shown.)

2. Configure basic RIP:

# Enable RIP 100, and configure RIPv2 on Switch A.

<SwitchA> system-view [SwitchA] rip 100 [SwitchA-rip-100] network 10.0.0.0 [SwitchA-rip-100] network 11.0.0.0 [SwitchA-rip-100] version 2 [SwitchA-rip-100] undo summary

[SwitchA-rip-100] quit

# Enable RIP 100 and RIP 200, and configure RIPv2 on Switch B.

<SwitchB> system-view [SwitchB] rip 100 [SwitchB-rip-100] network 11.0.0.0 [SwitchB-rip-100] version 2 [SwitchB-rip-100] undo summary [SwitchB-rip-100] quit [SwitchB] rip 200 [SwitchB-rip-200] network 12.0.0.0 [SwitchB-rip-200] version 2 [SwitchB-rip-200] undo summary [SwitchB-rip-200] quit

# Enable RIP 200, and configure RIPv2 on Switch C.

<SwitchC> system-view [SwitchC] rip 200 [SwitchC-rip-200] network 12.0.0.0 [SwitchC-rip-200] network 16.0.0.0 [SwitchC-rip-200] version 2 [SwitchC-rip-200] undo summary [SwitchC-rip-200] quit

# Display the IP routing table on Switch C.

[SwitchC] display ip routing-table

Destinations : 13 Routes : 13

Destination/Mask Proto Pre Cost NextHop Interface

0.0.0.0/32 Direct 0 0 127.0.0.1 InLoop0

12.3.1.0/24 Direct 0 0 12.3.1.2 Vlan200

12.3.1.0/32 Direct 0 0 12.3.1.2 Vlan200

12.3.1.2/32 Direct 0 0 127.0.0.1 InLoop0

12.3.1.255/32 Direct 0 0 12.3.1.2 Vlan200

16.4.1.0/24 Direct 0 0 16.4.1.1 Vlan400

16.4.1.0/32 Direct 0 0 16.4.1.1 Vlan400

16.4.1.1/32 Direct 0 0 127.0.0.1 InLoop0

16.4.1.255/32 Direct 0 0 16.4.1.1 Vlan400

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

3. Configure route redistribution:

# Configure RIP 200 to redistribute routes from RIP 100 and direct routes on Switch B.

[SwitchB] rip 200 [SwitchB-rip-200] import-route rip 100 [SwitchB-rip-200] import-route direct [SwitchB-rip-200] quit

# Display the IP routing table on Switch C.

[SwitchC] display ip routing-table

Destinations : 15 Routes : 15

Destination/Mask Proto Pre Cost NextHop Interface

0.0.0.0/32 Direct 0 0 127.0.0.1 InLoop0

10.2.1.0/24 RIP 100 1 12.3.1.1 Vlan200

11.1.1.0/24 RIP 100 1 12.3.1.1 Vlan200

12.3.1.0/24 Direct 0 0 12.3.1.2 Vlan200

12.3.1.0/32 Direct 0 0 12.3.1.2 Vlan200

12.3.1.2/32 Direct 0 0 127.0.0.1 InLoop0

12.3.1.255/32 Direct 0 0 12.3.1.2 Vlan200

16.4.1.0/24 Direct 0 0 16.4.1.1 Vlan400

16.4.1.0/32 Direct 0 0 16.4.1.1 Vlan400

16.4.1.1/32 Direct 0 0 127.0.0.1 InLoop0

16.4.1.255/32 Direct 0 0 16.4.1.1 Vlan400

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

Configuring an additional metric for a RIP interface

Network requirements

As shown in Figure 9, run RIPv2 on all the interfaces of Switch A, Switch B, Switch C, Switch D, and Switch E.

Switch A has two links to Switch D. The lin k from Switch B to Switch D is more stable than that from Switch C to Switch D. Configure an additional metric for RIP routes received from VLAN-interface 200 on Switch A so Switch A prefers route 1.1.5.0/24 learned from Switch B.

Figure 9 Network diagram

Configuration procedure

1. Configure IP addresses for interfaces. (Details not shown.)

2. Configure basic RIP:

# Configure Switch A.

<SwitchA> system-view [SwitchA] rip 1

Switch B

Switch C

Switch A

Switch D Switch E

Vlan-int100

1.1.1.1/24

Vlan-int100

1.1.1.2/24

Vlan-int200

1.1.2.1/24 Vlan-int200

1.1.2.2/24

Vlan-int400

1.1.3.1/24

Vlan-int300

1.1.4.1/24

Vlan-int400

1.1.3.2/24

Vlan-int300

1.1.4.2/24

Vlan-int500

1.1.5.1/24

Vlan-int500

1.1.5.2/24

[SwitchA-rip-1] network 1.0.0.0 [SwitchA-rip-1] version 2 [SwitchA-rip-1] undo summary [SwitchA-rip-1] quit

# Configure Switch B.

<SwitchB> system-view [SwitchB] rip 1 [SwitchB-rip-1] network 1.0.0.0 [SwitchB-rip-1] version 2 [SwitchB-rip-1] undo summary

# Configure Switch C.

<SwitchC> system-view [SwitchB] rip 1 [SwitchC-rip-1] network 1.0.0.0 [SwitchC-rip-1] version 2 [SwitchC-rip-1] undo summary

# Configure Switch D.

<SwitchD> system-view [SwitchD] rip 1 [SwitchD-rip-1] network 1.0.0.0 [SwitchD-rip-1] version 2 [SwitchD-rip-1] undo summary

# Configure Switch E.

<SwitchE> system-view [SwitchE] rip 1 [SwitchE-rip-1] network 1.0.0.0 [SwitchE-rip-1] version 2 [SwitchE-rip-1] undo summary

# Display the IP routing table on Switch A.

[SwitchA] display rip 1 database

1.0.0.0/8, cost 0, ClassfulSumm

1.1.1.0/24, cost 0, nexthop 1.1.1.1, Rip-interface

1.1.2.0/24, cost 0, nexthop 1.1.2.1, Rip-interface

1.1.3.0/24, cost 1, nexthop 1.1.1.2

1.1.4.0/24, cost 1, nexthop 1.1.2.2

1.1.5.0/24, cost 2, nexthop 1.1.1.2

1.1.5.0/24, cost 2, nexthop 1.1.2.2

The output shows two RIP routes destined for network 1.1.5.0/24, with the next hops as Switch B (1.1.1.2) and Switch C (1.1.2.2), and with the same cost of 2. Switch C is the next hop router to reach network 1.1.4.0/24, with a cost of 1.

3. Configure an additional metric of 3 for RIP-enabled VLAN-interface 200 on Switch A.

[SwitchA] interface vlan-interface 200 [SwitchA-Vlan-interface200] rip metricin 3 [SwitchA-Vlan-interface200] display rip 1 database

1.0.0.0/8, cost 0, auto-summary

1.1.1.0/24, cost 0, nexthop 1.1.1.1, RIP-interface

1.1.2.0/24, cost 0, nexthop 1.1.2.1, RIP-interface

1.1.3.0/24, cost 1, nexthop 1.1.1.2

1.1.4.0/24, cost 2, nexthop 1.1.1.2

1.1.5.0/24, cost 2, nexthop 1.1.1.2

The output shows that only one RIP route reaches network 1.1.5.0/24, with the next hop as Switch B (1.1.1.2) and a cost of 2.

Configuring RIP to advertise a summary route

Network requirements

As shown in Figure 10, Switch A and Switch B run OSPF, Switch D runs RIP, and Switch C runs OSPF and RIP. Configure RIP to redistribute OSPF routes on Switch C so Switch D can learn routes destined for networks 10.1.1.0/24, 10.2.1.0/24, 10.5.1.0/24, and 10.6.1.0/24.

To reduce the routing table size of Switch D, configure route summarization on Switch C to advertise only the summary route 10.0.0.0/8 to Switch D.

Figure 10 Network diagram

Configuration procedure

1. Configure IP addresses for interfaces. (Details not shown.)

2. Configure basic OSPF:

# Configure Switch A.

<SwitchA> system-view [SwitchA] ospf [SwitchA-ospf-1] area 0 [SwitchA-ospf-1-area-0.0.0.0] network 10.5.1.0 0.0.0.255 [SwitchA-ospf-1-area-0.0.0.0] network 10.2.1.0 0.0.0.255 [SwitchA-ospf-1-area-0.0.0.0] quit

# Configure Switch B.

<SwitchB> system-view [SwitchB] ospf [SwitchB-ospf-1] area 0 [SwitchB-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255 [SwitchB-ospf-1-area-0.0.0.0] network 10.6.1.0 0.0.0.255 [SwitchB-ospf-1-area-0.0.0.0] quit

# Configure Switch C.

<SwitchC> system-view

Switch A

Vlan-int100

10.2.1.2/24

Switch C

Vlan-int100

10.2.1.1/24

Vlan-int300

11.3.1.2/24

Switch D

RIP

OSPF

Switch B

Vlan-int200

10.1.1.2/24

Vlan-int200

10.1.1.1/24

Vlan-int300

11.3.1.1/24

Vlan-int400

11.4.1.2/24

Vlan-int500

10.6.1.2/24

Vlan-int600

10.5.1.2/24

[SwitchC] ospf [SwitchC-ospf-1] area 0 [SwitchC-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255 [SwitchC-ospf-1-area-0.0.0.0] network 10.2.1.0 0.0.0.255 [SwitchC-ospf-1-area-0.0.0.0] quit [SwitchC-ospf-1] quit

3. Configure basic RIP:

# Configure Switch C.

[SwitchC] rip 1 [SwitchC-rip-1] network 11.3.1.0 [SwitchC-rip-1] version 2 [SwitchC-rip-1] undo summary

# Configure Switch D.

<SwitchD> system-view [SwitchD] rip 1 [SwitchD-rip-1] network 11.0.0.0 [SwitchD-rip-1] version 2 [SwitchD-rip-1] undo summary [SwitchD-rip-1] quit

# Configure RIP to redistribute routes from OSPF process 1 and direct routes on Switch C.

[SwitchC-rip-1] import-route direct [SwitchC-rip-1] import-route ospf 1 [SwitchC-rip-1] quit

# Display the IP routing table on Switch D.

[SwitchD] display ip routing-table

Destinations : 15 Routes : 15

Destination/Mask Proto Pre Cost NextHop Interface

0.0.0.0/32 Direct 0 0 127.0.0.1 InLoop0

10.1.1.0/24 RIP 100 1 11.3.1.1 Vlan300

10.2.1.0/24 RIP 100 1 11.3.1.1 Vlan300

10.5.1.0/24 RIP 100 1 11.3.1.1 Vlan300

10.6.1.0/24 RIP 100 1 11.3.1.1 Vlan300

11.3.1.0/24 Direct 0 0 11.3.1.2 Vlan300

11.3.1.0/32 Direct 0 0 11.3.1.2 Vlan300

11.3.1.2/32 Direct 0 0 127.0.0.1 InLoop0

11.4.1.0/24 Direct 0 0 11.4.1.2 Vlan400

11.4.1.0/32 Direct 0 0 11.4.1.2 Vlan400

11.4.1.2/32 Direct 0 0 127.0.0.1 InLoop0

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

4. Configure route summarization:

# Configure route summarization on Switch C and advertise only the summary route 10.0.0.0/8.

[SwitchC] interface vlan-interface 300

[SwitchC-Vlan-interface300] rip summary-address 10.0.0.0 8

# Display the IP routing table on Switch D.

[SwitchD] display ip routing-table

Destinations : 12 Routes : 12

Destination/Mask Proto Pre Cost NextHop Interface

0.0.0.0/32 Direct 0 0 127.0.0.1 InLoop0

10.0.0.0/8 RIP 100 1 11.3.1.1 Vlan300

11.3.1.0/24 Direct 0 0 11.3.1.2 Vlan300

11.3.1.0/32 Direct 0 0 11.3.1.2 Vlan300

11.3.1.2/32 Direct 0 0 127.0.0.1 InLoop0

11.4.1.0/24 Direct 0 0 11.4.1.2 Vlan400

11.4.1.0/32 Direct 0 0 11.4.1.2 Vlan400

11.4.1.2/32 Direct 0 0 127.0.0.1 InLoop0

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

Configuring BFD for RIP (single-hop echo detection)

Network requirements

As shown in Figure 11, VLAN-interface 100 of Switch A and Switch C runs RIP process 1. VLAN-interface 200 of Switch A runs RIP process 2. VLAN-interface 300 of Switch C and VLAN-interface 200 and VLAN-interface 300 of Switch B run RIP process 1.

Configure a static route destined for 100.1.1.1/24 and enable static route redistribution into RIP on Switch C so Switch A can learn two routes destined for 100.1.1.1/24 through VLAN-interface 100 and VLAN-interface 200 respectively, and uses the one through VLAN-interface 100.

Enable BFD for RIP on VLAN-interface 100 of Switch A. When the link over VLAN-interface 100 fails, BFD can quickly detect the failure and notify RIP so RIP deletes the neighbor relationship and route information learned on VLAN-interface 100, and uses the route destined for 100.1.1.1/24 through VLAN-interface 200.

Figure 11 Network diagram

Configuration procedure

1. Configure IP addresses for interfaces. (Details not shown.)

2. Configure basic RIP:

# Configure Switch A.

<SwitchA> system-view [SwitchA] rip 1 [SwitchA-rip-1] version 2 [SwitchA-rip-1] undo summary [SwitchA-rip-1] network 192.168.1.0 [SwitchA-rip-1] quit [SwitchA] interface vlan-interface 100 [SwitchA-Vlan-interface100] rip bfd enable [SwitchA-Vlan-interface100] quit [SwitchA] rip 2 [SwitchA-rip-2] version 2 [SwitchA-rip-2] undo summary [SwitchA-rip-2] network 192.168.2.0 [SwitchA-rip-2] quit

# Configure Switch B.

<SwitchB> system-view [SwitchB] rip 1 [SwitchB-rip-1] version 2 [SwitchB-rip-1] undo summary [SwitchB-rip-1] network 192.168.2.0 [SwitchB-rip-1] network 192.168.3.0 [SwitchB-rip-1] quit

# Configure Switch C.

<SwitchC> system-view [SwitchC] rip 1 [SwitchC-rip-1] version 2 [SwitchC-rip-1] undo summary [SwitchC-rip-1] network 192.168.1.0

[SwitchC-rip-1] network 192.168.3.0 [SwitchC-rip-1] import-route static [SwitchC-rip-1] quit

3. Configure BFD parameters on VLAN-interface 100 of Switch A.

[SwitchA] bfd session init-mode active [SwitchA] bfd echo-source-ip 11.11.11.11 [SwitchA] interface vlan-interface 100 [SwitchA-Vlan-interface100] bfd min-transmit-interval 500 [SwitchA-Vlan-interface100] bfd min-receive-interval 500 [SwitchA-Vlan-interface100] bfd detect-multiplier 7 [SwitchA-Vlan-interface100] quit [SwitchA] quit

4. Configure a static route on Switch C.

[SwitchC] ip route-static 120.1.1.1 24 null 0

Verifying the configuration

# Display the BFD session information on Switch A.

<SwitchA> display bfd session

Total Session Num: 1 Up Session Num: 1 Init Mode: Active

IPv4 Session Working Under Echo Mode:

LD SourceAddr DestAddr State Holdtime Interface 4 192.168.1.1 192.168.1.2 Up 2000ms Vlan100

# Display RIP routes destined for 120.1.1.0/24 on Switch A.

<SwitchA> display ip routing-table 120.1.1.0 24 verbose

Summary Count : 1

Destination: 120.1.1.0/24 Protocol: RIP Process ID: 1 SubProtID: 0x1 Age: 04h20m37s Cost: 1 Preference: 100 Tag: 0 State: Active Adv OrigTblID: 0x0 OrigVrf: default-vrf TableID: 0x2 OrigAs: 0 NBRID: 0x26000002 LastAs: 0 AttrID: 0xffffffff Neighbor: 192.168.1.2 Flags: 0x1008c OrigNextHop: 192.168.1.2 Label: NULL RealNextHop: 192.168.1.2 BkLabel: NULL BkNextHop: N/A Tunnel ID: Invalid Interface: Vlan-interface100 BkTunnel ID: Invalid BkInterface: N/A

The output shows that Switch A communicates with Switch C through VLAN-interface 100. Then the link over VLAN-interface 100 fails.

# Display RIP routes destined for 120.1.1.0/24 on Switch A.

<SwitchA> display ip routing-table 120.1.1.0 24 verbose

Summary Count : 1

Destination: 120.1.1.0/24 Protocol: RIP Process ID: 2 SubProtID: 0x1 Age: 04h20m37s Cost: 1 Preference: 100 Tag: 0 State: Active Adv OrigTblID: 0x0 OrigVrf: default-vrf TableID: 0x2 OrigAs: 0 NBRID: 0x26000002 LastAs: 0 AttrID: 0xffffffff Neighbor: 192.168.2.2 Flags: 0x1008c OrigNextHop: 192.168.2.2 Label: NULL RealNextHop: 192.168.2.2 BkLabel: NULL BkNextHop: N/A Tunnel ID: Invalid Interface: Vlan-interface200 BkTunnel ID: Invalid BkInterface: N/A

The output shows that Switch A communicates with Switch C through VLAN-interface 200.

Configuring RIP FRR

Network requirements

As shown in Figure 12, Switch S, Switch A, and Switch D run RIPv2. Configure RIP FRR so that when Link A fails, services can be switched to Link B immediately.

Figure 12 Network diagram

Configuration procedure

1. Configure IP addresses and subnet masks for interfaces on the switches. (Details not shown.)

2. Configure RIPv2 on the switches to make sure Switch A, Switch D, and Switch S can communicate

with each other at Layer 3. (Details not shown.)

3. Configure RIP FRR:

# Configure Switch S.

<SwitchS> system-view [SwitchS] bfd echo-source-ip 1.1.1.1 [SwitchS] ip prefix-list abc index 10 permit 4.4.4.4 32 [SwitchS] route-policy frr permit node 10 [SwitchS-route-policy-frr-10] if-match ip address prefix-list abc

[SwitchS-route-policy-frr-10] apply fast-reroute backup-interface vlan-interface 100 backup-nexthop 12.12.12.2

[SwitchS-route-policy-frr-10] quit [SwitchS] rip 1 [SwitchS-rip-1] fast-reroute route-policy frr [SwitchS-rip-1] quit

# Configure Switch D.

<SwitchD> system-view [SwitchD] bfd echo-source-ip 4.4.4.4 [SwitchD] ip prefix-list abc index 10 permit 1.1.1.1 32 [SwitchD] route-policy frr permit node 10 [SwitchD-route-policy-frr-10] if-match ip address prefix-list abc [SwitchD-route-policy-frr-10] apply fast-reroute backup-interface vlan-interface

101 backup-nexthop 24.24.24.2 [SwitchD-route-policy-frr-10] quit [SwitchD] rip 1 [SwitchD-rip-1] fast-reroute route-policy frr [SwitchD-rip-1] quit

Verifying the configuration

# Display route 4.4.4.4/32 on Switch S to view the backup next hop information.

[SwitchS] display ip routing-table 4.4.4.4 verbose

Summary Count : 1

Destination: 4.4.4.4/32 Protocol: RIP Process ID: 1 SubProtID: 0x1 Age: 04h20m37s Cost: 1 Preference: 100 Tag: 0 State: Active Adv OrigTblID: 0x0 OrigVrf: default-vrf TableID: 0x2 OrigAs: 0 NBRID: 0x26000002 LastAs: 0 AttrID: 0xffffffff Neighbor: 13.13.13.2 Flags: 0x1008c OrigNextHop: 13.13.13.2 Label: NULL RealNextHop: 13.13.13.2 BkLabel: NULL BkNextHop: 12.12.12.2 Tunnel ID: Invalid Interface: Vlan-interface200 BkTunnel ID: Invalid BkInterface: Vlan-interface100

# Display route 1.1.1.1/32 on Switch D to view the backup next hop information.

[SwitchD] display ip routing-table 1.1.1.1 verbose

Summary Count : 1

Destination: 1.1.1.1/32 Protocol: RIP Process ID: 1 SubProtID: 0x1 Age: 04h20m37s Cost: 1 Preference: 100

Tag: 0 State: Active Adv OrigTblID: 0x0 OrigVrf: default-vrf TableID: 0x2 OrigAs: 0 NBRID: 0x26000002 LastAs: 0 AttrID: 0xffffffff Neighbor: 13.13.13.1 Flags: 0x1008c OrigNextHop: 13.13.13.1 Label: NULL RealNextHop: 13.13.13.1 BkLabel: NULL BkNextHop: 24.24.24.2 Tunnel ID: Invalid Interface: Vlan-interface200 BkTunnel ID: Invalid BkInterface: Vlan-interface101

Configuring OSPF

Open Shortest Path First (OSPF) is a link-state IGP developed by the OSPF working group of the IETF. OSPF version 2 is used for IPv4. OSPF refers to OSPFv2 throughout this chapter.

Overview

OSPF offers the following features:

• Wide scope—Supports various network sizes and up to several hundred routers in an OSPF routing

domain.

• Fast convergence—Advertises routing updates instantly upon network topology changes.

• Loop free—Computes routes with the SPF algorithm to avoid routing loops.

• Area-based network partition—Splits an AS into multiple areas to facilitate management. This

feature reduces the LSDB size on routers to save memory and CPU resources, and reduces route updates transmitted between areas to save bandwidth.

• ECMP routing—Supports multiple equal-cost routes to a destination.

• Routing hierarchy—Supports a 4-level routing hierarchy that prioritizes routes into intra-area,

inter-area, external Type-1, and external Type-2 routes.

• Authentication—Supports area- and interface-based packet authentication to ensure secure packet

exchange.

• Support for multicasting—Multicasts protocol packets on some types of links to avoid impacting

other devices.

OSPF packets

OSPF messages are carried directly over IP. The protocol number is 89.

OSPF uses the following packet types:

• Hello—Periodically sent to find and maintain neighbors, containing timer values, information about

the DR, BDR, and known neighbors.

• Database description (DD)—Describes the digest of each LSA in the LSDB, exchanged between two

routers for data synchronization.

• Link state request (LSR)—Requests needed LSAs from a neighbor. After exchanging the DD packets,

the two routers know which LSAs of the neighbor are missing from their LSDBs. They then exchange LSR packets requesting the missing LSAs. The LSA packet contains the digest of the missing LSAs.

• Link state update (LSU)—Transmits the requested LSAs to the neighbor.

• Link state acknowledgment (LSAck)—Acknowledges received LSU packets. It contains the headers

of received LSAs (an LSAck packet can acknowledge multiple LSAs).

LSA types

OSPF advertises routing information in Link State Advertisements (LSAs). The following LSAs are commonly used:

• Router LSA—Type-1 LSA, originated by all routers and flooded throughout a single area only. This

LSA describes the collected states of the router's interfaces to an area.

• Network LSA—Type-2 LSA, originated for broadcast and NBMA networks by the designated router,

and flooded throughout a single area only. This LSA contains the list of routers connected to the network.

• Network Summary LSA—Type-3 LSA, originated by Area Border Routers (ABRs), and flooded

throughout the LSA's associated area. Each summary-LSA describes a route to a destination outside the area, yet still inside the AS (an inter-area route).

• ASBR Summary LSA—Type-4 LSA, originated by ABRs and flooded throughout the LSA's

associated area. Type 4 summary-LSAs describe routes to Autonomous System Boundary Router (ASBR).

• AS External LSA—Type-5 LSA, originated by ASBRs, and flooded throughout the AS (except stub

and NSSA areas). Each AS-external-LSA describes a route to another AS.

• NSSA LSA—Type-7 LSA, as defined in RFC 1587, originated by ASBRs in NSSAs and flooded

throughout a single NSSA. NSSA LSAs describe routes to other ASs.

• Opaque LSA—A proposed type of LSA. Its format consists of a standard LSA header and

application specific information. Opaque LSAs are used by the OSPF protocol or by some applications to distribute information into the OSPF routing domain. The opaque LSA includes Type 9, Type 10, and Type 11. The Type 9 opaque LSA is flooded into the local subnet, the Type 10 is flooded into the local area, and the Type 11 is flooded throughout the AS.

OSPF areas

In large OSPF routing domains, SPF route computations consume too many storage and CPU resources, and enormous OSPF packets generated for route synchronization occupy excessive bandwidth.

To resolve these issues, OSPF splits an AS into multiple areas. Each area is identified by an area ID. The boundaries between areas are routers rather than links. A network segment (or a link) can only reside in one area as shown in Figure 13.

ou can configure route summarization on ABRs to reduce the number of LSAs advertised to other areas

and minimize the effect of topology changes.

Figure 13 Area-based OSPF network partition

Backbone area and virtual links

Each AS has a backbone area that distributes routing information between non-backbone areas. Routing information between non-backbone areas must be forwarded by the backbone area. OSPF includes the following requirements:

• All non-backbone areas must maintain connectivity to the backbone area.

• The backbone area must maintain connectivity within itself.

In practice, these requirements might not be satisfied due to lack of physical links. OSPF virtual links can resolve this issue.

A virtual link is established between two ABRs through a non-backbone area. It must be configured on both ABRs to take effect. The non-backbone area is called a transit area.

In Figure 14,

Area 2 has no direct physical link to the backbone area 0. You can configure a virtual link

between the two ABRs to connect Area 2 to the backbone area.

Figure 14 Virtual link application 1

Virtual links can also be used to provide redundant links. If the backbone area cannot maintain internal connectivity due to the failure of a physical link, you can configure a virtual link to replace the failed physical link, as shown in Figure 15.

Area 0

Area 1

Area 2

Area 3

Area 4

Figure 15 Virtual link application 2

The virtual link between the two ABRs acts as a point-to-point connection. You can configure interface parameters, such as hello interval, on the virtual link as they are configured on a physical interface.

The two ABRs on the virtual link unicast OSPF packets to each other, and the OSPF routers in between convey these OSPF packets as normal IP packets.

Stub area and totally stub area

A stub area does not distribute Type-5 LSAs to reduce the routing table size and LSAs advertised within the area. The ABR of the stub area advertises a default route in a Type-3 LSA so that the routers in the area can reach external networks through the default route.

To further reduce the routing table size and advertised LSAs, you can configure the stub area as a totally stub area. The ABR of a totally stub area does no advertise inter-area routes or external routes. It advertises a default route in a Type-3 LSA so that the routers in the area can reach external networks through the default route.

NSSA area and totally NSSA area

An NSSA area does not import AS external LSAs (Type-5 LSAs) but can import Type-7 LSAs generated by the NSSA ASBR. The NSSA ABR translates Type-7 LSAs into Type-5 LSAs and advertises the Type-5 LSAs to other areas.

In Figure 16, t

he OSPF AS contains Area 1, Area 2, and Area 0. The other two ASs run RIP. Area 1 is an NSSA area where the ASBR redist ri butes RIP routes i n Type-7 LSA s into Area 1. Upon receiving th e Type-7 LSAs, the NSSA ABR translates them to Type-5 LSAs, and advertises the Type-5 LSAs to Area 0.

The ASBR of Area 2 redistributes RIP routes in Type -5 LSAs into the OSPF routing domain. However, Area 1 does not receive Type-5 LSAs because it is an NSSA area.

Figure 16 NSSA area

Router types

OSPF routers are classified into the following types based on their positions in the AS:

Area 0

Area 1

Virtual link

• Internal router—All interfaces on an internal router belong to one OSPF area.

• ABR—Belongs to more than two areas, one of which must be the backbone area. ABR connects the

backbone area to a non-backbone area. An ABR and the backbone area can be connected through a physical or logical link.

• Backbone router—At least one interface of a backbone router must reside in the backbone area.

All ABRs and internal routers in area 0 are backbone routers.

• ASBR—Exchanges routing information with another AS is an ASBR. An ASBR might not reside on

the border of the AS. It can be an internal router or an ABR.

Figure 17 OSPF router types

Route types

OSPF prioritizes routes into the following route levels:

• Intra-area route

• Inter-area route

• Type-1 external route

• Type-2 external route

The intra-area and inter-area routes describe the network topology of the AS. The external routes describe routes to external ASs.

A Type-1 external route has high credibility. The cost from a router to the destination of a Type-1 external route = the cost from the router to the corresponding ASBR + the cost from the ASBR to the destination of the external route.

A Type-2 external route has low credibility. OSPF considers the cost from the ASBR to the destination of a Type-2 external route is much greater than the cost from the ASBR to an OSPF internal router. The cost from the internal router to the destination of the Type-2 external route = the cost from the ASBR to the

Area 1

Area 2

Area 3

Area 4

Backbone router

ASBR

IS-IS

RIP

Internal router

ABR

Area 0

destination of the Type-2 external route. If two Type-2 routes to the same destination have the same cost, OSPF takes the cost from the router to the ASBR into consideration to determine the best route.

Route calculation

OSPF computes routes in an area as follows:

• Each router generates LSAs based on the network topology around itself, and sends them to other

routers in update packets.

• Each OSPF router collects LSAs from other routers to compose an LSDB. An LSA describes the

network topology around a router, and the LSDB describes the entire network topology of the area.

• Each router transforms the LSDB to a weighted directed graph that shows the topology of the area.

All the routers within the area have the same graph.

• Each router uses the SPF algorithm to compute a shortest path tree that shows the routes to the nodes

in the area. The router itself is the root of the tree.

OSPF network types

OSPF classifies networks into the following types, depending on different link layer protocols:

• Broadcast—If the link layer protocol is Ethernet or FDDI, OSPF considers the network type as

broadcast by default. On a broadcast network, hello, LSU, and LSAck packets are multicast to

224.0.0.5 that identifies all OSPF routers or to 224.0.0.6 that identifies the DR; DD packets and LSR packets are unicast.

• NBMA—If the link layer protocol is Frame Relay, ATM, or X.25, OSPF considers the network type

as NBMA by default. OSPF packets are unicast on a NBMA network.

• P2MP—No link is P2MP type by default. P2MP must be a conversion from other network types such

as NBMA. On a P2MP network, OSPF packets are multicast to 224.0.0.5.

• P2P—If the link layer protocol is PPP or HDLC, OSPF considers the network type as P2P. On a P2P

network, OSPF packets are multicast to 224.0.0.5.

The following are the differences between NBMA and P2MP networks:

• NBMA networks are fully meshed. P2MP networks are not required to be fully meshed.

• NBMA networks require DR and BDR election. P2MP networks do not have DR or BDR.

• On a NBMA network, OSPF packets are unicast, and neighbors are manually configured. On a

P2MP network, OSPF packets are multicast by default, and you can configure OSPF to unicast protocol packets.

DR and BDR

On a broadcast or NBMA network, any two routers must establish an adjacency to exchange routing information with each other. If n routers are present on the network, n(n-1)/2 adjacencies are established. Any topology change on the network results in an increase in traffic for route synchronization, consuming many system and bandwidth resources.

The DR and BDR mechanisms can solve this problem.

• DR—Elected to advertise routing information among other routers. If the DR fails, routers on the

network must elect another DR and synchronize information with the new DR. Using this mechanism alone is time-consuming and prone to route calculation errors.

• BDR—Elected along with the DR to establish adjacencies with all other routers. If the DR fails, the

BDR immediately becomes the new DR, and other routers elect a new BDR.

Routers other than the DR and BDR are called "DROthers." They do not establish adjacencies with one another, so the number of adjacencies is reduced.

The role of a router is subnet (or interface) specific. It might be a DR on one interface and a BDR or DROther on another interface.

In Figure 18, s

olid lines are Ethernet physical links, and dashed lines represent OSPF adjacencies. With

the DR and BDR, only seven adjacencies are established.

Figure 18 DR and BDR in a network

NOTE:

In OSPF, "neighbor" and "adjacency" are different concepts. After startup, OSPF sends a hello packet on each OSPF interface. A receiving router checks parameters in the packet. If the parameters match its own, the receiving router considers the sending router an OSPF neighbor. Two OSPF neighbors establish an adjacency relationship after they synchronize their LSDBs through exchange of DD packets and LSAs.

DR and BDR election

DR election is performed on broadcast or NBMA networks but not on P2P and P2MP networks.

Routers in a broadcast or NBMA network elect the DR and BDR by router priority and ID. Routers with a router priority value higher than 0 are candidates for DR and BDR election.

The election votes are hello packets. Each router sends the DR elected by itself in a hello packet to all the other routers. If two routers on the network declare themselves as the DR, the router with the higher router priority wins. If router priorities are the same, the router with the higher router ID wins.

If a router with a higher router priority is added to the network after DR and BDR election, the router cannot become the DR or BDR immediately as no DR election is performed for it. Therefore, the DR of a network might not be the router with the highest priority, and the BDR might not be the router with the second highest priority.

Protocols and standards

• RFC 1765, OSPF Database Overflow

• RFC 2328, OSPF Version 2

• RFC 3101, OSPF Not-So-Stubby Area (NSSA) Option

DR BDR

DR other DR otherDR other

Physical links Adjacencies

• RFC 3137, OSPF Stub Router Advertisement

• RFC 4811, OSPF Out-of-Band LSDB Resynchronization

• R F C 4 812, OSPF Restart Signaling

• RFC 4813, OSPF Link-Local Signaling

OSPF configuration task list

To run OSPF, you must first enable OSPF on the router. Make a proper configuration plan to avoid incorrect settings that can result in route blocking and routing loops.

To configure OSPF, perform the following tasks:

Tasks at a glance

(Required.) Enabling OSPF

(Optional.) Configuring OSPF areas:

• Configuring a stub area

• Configuring an NSSA area

• Configuring a virtual link

(Optional.) Configuring OSPF network types:

• Configuring the broadcast network type for an interface

• Configuring the NBMA network type for an interface

• Configuring the P2MP network type for an interface

• Configuring the P2P network type for an interface

(Optional.) Configuring OSPF route control:

• Configuring OSPF route summarization

{ Configuring route summarization on an ABR { Configuring route summarization when redistributing routes into OSPF on an ASBR

• Configuring inbound OSPF route filtering

• Configuring Type-3 LSA filtering

• Configuring an OSPF cost for an interface

• Configuring the maximum number of ECMP routes

• Configuring OSPF preference

• Configuring OSPF route redistribution

{ Configuring OSPF to redistribute routes from another routing protocol { Configuring OSPF to redistribute a default route { Configuring default parameters for redistributed routes

• Advertising a host route

Tasks at a glance

(Optional.) Tuning and optimizing OSPF networks:

• Configuring OSPF timers

• Specifying LSA transmission delay

• Specifying SPF calculation interval

• Specifying the LSA arrival interval

• Specifying the LSA generation interval

• Disabling interfaces from receiving and sending OSPF packets

• Configuring stub routers

• Configuring OSPF authentication

• Adding the interface MTU into DD packets

• Configuring the maximum number of external LSAs in LSDB

• Configuring OSPF exit overflow interval

• Enabling compatibility with RFC 1583

• Logging neighbor state changes

• Configuring OSPF network management

• Configuring the LSU transmit rate

• Enabling OSPF ISPF

(Optional.) Configuring OSPF GR:

• Configuring the OSPF GR Restarter

• Configuring OSPF GR Helper

• Triggering OSPF GR

(Optional.) Configuring BFD for OSPF

(Optional.) Configuring OSPF FRR

Enabling OSPF

Enable OSPF before you perform other OSPF configuration tasks.

Configuration prerequisites

Configure the link layer protocol and IP addresses for interfaces to ensure IP connectivity between neighboring nodes.

Configuration guidelines

Complete the following tasks to enable an interface to run an OSPF process in an area:

• Enable the OSPF process.

• Create the area for the OSPF process.

• Add the network segment where the interface resides to the area. The OSPF process advertises the

direct route of the interface.

• Specify a router ID, the unique identifier of the router in the AS.

You can also specify a router ID when you create an OSPF process.

• If you specify a router ID when you create an OSPF process, any two routers in an AS must have

different router IDs. A common practice is to specify the IP address of an interface as the router ID.

• If you specify no router ID when you create the OSPF process, the global router ID is used. HP

recommends specifying a router ID when you create the OSPF process.

OSPF can run multiple processes and supports VPNs:

• To run multiple OSPF processes, you must specify an ID for each process. The process IDs take effect

locally and has no influence on packet exchange between routers. Two routers with different process IDs can exchange packets.

• VPN support enables an OSPF process to run in a specified VPN. For more information about VPN,

see MCE Configuration Guide.

Configuration procedure

To enable OSPF:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. (Optional.) Configure a

global router ID.

router id router-id

By default, no global r o u t e r ID is configured.

If no global router ID is configured, the highest loopback interface IP address, if any, is used as the router ID. If no loopback interface IP address is available, the highest physical interface IP address is used, regardless of the interface status (up or down).

3. Enable an OSPF process

and enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

By default, no OSPF process is enabled.

4. (Optional.) Configure a

description for the OSPF process.

description description

By default, no description is configured for the OSPF process.

HP recommends configuring a description for each OSPF process.

5. Create an OSPF area and

enter OSPF area view.

area area-id

By default, no OSPF area is created.

6. (Optional.) Configure a

description for the area.

description description

By default, no description is configured for the area.

HP recommends configuring a description for each OSPF area.

7. Specify a network to enable

the interface attached to the network to run the OSPF process in the area.

network ip-address wildcard-mask

By default, no network is specified.

A network can be added to only one area.

Configuring OSPF areas

Before you configure an OSPF area, complete the following tasks:

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

• Enable OSPF.

Configuring a stub area

You can configure a non-backbone area at an AS edge as a stub area. To do so, issue the stub command on all routers attached to the area. The routing table size is reduced because Type-5 LSAs will not be flooded within the stub area. The ABR generates a default route into the stub area so all packets destined outside of the AS are sent through the default route.

To further reduce the routing table size and routing information exchanged in the stub area, configure a totally stub area by using the stub [ no-summary ] command on the ABR. AS external routes and inter-area routes will not be distributed into the area. All the packets destined outside of the AS or area will be sent to the ABR for forwarding.

A stub or totally stub area cannot have an ASBR because external routes cannot be distributed into the area.

Virtual links cannot transit a stub area or totally stub area.

To configure an OSPF stub area:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id

router-id | vpn-instance vpn-instance-name ] *

N/A

3. Enter area view.

area area-id

N/A

4. Configure the area as a stub

area.

stub [ default-route-advertise-always | no-summary ] *

By default, no stub area is configured.

5. (Optional.) Specify a cost

for the default route advertised to the stub area.

default-cost cost

The default setting is 1.

The default-cost cost command takes effect only on the ABR of a stub area or totally stub area.

Configuring an NSSA area

A stub area cannot import external routes, but an NSSA area can import external routes into the OSPF routing domain while retaining other stub area characteristics.

Do not configure the backbone area as an NSSA area or totally NSSA area.

To configure an NSSA area, configure the nssa command on all the routers attached to the area.

To configure a totally NSSA area, configure the nssa command on all the routers attached to the area and configure the nssa no-summary command on the ABR. The ABR of a totally NSSA area does not advertise inter-area routes into the area.

Virtual links cannot transit a stub area or totally stub area.

To configure an NSSA area:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id

router-id | vpn-instance vpn-instance-name ] *

N/A

3. Enter area view.

area area-id

N/A

4. Configure the area as an

NSSA area.

nssa [ default-route-advertise | no-import-route | no-summary | translate-always | translator-stability-interval value ]

By default, no area is configured as an NSSA area.

5. (Optional.) Specify a cost for

the default route advertised to the NSSA area.

default-cost cost

The default setting is 1.

This command takes effect only on the ABR/ASBR of an NSSA or totally NSSA area.

Configuring a virtual link

Virtual links are configured for connecting backbone area routers that have no direct physical links.

Virtual links cannot transit a stub area, totally stub area, NSSA area, or totally NSSA area.

To configure a virtual link:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id

router-id | vpn-instance vpn-instance-name ] *

N/A

3. Enter area view.

area area-id

N/A

4. Configure a virtual link.

vlink-peer router-id [ dead seconds | hello seconds | { hmac-md5 | md5 } key-id { cipher cipher-string

| plain plain-string } | retransmit seconds | simple { cipher cipher-string | plain plain-string } |

trans-delay seconds ] *

By default, no virtual link is configured.

Configure this command on both ends of a virtual link, and the hello and dead intervals must be identical on both ends of the virtual link.

The authentication mode (MD5 or simple) of the virtual link is determined by the authentication mode configured for the backbone area.

Configuring OSPF network types

OSPF classifies networks into the following types based on the link layer protocol:

• Broadcast—When the link layer protocol is Ethernet or FDDI, OSPF classifies the network type as

broadcast by default.

• NBMA—When the link layer protocol is Frame Relay, ATM, or X.25, OSPF classifies the network

type as NBMA by default.

• P2P—When the link layer protocol is PPP, LAPB, or HDLC, OSPF classifies the network type as P2P

by default.

When you change the network type of an interface, follow these guidelines:

• When an NBMA network becomes fully meshed, change the network type to broadcast to avoid

manual configuration of neighbors.

• If any routers in a broadcast network do not support multicasting, change the network type to

NBMA.

• An NBMA network must be fully meshed. OSPF requires that an NBMA network be fully meshed.

If a network is partially meshed, change the network type to P2MP.

• If a router on an NBMA network has only one neighbor, you can change the network type to P2P

to save costs.

Two broadcast-, NBMA-, and P2MP-interfaces can establish a neighbor relationship only when they are on the same network segment.

Configuration prerequisites

Before you configure OSPF network types, complete the following tasks:

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

• Enable OSPF.

Configuring the broadcast network type for an interface

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter interface view.

interface interface-type

interface-number

N/A

3. Configure the OSPF network

type for the interface as broadcast.

ospf network-type broadcast

By default, the network type of an interface depends on the link layer protocol.

4. (Optional.) Configure a router

priority for the interface.

ospf dr-priority priority The default router priority is 1.

Configuring the NBMA network type for an interface

After you configure the network type as NBMA, you must specify neighbors and their router priorities because NBMA interfaces cannot find neighbors by broadcasting hello packets.

To configure the NBMA network type for an interface:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter interface view.

interface interface-type interface-number

N/A

3. Configure the OSPF

network type for the interface as NBMA.

ospf network-type nbma

By default, the network type of an interface depends on the link layer protocol.

4. (Optional.) Configure a

router priority for the interface.

ospf dr-priority priority

The default setting is 1.

The router priority configured with this command is for DR election.

5. Return to system view.

quit N/A

6. Enter OSPF view.

ospf [ process-id | router-id

router-id | vpn-instance vpn-instance-name ] *

N/A

7. Specify a neighbor and its

router priority.

peer ip-address [ cost value | dr-priority dr-priority ]

By default, no neighbor is specified.

The priority configured with this command indicates whether a neighbor has the election right or not. If you configure the router priority for a neighbor as 0, the local router determines the neighbor has no election right, and does not send hello packets to this neighbor. However, if the local router is the DR or BDR, it still sends hello packets to the neighbor for neighbor relationship establishment.

Configuring the P2MP network type for an interface

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter interface view.

interface interface-type interface-number

N/A

3. Configure the OSPF network

type for the interface as P2MP.

ospf network-type p2mp [ unicast ]

By default, the network type of an interface depends on the link layer protocol.

After you configure the OSPF network type for an interface as P2MP unicast, all packets are unicast over the interface. The interface cannot broadcast hello packets to discover neighbors, so you must manually specify the neighbors.

4. Exit to system view.

quit N/A

Step Command

Remarks

5. Enter OSPF view.

ospf [ process-id | router-id

router-id | vpn-instance vpn-instance-name ] *

N/A

6. (Optional.) Specify a

neighbor and its router priority.

peer ip-address [ cost value | dr-priority dr-priority ]

By default, no neighbor is specified.

This step must be performed if the network type is P2MP unicast, and is optional if the network type is P2MP.

Configuring the P2P network type for an interface

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter interface view.

interface interface-type interface-number

N/A

3. Configure the OSPF network

type for the interface as P2P.

ospf network-type p2p

By default, the network type of an interface depends on the link layer protocol.

Configuring OSPF route control

This section describes how to control the advertisement and reception of OSPF routing information, as well as route redistribution from other protocols.

Configuration prerequisites

Before you configure OSPF route control, complete the following tasks:

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

• Enable OSPF.

• Configure filters if routing information filtering is needed.

Configuring OSPF route summarization

Configure route summarization on an ABR or ASBR to summarize contiguous networks into a single network and distribute it to other areas.

Route summarization reduces the routing information exchanged between areas and the size of routing tables, and improves routing performance. For example, three internal networks 19.1.1.0/24,

19.1.2.0/24, and 19.1.3.0/24 are available within an area. You can summarize the three networks into network 19.1.0.0/16, and advertise the summary network to other areas.

Configuring route summarization on an ABR

After you configure a summary route on an ABR, the ABR generates a summary LSA instead of more specific LSAs so that the scale of LSDBs on routers in other areas and the influence of topology changes are reduced.

To configure route summarization on an ABR:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id

| vpn-instance vpn-instance-name ] *

N/A

3. Enter OSPF area view.

area area-id N/A

4. Configure ABR route

summarization.

abr-summary ip-address { mask | mask-length } [ advertise |

not-advertise ] [ cost cost ]

By default, no route summarization is configured.

The command takes effect only on an ABR.

Configuring route summarization when redistributing routes into OSPF on an ASBR

Without route summarization, an ASBR advertises each redistributed route in a separate ASE LSA. After you configure a summary route, the ASBR advertises only the summary route in an ASE LSA instead of more specific routes, reducing the number of LSAs in the LSDB.

The ASBR summarizes redistributed Type-5 LSAs that fall into the specified address range. If the ASBR is in an NSSA area, it also summarizes Type-7 LSAs that fall into the specified address range. If the ASBR is also the ABR, it summarizes Type-5 LSAs translated from Type-7 LSAs.

To configure route summarization when redistributing routes into OSPF on an ASBR:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id

| vpn-instance vpn-instance-name ]*

N/A

3. Configure ASBR route

summarization.

asbr-summary ip-address { mask | mask-length } [ tag tag | not-advertise

| cost cost ] *

By default, no ASBR route summarization is configured.

The command takes effect only on an ASBR.

Configuring inbound OSPF route filtering

Perform this task to filter routes calculated using received LSAs.

The following filtering methods are available:

• Use an ACL or IP prefix list to filter routing information by destination address.

• Use the gateway keyword to filter routing information by next hop.

• Use an ACL or IP prefix list to filter routing information by destination address and at the same time

use the gateway keyword to filter routing information by next hop.

• Use a routing policy to filter routing information.

To configure OSPF to filter routes calculated using received LSAs:

Step Command

Remarks

1. Enter system view.

system-view N/A

Step Command

Remarks

2. Enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Configure OSPF to

filter routes calculated using received LSAs.

filter-policy { acl-number [ gateway ip-prefix-name ] | gateway ip-prefix-name | ip-prefix ip-prefix-name [ gateway ip-prefix-name ] | route-policy route-policy-name } import

By default, OSPF accepts all routes calculated using received LSAs.

Configuring Type-3 LSA filtering

Perform this task to filter Type-3 LSAs advertised to an area on an ABR.

To configure Type-3 LSA filtering:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Enter area view.

area area-id N/A

4. Configure Type-3 LSA

filtering.

filter { acl-number | ip-prefix ip-prefix-name } { import | export }

By default, the ABR does not filter Type-3 LSAs.

Configuring an OSPF cost for an interface

Configure an OSPF cost for an interface by using either of the following methods:

• Configure the cost value in interface view.

• Configure a bandwidth reference value for the interface. OSPF computes the cost with this formula:

Interface OSPF cost = Bandwidth reference value (100 Mbps) / Interface bandwidth (Mbps). If the calculated cost is greater than 65535, the value of 65535 is used. If the calculated cost is less than 1, the value of 1 is used. If no cost or bandwidth reference value is configured for an interface, OSPF computes the interface cost based on the interface bandwidth and default bandwidth reference value.

To configure an OSPF cost for an interface:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter interface view.

interface interface-type interface-number

N/A

3. Configure an OSPF cost

for the interface.

ospf cost value

By default, the OSPF cost is calculated according to the interface bandwidth. For a loopback interface, the OSPF cost is 0 by default.

To configure a bandwidth reference value:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Configure a bandwidth

reference value.

bandwidth-reference value

The default setting is 100 Mbps.

Configuring the maximum number of ECMP routes

Perform this task to implement load sharing over ECMP routes.

To configure the maximum number of ECMP routes:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Configure the maximum

number of ECMP routes.

maximum load-balancing maximum

By default, the maximum number of ECMP routes is the same as that configured in the max-ecmp-num command. For more information about the max-ecmp-num command, see IP

Routing Command Reference.

Configuring OSPF preference

A router can run multiple routing protocols, and each protocol is assigned a preferen ce. If mul tiple routes are available to the same destination, the one with the highest protocol preference is selected as the best route.

To configure OSPF preference:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id

| vpn-instance vpn-instance-name ] *

N/A

3. Configure a

preference for OSPF.

preference [ ase ] [ route-policy route-policy-name ] value

By default, the preference of OSPF internal routes is 10 and the preference of OSPF external routes is 150.

Configuring OSPF route redistribution

On a router running OSPF and other routing protocols, you can configure OSPF to redistribute routes from other protocols, such as RIP, IS-IS, BGP, static, and direct, and advertise them in Type-5 LSAs or Type-7 LSAs. In addition, you can configure OSPF to filter redistributed routes so that OSPF advertises only permitted routes.

IMPORTANT:

The import-route bgp command redistributes only EBGP routes. Because the import-route bgp allow-ibgp command redistributes both EBGP and IBGP routes, and might cause routin

loops, use it with

caution.

Configuring OSPF to redistribute routes from another routing protocol

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Configure OSPF to

redistribute routes from another routing protocol.

import-route protocol [ process-id | all-processes | allow-ibgp ] [ cost cost | route-policy route-policy-name | tag tag

| type type ] *

By default, no route redistribution is configured.

This command redistributes only active routes. To view information about active routes, use the display ip routing-table protocol command.

4. (Optional.) Configure

OSPF to filter redistributed routes.

filter-policy { acl-number | prefix-list ip-prefix-name } export [ protocol

[ process-id ] ]

By default, OSPF accepts all redistributed routes.

Configuring OSPF to redistribute a default route

The import-route command cannot redistribute a default external route. Perform this task to redistribute a default route.

To redistribute a default route:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Redistribute a default

route.

default-route-advertise [ [ [ always | permit-calculate-other ] | cost cost | route-policy route-policy-name | type

type ] * | summary cost cost ]

By default, no default route is redistributed.

This command is applicable only to VPNs. The PE router advertises a default route in a Type-3 LSA to a CE router.

Configuring default parameters for redistributed routes

Perform this task to configure default parameters for redistributed routes, including cost, tag, and type. Tags indicate information about protocols. For example, when redistributing BGP routes, OSPF uses tags to identify AS IDs.

To configure the default parameters for redistributed routes:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Configure the default

parameters for redistributed routes (cost, upper limit, tag, and type).

default { cost cost | tag tag | type type } *

By default, the cost is 1, the tag is 1, and the type is Type-2.

Advertising a host route

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id

router-id | vpn-instance vpn-instance-name ] *

N/A

3. Enter area view.

area area-id

N/A

4. Advertise a host route.

host-advertise ip-address cost

By default, no host route is advertised.

Tuning and optimizing OSPF networks

You can use one of the following methods to optimize an OSPF network:

• Change OSPF packet timers to adjust the convergence speed and network load. On low-speed

links, consider the delay time for sending LSAs.

• Change the SPF calculation interval to reduce resource consumption caused by frequent network

changes.

• Configure OSPF authentication to improve security.

Configuration prerequisites

Before you configure OSPF network optimization, complete the following tasks:

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

• Enable OSPF.

Configuring OSPF timers

An OSPF interface includes the following timers:

• Hello timer—Interval for sending hello packets. It must be identical on OSPF neighbors.

• Poll timer—Interval for sending hello packets to a neighbor that is down on the NBMA network.

• Dead timer—Interval within which if the interface receives no hello packet from the neighbor, it

declares the neighbor is down.

• LSA retransmission timer—Interval within which if the interface receives no acknowledgement

packets after sending a LSA to the neighbor, it retransmits the LSA.

To configure OSPF timers:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter interface

view.

interface interface-type interface-number

N/A

3. Specify the hello

interval.

ospf timer hello seconds

By default:

• The hello interval on P2P and broadcast

interfaces is 10 seconds.

• The hello interval on P2MP and NBMA

interfaces is 30 seconds.

The default hello interval is restored when the network type for an interface is changed.

4. Specify the poll

interval.

ospf timer poll seconds

The default setting is 120 seconds.

The poll interval is at least four times the hello interval.

5. Specify the dead

interval.

ospf timer dead seconds

By default:

• The dead interval on P2P and broadcast

interfaces is 40 seconds.

• The dead interval on P2MP and NBMA

interfaces is 120 seconds.

The dead interval must be at least four times the hello interval on an interface.

The default dead interval is restored when the network type for an interface is changed.

6. Specify the

retransmission interval.

ospf timer retransmit interval

The default setting is 5 seconds.

A retransmission interval setting that is too small can cause unnecessary LSA retransmissions. This interval is typically set bigger than the round-trip time of a packet between two neighbors.

Specifying LSA transmission delay

To avoid LSAs from aging out during transmission, set an LSA retransmission delay especially for low speed links.

To specify the LSA transmission delay on an interface:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter interface view.

interface interface-type

interface-number

N/A

3. Specify the LSA transmission

delay.

ospf trans-delay seconds

The default setting is 1 second.

Specifying SPF calculation interval

LSDB changes result in SPF calculations. When the topology changes frequently, a large amount of network and router resources are occupied by SPF calculation. You can adjust the SPF calculation interval to reduce the impact.

When network changes are not frequent, the minimum-interval is adopted. If network changes become frequent, the SPF calculation interval is incremented by incremental-interval × 2

n-2

(n is the number of

calculation times) each time a calculation occurs until the maximum-interval is reached.

To configure the SPF calculation interval:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id

| vpn-instance vpn-instance-name ] *

N/A

3. Specify the SPF

calculation interval.

spf-schedule-interval

maximum-interval [ minimum-interval [ incremental-interval ] ]

By default:

• The maximum interval is 5 seconds.

• The minimum interval is 50

milliseconds.

• The incremental interval is 200

milliseconds.

Specifying the LSA arrival interval

If OSPF receives an LSA that has the same LSA type, LS ID, and router ID as the previously received LSA within the LSA arrival interval, OSPF discards the LSA to save bandwidth and route resources.

To configure the LSA arrival interval:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id

router-id | vpn-instance vpn-instance-name ] *

N/A

Step Command

Remarks

3. Configure the LSA arrival

interval.

lsa-arrival-interval interval

The default setting is 1000 milliseconds.

Make sure this interval is smaller than or equal to the interval set with the lsa-generation-interval command.

Specifying the LSA generation interval

Adjust the LSA generation interval to protect network resources and routers from being overwhelmed by LSAs at the time of frequent network changes.

When network changes are not frequent, LSAs are generated at the minimum-interval. If network changes become frequent, the LSA generation interval is incremented by incremental-interval × 2

n-2

(n is the number of generation times) each time a LSA generation occurs until the maximum-interval is reached.

To configure the LSA generation interval:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Configure the LSA

generation interval.

lsa-generation-interval maximum-interval [ minimum-interval [ incremental-interval ] ]

By default:

• The maximum interval is 5

seconds.

• The minimum interval is 0

milliseconds.

• The incremental interval is 0

milliseconds.

Disabling interfaces from receiving and sending OSPF packets

To enhance OSPF adaptability and reduce resource consumption, you can set an OSPF interface to "silent." A silent OSPF interface blocks OSPF packets and cannot establish any OSPF neighbor relationship. However, other interfaces on the router can still advertise direct routes of the interface in Router LSAs.

To disable interfaces from receiving and sending routing information:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id

| vpn-instance vpn-instance-name ] *

N/A

Step Command

Remarks

3. Disable interfaces from

receiving and sending OSPF packets.

silent-interface { interface-type interface-number | all }

By default, an OSPF interface can receive and send OSPF packets.

The silent-interface command disables only the interfaces associated with the current process rather than other processes. Multiple OSPF processes can disable the same interface from receiving and sending OSPF packets.

Configuring stub routers

A stub router is used for traffic control. It reports its status as a stub router to neighboring OSPF routers. The neighboring routers do not use the stub router to forward data although they have a route to it.

Router LSAs from the stub router might contain different link type values. A value of 3 means a link to a stub network, and the cost of the link will not be changed. A value of 1, 2 or 4 means a point-to-point link, a link to a transit network, or a virtual link. On such links, a maximum cost value of 65535 is used. Neighbors do not send packets to the stub router as long as they have a route with a smaller cost.

To configure a router as a stub router:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Configure the router as a

stub router.

stub-router

By default, the router is not configured as a stub router.

A stub router has no associations with a stub area.

Configuring OSPF authentication

Configure OSPF packet authentication to ensure the packet exchange security.

After authentication is configured, OSPF only receives packets that pass authentication. Failed packets cannot establish neighboring relationships.

You must configure the same area authentication mode on all the routers in an area. In addition, the authentication mode and password for all interfaces attached to the same area must be identical.

To configure OSPF authentication:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

Step Command

Remarks

3. Enter area view.

area area-id N/A

4. Configure area authentication

mode.

authentication-mode { md5 | simple }

By default, no authentication is configured.

5. Return to OSPF view.

quit N/A

6. Return to system view.

quit N/A

7. Enter interface view.

interface interface-type interface-number N/A

8. Configure interface

authentication mode.

• Configure simple authentication:

ospf authentication-mode simple { cipher cipher-string | plain plain-string }

• Configure MD5 authentication:

ospf authentication-mode { hmac-md5 | md5 } key-id { cipher cipher-string | plain

plain-string }

Use either method.

By default, no interface authentication is configured.

Adding the interface MTU into DD packets

By default, an OSPF interface adds a value of 0 into the interface MTU field of a DD packet rather than the actual interface MTU. You can enable an interface to add its MTU into DD packets.

To add the interface MTU into DD packets:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter interface view.

interface interface-type

interface-number

N/A

3. Enable the interface to add its

MTU into DD packets.

ospf mtu-enable

By default, the interface adds an MTU value of 0 into DD packets.

Configuring the maximum number of external LSAs in LSDB

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Specify the maximum number

of external LSAs in the LSDB.

lsdb-overflow-limit number

By default, the maximum number of external LSAs in the LSDB is not limited.

Configuring OSPF exit overflow interval

When the number of LSAs in the LSDB exceeds the upper limit, the LSDB is in an overflow state. To save resources, OSPF does not receive any external LSAs and deletes the external LSAs generated by itself when in this state.

Perform this task to configure the interval that OSPF exits overflow state.

To configure the OSPF exit overflow interval:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Configure the OSPF exit

overflow interval.

lsdb-overflow-interval interval

The default setting is 300 seconds.

The value of 0 indicates that OSPF does not exit overflow state.

Enabling compatibility with RFC 1583

RFC 1583 specifies a different method than RFC 2328 for selecting an external route from multiple LSAs. This task enables RFC 2328 to be compatible with RFC 1583 so that the intra-area route in the backbone area is preferred. If they are not compatible, the intra-area route in a non-backbone area is preferred to reduce the burden of the backbone area.

To avoid routing loops, HP recommends enabling or disabling RFC 1583-compatibility on all routers in a routing domain.

To enable compatibility with RFC 1583:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Enable compatibility

with RFC 1583.

rfc1583 compatible By default, this feature is enabled.

Logging neighbor state changes

Perform this task to enable output of log information to the terminal upon neighbor state changes.

To enable the logging of neighbor state changes:

Step Command

Remarks

1. Enter system view.

system-view N/A

Step Command

Remarks

2. Enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Enable the logging of

neighbor state changes.

log-peer-change

By default, this feature is enabled.

Configuring OSPF network management

OSPF network management allows you to save system resources by enabling trap generation to report important events and configuring the maximum number of output traps for a specific time period.

To configure OSPF network management:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Bind OSPF MIB to an

OSPF process.

ospf mib-binding process-id

By default, OSPF MIB is bound to the process with the smallest process ID.

3. Enable SNMP traps

for OSPF.

snmp-agent trap enable ospf [ authentication-failure | bad-packet |

By default, SNMP traps for OSPF is enabled.

4. Configure the

number of output SNMP traps within a specified time interval.

snmp trap rate-limit interval trap-interval count trap-number

By default, OSPF outputs up to 7 SNMP traps within 10 seconds.

Configuring the LSU transmit rate

Sending large numbers of LSU packets affects router performance and consumes too much network bandwidth. You can configure the router to send LSU packets at a proper interval and limit the maximum number of LSU packets sent out of an OSPF interface each time.

To configure the LSU transmit rate:

Step Command

Remarks

1. Enter system view.

system-view N/A

Step Command

Remarks

2. Enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Configure the LSU

transmit rate.

transmit-pacing interval interval count count

By default, an OSPF interface sends up to three LSU packets every 20 milliseconds.

Enabling OSPF ISPF

When the topology changes, Incremental Shortest Path First (ISPF) computes only the affected part of the SPT, instead of the entire SPT.

To enable OSPF ISPF:

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enter OSPF view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Enable OSPF ISPF.

ispf enable

By default, OSPF ISPF is enabled.

Configuring OSPF GR

GR ensures forwarding continuity when a routing protocol restarts or an active/standby switchover occurs.

Two routers are required to complete a GR process. The following are router roles in a GR process.

• GR Restarter—Graceful restarting router. It must have GR capability.

• GR Helper—A neighbor of the GR Restarter. It helps the GR Restarter to complete the GR process.

OSPF GR has the following types:

• IETF GR—Uses Opaque LSAs to implement GR.

• Non-IETF GR—Uses link local signaling (LLS) to advertise GR capability and uses out of band

synchronization to synchronize the LSDB.

A device can act as a GR Restarter and GR Helper at the same time.

Configuring the OSPF GR Restarter

You can configure the IETF or non IETF OSPF GR Restarter.

Configuring the IETF OSPF GR Restarter

Step Command

Remarks

1. Enter system view.

system-view

N/A

Step Command

Remarks

2. Enable OSPF and enter its

view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Enable opaque LSA reception

and advertisement capability.

opaque-capability enable

By default, opaque LSA reception and advertisement capability is enabled.

4. Enable the IETF GR.

graceful-restart ietf [ global | planned-only ] *

By default, the IETF GR capability is disabled.

5. (Optional.) Configure GR

interval.

graceful-restart interval interval-value

The default setting is 120 seconds.

Configuring the non-IETF OSPF GR Restarter

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enable OSPF and enter its

view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Enable the link-local signaling

capability.

enable link-local-signaling

By default, the link-local signaling capability is disabled.

4. Enable the out-of-band

re-synchronization capability.

enable out-of-band-resynchronization

By default, the out-of-band re-synchronization capability is disabled.

5. Enable non-IETF GR.

graceful-restart [ nonstandard ]

[ global | planned-only ] *

By default, non-IETF GR capability is disabled.

6. (Optional.) Configure GR

interval.

graceful-restart interval interval-value

The default setting is 120.

Configuring OSPF GR Helper

You can configure the IETF or non IETF OSPF GR Helper.

Configuring the IETF OSPF GR Helper

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enable OSPF and enter its

view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Enable opaque LSA reception

and advertisement capability.

opaque-capability enable

By default, opaque LSA reception and advertisement capability is enabled.

4. (Optional.) Enable GR Helper

capability.

graceful-restart helper enable

[ planned-only ]

By default, GR Helper capability is enabled.

Step Command

Remarks

5. (Optional.) Enable strict LSA

checking for the GR Helper.

graceful-restart helper strict-lsa-checking

By default, strict LSA checking for the GR Helper is disabled.

Configuring the non-IETF OSPF GR Helper

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Enable OSPF and enter its

view.

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] *

N/A

3. Enable the link-local signaling

capability.

enable link-local-signaling

By default, the link-local signaling capability is disabled.

4. Enable the out-of-band

re-synchronization capability.

enable out-of-band-resynchronization

By default, the out-of-band re-synchronization capability is disabled.

5. (Optional.) Enable GR

Helper.

graceful-restart helper enable By default, GR Helper is enabled.

6. (Optional.) Enable strict LSA

checking for the GR Helper.

graceful-restart helper strict-lsa-checking

By default, strict LSA checking for the GR Helper is disabled.

Triggering OSPF GR

To trigger OSPF GR, perform the following command in user view:

Task Command

Trigger OSPF GR. reset ospf [ process-id ] process graceful-restart

Configuring BFD for OSPF

BFD provides a single mechanism to quickly detect and monitor the connectivity of links between OSPF neighbors, which improves the network convergence speed. For more information about BFD, see High Availability Configuration Guide.

OSPF supports the following BFD detection modes:

• Bidirectional control detection—Requires BFD configuration to be made on both OSPF routers on

the link.

• Single-hop echo detection—Requires BFD configuration to be made on one OSPF router on the link.

Configuring bidirectional control detection

Step Command

Remarks

1. Enter system view.

system-view N/A

Step Command

Remarks

2. Enter interface view.

interface interface-type

interface-number

N/A

3. Enable BFD bidirectional control

detection.

ospf bfd enable

By default, BFD bidirectional control detection is disabled.

Both ends of a BFD session must be on the same network segment and in the same area.

Configuring single-hop echo detection

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Configure the source address of echo

packets.

bfd echo-source-ip ip-address

By default, the source address of echo packets is not configured.

3. Enter interface view.

interface interface-type

interface-number

N/A

4. Enable BFD single-hop echo

detection.

ospf bfd enable echo

By default, BFD single-hop echo detection is disabled.

Configuring OSPF FRR

A link or router failure on a path can cause packet loss and even routing loop until OSPF completes routing convergence based on the new network topology. FRR uses BFD to detect failures and enables fast rerouting to minimize the impact of link or node failures.

Figure 19 Network diagram for OSPF FRR

In Figure 19, configure FRR on Router B by using a routing policy to specify a backup next hop. When the primary link fails, OSPF directs packets to the backup next hop. At the same time, OSPF calculates the shortest path based on the new network topology, and forwards packets over the path after network convergence.

You can configure OSPF FRR to calculate a backup next hop by using the loop free alternate (LFA) algorithm, or specify a backup next hop by using a routing policy.

Configuration prerequisites

Before you configure OSPF FRR, complete the following tasks:

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

• Enable OSPF.

Configuration guidelines

• Do not use FRR and BFD at the same time. Otherwise, FRR might fail to take effect.

• Do not use the fast-reroute lfa command together with the command vlink-peer.

Configuring OSPF FRR to calculate a backup next hop using the LFA algorithm

Step Command

Remarks

1. Enter system view.

system-view N/A

2. Configure the source address

of echo packets.

bfd echo-source-ip ip-address

By default, the source address of echo packets is not configured.

3. Enter interface view.

interface interface-type interface-number

N/A

4. Enable LFA calculation on an

interface.

ospf fast-reroute lfa-backup

By default, the interface on which LFA calculation is enabled can be selected as a backup interface.

5. Return to system view.

quit N/A

6. Enter OSPF view.

ospf [ process-id | router-id

router-id | vpn-instance vpn-instance-name ] *

N/A

7. Enable OSPF FRR to calculate

a backup next hop by using the LFA algorithm.

fast-reroute lfa [ abr-only ]

By default, OSPF FRR is n o t c onfigured.

If abr-only is specified, the route to the ABR is selected as the backup path.

Configuring OSPF FRR to specify a backup next hop using a routing policy

Before you configure this task, use the apply fast-reroute backup-interface command to specify a backup next hop in the routing policy to be referenced. For more information about the apply fast-reroute backup-interface command and routing policy configuration, see "Configuring routing policies."

To configure OSPF FRR to specify a backup next hop using a routing policy:

Step Command

Remarks

1. Enter system view.

system-view N/A

Step Command

Remarks

2. Configure the source address

of echo packets.

bfd echo-source-ip ip-address

By default, the source address of echo packets is not configured.

3. Enter OSPF view.

ospf [ process-id | router-id

router-id | vpn-instance vpn-instance-name ] *

N/A

4. Enable OSPF FRR to specify a

backup next hop by using a routing policy.

fast-reroute route-policy route-policy-name

By default, OSPF FRR is not configured.

Displaying and maintaining OSPF

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

Task Command

Display OSPF brief information.

display ospf [ process-id ] brief

Display OSPF statistics.

display ospf [ process-id ] cumulative

Display GR status of the specified OSPF process.

display ospf [ process-id ] graceful-restart [ verbose ]

Display Link State Database information.

display ospf [ process-id ] lsdb [ brief | [ { ase | router | network | summary | asbr | nssa | opaque-link | opaque-area | opaque-as }

[ link-state-id ] ] [ originate-router advertising-router-id | self-originate ] ]

Display OSPF neighbor information.

display ospf [ process-id ] peer [ verbose ] [ interface-type interface-number ] [ neighbor-id ]

Display neighbor statistics for OSPF areas.

display ospf [ process-id ] peer statistics

Display routing table information.

display ospf [ process-id ] routing [ interface interface-type interface-number ] [ nexthop nexthop-address ] [ verbose ]

Display virtual link information.

display ospf [ process-id ] vlink

Display OSPF request queue information.

display ospf [ process-id ] request-queue [ interface-type interface-number ] [ neighbor-id ]

Display OSPF retransmission queue information.

display ospf [ process-id ] retrans-queue [ interface-type interface-number ] [ neighbor-id ]

Display OSPF ABR and ASBR information.

display ospf [ process-id ] abr-asbr

Display OSPF interface information.

display ospf [ process-id ] interface [ all | interface-type interface-number ]

Display OSPF error information.

display ospf [ process-id ] error

Display OSPF ASBR route summarization information.

display ospf [ process-id ] asbr-summary [ ip-address { mask | mask-length } ]

Display the global route ID. display router id

Clear OSPF statistics. reset ospf [ process-id ] counters

Reset an OSPF process. reset ospf [ process-id ] process [ graceful-restart ]

Task Command

Re-enable OSPF route redistribution.

reset ospf [ process-id ] redistribution

OSPF configuration examples

These configuration examples only cover commands for OSPF configuration.

Configuring basic OSPF

Network requirements

• Enable OSPF on all switches, and split the AS into three areas.

• Configure Switch A and Switch B as ABRs.

Figure 20 Network diagram

Configuration procedure

1. Configure IP addresses for interfaces. (Details not shown.)

2. Enable OSPF:

# Configure Switch A.

<SwitchA> system-view [SwitchA] router id 10.2.1.1 [SwitchA] ospf [SwitchA-ospf-1] area 0 [SwitchA-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255 [SwitchA-ospf-1-area-0.0.0.0] quit [SwitchA-ospf-1] area 1 [SwitchA-ospf-1-area-0.0.0.1] network 10.2.1.0 0.0.0.255 [SwitchA-ospf-1-area-0.0.0.1] quit [SwitchA-ospf-1] quit

# Configure Switch B.

<SwitchB> system-view [SwitchB] router id 10.3.1.1 [SwitchB] ospf

Area 0

Area 1

Area 2

Switch C

Vlan-int100

10.1.1.2/24

Vlan-int100

10.1.1.1/24

Vlan-int300

10.4.1.1/24

Vlan-int200

10.2.1.2/24

Switch B

Vlan-int200

10.3.1.1/24

Vlan-int200

10.3.1.2/24

Switch A

Vlan-int200

10.2.1.1/24

Vlan-int300

10.5.1.1/24

Switch D

[SwitchB-ospf-1] area 0 [SwitchB-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255 [SwitchB-ospf-1-area-0.0.0.0] quit [SwitchB-ospf-1] area 2 [SwitchB-ospf-1-area-0.0.0.2] network 10.3.1.0 0.0.0.255 [SwitchB-ospf-1-area-0.0.0.2] quit [SwitchB-ospf-1] quit

# Configure Switch C.

<SwitchC> system-view [SwitchC] router id 10.4.1.1 [SwitchC] ospf [SwitchC-ospf-1] area 1 [SwitchC-ospf-1-area-0.0.0.1] network 10.2.1.0 0.0.0.255 [SwitchC-ospf-1-area-0.0.0.1] network 10.4.1.0 0.0.0.255 [SwitchC-ospf-1-area-0.0.0.1] quit [SwitchC-ospf-1] quit

# Configure Switch D.

<SwitchD> system-view [SwitchD] router id 10.5.1.1 [SwitchD] ospf [SwitchD-ospf-1] area 2 [SwitchD-ospf-1-area-0.0.0.2] network 10.3.1.0 0.0.0.255 [SwitchD-ospf-1-area-0.0.0.2] network 10.5.1.0 0.0.0.255 [SwitchD-ospf-1-area-0.0.0.2] quit [SwitchD-ospf-1] quit

Verifying the configuration

# Display information about neighbors on Switch A.

[SwitchA] display ospf peer verbose

OSPF Process 1 with Router ID 10.2.1.1 Neighbors

Area 0.0.0.0 interface 10.1.1.1(Vlan-interface100)'s neighbors Router ID: 10.3.1.1 Address: 10.1.1.2 GR State: Normal State: Full Mode: Nbr is Master Priority: 1 DR: 10.1.1.1 BDR: 10.1.1.2 MTU: 0 Options is 0x02 (-|-|-|-|-|-|E|-) Dead timer due in 37 sec Neighbor is up for 06:03:59 Authentication Sequence: [ 0 ] Neighbor state change count: 5

Neighbors

Area 0.0.0.1 interface 10.2.1.1(Vlan-interface200)'s neighbors Router ID: 10.4.1.1 Address: 10.2.1.2 GR State: Normal State: Full Mode: Nbr is Master Priority: 1

DR: 10.2.1.1 BDR: 10.2.1.2 MTU: 0 Options is 0x02 (-|-|-|-|-|-|E|-) Dead timer due in 32 sec Neighbor is up for 06:03:12 Authentication Sequence: [ 0 ] Neighbor state change count: 5

# Display OSPF routing information on Switch A.

[SwitchA] display ospf routing

OSPF Process 1 with Router ID 10.2.1.1 Routing Tables

Routing for Network Destination Cost Type NextHop AdvRouter Area

10.2.1.0/24 1 Transit 10.2.1.1 10.2.1.1 0.0.0.1

10.3.1.0/24 2 Inter 10.1.1.2 10.3.1.1 0.0.0.0

10.4.1.0/24 2 Stub 10.2.1.2 10.4.1.1 0.0.0.1

10.5.1.0/24 3 Inter 10.1.1.2 10.3.1.1 0.0.0.0

10.1.1.0/24 1 Transit 10.1.1.1 10.2.1.1 0.0.0.0

Total Nets: 5 Intra Area: 3 Inter Area: 2 ASE: 0 NSSA: 0

# Display OSPF routing information on Switch D.

[SwitchD] display ospf routing

OSPF Process 1 with Router ID 10.5.1.1 Routing Tables

Routing for Network Destination Cost Type NextHop AdvRouter Area

10.2.1.0/24 3 Inter 10.3.1.1 10.3.1.1 0.0.0.2

10.3.1.0/24 1 Transit 10.3.1.2 10.3.1.1 0.0.0.2

10.4.1.0/24 4 Inter 10.3.1.1 10.3.1.1 0.0.0.2

10.5.1.0/24 1 Stub 10.5.1.1 10.5.1.1 0.0.0.2

10.1.1.0/24 2 Inter 10.3.1.1 10.3.1.1 0.0.0.2

Total Nets: 5 Intra Area: 2 Inter Area: 3 ASE: 0 NSSA: 0

# On Switch D, ping the IP address 10.4.1.1 to test reachability.

[SwitchD] ping 10.4.1.1 PING 10.4.1.1: 56 data bytes, press CTRL_C to break Reply from 10.4.1.1: bytes=56 Sequence=2 ttl=253 time=2 ms Reply from 10.4.1.1: bytes=56 Sequence=2 ttl=253 time=1 ms Reply from 10.4.1.1: bytes=56 Sequence=3 ttl=253 time=1 ms Reply from 10.4.1.1: bytes=56 Sequence=4 ttl=253 time=1 ms Reply from 10.4.1.1: bytes=56 Sequence=5 ttl=253 time=1 ms

--- 10.4.1.1 ping statistics -- 5 packet(s) transmitted 5 packet(s) received

0.00% packet loss round-trip min/avg/max = 1/1/2 ms

Configuring OSPF route redistribution

Network requirements

• Enable OSPF on all the switches.

• Split the AS into three areas.

• Configure Switch A and Switch B as ABRs.

• Configure Switch C as an ASBR to redistribute external routes (static routes).

Figure 21 Network diagram

Configuration procedure

1. Configure IP addresses for interfaces. (Details not shown.)

2. Enable OSPF (see "Configuring basic OSPF").

3. Config

ure OSPF to redistribute routes:

# On Switch C, configure a static route destined for network 3.1.2.0/24.

<SwitchC> system-view [SwitchC] ip route-static 3.1.2.1 24 10.4.1.2

# On Switch C, configure OSPF to redistribute static routes.

[SwitchC] ospf 1 [SwitchC-ospf-1] import-route static

Verifying the configuration

# Display the ABR/ASBR information of Switch D.

<SwitchD> display ospf abr-asbr

OSPF Process 1 with Router ID 10.5.1.1 Routing Table to ABR and ASBR

Type Destination Area Cost Nexthop RtType Intra 10.3.1.1 0.0.0.2 10 10.3.1.1 ABR

Inter 10.4.1.1 0.0.0.2 22 10.3.1.1 ASBR

# Display the OSPF routing table on Switch D.

<SwitchD> display ospf routing

OSPF Process 1 with Router ID 10.5.1.1 Routing Tables

Routing for Network Destination Cost Type NextHop AdvRouter Area

10.2.1.0/24 22 Inter 10.3.1.1 10.3.1.1 0.0.0.2

10.3.1.0/24 10 Transit 10.3.1.2 10.3.1.1 0.0.0.2

10.4.1.0/24 25 Inter 10.3.1.1 10.3.1.1 0.0.0.2

10.5.1.0/24 10 Stub 10.5.1.1 10.5.1.1 0.0.0.2

10.1.1.0/24 12 Inter 10.3.1.1 10.3.1.1 0.0.0.2

Routing for ASEs Destination Cost Type Tag NextHop AdvRouter

3.1.2.0/24 1 Type2 1 10.3.1.1 10.4.1.1

Total Nets: 6 Intra Area: 2 Inter Area: 3 ASE: 1 NSSA: 0

Configuring OSPF to advertise a summary route

Network requirements

• Configure OSPF on Switch A and Switch B in AS 200.

• Configure OSPF on Switch C, Switch D, and Switch E in AS 100.

• Configure an EBGP connection between Switch B and Switch C. Configure Switch B and Switch C

to redistribute OSPF routes and direct routes into BGP and BGP routes into OSPF.

• Configure Switch B to advertise only summary route 10.0.0.0/8 to Switch A.

Figure 22 Network diagram

Configuration procedure

1. Configure IP addresses for interfaces. (Details not shown.)

2. Enable OSPF:

# Configure Switch A.

<SwitchA> system-view [SwitchA] router id 11.2.1.2 [SwitchA] ospf [SwitchA-ospf-1] area 0 [SwitchA-ospf-1-area-0.0.0.0] network 11.2.1.0 0.0.0.255 [SwitchA-ospf-1-area-0.0.0.0] quit [SwitchA-ospf-1] quit

# Configure Switch B.

<SwitchB> system-view [SwitchB] router id 11.2.1.1 [SwitchB] ospf [SwitchB-ospf-1] area 0 [SwitchB-ospf-1-area-0.0.0.0] network 11.2.1.0 0.0.0.255 [SwitchB-ospf-1-area-0.0.0.0] quit [SwitchB-ospf-1] quit

# Configure Switch C.

<SwitchC> system-view [SwitchC] router id 11.1.1.2 [SwitchC] ospf [SwitchC-ospf-1] area 0 [SwitchC-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255 [SwitchC-ospf-1-area-0.0.0.0] network 10.2.1.0 0.0.0.255 [SwitchC-ospf-1-area-0.0.0.0] quit [SwitchC-ospf-1] quit

Switch A

Switch B

Switch D

Switch E

Switch C

Vlan-int400

10.1.1.1/24

Vlan-int400

10.1.1.2/24

Vlan-int300

10.2.1.2/24

Vlan-int300

10.2.1.1/24

Vlan-int200

11.1.1.2/24

Vlan-int200

11.1.1.1/24

EBGP

AS 200

AS 100

Vlan-int100

11.2.1.1/24

Vlan-int100

11.2.1.2/24

Vlan-int500

10.3.1.1/24

Vlan-int600

10.4.1.1/24

# Configure Switch D.

<SwitchD> system-view [SwitchD] router id 10.3.1.1 [SwitchD] ospf [SwitchD-ospf-1] area 0 [SwitchD-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255 [SwitchD-ospf-1-area-0.0.0.0] network 10.3.1.0 0.0.0.255 [SwitchD-ospf-1-area-0.0.0.0] quit

# Configure Switch E.

<SwitchE> system-view [SwitchE] router id 10.4.1.1 [SwitchE] ospf [SwitchE-ospf-1] area 0 [SwitchE-ospf-1-area-0.0.0.0] network 10.2.1.0 0.0.0.255 [SwitchE-ospf-1-area-0.0.0.0] network 10.4.1.0 0.0.0.255 [SwitchE-ospf-1-area-0.0.0.0] quit [SwitchE-ospf-1] quit

3. Configure BGP to redistribute OSPF routes and direct routes:

# Configure Switch B.

[SwitchB] bgp 200 [SwitchB-bgp] peer 11.1.1.2 as 100 [SwitchB-bgp] ipv4-family unicast [SwitchB-bgp-ipv4] import-route ospf [SwitchB-bgp-ipv4] import-route direct [SwitchB-bgp ipv4] quit [SwitchB-bgp] quit

# Configure Switch C.

[SwitchC] bgp 100 [SwitchC-bgp] peer 11.1.1.1 as 200 [SwitchC-bgp] ipv4-family unicast [SwitchC-bgp-ipv4] import-route ospf [SwitchC-bgp-ipv4]import-route direct [SwitchC-bgp-ipv4] quit [SwitchC-bgp] quit

4. Configure Switch B and Switch C to redistribute BGP routes into OSPF:

# Configure OSPF to redistribute routes from BGP on Switch B.

[SwitchB] ospf [SwitchB-ospf-1] import-route bgp

# Configure OSPF to redistribute routes from BGP on Switch C.

[SwitchC] ospf [SwitchC-ospf-1] import-route bgp

# Display the OSPF routing table on Switch A.

[SwitchA] display ip routing-table

Destinations : 16 Routes : 16

Destination/Mask Proto Pre Cost NextHop Interface

0.0.0.0/32 Direct 0 0 127.0.0.1 InLoop0

10.1.1.0/24 OSPF 150 1 11.2.1.1 Vlan100

10.2.1.0/24 OSPF 150 1 11.2.1.1 Vlan100

10.3.1.0/24 OSPF 150 1 11.2.1.1 Vlan100

10.4.1.0/24 OSPF 150 1 11.2.1.1 Vlan100

11.2.1.0/24 Direct 0 0 11.2.1.2 Vlan100

11.2.1.0/32 Direct 0 0 11.2.1.2 Vlan100

11.2.1.2/32 Direct 0 0 127.0.0.1 InLoop0

11.2.1.255/32 Direct 0 0 11.2.1.2 Vlan100

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

5. Configure route summarization:

# Configure route summarization on Switch B to advertise a summary route 10.0.0.0/8.

[SwitchB-ospf-1] asbr-summary 10.0.0.0 8

# Display the IP routing table on Switch A.

[SwitchA] display ip routing-table

Destinations : 13 Routes : 13

Destination/Mask Proto Pre Cost NextHop Interface

0.0.0.0/32 Direct 0 0 127.0.0.1 InLoop0

10.0.0.0/8 OSPF 150 2 11.2.1.1 Vlan100

11.2.1.0/24 Direct 0 0 11.2.1.2 Vlan100

11.2.1.0/32 Direct 0 0 11.2.1.2 Vlan100

11.2.1.2/32 Direct 0 0 127.0.0.1 InLoop0

11.2.1.255/32 Direct 0 0 11.2.1.2 Vlan100

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

The output shows that routes 10.1.1.0/24, 10.2.1.0/24, 10.3.1.0/24 and 10.4.1.0/24 are summarized into a single route 10.0.0.0/8.

Configuring an OSPF stub area

Network requirements

• Enable OSPF on all switches, and split the AS into three areas.

• Configure Switch A and Switch B as ABRs to forward routing information between areas.

• Configure Switch D as the ASBR to redistribute static routes.

• Configure Area 1 as a stub area to reduce advertised LSAs without influencing reachability.

Figure 23 Network diagram

Configuration procedure

1. Configure IP addresses for interfaces. (Details not shown.)

2. Enable OSPF (see "Configuring basic OSPF").

3. Config

ure route redistribution:

# Configure Switch D to redistribute static routes.

<SwitchD> system-view [SwitchD] ip route-static 3.1.2.1 24 10.5.1.2 [SwitchD] ospf [SwitchD-ospf-1] import-route static [SwitchD-ospf-1] quit

# Display ABR/ASBR information on Switch C.

<SwitchC> display ospf abr-asbr

OSPF Process 1 with Router ID 10.4.1.1 Routing Table to ABR and ASBR

Type Destination Area Cost Nexthop RtType Intra 10.2.1.1 0.0.0.1 3 10.2.1.1 ABR Inter 10.5.1.1 0.0.0.1 7 10.2.1.1 ASBR

# Display OSPF routing table on Switch C.

<SwitchC> display ospf routing

OSPF Process 1 with Router ID 10.4.1.1 Routing Tables

Routing for Network Destination Cost Type NextHop AdvRouter Area

10.2.1.0/24 3 Transit 10.2.1.2 10.2.1.1 0.0.0.1

10.3.1.0/24 7 Inter 10.2.1.1 10.2.1.1 0.0.0.1

10.4.1.0/24 3 Stub 10.4.1.1 10.4.1.1 0.0.0.1

10.5.1.0/24 17 Inter 10.2.1.1 10.2.1.1 0.0.0.1

Area 0

Area 1 Stub

Area 2

Switch C

Vlan-int100

10.1.1.2/24

Vlan-int100

10.1.1.1/24

Vlan-int300

10.4.1.1/24

Vlan-int200

10.2.1.2/24

Switch B

Vlan-int200

10.3.1.1/24

Vlan-int200

10.3.1.2/24

Switch A

Vlan-int200

10.2.1.1/24

Vlan-int300

10.5.1.1/24

Switch D

ASBR

HP 6125XLG Layer 3—IP Routing Configuration Guide

Specifications and Main Features

Frequently Asked Questions

User Manual