HP FlexNetwork 7500 Configuration Manual

HPE FlexNetwork 7500 Switch Series

IP Multicast Configuration Guide

Part number: 5998-7469R Software version: 7500-CMW710-R7178 Document version: 6W100-20160129

Enterprise products and services are set forth in the express warranty statements acco mpanying such products and services. Nothing herein should be construe d as constituting an additional warranty. Hewlett Packard Enterprise shall not be liable for technical or editorial errors or omissions co ntained herein.

Confidential computer software. V alid license from Hewlett Packard Enterprise required for possession, use, or copying. Consistent with FAR 12.211 and 12.212, Commercial Computer Software, Computer Software Documentation, and T e chnical Data for Commercial Items are licensed to the U.S. Government under vendor’s standard commercial license.

Links to third-party websites take you outside the Hewlett Packard Enterprise website. Hewlett Packard Enterprise has no control over and is not responsible for information outside the Hewlett Packard Enterprise website.

Acknowledgments

Intel®, Itanium®, Pentium®, Intel Inside®, and the Intel Inside logo are trademarks of Intel Corporation in the United States and other countries.

Microsoft® and Windows® are trademarks of the Microsoft group of companies. Adobe® and Acrobat® are trademarks of Adobe Systems In corporated. Java and Oracle are registered trademarks of Oracle and/or its affiliates. UNIX® is a registered trademark of The Open Group.

Multicast overview ··························································································· 1

Introduction to multicast ····································································································································· 1

Information transmission techniques ·········································································································· 1 Multicast features ······································································································································· 3 Common notations in multicast ·················································································································· 4

Multicast benefits and applications ············································································································ 4 Multicast models ················································································································································ 4 Multicast architecture ········································································································································· 5

Multicast addresses ··································································································································· 5

Multicast protocols ····································································································································· 8 Multicast packet forwarding mechanism ·········································································································· 11

Configuring IGMP snooping ·········································································· 12

IGMP snooping ports ······························································································································· 12

How IGMP snooping works ······················································································································ 14

Protocols and standards ·························································································································· 15 General configuration restrictions and guidelines ···························································································· 15 IGMP snooping configuration task list ·············································································································· 16 Configuring basic IGMP snooping features ····································································································· 16

Enabling IGMP snooping ························································································································· 16

Specifying an IGMP snooping version ····································································································· 17

Setting the maximum number of IGMP snooping forwarding entries ······················································· 18

Setting the IGMP last member query interval ·························································································· 18 Configuring IGMP snooping port features ········································································································ 19

Setting aging timers for dynamic ports ····································································································· 19

Configuring static ports ···························································································································· 20

Configuring a port as a simulated member host ······················································································ 20

Enabling fast-leave processing ················································································································ 21

Disabling a port from becoming a dynamic router port ············································································ 21 Configuring the IGMP snooping querier ··········································································································· 22

Configuration prerequisites ······················································································································ 22

Enabling the IGMP snooping querier ······································································································· 22

Configuring parameters for IGMP general queries and responses ·························································· 23 Configuring parameters for IGMP messages ··································································································· 23

Configuration prerequisites ······················································································································ 24

Configuring source IP addresses for IGMP messages ············································································ 24

Setting the 802.1p priority for IGMP messages ······················································································· 25 Configuring IGMP snooping policies ················································································································ 25

Configuring a multicast group policy ········································································································ 25

Enabling multicast source port filtering ···································································································· 26

Enabling dropping unknown multicast data ······························································································ 27

Enabling IGMP report suppression ·········································································································· 27

Setting the maximum number of multicast groups on a port ···································································· 28

Enabling multicast group replacement ····································································································· 28 Displaying and maintaining IGMP snooping ···································································································· 29 IGMP snooping configuration examples ·········································································································· 30

Group policy and simulated joining configuration example ······································································ 30

Static port configuration example ············································································································· 32

IGMP snooping querier configuration example ························································································ 35 Troubleshooting IGMP snooping ····················································································································· 37

Layer 2 multicast forwarding cannot function ··························································································· 37

Multicast group policy does not work ······································································································· 38

Configuring PIM snooping ············································································· 39

Displaying and maintaining PIM snooping ······································································································· 41 PIM snooping configuration example ··············································································································· 41 Troubleshooting PIM snooping ························································································································ 45

PIM snooping does not work on a Layer 2 device ··················································································· 45

Configuring multicast VLANs ········································································ 46

Configuration prerequisites ······················································································································ 48

Configuration guidelines ··························································································································· 48

Configuration procedure ··························································································································· 48 Configuring a port-based multicast VLAN ········································································································ 49

Configuration prerequisites ······················································································································ 49

Configuring user port attributes ················································································································ 49

Assigning user ports to a multicast VLAN ································································································ 50 Setting the maximum number of multicast VLAN forwarding entries ······························································· 50 Displaying and maintaining multicast VLANs ··································································································· 51 Multicast VLAN configuration examples ·········································································································· 51

Sub-VLAN-based multicast VLAN configuration example ······································································· 51

Port-based multicast VLAN configuration example ·················································································· 54

Configuring multicast routing and forwarding ················································ 58

RPF check mechanism ···························································································································· 58

Static multicast routes ······························································································································ 60

Multicast forwarding across unicast subnets ···························································································· 61 Configuration task list ······································································································································· 62 Enabling IP multicast routing ··························································································································· 62 Configuring multicast routing and forwarding ··································································································· 62

Configuring static multicast routes ··········································································································· 62

Specifying the longest prefix match principle ··························································································· 63

Configuring multicast load splitting ··········································································································· 63

Configuring a multicast forwarding boundary ··························································································· 64

Configuring static multicast MAC address entries ···················································································· 64 Enabling multicast forwarding between sub-VLANs of a super VLAN ····························································· 65 Displaying and maintaining multicast routing and forwarding ·········································································· 65 Multicast routing and forwarding configuration examples ················································································ 67

Changing an RPF route ··························································································································· 67

Creating an RPF route ····························································································································· 69

Multicast forwarding over a GRE tunnel ··································································································· 71 Troubleshooting multicast routing and forwarding ··························································································· 73

Static multicast route failure ····················································································································· 73

Configuring IGMP ························································································· 75

IGMPv1 overview ····································································································································· 75

IGMPv2 enhancements ···························································································································· 76

IGMPv3 enhancements ···························································································································· 77

IGMP SSM mapping ································································································································ 78

IGMP support for VPNs ···························································································································· 79

Protocols and standards ·························································································································· 79 IGMP configuration task list ····························································································································· 80 Configuring basic IGMP features ····················································································································· 80

Enabling IGMP ········································································································································· 80

Specifying an IGMP version ····················································································································· 81

Configuring a static group member ·········································································································· 81

Configuring a multicast group policy ········································································································ 81 Adjusting IGMP performance ··························································································································· 82

Configuring IGMP query and response parameters ················································································· 82

Enabling fast-leave processing ················································································································ 84 Enabling IGMP NSR ········································································································································ 85

Configuring IGMP SSM mappings ··················································································································· 85

Configuration prerequisites ······················································································································ 85

Configuration procedure ··························································································································· 85 Displaying and maintaining IGMP ···················································································································· 85 IGMP configuration examples ·························································································································· 86

Basic IGMP features configuration examples ·························································································· 86

IGMP SSM mapping configuration example ···························································································· 88 Troubleshooting IGMP ····································································································································· 91

No membership information on the receiver-side router ·········································································· 91

Inconsistent membership information on the routers on the same subnet ··············································· 92

Configuring PIM ···························································································· 94

PIM-DM overview ····································································································································· 94

PIM-SM overview ····································································································································· 96

BIDIR-PIM overview ······························································································································· 100

Administrative scoping overview ············································································································ 103

PIM-SSM overview ································································································································· 105

Relationship among PIM protocols ········································································································ 106

PIM support for VPNs ···························································································································· 107

Protocols and standards ························································································································ 107 Configuring PIM-DM ······································································································································ 107

PIM-DM configuration task list ··············································································································· 108

Configuration prerequisites ···················································································································· 108

Enabling PIM-DM ··································································································································· 108

Enabling the state refresh feature ·········································································································· 108

Configuring state refresh parameters ····································································································· 109

Configuring PIM-DM graft retry timer ····································································································· 109 Configuring PIM-SM ······································································································································· 110

PIM-SM configuration task list ················································································································ 110

Configuration prerequisites ···················································································································· 110

Enabling PIM-SM ··································································································································· 110

Configuring an RP ·································································································································· 111

Configuring a BSR ································································································································· 112

Configuring multicast source registration ······························································································· 114

Configuring the switchover to SPT ········································································································· 115 Configuring BIDIR-PIM ·································································································································· 115

Configuration restrictions and guidelines ······························································································· 115

BIDIR-PIM configuration task list ··········································································································· 115

Configuration prerequisites ···················································································································· 116

Enabling BIDIR-PIM ······························································································································· 116

Configuring an RP ·································································································································· 117

Configuring a BSR ································································································································· 118 Configuring PIM-SSM ···································································································································· 120

PIM-SSM configuration task list ············································································································· 120

Configuration prerequisites ···················································································································· 120

Enabling PIM-SM ··································································································································· 121

Configuring the SSM group range ·········································································································· 121 Configuring common PIM features ················································································································ 122

Configuration task list ····························································································································· 122

Configuration prerequisites ···················································································································· 122

Configuring a multicast source policy ····································································································· 122

Configuring a PIM hello policy ················································································································ 122

Configuring PIM hello message options ································································································· 123

Configuring common PIM timers ············································································································ 124

Setting the maximum size of each join or prune message ····································································· 126

Enabling BFD for PIM ···························································································································· 126

Enabling PIM passive mode ··················································································································· 126

Enabling PIM NSR ································································································································· 127 Displaying and maintaining PIM ····················································································································· 127 PIM configuration examples ··························································································································· 128

PIM-DM configuration example ·············································································································· 128

iii

PIM-SM non-scoped zone configuration example ················································································· 131

PIM-SM admin-scoped zone configuration example ·············································································· 134

BIDIR-PIM configuration example ·········································································································· 139

PIM-SSM configuration example ············································································································ 143 Troubleshooting PIM ······································································································································ 146

A multicast distribution tree cannot be correctly built ············································································· 146

Multicast data is abnormally terminated on an intermediate router ························································ 147

An RP cannot join an SPT in PIM-SM ···································································································· 147

An RPT cannot be built or multicast source registration fails in PIM-SM ··············································· 147

Configuring MSDP ······················································································ 149

How MSDP works ·································································································································· 149

MSDP support for VPNs ························································································································ 154

Protocols and standards ························································································································ 154 MSDP configuration task list ·························································································································· 155 Configuring basic MSDP features ·················································································································· 155

Configuration prerequisites ···················································································································· 155

Enabling MSDP ······································································································································ 155

Specifying an MSDP peer ······················································································································ 156

Configuring a static RPF peer ················································································································ 156 Configuring an MSDP peering connection ····································································································· 156

Configuration prerequisites ···················································································································· 157

Configuring a description for an MSDP peer ·························································································· 157

Configuring an MSDP mesh group ········································································································ 157

Controlling MSDP peering connections ································································································· 157 Configuring SA message-related parameters ································································································ 158

Configuration prerequisites ···················································································································· 158

Enabling multicast data encapsulation in SA messages ········································································ 159

Configuring the originating RP of SA messages ···················································································· 159

Configuring SA request messages ········································································································· 159

Configuring SA message policies ·········································································································· 160

Configuring the SA cache mechanism ··································································································· 161 Displaying and maintaining MSDP ················································································································· 161 MSDP configuration examples ······················································································································· 162

PIM-SM inter-domain multicast configuration ························································································ 162

Inter-AS multicast configuration by leveraging static RPF peers ··························································· 167

Anycast RP configuration ······················································································································· 171

SA message filtering configuration ········································································································· 175 Troubleshooting MSDP ·································································································································· 178

MSDP peers stay in disabled state ········································································································ 178

No SA entries exist in the router's SA message cache ·········································································· 178

No exchange of locally registered (S, G) entries between RPs ····························································· 178

Configuring multicast VPN ·········································································· 180

MD VPN overview ·································································································································· 181

Protocols and standards ························································································································ 184 How MD VPN works······································································································································· 185

Default-MDT establishment ···················································································································· 185

Default-MDT-based delivery ·················································································································· 187

MDT switchover ····································································································································· 190

Inter-AS MD VPN ··································································································································· 191 Multicast VPN configuration task list ·············································································································· 193 Configuring MD VPN ······································································································································ 194

Configuration prerequisites ···················································································································· 194

Enabling IP multicast routing in a VPN instance ···················································································· 194

Creating an MD for a VPN instance ······································································································· 195

Specifying the default-group ·················································································································· 195

Specifying the MD source interface ······································································································· 195

Configuring MDT switchover parameters ······························································································· 196

Enabling data-group reuse logging ········································································································ 196

Configuring BGP MDT ··································································································································· 196

Configuration prerequisites ···················································································································· 197

Enabling BGP MDT peers or peer groups ····························································································· 197

Configuring a BGP MDT route reflector ································································································· 197 Displaying and maintaining multicast VPN ···································································································· 198 Multicast VPN configuration examples ·········································································································· 199

Intra-AS MD VPN configuration example ······························································································· 199

MD VPN inter-AS option C configuration example ················································································· 212 Troubleshooting MD VPN ······························································································································ 225

A default-MDT cannot be established ···································································································· 225

An MVRF cannot be created ·················································································································· 226

Configuring MLD snooping ········································································· 227

MLD snooping ports ······························································································································· 227

How MLD snooping works ····················································································································· 229

Protocols and standards ························································································································ 230 General configuration restrictions and guidelines ·························································································· 230 MLD snooping configuration task list ············································································································· 231 Configuring basic MLD snooping features ····································································································· 231

Enabling MLD snooping ························································································································· 231

Specifying an MLD snooping version ····································································································· 232

Setting the maximum number of MLD snooping forwarding entries ······················································ 233

Setting the MLD last listener query interval ···························································································· 233 Configuring MLD snooping port features ······································································································· 234

Setting aging timers for dynamic ports ··································································································· 234

Configuring static ports ·························································································································· 235

Configuring a port as a simulated member host ···················································································· 235

Enabling fast-leave processing ·············································································································· 236

Disabling a port from becoming a dynamic router port ·········································································· 237 Configuring the MLD snooping querier ·········································································································· 237

Configuration prerequisites ···················································································································· 237

Enabling the MLD snooping querier ······································································································· 237

Configuring parameters for MLD general queries and responses ························································· 238 Configuring parameters for MLD messages ·································································································· 239

Configuration prerequisites ···················································································································· 239

Configuring source IPv6 addresses for MLD messages ········································································ 239

Setting the 802.1p priority for MLD messages ······················································································· 240 Configuring MLD snooping policies ··············································································································· 241

Configuring an IPv6 multicast group policy ···························································································· 241

Enabling IPv6 multicast source port filtering ·························································································· 242

Enabling dropping unknown IPv6 multicast data ··················································································· 242

Enabling MLD report suppression ·········································································································· 243

Setting the maximum number of IPv6 multicast groups on a port ·························································· 243

Enabling IPv6 multicast group replacement ··························································································· 244 Displaying and maintaining MLD snooping ···································································································· 244 MLD snooping configuration examples ·········································································································· 246

IPv6 group policy and simulated joining configuration example ····························································· 246

Static port configuration example ··········································································································· 248

MLD snooping querier configuration example ························································································ 251 Troubleshooting MLD snooping ····················································································································· 253

Layer 2 multicast forwarding cannot function ························································································· 253

IPv6 multicast group policy does not work ····························································································· 253

Configuring IPv6 PIM snooping ·································································· 255

Overview ························································································································································ 255 Configuring IPv6 PIM snooping ····················································································································· 256 Displaying and maintaining IPv6 PIM snooping ····························································································· 257 IPv6 PIM snooping configuration example ····································································································· 257 Troubleshooting IPv6 PIM snooping ·············································································································· 261

IPv6 PIM snooping does not work on a Layer 2 device ········································································· 261

Configuring IPv6 multicast VLANs ······························································ 262

Configuration prerequisites ···················································································································· 264

Configuration guidelines ························································································································· 264

Configuration procedure ························································································································· 264 Configuring a port-based IPv6 multicast VLAN ······························································································ 265

Configuration prerequisites ···················································································································· 265

Configuring user port attributes ·············································································································· 265

Assigning user ports to an IPv6 multicast VLAN ···················································································· 266 Setting the maximum number of IPv6 multicast VLAN forwarding entries ····················································· 266 Displaying and maintaining IPv6 multicast VLANs ························································································ 267 IPv6 multicast VLAN configuration examples ································································································ 267

Sub-VLAN-based IPv6 multicast VLAN configuration example ····························································· 267

Port-based IPv6 multicast VLAN configuration example ········································································ 270

Configuring IPv6 multicast routing and forwarding ······································ 274

RPF check mechanism ·························································································································· 274

IPv6 multicast forwarding across IPv6 unicast subnets ········································································· 276 Configuration task list ····································································································································· 276 Enabling IPv6 multicast routing ······················································································································ 276 Configuring IPv6 multicast routing and forwarding ························································································ 277

Specifying the longest prefix match principle ························································································· 277

Configuring IPv6 multicast load splitting ································································································ 277

Configuring an IPv6 multicast forwarding boundary ··············································································· 278

Configuring IPv6 static multicast MAC address entries ········································································· 278

Enabling IPv6 multicast forwarding between sub-VLANs of a super VLAN ··········································· 279 Displaying and maintaining IPv6 multicast routing and forwarding ································································ 279 IPv6 multicast forwarding over a GRE tunnel configuration example ···························································· 281

Network requirements ···························································································································· 281

Configuration procedure ························································································································· 281

Verifying the configuration ······················································································································ 283

Configuring MLD ························································································· 284

How MLDv1 works ································································································································· 284

MLDv2 enhancements ··························································································································· 286

MLD SSM mapping ································································································································ 287

MLD support for VPNs ··························································································································· 288

Protocols and standards ························································································································ 288 MLD configuration task list ····························································································································· 288 Configuring basic MLD features ····················································································································· 288

Enabling MLD ········································································································································· 288

Specifying an MLD version ···················································································································· 289

Configuring a static group member ········································································································ 289

Configuring an IPv6 multicast group policy ···························································································· 290 Adjusting MLD performance ·························································································································· 290

Configuring MLD query and response parameters ················································································ 290

Enabling fast-leave processing ·············································································································· 292 Enabling MLD NSR ········································································································································ 292 Configuring MLD SSM mappings ··················································································································· 293

Configuration prerequisites ···················································································································· 293

Configuration procedure ························································································································· 293 Displaying and maintaining MLD ··················································································································· 293 MLD configuration examples ························································································································· 294

Basic MLD features configuration example ···························································································· 294

MLD SSM mapping configuration example ···························································································· 296 Troubleshooting MLD ····································································································································· 299

No member information exists on the receiver-side router ···································································· 299

Inconsistent membership information on the routers on the same subnet ············································· 300

Configuring IPv6 PIM ·················································································· 301

IPv6 PIM-DM overview ··························································································································· 301

IPv6 PIM-SM overview ··························································································································· 303

IPv6 BIDIR-PIM overview ······················································································································· 308

IPv6 administrative scoping overview ···································································································· 311

IPv6 PIM-SSM overview ························································································································ 313

Relationship among IPv6 PIM protocols ································································································ 314

IPv6 PIM support for VPNs ···················································································································· 315

Protocols and standards ························································································································ 315 Configuring IPv6 PIM-DM ······························································································································ 315

IPv6 PIM-DM configuration task list ······································································································· 316

Configuration prerequisites ···················································································································· 316

Enabling IPv6 PIM-DM ··························································································································· 316

Enabling the state refresh feature ·········································································································· 316

Configuring state refresh parameters ····································································································· 317

Configuring IPv6 PIM-DM graft retry timer ····························································································· 317 Configuring IPv6 PIM-SM ······························································································································ 318

IPv6 PIM-SM configuration task list ······································································································· 318

Configuration prerequisites ···················································································································· 318

Enabling IPv6 PIM-SM ··························································································································· 318

Configuring an RP ·································································································································· 319

Configuring a BSR ································································································································· 320

Configuring IPv6 multicast source registration ······················································································· 322

Configuring the switchover to SPT ········································································································· 322 Configuring IPv6 BIDIR-PIM ·························································································································· 323

Configuration restrictions and guidelines ······························································································· 323

IPv6 BIDIR-PIM configuration task list ··································································································· 323

Configuration prerequisites ···················································································································· 323

Enabling IPv6 BIDIR-PIM ······················································································································· 323

Configuring an RP ·································································································································· 324

Configuring a BSR ································································································································· 326 Configuring IPv6 PIM-SSM ···························································································································· 327

IPv6 PIM-SSM configuration task list ····································································································· 328

Configuration prerequisites ···················································································································· 328

Enabling IPv6 PIM-SM ··························································································································· 328

Configuring the IPv6 SSM group range ································································································· 328 Configuring common IPv6 PIM features ········································································································ 329

Configuration task list ····························································································································· 329

Configuration prerequisites ···················································································································· 329

Configuring an IPv6 multicast source policy ·························································································· 329

Configuring an IPv6 PIM hello policy ····································································································· 330

Configuring IPv6 PIM hello message options ························································································ 330

Configuring common IPv6 PIM timers ···································································································· 332

Setting the maximum size of each join or prune message ····································································· 333

Enabling BFD for IPv6 PIM ···················································································································· 333

Enabling IPv6 PIM passive mode ·········································································································· 334

Enabling IPv6 PIM NSR ························································································································· 334 Displaying and maintaining IPv6 PIM ············································································································ 335 IPv6 PIM configuration examples ·················································································································· 335

IPv6 PIM-DM configuration example ······································································································ 335

IPv6 PIM-SM non-scoped zone configuration example ········································································· 338

IPv6 PIM-SM admin-scoped zone configuration example ····································································· 341

IPv6 BIDIR-PIM configuration example ·································································································· 347

IPv6 PIM-SSM configuration example ··································································································· 351 Troubleshooting IPv6 PIM ······························································································································ 354

A multicast distribution tree cannot be correctly built ············································································· 354

IPv6 multicast data is abnormally terminated on an intermediate router ··············································· 354

An RP cannot join an SPT in IPv6 PIM-SM ··························································································· 355

An RPT cannot be built or IPv6 multicast source registration fails in IPv6 PIM-SM ······························· 355

vii

Document conventions and icons ······························································· 356

Conventions ··················································································································································· 356 Network topology icons ·································································································································· 357

Support and other resources ······································································ 358

Accessing Hewlett Packard Enterprise Support ···························································································· 358 Accessing updates ········································································································································· 358

Websites ················································································································································ 359

Customer self repair ······························································································································· 359

Remote support ······································································································································ 359

Documentation feedback ······················································································································· 359

Index ··········································································································· 361

viii

Multicast overview

Introduction to multicast

As a technique that coexists with unicast and broadcast, the multicast technique effectively addresses the issue of point-to-multipoint data transmission. By enabling high-efficiency point-to-multipoint data transmission over a network, multicast greatly saves network bandwidth and reduces network load.

By using multicast technology, a network operator can easily provide bandwidth-critical and time-critical information services. These services include live webcasting, Web TV, distance learning, telemedicine, Web radio, and real-time video conferencing.

Information transmission techniques

The information transmission techniques include unicast, broadcast, and multicast.

Unicast

In unicast transmission, the information source must send a separate copy of information to each host that needs the information.

Figure 1 Unicast transmission

Host A

Receiver

Host B

Source

Host C

Receiver

Host D

IP network

Packets for Host B

Packets for Host D

Packets for Host E

In Figure 1, Host B, Host D, and Host E need the information. A separate transmission channel must be established from the information source to each of these hosts.

Receiver

Host E

In unicast transmission, the traffic transmitted over the network is proportional to the number of hosts that need the information. If a large number of hosts need the information, the information source must send a separate copy of the same information to each of these hosts. Sending many copies can place a tremendous pressure on the information source and the network bandwidth.

Unicast is not suitable for batch transmission of information.

Broadcast

In broadcast transmission, the information source sends information to all hosts on the subnet, even if some hosts do not need the information.

Figure 2 Broadcast transmission

Multicast

In Figure 2, only Host B, Host D, and Host E need the information. If the information is broadcast to the subnet, Host A and Host C also receive it. In addition to information security issues, broadcasting to hosts that do not need the information also causes traffic flooding on the same subnet.

Broadcast is disadvantageous in transmitting data to specific hosts. Moreover, broadcast transmission is a significant waste of network resources.

Multicast provides point-to-multipoint data transmissions with the minimum network consumption. When some hosts on the network need multicast information, the information sender, or multicast source, sends only one copy of the information. Multicast distribution trees are built through multicast routing protocols, and the packets are replicated only on nodes where the trees branch.

Figure 3 Multicast transmission

The multicast source sends only one copy of the information to a multicast group. Host B, Host D, and Host E, which are information receivers, must join the multicast group. The routers on the network duplicate and forward the information based on the distribution of the group members. Finally, the information is correctly delivered to Host B, Host D, and Host E.

To summarize, multicast has the following advantages:

• Advantages over unicast—Multicast data is replicated and distributed until it flows to the

farthest-possible node from the source. The increase of receiver hosts will not remarkably increase the load of the source or the usage of network resources.

• Advantages over broadcast—Multicast data is sent only to the receivers that need it. This

saves network bandwidth and enhances network security. In addition, multicast data is not confined to the same subnet.

Multicast features

• A multicast group is a multicast receiver set identified by an IP multicast address. Hosts must

join a multicast group to become members of the multicast group before they receive the multicast data addressed to that multicast group. Typically, a multicast source does not need to join a multicast group.

• A multicast source is an information sender. It can send data to multiple multicast groups at the

same time. Multiple multicast sources can send data to the same multicast group at the same time.

• The group memberships are dynamic. Hosts can join or leave multicast groups at any time.

Multicast groups are not subject to geographic restrictions.

• Multicast routers or Layer 3 multicast devices are routers or Layer 3 switches that support Layer

3 multicast. They provide multicast routing and manage multicast group memberships on stub subnets with attached group members. A multicast router itself can be a multicast group member.

For a better understanding of the multicast concept, you can compare multicast transmission to the transmission of TV programs.

Table 1 Comparing TV program transmission and multicast transmission

TV program transmission Multicast transmission

A TV station transmits a TV program through a channel.

A user tunes the TV set to the channel. A receiver joins the multicast group.

The user starts to watch the TV program transmitted by the TV station on the channel.

The user turns off the TV set or tunes to another channel.

Common notations in multicast

The following notations are commonly used in multicast transmission:

• (*, G)—Rendezvous point tree (RPT), or a multicast packet that any multicast source sends to

multicast group G. The asterisk (*) represents any multicast source, and "G" represents a specific multicast group.

• (S, G)—Shortest path tree (SPT), or a multicast packet that multicast source "S" sends to

multicast group "G." "S" represents a specific multicast source, and "G" represents a specific multicast group.

For more information about the concepts RPT and SPT, see "Configuring PIM" and "Configuring

IPv6 PIM."

A multicast source sends multicast data to a multicast group.

The receiver starts to receive the multicast data sent by the source to the multicast group.

The receiver leaves the multicast group or joins another group.

Multicast benefits and applications

Multicast benefits

• Enhanced efficiency—Reduces the processor load of information source servers and network

devices.

• Optimal performance—Reduces redundant traffic.

• Distributed application—Enables point-to-multipoint applications at the price of minimum

network resources.

Multicast applications

• Multimedia and streaming applications, such as Web TV, Web radio, and real-time video/audio

conferencing

• Communication for training and cooperative operations, such as distance learning and

telemedicine

• Data warehouse and financial applications (stock quotes)

• Any other point-to-multipoint application for data distribution

Multicast models

Based on how the receivers treat the multicast sources, the multicast models include any-source multicast (ASM), source-filtered multicast (SFM), and source-specific multicast (SSM).

ASM model

In the ASM model, any multicast sources can send information to a multicast group. Receivers can join a multicast group and get multicast information addressed to that multicast group from any multicast sources. In this model, receivers do not know the positions of the multicast sources in advance.

SFM model

The SFM model is derived from the ASM model. To a multicast source, the two models appear to have the same multicast membership architecture.

The SFM model functionally extends the ASM model. The upper-layer software checks the source address of received multicast packets and permits or denies multicast traffic from specific sources. The receivers obtain the multicast data from only part of the multicast sources. To a receiver, multicast sources are not all valid, but are filtered.

SSM model

The SSM model provides a transmission service that enables multicast receivers to specify the multicast sources in which they are interested.

In the SSM model, receivers have already determined the locations of the multicast sources. This is the main difference between the SSM model and the ASM model. In addition, the SSM model uses a different multicast address range than the ASM/SFM model. Dedicated multicast forwarding paths are established between receivers and the specified multicast sources.

Multicast architecture

IP multicast addresses the following issues:

• Where should the multicast source transmit information to? (Multicast addressing.)

• What receivers exist on the network? (Host registration.)

• Where is the multicast source that will provide data to the receivers? (Multicast source

discovery.)

• How is the information transmitted to the receivers? (Multicast routing.)

IP multicast is an end-to-end service. The multicast architecture involves the following parts:

• Addressing mechanism—A multicast source sends information to a group of receivers

through a multicast address.

• Host registration—Receiver hosts can join and leave multicast groups dynamically. This

mechanism is the basis for management of group memberships.

• Multicast routing—A multicast distribution tree (a forwarding path tree for multicast data on the

network) is constructed for delivering multicast data from a multicast source to receivers.

• Multicast applications—A software system that supports multicast applications, such as video

conferencing, must be installed on multicast sources and receiver hosts. The TCP/IP stack must support reception and transmission of multicast data.

Multicast addresses

IP multicast addresses

• IPv4 multicast addresses:

IANA assigned the Class D address block (224.0.0.0 to 239.255.255.255) to IPv4 multicast.

Table 2 Class D IP address blocks and description

Address block Description

Reserved permanent group addresses. The IP address

224.0.0.0 is reserved. Other IP addresses can be used by routing protocols and for topology searching, protocol

224.0.0.0 to 224.0.0.255

224.0.1.0 to 238.255.255.255

239.0.0.0 to 239.255.255.255

NOTE:

maintenance, and so on. Table 3 lists comm group addresses. A packet destined for an address in this block will not be forwarded beyond the local subnet regardless of the TTL value in the IP header.

Globally scoped group addresses. This block includes the following types of designated group addresses:

• 232.0.0.0/8—SSM group addresses.

• 233.0.0.0/8—Glop group addresses.

Administratively scoped multicast addresses. These addresses are considered locally unique rather than globally unique. You can reuse them in domains administered by different organizations without causing conflicts. For more information, see RFC 2365.

on permanent

Glop is a mechanism for assigning multicast addresses between different ASs. By filling an AS number into the middle two bytes of 233.0.0.0, you get 255 multicast addresses for that AS. Fo more information, see RFC 2770.

Table 3 Common permanent multicast group addresses

Address Description

224.0.0.1 All systems on this subnet, including hosts and routers.

224.0.0.2 All multicast routers on this subnet.

224.0.0.3 Unassigned.

224.0.0.4 DVMRP routers.

224.0.0.5 OSPF routers.

224.0.0.6 OSPF designated routers and backup designated routers.

224.0.0.7 Shared Tree (ST) routers.

224.0.0.8 ST hosts.

224.0.0.9 RIPv2 routers.

224.0.0.11 Mobile agents.

224.0.0.12 DHCP server/relay agent.

224.0.0.13 All Protocol Independent Multicast (PIM) routers.

224.0.0.14 RSVP encapsulation.

224.0.0.15 All Core-Based Tree (CBT) routers.

224.0.0.16 Designated SBM.

224.0.0.17 All SBMs.

224.0.0.18 VRRP.

• IPv6 multicast addresses:

Figure 4 IPv6 multicast format

The following describes the fields of an IPv6 multicast address:

{ 0xFF—The most significant eight bits are 11111111. { Flags—The Flags field contains four bits.

Figure 5 Flags field format

Table 4 Flags field description

Bit Description

0 Reserved, set to 0.

• When set to 0, this address is an IPv6 multicast address without an embedded RP address.

• When set to 1, this address is an IPv6 multicast address with an embedded RP address. (The P and T bits must also be set to 1.)

• When set to 0, this address is an IPv6 multicast address not based on a unicast prefix.

• When set to 1, this address is an IPv6 multicast address based on a unicast prefix. (The T bit must also be set to 1.)

• When set to 0, this address is an IPv6 multicast

address permanently-assigned by IANA.

• When set to 1, this address is a transient, or dynamically assigned IPv6 multicast address.

Scope—The Scope field contains four bits, which represent the scope of the IPv6

{

internetwork for which the multicast traffic is intended.

Table 5 Values of the Scope field

Value Meaning

0, F Reserved.

1 Interface-local scope.

2 Link-local scope.

3 Subnet-local scope.

4 Admin-local scope.

5 Site-local scope.

6, 7, 9 through D Unassigned.

8 Organization-local scope.

Value Meaning

E Global scope.

{ Group ID—The Group ID field contains 112 bits. It uniquely identifies an IPv6 multicast

group in the scope that the Scope field defines.

Ethernet multicast MAC addresses

• IPv4 multicast MAC addresses:

As defined by IANA, the most significant 24 bits of an IPv4 multicast MAC address are 0x01005E. Bit 25 is 0, and the other 23 bits are the least significant 23 bits of an IPv4 multicast address.

Figure 6 IPv4-to-MAC address mapping

The most significant four bits of an IPv4 multicast address are fixed at 1110. In an IPv4-to-MAC address mapping, five bits of the IPv4 multicast address are lost. As a result, 32 IPv4 multicast addresses are mapped to the same IPv4 multicast MAC address. A device might receive unwanted multicast data at Layer 2 processing, which needs to be filtered by the upper layer.

• IPv6 multicast MAC addresses:

As defined by IANA, the most significant 16 bits of an IPv6 multicast MAC address are 0x3333. The least significant 32 bits are mapped from the least significant 32 bits of an IPv6 multicast address. Therefore, the problem of duplicate IPv6-to-MAC address mapping also arises like IPv4-to-MAC address mapping.

Figure 7 IPv6-to-MAC address mapping

Multicast protocols

Multicast protocols include the following categories:

• Layer 3 and Layer 2 multicast protocols:

{ Layer 3 multicast refers to IP multicast operating at the network layer.

Layer 3 multicast protocols—IGMP, MLD, PIM, IPv6 PIM, MSDP, MBGP, and IPv6

MBGP.

{ Layer 2 multicast refers to IP multicast operating at the data link layer.

Layer 2 multicast protocols—IGMP snooping, MLD snooping, PIM snooping, IPv6 PIM

snooping, multicast VLAN, and IPv6 multicast VLAN.

• IPv4 and IPv6 multicast protocols:

{ For IPv4 networks—IGMP snooping, PIM snooping, multicast VLAN, IGMP, PIM, MSDP,

and MBGP.

{ For IPv6 networks—MLD snooping, IPv6 PIM snooping, IPv6 multicast VLAN, MLD, IPv6

PIM, and IPv6 MBGP.

This section provides only general descriptions about applications and functions of the Layer 2 and Layer 3 multicast protocols in a network. For more information about these protocols, see the related chapters.

Layer 3 multicast protocols

Layer 3 multicast protocols include multicast group management protocols and multicast routing protocols.

Figure 8 Positions of Layer 3 multicast protocols

• Multicast group management protocols:

Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) protocol are multicast group management protocols. Typically, they run between hosts and Layer 3 multicast devices that directly connect to the hosts to establish and maintain multicast group memberships.

• Multicast routing protocols:

A multicast routing protocol runs on Layer 3 multicast devices to establish and maintain multicast routes and correctly and efficiently forward multicast packets. Multicast routes constitute loop-free data transmission paths (also known as multicast distribution trees) from a data source to multiple receivers.

In the ASM model, multicast routes include intra-domain routes and inter-domain routes.

{ An intra-domain multicast routing protocol discovers multicast sources and builds multicast

distribution trees within an AS to deliver multicast data to receivers. Among a variety of mature intra-domain multicast routing protocols, PIM is most widely used. Based on the forwarding mechanism, PIM has dense mode (often referred to as PIM-DM) and sparse mode (often referred to as PIM-SM).

{ An inter-domain multicast routing protocol is used for delivering multicast information

between two ASs. So far, mature solutions include Multicast Source Discovery Protocol (MSDP) and MBGP. MSDP propagates multicast source information among different ASs. MBGP is an extension of the MP-BGP for exchanging multicast routing information among different ASs.

For the SSM model, multicast routes are not divided into intra-domain routes and inter-domain routes. Because receivers know the positions of the multicast sources, channels established through PIM-SM are sufficient for the transport of multicast information.

Layer 2 multicast protocols

Layer 2 multicast protocols include IGMP snooping, MLD snooping, PIM snooping, IPv6 PIM snooping, multicast VLAN, and IPv6 multicast VLAN.

Figure 9 Positions of Layer 2 multicast protocols

• IGMP snooping and MLD snooping:

IGMP snooping and MLD snooping are multicast constraining mechanisms that run on Layer 2 devices. They manage and control multicast groups by monitoring and analyzing IGMP or MLD messages exchanged between the hosts and Layer 3 multicast devices. This effectively controls the flooding of multicast data in Layer 2 networks.

• PIM snooping and IPv6 PIM snooping:

PIM snooping and IPv6 PIM snooping run on Layer 2 devices. They work with IGMP snooping or MLD snooping to analyze received PIM messages. Then, they add the ports that are interested in specific multicast data to a PIM snooping routing entry or IPv6 PIM snooping routing entry. In this way, multicast data can be forwarded to only the ports that are interested in the data.

• Multicast VLAN and IPv6 multicast VLAN:

Multicast VLAN or IPv6 multicast VLAN runs on a Layer 2 device in a multicast network where multicast receivers for the same group exist in different VLANs. With these protocols, the Layer 3 multicast device sends only one copy of multicast to the multicast VLAN or IPv6 multicast VLAN on the Layer 2 device. This method avoids waste of network bandwidth and extra burden on the Layer 3 device.

Multicast packet forwarding mechanism

In a multicast model, receiver hosts of a multicast group are usually located at different areas on the network. They are identified by the same multicast group address. To deliver multicast packets to these receivers, a multicast source encapsulates the multicast data in an IP packet with the multicast group address as the destination address. Multicast routers on the forwarding paths forward multicast packets that an incoming interface receives through multiple outgoing interfaces. Compared to a unicast model, a multicast model is more complex in the following aspects:

• To ensure multicast packet transmission on the network, different routing tables are used to

guide multicast forwarding. These routing tables include unicast routing tables, routing tables for multicast (for example, the MBGP routing table), and static multicast routing tables.

• To process the same multicast information from different peers received on different interfaces,

the multicast device performs an RPF check on each multicast packet. The RPF check result determines whether the packet will be forwarded or discarded. The RPF check mechanism is the basis for most multicast routing protocols to implement multicast forwarding.

For more information about the RPF mechanism, see "Configuring multicast routing and

rding" and "Configuring IPv6 multicast routing and forwarding."

forwa

Configuring IGMP snooping

Overview

IGMP snooping runs on a Layer 2 device as a multicast constraining mechanism to improve multicast forwarding efficiency. It creates Layer 2 multicast forwarding entries from IGMP packets that are exchanged between the hosts and the router.

As shown in Figure 10, when IGMP packets to all hosts in a VLAN. When IGMP snooping is enabled, the Layer 2 switch forwards multicast packets of known multicast groups to only the receivers.

Figure 10 Multicast packet transmission without and with IGMP snooping

snooping is not enabled, the Layer 2 switch floods multicast

IGMP snooping ports

As shown in Figure 11, IGMP snooping runs on Switch A and Switch B, and Host A and Host C are receivers in a multicast group. IGMP snooping ports are divided into member ports and router ports.

Figure 11 IGMP snooping ports

Router ports

On an IGMP snooping Layer 2 device, the ports toward Layer 3 multicast devices are called router ports. In Figure 11, Gig router ports.

abitEthernet 1/0/1 of Switch A and GigabitEthernet 1/0/1 of Switch B are

Router ports contain the following types:

• Dynamic router port—When a port receives an IGMP general query whose source address is

not 0.0.0.0 or receives a PIM hello message, the port is added into the dynamic router port list. At the same time, an aging timer is started for the port. If the port receives either of the messages before the timer expires, the timer is reset. If the port does not receive either of the messages when the timer expires, the port is removed from the dynamic router port list.

• Static router port—When a port is statically configured as a router port, it is added into the

static router port list. The static router port does not age out, and it can be deleted only manually.

Do not confuse the "router port" in IGMP snooping with the "routed interface" commonly known as the "Layer 3 interface." The router port in IGMP snooping is a Layer 2 interface.

Member ports

On an IGMP snooping Layer 2 device, the ports toward receiver hosts are called member ports. In Figure 11, GigabitEthe of Switch B are member ports.

Member ports contain the following types:

• Dynamic member port—When a port receives an IGMP report, it is added to the associated

dynamic IGMP snooping forwarding entry as an outgoing interface. At the same time, an aging timer is started for the port. If the port receives an IGMP report before the timer expires, the timer is reset. If the port does not receive an IGMP report when the timer expires, the port is removed from the associated dynamic forwarding entry.

• Static member port—When a port is statically configured as a member port, it is added to the

associated static IGMP snooping forwarding entry as an outgoing interface. The static member port does not age out, and it can be deleted only manually.

rnet 1/0/2 and GigabitEthernet 1/0/3 of Switch A and GigabitEthernet 1/0/2

Unless otherwise specified, router ports and member ports in this document include both static and dynamic router ports and member ports.

How IGMP snooping works

The ports in this section are dynamic ports. For information about how to configure and remove static ports, see "Configuring static ports."

messages types include general query, IGMP report, and leave message. An IGMP

IGMP snooping-enabled Layer 2 device performs differently depending on the message types.

General query

The IGMP querier periodically sends IGMP general queries to all hosts and routers on the local subnet to check for the existence of multicast group members.

After receiving an IGMP general query, the Layer 2 device forwards the query to all ports in the VLAN except the receiving port. The Layer 2 device also performs one of the following actions:

• If the receiving port is a dynamic router port in the dynamic router port list, the Layer 2 device

restarts the aging timer for the port.

• If the receiving port does not exist in the dynamic router port list, the Layer 2 device adds the

port to the dynamic router port list. It also starts an aging timer for the port.

IGMP report

A host sends an IGMP report to the IGMP querier for the following purposes:

• Responds to queries if the host is a multicast group member.

• Applies for a multicast group membership.

After receiving an IGMP report from a host, the Layer 2 device forwards the report through all the router ports in the VLAN. It also resolves the address of the reported multicast group, and looks up the forwarding table for a matching entry as follows:

• If no match is found, the Layer 2 device creates a forwarding entry with the receiving port as an

outgoing interface. It also marks the receiving port as a dynamic member port and starts an aging timer for the port.

• If a match is found but the matching forwarding entry does not contain the receiving port, the

Layer 2 device adds the receiving port to the outgoing interface list. It also marks the receiving port as a dynamic member port and starts an aging timer for the port.

• If a match is found and the matching forwarding entry contains the receiving port, the Layer 2

device restarts the aging timer for the port.

In an application with a group policy configured on an IGMP snooping-enabled Layer 2 device, when a user requests a multicast program, the user's host initiates an IGMP report. After receiving this report, the Layer 2 device resolves the multicast group address in the report and performs ACL filtering on the report. If the report passes ACL filtering, the Layer 2 device creates an IGMP snooping forwarding entry for the multicast group with the receiving port as an outgoing interface. If the report does not pass ACL filtering, the Layer 2 device drops this report. The multicast data for the multicast group is not sent to this port, and the user cannot retrieve the program.

A Layer 2 device does not forward an IGMP report through a non-router port because of the host IGMP report suppression mechanism. For more information about the mechanism, see "Configuring

IGMP."

Leave message

An IGMPv1 receiver host does not send any leave messages when it leaves a multicast group. The Layer 2 device cannot immediately update the status of the port that connects to the receiver host. The Layer 2 device does not remove the port from the outgoing interface list in the associated forwarding entry until the aging time for the group expires.

An IGMPv2 or IGMPv3 host sends an IGMP leave message when it leaves a multicast group.

When the Layer 2 device receives an IGMP leave message on a dynamic member port, the Layer 2 device first examines whether a forwarding entry matches the group address in the message.

• If no match is found, the Layer 2 device discards the IGMP leave message.

• If a match is found but the receiving port is not an outgoing interface in the forwarding entry, the

Layer 2 device discards the IGMP leave message.

• If a match is found and the receiving port is not the only outgoing interface in the forwarding

entry, the Layer 2 device performs the following actions:

{ Discards the IGMP leave message.

{ Sends an IGMP group-specific query to identify whether the group has active receivers

attached to the receiving port.

{ Sets the aging timer for the receiving port to twice the IGMP last member query interval.

• If a match is found and the receiving port is the only outgoing interface in the forwarding entry,

the Layer 2 device performs the following actions:

{ Forwards the IGMP leave message to all router ports in the VLAN.

{ Sends an IGMP group-specific query to identify whether the group has active receivers

attached to the receiving port.

{ Sets the aging timer for the receiving port to twice the IGMP last member query interval.

After receiving the IGMP leave message on a port, the IGMP querier resolves the multicast group address in the message. Then, it sends an IGMP group-specific query to the multicast group through the receiving port.

After receiving the IGMP group-specific query, the Layer 2 device forwards the query through all its router ports in the VLAN and all member ports of the multicast group. Then, it waits for the responding IGMP report from the directly connected hosts. For the dynamic member port that received the leave message, the Layer 2 device also performs one of the following actions:

• If the port receives an IGMP report before the aging timer expires, the Layer 2 device resets the

aging timer.

• If the port does not receive an IGMP report when the aging timer expires, the Layer 2 device

removes the port from the forwarding entry for the multicast group.

Protocols and standards

RFC 4541, Considerations for Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Snooping Switches

General configuration restrictions and guidelines

When you configure IGMP snooping, follow these restrictions and guidelines:

• For a VLAN configured with IGMP snooping, if you change the VPN instance bound to the

VLAN interface, Layer 2 multicast traffic for the VLAN is interrupted. In this case, you must

execute the reset igmp-snooping group command so that new IGMP snooping forwarding

entries can be created.

• For IGMP reports received from secondary VLANs, the relevant IGMP snooping forwarding

entries are maintained by the primary VLAN. Therefore, you need to configure IGMP snooping only for the primary VLAN. The IGMP snooping configuration made for secondary VLANs does

not take effect. For more information about primary VLANs and secondary VLANs, see Layer 2—LAN Switching Configuration Guide.

• The IGMP snooping configurations made on Layer 2 aggregate interfaces do not interfere with

the configurations made on member ports. In addition, the configurations made on Layer 2 aggregate interfaces do not take part in aggregation calculations. The configuration made on a member port of the aggregate group takes effect after the port leaves the aggregate group.

IGMP snooping configuration task list

Tasks at a glance

Configuring basic IGMP snooping features:

• (Required.) Enabling IGMP snooping

• (Optiona

• (Optional.) Setting the maximum number of IGMP snooping forwarding entries

• (Optional.) Setting the IGMP last member query interval

Configuring IGMP snooping port features:

• (Optional.) Setting aging timers for dynamic ports

• (Optional.) Configuring static ports

• (Optional.) Configuring a port as a simulated member host

• (Optiona

• (Optional.) Disabling a port from becoming a dynamic router port

Configuring the IGMP snooping querier:

• (Optional.) Enabling the IGMP snooping querier

• (Optional.) Configuring parameters for IGMP general queries and responses

Configuring parameters for IGMP messages:

• (Optional.) Configuring source IP addresses for IGMP messages

• (Optiona

Configuring IGMP snooping policies:

• (Optional.) Configuring a multicast group policy

• (Optiona

• (Optional.) Enabling dropping unknown multicast data

• (Optional.) Enabling IGMP report suppression

• (Optional.) Setting the maximum number of multicast groups on a port

• (Optional.) Enabling multicast group replacement

l.) Specifying an IGMP snooping version

l.) Enabling fast-leave processing

l.) Setting the 802.1p priority for IGMP messages

l.) Enabling multicast source port filtering

Configuring basic IGMP snooping features

Before you configure basic IGMP snooping features, complete the following tasks:

• Configure VLANs.

• Determine the IGMP snooping version.

• Determine the maximum number of IGMP snooping forwarding entries.

• Determine the IGMP last member query interval.

Enabling IGMP snooping

When you enable IGMP snooping, follow these guidelines:

• You must enable IGMP snooping globally before you enable it for a VLAN.

• IGMP snooping configuration made in VLAN view takes effect only on the member ports in that

VLAN.

• You can enable IGMP snooping for the specified VLANs in IGMP-snooping view or for a VLAN

in VLAN view. For a VLAN, the configuration in VLAN view has the same priority as the configuration in IGMP-snooping view, and the most recent configuration takes effect.

Enabling IGMP snooping for the specified VLANs

Step Command Remarks

1. Enter system view.

2. Enable IGMP snooping

globally and enter IGMP-snooping view.

3. Enable IGMP snooping for

the specified VLANs.

system-view

igmp-snooping

enable vlan

vlan-list

Enabling IGMP snooping for a VLAN

Step Command Remarks

1. Enter system view.

2. Enable IGMP snooping

globally and enter IGMP-snooping view.

3. Return to system view.

4. Enter VLAN view.

5. Enable IGMP snooping for

the VLAN.

system-view

igmp-snooping

quit vlan

vlan-id

igmp-snooping enable

Specifying an IGMP snooping version

N/A

By default, IGMP snooping is globally disabled.

By default, IGMP snooping is disabled for a VLAN.

N/A

By default, IGMP snooping is disabled.

N/A

By default, IGMP snooping is disabled in a VLAN.

Different IGMP snooping versions process different versions of IGMP messages.

• IGMPv2 snooping processes IGMPv1 and IGMPv2 messages, but it floods IGMPv3 messages

in the VLAN instead of processing them.

• IGMPv3 snooping processes IGMPv1, IGMPv2, and IGMPv3 messages.

If you change IGMPv3 snooping to IGMPv2 snooping, the switch does the following:

• Clears all IGMP snooping forwarding entries that are dynamically added.

• Keeps static IGMPv3 snooping forwarding entries (*, G).

• Clears static IGMPv3 snooping forwarding entries (S, G), which will be restored when IGMP

snooping is switched back to IGMPv3 snooping.

For more information about static IGMP snooping forwarding entries, see "Configuring static ports."

You can specify the version for the specified VLANs in IGMP-snooping view or for a VLAN in VLAN view. For a VLAN, the configuration in VLAN view has the same priority as the configuration in IGMP-snooping view, and the most recent configuration takes effect.

Specifying an IGMP snooping version for the specified VLANs

Step Command Remarks

1. Enter system view.

2. Enable IGMP snooping

globally and enter IGMP-snooping view.

system-view

igmp-snooping

N/A

3. Specify an IGMP snooping

version for the specified

version

vlan-list

version-number

vlan

The default setting is 2.

VLANs.

Specifying an IGMP snooping version for a VLAN

Step Command Remarks

1. Enter system view.

2. Enter VLAN view.

3. Specify an IGMP snooping

version for the VLAN.

system-view vlan

vlan-id

igmp-snooping version

version-number

N/A

The default setting is 2.

Setting the maximum number of IGMP snooping forwarding entries

You can set the maximum number of IGMP snooping forwarding entries, including dynamic entries and static entries. When the number of forwarding entries on the switch reaches the upper limit, the switch does not automatically remove any existing entries. As a best practice, manually remove some entries to allow new entries to be created.

To set the maximum number of IGMP snooping forwarding entries:

Step Command Remarks

1. Enter system view.

2. Enter IGMP-snooping view.

3. Set the maximum number of

IGMP snooping forwarding entries.

system-view igmp-snooping

entry-limit

N/A

limit

N/A

The default setting is

4294967295.

Setting the IGMP last member query interval

A receiver host starts a report delay timer for a multicast group when it receives an IGMP group-specific query for the group. This timer is set to a random value in the range of 0 to the maximum response time advertised in the query. When the timer value decreases to 0, the host sends an IGMP report to the group.

The IGMP last member query interval defines the maximum response time advertised in IGMP group-specific queries. Set an appropriate value for the IGMP last member query interval to speed up hosts' responses to IGMP group-specific queries and avoid IGMP report traffic bursts.

Configuration restrictions and guidelines

When you set the IGMP last member query interval, follow these restrictions and guidelines:

• The Layer 2 device does not send an IGMP group-specific query if it receives an IGMP leave

message from a port enabled with fast-leave processing.

• You can set the IGMP last member query interval globally for all VLANs in IGMP-snooping view

or for a VLAN in VLAN view. For a VLAN, the VLAN-specific configuration takes priority over the global configuration.

Setting the IGMP last member query interval globally

Step Command Remarks

1. Enter system view.

system-view

N/A

Step Command Remarks

2. Enter IGMP-snooping view.

3. Set the IGMP last member

query interval globally.

igmp-snooping last-member-query-interval

interval

Setting the IGMP last member query interval in a VLAN

Step Command Remarks

1. Enter system view.

2. Enter VLAN view.

system-view vlan

vlan-id N/A

N/A

The default setting is 1 second.

N/A

3. Set the IGMP last member

query interval for the VLAN.

igmp-snooping last-member-query-interval

interval

The default setting is 1 second.

Configuring IGMP snooping port features

Before you configure IGMP snooping port features, complete the following tasks:

• Enable IGMP snooping for the VLAN.

• Determine the aging timer for dynamic router ports.

• Determine the aging timer for dynamic member ports.

• Determine the addresses of the multicast group and multicast source.

Setting aging timers for dynamic ports

When you set aging timers for dynamic ports, follow these guidelines:

• If the memberships of multicast groups frequently change, you can set a relatively small value

for the aging timer of the dynamic member ports. If the memberships of multicast groups rarely change, you can set a relatively large value.

• If a dynamic router port receives a PIMv2 hello message, the aging timer for the port is specified by the hello message. In this case, the router-aging-time or igmp-snooping router-aging-time command does not take effect on the port.

• IGMP group-specific queries originated by the Layer 2 device trigger the adjustment of aging

timers for dynamic member ports. If a dynamic member port receives such a query, its aging timer is set to twice the IGMP last member query interval. For more information about setting the IGMP last member query interval on the Layer 2 device, see "Setting the IGMP last member

query inte

• You can set the timers globally for all VLANs in IGMP-snooping view or for a VLAN in VLAN

view. For a VLAN, the VLAN-specific configuration takes priority over the global configuration.

rval."

Setting the aging timers for dynamic ports globally

Step Command Remarks

1. Enter system view.

2. Enter IGMP-snooping view.

3. Set the aging timer for

dynamic router ports globally.

4. Set the global aging timer for

dynamic member ports

system-view igmp-snooping

router-aging-time

host-aging-time

N/A

interval

N/A

The default setting is 260 seconds.

globally.

Setting the aging timers for dynamic ports in a VLAN

Step Command Remarks

1. Enter system view.

2. Enter VLAN view.

3. Set the aging timer for

dynamic router ports in the VLAN.

4. Set the aging timer for

dynamic member ports in the VLAN.

system-view vlan

vlan-id

igmp-snooping router-aging-time

igmp-snooping host-aging-time

N/A

interval

Configuring static ports

You can configure the following types of static ports:

• Static member port—When you configure a port as a static member port for a multicast group,

all hosts attached to the port will receive multicast data for the group.

The static member port does not respond to IGMP queries. When you complete or cancel this configuration on a port, the port does not send an unsolicited IGMP report or leave message.

• Static router port—When you configure a port as a static router port for a multicast group, all

multicast data for the group received on the port will be forwarded.

interval

N/A

The default setting is 260 seconds.

To configure static ports:

Step Command Remarks

1. Enter system view.

2. Enter Layer 2 Ethernet

interface view or Layer 2 aggregate interface view.

3. Configure the port as a static

port.

system-view

interface

interface-number

• Configure the port as a static

member port:

igmp-snooping static-group group-address [ source-ip source-address ] vlan vlan-id

• Configure the port as a static router port:

igmp-snooping static-router-port vlan

vlan-id

N/A

interface-type

N/A

By default, a port is not a static member port or static router port.

Configuring a port as a simulated member host

When a port is configured as a simulated member host, it is equivalent to an independent host in the following ways:

• It sends an unsolicited IGMP report when you complete the configuration.

• It responds to IGMP general queries with IGMP reports.

• It sends an IGMP leave message when you cancel the configuration.

+ 338 hidden pages

HP FlexNetwork 7500 Configuration Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Contents

Multicast overview

Introduction to multicast

Information transmission techniques

Broadcast

Multicast

Multicast features

Common notations in multicast

Multicast benefits and applications

Multicast benefits

Multicast applications

Multicast models

ASM model

SFM model

SSM model

Multicast architecture

Multicast addresses

IP multicast addresses

Ethernet multicast MAC addresses

Multicast protocols

Layer 3 multicast protocols

Layer 2 multicast protocols

Multicast packet forwarding mechanism

Configuring IGMP snooping

Overview

IGMP snooping ports

Router ports

Member ports

How IGMP snooping works

General query

IGMP report

Leave message

Protocols and standards

General configuration restrictions and guidelines

IGMP snooping configuration task list

Configuring basic IGMP snooping features

Enabling IGMP snooping

Enabling IGMP snooping for the specified VLANs

Enabling IGMP snooping for a VLAN

Specifying an IGMP snooping version

Specifying an IGMP snooping version for the specified VLANs

Specifying an IGMP snooping version for a VLAN

Setting the maximum number of IGMP snooping forwarding entries

Setting the IGMP last member query interval

Configuration restrictions and guidelines

Setting the IGMP last member query interval globally

Setting the IGMP last member query interval in a VLAN

Configuring IGMP snooping port features

Setting aging timers for dynamic ports

Setting the aging timers for dynamic ports globally

Setting the aging timers for dynamic ports in a VLAN

Configuring static ports

Configuring a port as a simulated member host