Multi Cast Configuration Extreme Switch

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ExtremeXOS 15.5 User Guide

120936-00 Rev. 2

Published June 2014


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Copyright 20112014 All rights reserved.

Legal Notice

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Inc., reserves the right to make changes in specifications and other information contained in this

document and its website without prior notice. The reader should in all cases consult

representatives of Extreme Networks to determine whether any such changes have been made.

The hardware, firmware, software or any specifications described or referred to in this document

are subject to change without notice.

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All other names (including any product names) mentioned in this document are the property of

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For information, contact:

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Table of Contents

Preface......................................................................................................................................... 8

Conventions.............................................................................................................................................................................8

Related Publications............................................................................................................................................................9

Providing Feedback to Us........................ ....................... ........................ ........................ ....................... ........................ 10Navigating the ExtremeXOS User Guide...........................................................................................................................11

Chapter 1: Multicast Routing and Switching.........................................................................12

Multicast Routing Overview.................................... ....................... ........................ ....................... ........................ ......... 12

Multicast Table Management.........................................................................................................................................13

PIM Overview.........................................................................................................................................................................19

IGMP Overview...................... ........................ ....................... ........................ ........................ ....................... ........................ 32

Configuring EAPS Support for Multicast Traffic.................................................................................................37

Configuring IP Multicast Routing................................................................................................................................38

Multicast VLAN Registration................................... ........................ ....................... ........................ ........................ ...... 47

Displaying Multicast Information.................................... ....................... ........................ ....................... ...................... 58

Troubleshooting PIM.........................................................................................................................................................58

Chapter 2: IPv6 Multicast....................................................................................................... 60

Multicast Listener Discovery (MLD) Overview....................................................................................................60

Managing MLD......................... ....................... ........................ ........................ ....................... ........................ ..................... 60

Chapter 3: MSDP...................................................................................................................... 69

MSDP Overview..................................... ........................ ........................ ....................... ........................ ....................... ....... 69

PIM Border Configuration..................................... ....................... ........................ ....................... ........................ ........... 70

MSDP Peers...........................................................................................................................................................................70

MSDP Mesh-Groups...........................................................................................................................................................72

Anycast RP................................ ........................ ....................... ........................ ....................... ........................ ...................... 73

SA Cache................................... ....................... ........................ ....................... ........................ ....................... ........................ 75

Redundancy.............................. ........................ ....................... ........................ ....................... ........................ ...................... 76SNMP MIBs.............................................................................................................................................................................76

Chapter 4: Multicast Commands............................................................................................77

clear igmp group........................... ........................ ........................ ....................... ........................ ....................... ................ 81

clear igmp snooping........................... ........................ ....................... ........................ ........................ ....................... ........ 82

clear mld counters.......................... ....................... ........................ ....................... ........................ ........................ ............. 83

clear mld group...................................................................................................................................................................84

clear mld snooping............................................................................................................................................................84

clear msdp counters............................. ....................... ........................ ........................ ....................... ........................ ...... 85

clear msdp sa-cache.........................................................................................................................................................87

clear pim cache...................... ........................ ........................ ....................... ........................ ....................... ....................... 88

clear pim snooping............................................................................................................................................................89

configure forwarding ipmc compression...............................................................................................................90

configure forwarding ipmc lookup-key....................................................................................................................91

configure igmp router-alert receive-required......................................................................................................92

configure igmp router-alert transmit.................................... ....................... ........................ ....................... ............. 93

configure igmp snooping filters..................................................................................................................................94

configure igmp snooping flood-list...........................................................................................................................96

configure igmp snooping leave-timeout......................................... ....................... ........................ ....................... .98

configure igmp snooping timer................................ ........................ ....................... ........................ ....................... .... 98

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configure igmp snooping vlan ports add dynamic group...........................................................................100

configure igmp snooping vlan ports add static group.......................................... ....................... .................. 101

configure igmp snooping vlan ports add static router..................................................................................103

configure igmp snooping vlan ports delete static group.............................................................................104

configure igmp snooping vlan ports delete static router.............................................................................105

configure igmp snooping vlan ports filter............................................................................................................105

configure igmp snooping vlan ports set join-limit........................................ ........................ ....................... .... 107

configure igmp ssm-map add....................................................................................................................................108

configure igmp ssm-map delete...............................................................................................................................109

configure igmp....................................................................................................................................................................110

configure ipmcforwarding.................................... ....................... ........................ ........................ ....................... ............ 111

configure ipmroute add....................... ........................ ........................ ....................... ........................ ....................... ..... 112

configure ipmroute delete.............................................................................................................................................113

configure iproute add (Multicast)..............................................................................................................................114

configure iproute delete.............................. ........................ ....................... ........................ ....................... ..................... 115

configure mcastipv4 cache timeout................................... ........................ ....................... ........................ ............. 116

configure mcast ipv6 cache timeout........................................................................................................................117

configure mld.......................................................................................................................................................................118

configure mld snooping fast-learning................................. ....................... ........................ ....................... ............. 120

configure mld snooping filters.............................. ....................... ........................ ....................... ........................ ....... 120

configure mld snooping flood-list..............................................................................................................................121

configure mld snooping leave-timeout..................................................................................................................123

configure mld snooping timer....................................................................................................................................124

configure mld snooping vlan ports add dynamic group...............................................................................125

configure mld snooping vlan ports add static group............................. ........................ ....................... ......... 127

configure mld snooping vlan ports add static router.....................................................................................128

configure mld snooping vlan ports delete static group........................ ....................... ........................ ......... 129

configure mld snooping vlan ports delete static router........................... ....................... ........................ ..... 130

configure mld snooping vlan ports filter.............................. ........................ ....................... ........................ ........... 131

configure mld snooping vlan ports join-limit........................................ ....................... ........................ ............... 132configure mld ssm-map add........................ ....................... ........................ ....................... ........................ ................. 133

configure mld ssm-map delete..................................................................................................................................134

configure msdp as-display-format...........................................................................................................................135

configure msdp max-rejected-cache......................................................................................................................136

configure msdp originator-id......................................................................................................................................137

configure msdp peer default-peer................................. ........................ ........................ ....................... ................... 138

configure msdp peer description.............................................................................................................................140

configure msdp peer mesh-group................................... ........................ ....................... ........................ .................. 141

configure msdp peer no-default-peer....................................................................................................................142

configure msdp peer password.................................................................................................................................143

configure msdp peer sa-filter.....................................................................................................................................144

configure msdp peer sa-limit......................................................................................................................................145configure msdp peer source-interface...................................... ........................ ....................... ........................ ..... 146

configure msdp peer timer................................ ........................ ....................... ........................ ........................ ........... 147

configure msdp peer ttl-threshold...........................................................................................................................148

configure msdp sa-cache-server............................... ....................... ........................ ........................ ....................... . 149

configure mvr add receiver............................... ........................ ....................... ........................ ....................... ............ 150

configure mvr add vlan......................... ....................... ........................ ....................... ........................ ........................ .... 151

configure mvr delete receiver.....................................................................................................................................152

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configure mvr delete vlan.............................................................................................................................................153

configure mvr mvr-address.........................................................................................................................................154

configure mvr static group............................ ....................... ........................ ........................ ....................... ................ 155

configure pim add vlan............................ ........................ ....................... ........................ ....................... ........................ 156

configure pim border......................................................................................................................................................158

configure pim cbsr......................... ........................ ....................... ........................ ....................... ........................ ............ 159

configure pim crp static................................................................................................................................................160

configure pim crp timer..................................................................................................................................................161

configure pim crp vlan.......................... ....................... ........................ ........................ ....................... ........................ ... 162

configure pim delete vlan.............................................................................................................................................163

configure pim dr-priority..................................... ....................... ........................ ....................... ........................ ........... 164

configure pim iproute sharing hash.........................................................................................................................165

configure pim register-policy rp ..............................................................................................................................166

configure pim register-policy................................... ........................ ........................ ....................... ........................ ... 167

configure pim register-checksum-to........................................ ....................... ........................ ........................ ....... 168

configure pim register-rate-limit-interval............................... ....................... ........................ ........................ ....... 169

configure pim register-suppress-interval register-probe-interval........................... ....................... ......... 170

configure pim shutdown-priority....................... ....................... ........................ ........................ ....................... .......... 171

configure pim spt-threshold........................................................................................................................................172

configure pim ssm range...............................................................................................................................................173

configure pim ssm............................................................................................................................................................174

configure pim state-refresh timer origination-interval...................................................................................175

configure pim state-refresh timer source-active-timer..................... ....................... ........................ ............. 176

configure pim state-refresh ttl........................... ........................ ........................ ....................... ........................ ......... 177

configure pim state-refresh................................. ........................ ....................... ........................ ........................ ......... 178

configure pim timer vlan......................... ........................ ....................... ........................ ....................... ........................ 179

configure pim vlan trusted-gateway...................................... ........................ ....................... ........................ ......... 180

create msdp mesh-group............................. ....................... ........................ ........................ ....................... ................... 181

create msdp peer..............................................................................................................................................................182

delete msdp mesh-group............................... ....................... ........................ ....................... ........................ ................ 183delete msdp peer..............................................................................................................................................................184

disable igmp snooping vlan fast-leave...................................................................................................................185

disable igmp snooping................................. ....................... ........................ ........................ ....................... .................... 185

disable igmp ssm-map.............................. ....................... ........................ ........................ ....................... ....................... 187

disable igmp............................. ........................ ....................... ........................ ........................ ....................... ..................... 187

disable ipmcforwarding ipv6.............................. ....................... ........................ ........................ ....................... .......... 188

disable ipmcforwarding.................................................................................................................................................189

disable mld...........................................................................................................................................................................190

disable mld snooping.......................................................................................................................................................191

disable mld-ssmmap......................... ........................ ....................... ........................ ....................... ........................ ....... 192

disable msdp data-encapsulation.............................................................................................................................193

disable msdp export local-sa......................................................................................................................................194disable msdp peer......................... ........................ ....................... ........................ ....................... ........................ ............. 195

disable msdp process-sa-request.............................................................................................................................195

disable msdp............................ ....................... ........................ ....................... ........................ ....................... ...................... 197

disable mvr...........................................................................................................................................................................197

disable pim iproute sharing............................ ....................... ........................ ........................ ....................... ............... 198

disable pim snooping......................................................................................................................................................199

disable pim ssmvlan.......................... ........................ ....................... ........................ ....................... ........................ ..... 200

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disable pim...........................................................................................................................................................................201

enable igmp snooping vlan fast-leave............................. ....................... ........................ ....................... ............... 202

enable igmp snooping with-proxy..........................................................................................................................203

enable igmp snooping................................ ........................ ....................... ........................ ........................ ................... 204

enable igmp ssm-map...................................................................................................................................................205

enable igmp........................................................................................................................................................................206

enable ipmcforwarding ipv6......................................................................................................................................207

enable ipmcforwarding........................... ....................... ........................ ........................ ....................... ....................... 208

enable mld................................ ....................... ........................ ........................ ....................... ........................ .................... 209

enable mld snooping with-proxy..............................................................................................................................210

enable mld snooping........................... ........................ ........................ ....................... ........................ ....................... ....... 211

enable mld-ssm map........................ ........................ ........................ ....................... ........................ ....................... .......... 211

enable msdp data-encapsulation..............................................................................................................................212

enable msdp export local-sa........................... ....................... ........................ ....................... ........................ .............. 213

enable msdp peer........................ ........................ ........................ ....................... ........................ ....................... ............... 215

enable msdp process-sa-request..............................................................................................................................216

enable msdp............................... ........................ ....................... ........................ ....................... ........................ ................... 217

enable mvr............................................................................................................................................................................218

enable pim iproute sharing............................... ........................ ....................... ........................ ........................ ............ 219

enable pim snooping........................... ........................ ........................ ....................... ........................ ....................... .... 220

enable pim ssm vlan......................... ........................ ........................ ....................... ........................ ....................... ......... 221

enable pim................................ ....................... ........................ ........................ ....................... ........................ ..................... 222

mrinfo.....................................................................................................................................................................................223

mtrace........................................... ........................ ........................ ....................... ........................ ....................... .................. 224

refresh mld ssm-map.......................... ....................... ........................ ....................... ........................ ........................ ..... 227

rtlookup rpf.........................................................................................................................................................................228

rtlookup...................................... ........................ ........................ ....................... ........................ ....................... .................... 229

show igmp group...................... ....................... ........................ ........................ ....................... ........................ ................ 230

show igmp snooping cache........................................................................................................................................232

show igmp snooping vlan filter.................................................................................................................................233show igmp snooping vlan static............................. ........................ ....................... ........................ ....................... ... 234

show igmp snooping vlan............................................................................................................................................235

show igmp snooping......................................................................................................................................................236

show igmp ssm-map......................................................................................................................................................237

show igmp...........................................................................................................................................................................238

show ipmroute.......................... ....................... ........................ ....................... ........................ ........................ .................. 239

show iproute multicast.................................................................................................................................................240

show L2stats.............................. ....................... ........................ ....................... ........................ ........................ .................. 242

show mcast cache...........................................................................................................................................................243

show mcast ipv6 cache........................... ....................... ........................ ....................... ........................ ....................... 245

show mld..................................... ........................ ....................... ........................ ....................... ........................ .................. 246

show mld counters........................ ........................ ....................... ........................ ....................... ........................ ........... 248show mld group..................... ........................ ....................... ........................ ....................... ........................ .................... 249

show mld snooping vlan filter............................... ....................... ........................ ....................... ........................ ...... 250

show mld snooping vlan static............................ ........................ ....................... ........................ ....................... ....... 250

show mld snooping..........................................................................................................................................................251

show mld ssm-map.........................................................................................................................................................253

show msdp memory.......................................................................................................................................................255

show msdp mesh-group.............................. ........................ ....................... ........................ ....................... .................. 256

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show msdp peer...............................................................................................................................................................257

show msdp sa-cache........................ ....................... ........................ ....................... ........................ ....................... ........ 259

show msdp...........................................................................................................................................................................261

show mvr cache......................... ........................ ........................ ....................... ........................ ....................... ................ 262

show mvr.............................. ....................... ........................ ....................... ........................ ........................ ....................... .. 263

show pim cache................................................................................................................................................................263

show pim snooping................................. ....................... ........................ ....................... ........................ ....................... .. 265

show pim..............................................................................................................................................................................266

unconfigure igmp snooping vlan ports set join-limit....................................... ........................ ...................... 272

unconfigure igmp ssm-map........................................................................................................................................273

unconfigure igmp.............................................................................................................................................................273

unconfigure mld............................ ....................... ........................ ........................ ....................... ........................ ............. 274

unconfigure mld ssm-map............................ ........................ ....................... ........................ ........................ ............... 275

unconfigure msdp sa-cache-server........................................................................................................................276

unconfigure pim border................................................................................................................................................277

unconfigure pim ssm range.......................... ....................... ........................ ....................... ........................ ................ 278

unconfigure pim............................ ....................... ........................ ........................ ....................... ........................ ............. 279

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Preface

Conventions

This section discusses the conventions used in this guide.

Text Conventions

The following tables list text conventions that are used throughout this guide.

Table 1: Notice Icons

Icon Notice Type Alerts you to...

Note Important features or instructions.

Caution Risk of personal injury, system damage, or loss of data.

Warning Risk of severe personal injury.

New This command or section is new for this release.

Table 2: Text Conventions

Convention Description

Screen displaysThis typeface indicates command syntax, or represents information as it appears on

the screen.

The wordsenter

and

type

When you see the word enter in this guide, you must type something, and then press

the Return or Enter key. Do not press the Return or Enter key when an instruction

simply says type.

[Key]

names Key names are written with brackets, such as [Return] or [Esc]. If you must press two

or more keys simultaneously, the key names are linked with a plus sign (+). Example:Press

[Ctrl]

+[Alt]

+[Del]

Words in italicized type Italics emphasize a point or denote new terms at the place where they are defined in

the text. Italics are also used when referring to publication titles.

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Platform-Dependent Conventions

Unless otherwise noted, all information applies to all platforms supported by ExtremeXOS software,

which are the following:

BlackDiamondX8 series switch

BlackDiamond 8800 series switches Cell Site Routers (E4G-200 and E4G-400)

Summitfamily switches

SummitStack

When a feature or feature implementation applies to specific platforms, the specific platform is noted in

the heading for the section describing that implementation in the ExtremeXOS command

documentation. In many cases, although the command is available on all platforms, each platform uses

specific keywords. These keywords specific to each platform are shown in the Syntax Description and

discussed in the Usage Guidelines.

Terminology

When features, functionality, or operation is specific to a switch family, the family name is used.

Explanations about features and operations that are the same across all product families simply refer to

the product as the switch.

Related Publications

Documentation for Extreme Networks products is available at: www.extremenetworks.com. The

following is a list of related publications currently available:

ExtremeXOS User Guide

ExtremeXOS Hardware and Software Compatibility Matrix

ExtremeXOS Legacy CLI Quick Reference Guide

ExtremeXOS ScreenPlay User Guide

Using AVB with Extreme Switches

BlackDiamond 8800 Series Switches Hardware Installation Guide

BlackDiamond X8 Switch Hardware Installation Guide

Extreme Networks Pluggable Interface Installation Guide

Summit Family Switches Hardware Installation Guide

Ridgeline Installation and Upgrade Guide

Ridgeline Reference Guide

SDN OpenFlow Implementation Guide

SDN OpenStack Install Guide

Some ExtremeXOS software files have been licensed under certain open source licenses. Information is

available at: www.extremenetworks.com/services/osl-exos.aspx

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Providing Feedback to Us

We are always striving to improve our documentation and help you work better, so we want to hear

from you! We welcome all feedback but especially want to know about:

Content errors or confusing or conflicting information.

Ideas for improvements to our documentation so you can find the information you need faster. Broken links or usability issues.

If you would like to provide feedback to the Extreme Networks Information Development team about

this document, please contact us using our short online feedback form. You can also email us directly at

[email protected].

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Navigating the ExtremeXOS User Guide

This guide consists of the following eight volumes that contain feature descriptions, conceptual

material, configuration details, command references and examples:

Basic Switch Operation

Policies and Security

Layer 2 Basics

Layer 2 Protocols

Layer 3 Basics

Layer 3 Unicast Protocols

Multicast

Advanced Features

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1Multicast Routing and SwitchingMulticast Routing Overview

Multicast Table Management

PIM Overview

IGMP Overview

Configuring EAPS Support for Multicast Traffic

Configuring IP Multicast Routing

Multicast VLAN Registration

Displaying Multicast Information

Troubleshooting PIM

This chapter introduces the features and usage of IP multicasting, which allows a single host on anetwork to send a packet to a group of hosts. For more information on IP multicasting, refer to the

following publications:

RFC 1112Host Extension for IP Multicasting

RFC 2236Internet Group Management Protocol, Version 2

RFC 3569SSM for IPv4/IPv6 (only for IPv4)

PIM-SM Version 2draft-ietf-pim-sm--v2-new-05

RFC 4601PIM SM (only for IPv4)

PIM-SM for IPv4/IPv6 (only for IPv4)

RFC 2362 PIM-SM (Edge Mode)

RFC 3973 PIM-DM (only for IPv4)

RFC 3569draft-ietf-ssm-arch-06.txt PIM-SSM PIM Source Specific Multicast

PIM-DM Draft IETF Dense Modedraft-ieft-idmr-pimdm-05.txt, draft-ieft-pim-dm-new-v2-04.txt

RFC 3376Internet Group Management Protocol, Version 3

The following URL points to the website for the IETF PIM Working Group: www.ietf.org/html.charters/

pim-charter.html.

Multicast Routing Overview

Multicast routing and switching is thefunctionality of a network that allows a single host (the multicast

server) to send a packet to a group of hosts. With multicast, the server is not forced to duplicate and

send enough packets for all the hosts in a group. Instead, multicast allows the network to duplicatepackets for allof the hosts in a group. Multicast greatly reduces the bandwidth required to send data to

a group of hosts. IP multicast routing is a function that allows multicast traffic to be forwarded from

one subnetto another across a routing domain.

IP multicastrouting requires the following functions:

A routerthat can forward IP multicast packets

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A router-to-router multicast routing protocol (for example, Protocol Independent Multicast (PIM))to discover multicast routes

A method for the IP host to communicate its multicast group membership to a router (for example,Internet Group Management Protocol (IGMP))

Note

You should configure IP unicast routing before you configure IP multicast routing.

Multicast Table Management

The ExtremeXOS software uses the following tables to support IP multicast traffic:

IPv4 multicast route table

L3 hash table

IP multicast group table

FDB table (L2 table)

L2 multicast table (L2MC table)

IP Multicast Hardware Lookup Modes

Extreme platforms support various hardware forwarding lookup modes by using a combination of L3

hash table and L2 (FDB) table. Refer to Multicast Table Management for details on these tables. The

scalability limits vary based on the lookup mode used.

Configuration Options

Configuration options allow you to choose the hardware forwarding lookup mode for multicast

forwarding. Here is a list of options:

source-group-vlan -- Uses L3 hash table with S,G,V lookup. This is the default mode for all platformsexcept the Summit X430.

group-vlan -- Uses L3 hash table with *,G,V lookup.

mac-vlan -- Uses L2 table with DMAC, VLAN lookup. This is the default mode for x430.

mixed-mode -- Uses both L2 and L3 tables for multicast. In this mode, the following logic is appliedon installing the cache entries in the hardware:

Multicast cache entries requiring forwarding across VLANs would be installed in the L3 IP

multicast table. This includes PIM, MVR, and PVLAN cache entries.

Multicast cache entries requiring L2 forwarding within a VLAN are installed in the L2 table. This

includes entries corresponding to IGMP Snooping, PIM snooping, and MLD snooping.

Any IPv4/v6 reserved multicast addresses (for example, 224.0.0.x or IPv6 equivalent) are

installed in the L3 IP multicast table as needed. These reserved addresses map to the following

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multicast MAC addresses: 01:00:5e:00:00:xx, 33:33:00:00:00:xx, 33:33:00:00:01:xx, or

33:33:ff:xx:xx:xx.

Note

Any change in the lookup key configuration causes all cache entries to be cleared, and

traffic is temorarily dropped until the system re-learns the multicast caches and

associated subscriptions.

Note

mac-vlan mode helps increase scaling and is particularly useful on platforms like the

Summit X440, which has limited L3 hardware table entries. This mode is also supported in

other Summit platforms, and the BlackDiamond8K and BlackDiamond X.

Note

mac-vlan and mixed-mode are not supported prior to ExtremeXOS 15.3.1.

The EXOS multicast process continues to maintain the cache entries as "S,G,V", and interacts with HAL

the same way as today. EXOS hardware abstraction layer (HAL) applies the logic explained above and

installs the cache entries in the appropriate hardware table. If the cache entry needs to be installed in

the L2 multicast table, HAL derives the MAC address based on the standard logic and installs the MAC

entry in the L2 table.

The IP multicast address to MAC address mapping is not validated for the received/forwarded

multicast packets in EXOS to date. If the lookup mode is configured either as "mac-vlan" or "mixed-

mode", the multicast kernel module is modified to validate this mapping and, if a packet does not use

the standard mapping, the packet is dropped.

IPMC Compression

In order to increase the scaling of multicast entries, EXOS implements a feature called IPMC

compression which allows multiple (or ) IP multicast FDB entries to utilize the same IPmulticast group table entry when the associated egress port lists are the same. The base IP multicast

compression implementation will be reused for achieving L2 multicast entry reuse. In this case, multiple

multicast FDB entries can use a single L2MC index if the egress port lists of the cache

entries are the same.

Interactions with Static FDBs

EXOS allows you to create FDB entries for multicast MAC address using the create fdb

{vlan}vlan_nameportsport_listcommand. These entries also get installed in

the L2 table and use the L2MC table for hardware forwarding. If there is a dynamic entry

from MCMGR and a static entry from FDB manager, the static entry takes precedence and the dynamic

entry would get deleted in hardware. Compression of L2MC indices is not supported on these types of

entries. Each newly created static multicast FDB will cause the allocation of a new L2MC index.

Interactions with Dynamic FDBs

When IP multicast forwarding entries are utilizing the L2 MAC table, the multicast entries are installed

as static in the hardware L2 table to avoid undesirable interactions with L2 protocol or user

administered FDB flushing. These multicast L2 entries also take precedence over dynamic unicast L2

MAC entries. If there is a hash bucket collision upon inserting an L2 multicast entry, it will replace

another dynamic unicast L2 entry if one exists in the same hash bucket.


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Platforms with External-Tables (TCAM)

The X480 and BD8K xl-series have a large external TCAM that can be used to store MAC FDBs, L3

routes, ACLs, and/or IPMC forwarding entries based on configuration. Only the internal L2 table is used

to store forwarding entries for IP multicast caches on these platforms due to a hardware

limitation. Additionally, the configure forwarding external-table l2-and-l3-and-

ipmcconfiguration option, which uses the external TCAM to store entries, is not compatiblewith the "mac-vlan" and "mixed-mode" options of this feature.

Virtual Router Support

Current IPMC cache hardware entries stored as additionally include the VRID associated with

the ingress virtual router. In this feature, cache entries are stored in the L2 table which

does not additionally include the VRID. However, user VRs are still supported since the VLAN portion of

the lookup key is unique across all VRs.

IPMC Cache Rate Limiting

Based on the number of cache entries supported on each platform, there is a software cache limiting

implementation present in EXOS multicast. The HAL module informs MCMGR about the supported limit,

MCMGR creates cache entries up to MAX supported limit, and the remaining traffic is dropped in

software.

Supported Platforms

This feature is implemented on all Summit, BD8K, and BDX8 platforms.

Note

The mixed-mode setting is supported on all platforms except: BD8K "e2-series", 8500-G48T-

e.

Limitations

The following limitations exist for the L2MC table feature:

The "mixed-mode" configuration option is not allowed on platforms using older chipsets. Please seethe "Platforms Supported" section for details.

When the "mixed-mode" configuration option is engaged on BD8K platforms, newly inserted slotswhich do not support "mixed-mode" will fail initialization.

On SummitStack, this same condition causes the following log to be displayed repeatedly every 30seconds:

Stack slot %d is incompatible with the multicast

forwarding lookup configuration.

Either remove this node from the stack or change the multicast forwarding lookup configuration. When using the "mac-vlan" configuration option:

PIMv4/V6, MVR features cannot be used.

IGMPv3 should not be used in conjunction with this mode

Private VLAN multicast should not be used.

Issues with IP multicast address to MAC address mapping:


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All IPv4 multicast frames use multicast mac addresses starting with 01:00:5e:xx:xx:xx. The lower

order 23 bits of the IP multicast address is used in the MAC address derivation. As only 23 bits of

MAC addresses are available for mapping layer 3 IP multicast addresses to layer 2 MAC addresses,

this mapping results in 32:1 address ambiguity.

When traffic is received for 1 out of these 32 overlapping address, then the MAC, Vlan entry is

installed in hardware based on the IGMP group membership of received traffics destinationmulticast IP address. After this installation, traffic to any of the remaining 31 addresses is delivered

based on the existing cache entry and the actual receiver list of the remaining 31 addresses will not

be honored.

IPv6 multicast streams use multicast MAC addresses in the form 33:33:xx:xx:xx:xx. The lower 24 bits

of the IPv6 multicast address are used to derive the MAC address. So, the address ambiguity issue is

also applicable to IPv6 with more severity. Given this condition, we do not recommend using

overlapping IP multicast addresses with this mode.

This limitation applies to "mixed-mode", too.

IPv4 multicast addresses consist of a block of addresses (224.0.0.x) used for network control traffic.

Packets having IP destination addresses from the LNCB are always flooded to all ports of the VLAN.The address ambiguity issue discussed above is applicable for the addresses in this block too. For

example, 224.0.0.5 (address used for OSPF) and 225.0.0.5 would use the same MAC address

01:00:5e:00:00:05. If a mac based multicast FDB entry is installed on the hardware for 01:00:5e:

00:00:05 based on the 225.0.0.5 join list, it would break OSPF functionality. Hence, MAC addresses

mapping to the LNCB block will not be installed in the L2 table, resulting in software forwarding for

those streams. We recommend that you avoid useing multicast addresses that map to the 01:00:5e:

00:00:xx MAC address range.

As per RFC 3307, IANA assigned reserved IPv6 multicast addresses could be in the group Id rangeof 0x00000001 to 0x3FFFFFFF. As a result, EXOS switches flood traffic addressed to ff02::/98 to

all ports of the VLAN. Since the lower 32 bits of IPv6 multicast addresses are mapped to the

multicast mac address, not installing all of the addresses in this range would make it too restrictive.So, installing entries for 33:33:00:00:00:xx in hardware would be avoided, and the traffic would be

software forwarded.

In addition, the following important IPv6 multicast addresses cannot be installed as hardware

forwarding entries:

DHCP: All-dhcp-agents address FF02:0:0:0:0:0:1:2

All-dhcp-servers address FF05:0:0:0:0:0:1:3

Neighbor Discovery (ND): Solicited-node-address FF02::1:FF00:0000/104

Therefore, the following multicast MAC addresses are not programmed in hardware, and the

corresponding packets are handled in slowpath: 33:33:00:00:01:xx , 33:33:ff:xx:xx:xx

Given the issues with IP multicast address to MAC address mapping, no attempt is made to mergesubscriber lists of multiple overlapping IP groups.

The following limitation regarding IPMC compression is also applicable for this feature, because thisfeature uses the same L2MC entry for multiple l2 multicast entries with same egress ports. All MAC-

VLAN forwarding entries utilizing the same L2MC entry will be subject to a single BD8K backplane

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On those platforms supporting the "external-table" (X480, BD8K "xl-series"), any IP multicastcaches installed in the L2 table will be only installed in the internal L2 table due to a hardware

limitation which prevents L2MC access from the ESM (External Search Machine).

When IP multicast forwarding entries are installed as , IGMP or MLD packets whichhave a MAC-DA= will cause the refresh of the IP multicast cache, preventing timely entry

age-out.

The L2MC table is limited to 1K entries on all platforms. This means that only up to 1K unique portlists can be addressed from the IP multicast forwarding entries that are stored in the

L2 table. Additionally, statically created multicast FDB entries do not perform L2MC index

compression.

IPv4 Multicast Route Table

Beginning with Release 12.1, all IP multicast routes are stored and maintained in the software multicast

route table. Routes are added to the multicast route table from the following sources:

Multicast static routes (configured manually by the network administrator)

Multicast dynamic routes (learned through protocols such as MBGP and MISIS)

The multicast route table is used for reverse path forwarding (RPF) checks, not for packet forwarding.

The switch uses RPF checks to avoid multicast forwarding loops. When a multicast packet is received,

the switch does an RPF lookup, which checks the routing tables to see if the packet arrived on the

interface on which the router would send a packet to the source. The switch forwards only those

packets that arrive on the interface specified for the source in the routing tables.

The RPF lookup uses the multicast routing table first, and if no entry is found for the source IP address,

the RPF lookup uses the unicast routing table.

Note

Because the multicast routing table is used only for RPF checks (and not for routing), IP route

compression and ECMP do not apply to multicast routes in the multicast routing table.

Beginning with ExtremeXOS software version 12.1, the route metric is no longer used to select

between multicast and unicast routes. If the RPF lookup finds a route in the multicast table,

that route is used. The unicast routing table is used only when no route is found in the

multicast table.

The advantage to having separate routing tables for unicast and multicast traffic is that the two types

of traffic can be separated, using different paths through the network.

L3 Hash Table

The L3 hash table is introduced in Introduction to Hardware Forwarding Tables. The L3 hash table

stores entries for IPv4 routes, IPv4 and IPv6 hosts, and IPv4 and IPv6 multicast groups. For multicast,

L3 hash table supports and lookups. The entry from this table provides an index to IP

Multicast Group table.

To make more space available in the L3 hash table for IPv4 and IPv6 multicast groups, you can do the

following:


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Configure the extended IPv4 host cache feature to move IPv4 local and remote routes to the LPMtable as described in Extended IPv4 Host Cache.

Configure BlackDiamond 8900 xl-series modules or Summit X480 series switches to do one of thefollowing:

Move IPv4 local and remote hosts to the external LPM table.

Move IPv6 local hosts to the external LPM table. Move IPv4 local and remote hosts to the external LPM table and support IPv4 multicast entries in

the external LPM table.

For more information, see the description for the configure forwarding external-tablescommand.

Note

To benefit from the use of the external LPM tables, you must leave the IP multicast

compression feature enabled, which is the default setting.

IP Multicast Group Table

The IP multicast group table specifies the egress ports for Layer 2 and Layer 3 multicast traffic groups.

To make more space available in the IP multicast group table, you can do the following:

Leave IP multicast compression enabled (it is enabled by default). This allows multiple L3 hashentries to share the same IP multicast group entry if the the egress list is the same.

Use the following I/O modules, which provide higher capacity tables: BlackDiamond 8900 xl-series modules

BlackDiamond 8900-G96T-c

Capacity Restrictions for Mixed Installations

A mixed installation is a switch configuration that contains I/O modules with different table sizes. The

actual IP multicast group table capacity for the switch is set to that supported on the I/O module with

the smallest tables. To increase the capacity of IP multicast tables, all I/O modules must support the

minimum table size you want.

Multicast forwarding entries are programmed in all I/O modules. Only multicast traffic ingressing a

given I/O module utilize these forwarding entries. Other egress-only I/O modules only require the

multicast group table entry.

If you add a higher-capacity I/O module to a switch that has been running with lower capacity

modules, the switch generates a message and adjusts the table capacity on the higher-capacity card to

that of the lower-capacity card.

Compared to the L3 hash table that uses an IP address for forwarding, the L2 table uses a MAC address.

The L2 table stores unicast and multicast MAC entries, and it supports lookup. The

entry from this table provides an index to the L2MC table that specifies the egress ports.


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PIM Overview

Protocol Independent Multicast (PIM) is the de-facto standard for routing multicast traffic over the

Internet. Other multicast routing protocols such as DVMRP and MOSPF are sometimes used in

controlled environment, but are not widely deployed. PIM does not depend on a particular unicast

routing protocol for its operation. Also, it does not have any mechanism of its own for route discovery.

PIM operation is based on the routing table being populated by another routing protocol, or by theuser. This provides flexibility in routing unicast and multicast traffic based on a common database.

PIM has two flavors, sparse and dense mode, that are deployed in different topologies. These two

flavors, called PIM-SM and PIM-DM, are different in operation. PIM-SM is based on a "join protocol",

where traffic is not forwarded on a segment unless an explicit request originates (typically through

IGMP) from the network segment. PIM-DM is based on a "flood and prune" mechanism, where every

one receives traffic until they explicitly inform (through the PIM-DM prune mechanism) that they do not

want that particular stream. Thus, PIM-DM is typically deployed in topologies where listeners are

densely populated. And PIM-SM is typically deployed where the receivers are sparsely populated over

the network, so that most of the network segments bandwidth is conserved.

You can configure dense mode or sparse mode on a per-interface basis. After they are enabled, someinterfaces can run dense mode, while others run sparse mode. The switch supports both dense mode

and sparse mode operation.

The switch also supports PIM snooping.

PIM Edge Mode

PIM Edge Mode is a subset of PIM that operates with the following restrictions:

The switch does not act as a candidate rendezvous point (CRP).

The switch does not act as a candidate bootstrap router (CBSR).

At most, four active PIM-SM interfaces are permitted. There is no restriction on the number ofpassive interfaces (within the limit of the maximum IP interfaces).

Only PIM Sparse Mode (PIM-SM) is supported.

Note

This feature is supported at and above the license level listed for this feature in the license

tables in the Feature License Requirementsdocument.

Active PIM interfaces can have other PIM enabled routers on them. Passive interfaces should only have

hosts sourcing or receiving multicast traffic. If another PIM router is connected to a multi-access VLAN

then passive mode should not be enabled for that respective VLAN. OSPF passive mode should not be

enabled for a VLAN when a PIM neighbor is present.

PIM Dense Mode

Protocol-Independent Multicast - Dense Mode (PIM-DM) is a multicast routing protocol. PIM dense-

mode is a flood and prune-based protocol. Convergence is based on the downstream routers' response

for the traffic received. The downstream router in turn floods the traffic to its own downstream

interfaces. Each router sends prune to the interface on which it received the traffic under the following

conditions:


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Traffic was not received on RPF interface towards the source.

The PIM router is a leaf router, and there are no IGMP/MLD members.

All the downstream PIM routers have pruned the stream, and there are no IGMP/MLD members.

A new feature, called PIM-DM state refresh, creates two PIM-DM operating modes, which are described

in the following sections:

Note

For additional information on PIM-DM, see RFC 3973, Protocol Independent Multicast - Dense

Mode (PIM-DM): Protocol Specification.

PIM-DM Without State Refresh

PIM-DM is a broadcast and prune protocol, which means that multicast servers initially broadcast traffic

to all destinations, and then switches later prune paths on which there are no receivers. The following

figure shows a dense mode multicast tree with an active branch and a pruned branch.

Figure 1: PIM-DM Operation

In the previous figure, multicast traffic is flowing from VLAN V1 connected to switch S1. S1 floods

multicast traffic to both neighbors S2 and S3 which in turn flood multicast traffic to S4 and S5. S4 has

IGMP members, so it floods multicast traffic down to VLAN V6. S5, which has no multicast members,

sends a prune upstream towards the source. The green line shows the flow of traffic on the active

branch, and the red line shows the prune sent upstream for the pruned branch. After outgoing interface

V2 is pruned from the multicast tree, subsequent multicast traffic from S1 flows only through S2 and S4

and is not forwarded to S3.

After S3 sends a prune upstream, S3 starts a prune hold time timer on outgoing interface V5. When this

timer expires, S3 adds V5 back to the multicast egress list and sends a graft upstream to pull multicast

traffic down again. When multicast traffic arrives from S1, it is forwarded to S5, which repeats the

upstream prune message because it still has no members. This prune, time-out, and flood process

repeats as long as the traffic flow exists and no members are on the pruned branch, and this process

consumes bandwidth during every cycle.

Note




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PIM-DM routers perform reverse path multicasting (RPM). However, instead of exchanging its own

unicast route tables for the RPM algorithm, PIM-DM uses the existing unicast routing table for the

reverse path. As a result, PIM-DM requires less system memory.

PIM-DM with State Refresh

The PIM-DM State Refresh feature keeps the PIM-DM prune state from timing out by periodically

sending a state refresh control message down the source tree. These control messages reset the prune

hold time timer on each pruned interface and prevent the bandwidth waste that occurs with each

prune, time-out, and flood cycle.

When a topology change occurs, the PIM-DM State Refresh feature improves network convergence.

For example, suppose that an S, G entry on S5 in the following figure is removed due to non-availability

of a route. Without PIM-DM State Refresh, multicast traffic is blocked for minutes (due to a time-out on

the upstream routers). In the meantimeif an IGMP member or a PIM-DM neighbor joins S5, there is no

way to pull traffic down immediately because S5 does not have any S, G information. State refresh

control messages solve this problem by indicating S, G state information periodically to all downstream

routers. When S5 receives a state refresh from S3, it scans the S, G information and all pending requestsfrom PIM-DM neighbors and IGMP members. If there are pending requests for the group in the state

refresh message, S5 can immediately send a graft message upstream to circumvent the upstream

timers and pull multicast traffic to its members and neighbors.

To enable, configure, and disable the PIM-DM State Refresh feature, use the following commands:

configure pim state-refresh {vlan} [vlanname| all] [on| off]

configure pim state-refresh timer origination-interval interval

configure pim state-refresh timer source-active-timer interval

configure pim state-refresh ttl ttlvalue

PIM Sparse Mode

Unlike PIM-DM, Protocol-Independent Multicast - Sparse Mode (PIM-SM) is an explicit join and prune

protocol, which means that multicast receivers, and the routers that support them, must join multicast

groups before they receive multicast traffic. When all receivers on a network branch leave a multicast

group, that branch is pruned so that the multicast traffic does not continue to consume bandwidth on

that branch. PIM-SM supports shared trees as well as shortest path trees (SPTs). PIM-SM is beneficial

for large networks that have group members that are sparsely distributed.

Note



Using PIM-SM, the router sends a join message to the rendezvous point (RP). The RP is a central

multicast router that is responsible for receiving and distributing the initial multicast packets. You can

configure a dynamic or static RP.

When a router has a multicast packet to distribute, it encapsulates the packet in a unicast message and

sends it to the RP. The RP decapsulates the multicast packet and distributes it among all member

routers.


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When a router determines that the multicast rate has exceeded a configured threshold, that router can

send an explicit join to the originating router. When this occurs, the receiving router gets the multicast

directly from the sending router and bypasses the RP.

Note

You can run either PIM-DM or PIM-SM per virtual LAN (VLAN).

PIM Mode Interoperation

An Extreme Networks switch can function as a PIM multicast border router (PMBR). A PMBR integrates

PIM-SM and PIM-DM traffic.

When forwarding PIM-DM traffic into a PIM-SM network, the PMBR acts as a virtual first hop and

encapsulates the initial traffic for the RP. The PMBR forwards PIM-DM multicast packets to the RP,

which, in turn, forwards the packets to those routers that have joined the multicast group.

The PMBR also forwards PIM-SM traffic to a PIM-DM network, based on the (*.*.RP) entry. The PMBR

sends a (*.*.RP) join message to the RP,and the PMBR forwards trafficfrom the RP into the PIM-DMnetwork.

No commands are required to enable PIM mode interoperation. PIM mode interoperation is

automatically enabled when a dense mode interface and a sparse mode interface are enabled on the

same switch.

PIM Source Specific Multicast

PIM-SM works well in many-to-many multicasting situations. For example, in video conferencing, each

participating site multicasts a stream that is sent to all the other participating sites. However, PIM-SM is

overly complex for one-to-many multicast situations, such as multimedia content distribution or

streaming stock quotes. In these and similar applications, the listener is silent and can know the source

of the multicast in advance, or can obtain it. In these situations, there is no need to join an RP, as the

join request can be made directly towards the source.

Note



Note

(*;G)s are created for groups inside the SSM range. SSM is not enabled for the ingress VLAN.

PIM Source Specific Multicast (PIM-SSM) is a special case of PIM-SM, in which a host explicitly sends a

request to receive a stream from a specific source, rather than from any source.


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IGMPv3 hosts can use PIM SSM directly, because the ability to request a stream from a specific source

first became available with IGMPv3. The PIM-SSM capable router interprets the IGMPv3 message to

initiate a PIM-SM join towards the source.

Note

IGMPv1 and IGMPv2 hosts can use PIM SSM if IGMP-SSM mapping is enabled and configured

on the ExtremeXOS switch. For more information, see Using IGMP-SSM Mapping.

The following table describes PIM-SSM behavior while sending IGMPV3 joins in the SSM range and

outside the SSM range for IPv4:

Table 3: Using PIM-SSM While Sending IGMPV3 Joins (IPv4)

ExtremeXOS 15.4 ExtremeXOS 15.5

SSM

Enabled

SSM range Mode Include Src Action Observation Action Observation

No Yes Incl Yes Send IGMPv3

join in SSM

range

-the group is

learned -(*;G)

is not created

Send IGMPv3

join in SSM

range

-the group is

learned - (*;G)

is created

No Yes Incl Yes Send IGMPv3

out of SSM

range

-the group is

learned -no

(*;G) is

created

Send IGMPv3

out of SSM

range

-the group is

learned - (*;G)

is created

No Yes Excl No Send IGMPv3

join in SSM

range

-the group is

not learned

(PD4-3138792

131) -no (*;G)

is created

Send IGMPv3

join in SSM

range

-the group is

not learned

(PD4-3138792

131) -no (*;G)

is created

No Yes Excl No Send IGMPv3

join out of

SSM range

-the group is

learned - (*;G)

is created

Send IGMPv3

join out of

SSM range

-the group is

learned - (*;G)

is created

No Yes Excl Yes Send IGMPv3

join in SSM

range

-the group is

not learned -

no (*;G) is

created

Send IGMPv3

join in SSM

range

-the group is

not learned -

no (*;G) is

created

No Yes Excl Yes Send IGMPv3

join out SSM

range

-the group is

learned -no

(*;G) is

created

Send IGMPv3

join out SSM

range

-the group is

learned -no

(*;G) is

created

No No Incl Yes Send IGMPv3

join

-the group is

learned -no

(*;G) is

created

Send IGMPv3

join

-the group is

learned -(*;G)

is created

No No Excl No Send IGMPv3

join

-the group is

learnt - (*;G)

is created

Send IGMPv3

join

-the group is

learnt - (*;G)

is created

No No Excl Yes Send IGMPv3

join

-the group is

learned -no

(*;G) is

created

Send IGMPv3

join

-the group is

learned -no

(*;G) is

created


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Table 3: Using PIM-SSM While Sending IGMPV3 Joins (IPv4) (continued)

ExtremeXOS 15.4 ExtremeXOS 15.5

SSM

Enabled


Yes Yes Incl Yes Send IGMPv3join in SSM

range

-the group islearned -(S;G)

is created

Send IGMPv3join in SSM

range

-the group islearned -(S;G)

is created

Yes Yes Incl Yes Send IGMPv3

out of SSM

range

-the group is

learned -no

(*;G) is

created

Send IGMPv3

out of SSM

range

-the group is

learned - (*;G)

is created

Yes Yes Excl No Send IGMPv3

join in SSM

range

-the group is

not learned -

no (*;G) is

created

Send IGMPv3

join in SSM

range

-the group is

not learned -

no (*;G) is

created

Yes Yes Excl No Send IGMPv3

join out of

SSM range

-the group is

learned - (*;G)

is created

Send IGMPv3

join out of

SSM range

-the group is

learned - (*;G)

is created

Yes Yes Excl Yes Send IGMPv3

join in SSM

range

-the group is

not learned -

no (*;G) is

created

Send IGMPv3

join in SSM

range

-the group is

not learned -

no (*;G) is

created

Yes Yes Excl Yes Send IGMPv3

join out SSM

range

-the group is

learned -no

(*;G) is

created

Send IGMPv3

join out SSM

range

-the group is

learned -no

(*;G) is

created

Yes No Incl Yes Send IGMPv3

join

-the group is

learned -no

(*;G) is

created

Send IGMPv3

join

-the group is

learned -(*;G)

is created

Yes No Excl No Send IGMPv3

join

-the group is

learned - (*;G)

is created

Send IGMPv3

join

-the group is

learned - (*;G)

is created

Yes No Excl Yes Send IGMPv3

join

-the group is

learned -no

(*;G) is

created

Send IGMPv3

join

-the group is

learned -no

(*;G) is

created

The following table describes PIM-SSM behavior while sending MLDV2 joins in the SSM range and

outside the SSM range for IPv6:


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Table 4: Using PIM-SSM While Sending MLDV2 Joins (IPv6)

ExtremeXOS

15.4

ExtremeXOS

15.5

SSM

Enabled


No Yes Incl Yes Send MLDv2

join in SSM

range

-the group is

learned - no

(*;G) is

created

Send MLDv2

join in SSM

range

-the group is

learned -(*;G)

is created

No Yes Incl Yes Send MLDv2

out of SSM

range

-the group is

learned - no

(*;G) is

created -

(S;G) is

created

Send MLDv2

out of SSM

range

-the group is

learned -(*;G)

is created

No Yes Excl No Send MLDv2

join in SSM

range

-the group is

learned -(*;G)

is created

Send MLDv2

join in SSM

range

-the group is

not learned -

no (*;G) iscreated

No Yes Excl No Send MLDv2

join out of

SSM range

-the group is

learned -(*;G)

is created

Send MLDv2

join out of

SSM range

-the group is

learned -(*;G)

is created

No Yes Excl Yes Send MLDv2

join in SSM

range

-the group is

learned -(*;G)

is created

Send MLDv2

join in SSM

range

-the group is

not learned -

no (*;G) is

created

No Yes Excl Yes Send MLDv2

join out SSM

range

-the group is

learned -(*;G)

is created

Send MLDv2

join out SSM

range

-the group is

learned -(*;G)

is created

No No Incl Yes Send MLDv2

join

-the group is

learned -

(S;G) is

created

Send MLDv2

join

-the group is

learned - (*;G)

is created

No No Excl No Send MLDv2

join

-the group is

learned -(*;G)

is created

Send MLDv2

join

-the group is

learned -(*;G)

is created

No No Excl Yes Send MLDv2

join

-the group is

learned -(*;G)

is created

Send MLDv2

join

-the group is

learned -(*;G)

is created

Yes Yes Incl Yes Send MLDv2

join in SSM

range

-the group is

learned -

(S;G) is

created

Send MLDv2

join in SSM

range

-the group is

learned -

(S;G) is

created

Yes Yes Incl Yes Send MLDv2

out of SSM

range

-the group is

learned - no

(*;G) is

created -

(S;G) is

created

Send MLDv2

out of SSM

range

-the group is

learned -(*;G)

is created


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Table 4: Using PIM-SSM While Sending MLDV2 Joins (IPv6) (continued)

ExtremeXOS

15.4

ExtremeXOS

15.5

SSM

Enabled


Yes Yes Excl No Send MLDv2

join in SSM

range

-the group is

learned -(*;G)

is created

Send MLDv2

join in SSM

range

-the group is

not learned -

no (*;G) is

created

Yes Yes Excl No Send MLDv2

join out of

SSM range

-the group is

learned -(*;G)

is created

Send MLDv2

join out of

SSM range

-the group is

learned -(*;G)

is created

Yes Yes Excl Yes Send MLDv2

join in SSM

range

-the group is

learned -(*;G)

is created

Send MLDv2

join in SSM

range

-the group is

not learned -

no (*;G) is

created

Yes Yes Excl Yes Send MLDv2

join out SSM

range

-the group is

learned -(*;G)

is created

Send MLDv2

join out SSM

range

-the group is

learned -(*;G)

is created

Yes No Incl Yes Send MLDv2

join

-the group is

learned -

(S;G) is

created

Send MLDv2

join

-the group is

learned - (*;G)

is created

Yes No Excl No Send MLDv2

join

-the group is

learned -(*;G)

is created

Send MLDv2

join

-the group is

learned -(*;G)

is created

Yes No Excl Yes Send MLDv2

join

-the group is

learned -(*;G)

is created

Send MLDv2

join

-the group is

learned -(*;G)

is created

PIM-SSM has the following advantages:

No overhead of switching to the source-specific tree and waiting for the first packet to arrive

No need to learn and maintain an RP

Fewer states to maintain on each router

No need for the complex register mechanism from the source to the RP

Better security, as each stream is forwarded from sources known in advance

PIM-SSM has the following requirements:

Any host that participates directly in PIM-SSM must use IGMPv3.

To support IGMPv1 and IGMPv2 hosts, IGMP-SSM mapping must be enabled and configured.

PIM-SSM is designed as a subset of PIM-SM and all messages are compliant with PIM-SM. PIM-SSM and

PIM-SM can coexist in a PIM network; only the last hop router need to be configured for PIM-SSM if

both source and receivers are present all the time. However, to avoid any JOIN delay, it is

recommended that you enable all routers along the (s,g) path for PIM-SSM.


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Configuring the PIM-SSM Address Range

A range of multicast addresses is used for PIM-SSM. Within that address range, non-IGMPv3 messages

are ignored, and any IGMPv3 exclude messages are ignored. These messages are ignored for all router

interfaces, even those not configured for PIM-SSM. By default there is no PIM-SSM range specified on

the router. If you choose the default keyword in the CLI when specifying the PIM-SSM range, you

configure the range 232.0.0.0/8. You can also choose to specify a different range for PIM-SSM by usinga policy file.

To configure the PIM-SSM address range, use the following command:

configure pim ssm range [default|policypolicy-name]

PIM Snooping

PIM snooping provides a solution for handling multicast traffic on a shared media network more

efficiently. In networks where routers are connected to a L2 switch, multicast traffic is essentially

treated as broadcast traffic (see the following figure).

Figure 2: Multicast Without PIM Snooping

IGMP snooping does not solve this flooding issue when routers are connected to a L2 switch. Switch

ports are flo

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Multi Cast Configuration Extreme Switch