Brocade Communications Systems IPMC5000PEF User Manual
53-1003085-02
17 February 2014
FastIron Ethernet Switch IP
Multicast
Configuration Guide
Supporting FastIron Software Release 08.0.10a
©
2014, Brocade Communications Systems, Inc. All Rights Reserved.
Brocade, the B-wing symbol, Brocade Assurance, ADX, AnyIO, DCX, Fabric OS, FastIron, HyperEdge, ICX, MLX, MyBrocade, NetIron,
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Contents
Preface.....................................................................................................................................7
Document conventions......................................................................................7
Text formatting conventions.................................................................. 7
Command syntax conventions.............................................................. 7
Notes, cautions, and warnings.............................................................. 8
Brocade resources............................................................................................ 9
Getting technical help........................................................................................9
Document feedback........................................................................................ 10
About This Guide.....................................................................................................................11
Introduction..................................................................................................... 11
Supported hardware............................................................................11
What’s new in this document.......................................................................... 11
How command information is presented in this guide.....................................12
IPv4 Multicast Traffic Reduction.............................................................................................. 13
Supported IPv4 Multicast Traffic Reduction.................................................... 13
IGMP snooping overview................................................................................ 13
Queriers and non-queriers.................................................................. 14
VLAN-specific configuration................................................................ 15
Tracking and fast leave....................................................................... 15
Support for IGMP snooping and Layer 3 multicast routing
together on the same device......................................................... 15
Forwarding mechanism in hardware................................................... 15
Hardware resources for IGMP and PIM-SM snooping........................16
Configuration notes and feature limitations for IGMP snooping
and Layer 3 multicast routing........................................................ 16
IGMP snooping configuration..........................................................................17
IGMP snooping mcache entries and group addresses....................... 18
Changing the maximum number of supported IGMP snooping
mcache entries.............................................................................. 18
Setting the maximum number of IGMP group addresses................... 19
Enabling IGMP snooping globally on the device.................................19
Configuring the IGMP mode................................................................19
Configuring the IGMP version............................................................. 20
Configuring static groups to specific ports.......................................... 21
Disabling IGMP snooping on a VLAN................................................. 22
Modifying the age interval for group membership entries................... 22
Modifying the query interval (active IGMP snooping mode only)........ 22
Modifying the maximum response time...............................................22
Configuring report control....................................................................23
Modifying the wait time before stopping traffic when receiving a
leave message.............................................................................. 23
Modifying the multicast cache age time.............................................. 23
Enabling or disabling error and warning messages............................ 24
Configuring static router ports............................................................. 24
Turning off static group proxy..............................................................24
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Enabling IGMP V3 membership tracking and fast leave for the
VLAN........................................................................................... 24
Enabling fast leave for IGMP V2.......................................................25
Enabling fast convergence ...............................................................25
IGMP snooping show commands................................................................. 26
Displaying the IGMP snooping configuration.................................... 26
Displaying IGMP snooping errors..................................................... 27
Displaying IGMP group information.................................................. 27
Displaying IGMP snooping mcache information............................... 28
Displaying software resource usage for VLANs................................29
Displaying the status of IGMP snooping traffic................................. 30
Displaying querier information...........................................................31
Clear commands for IGMP snooping............................................................34
Clearing the IGMP mcache...............................................................34
Clearing the mcache on a specific VLAN..........................................34
Clearing traffic on a specific VLAN....................................................34
Clearing IGMP counters on VLANs...................................................35
Disabling the flooding of unregistered IPv4 multicast frames in an
IGMP-snooping-enabled VLAN............................................................... 35
PIM SM traffic snooping overview.................................................................35
Application examples of PIM SM traffic snooping.............................35
Configuration notes and limitations for PIM SM snooping................ 37
PIM SM snooping configuration.................................................................... 38
Enabling or disabling PIM SM snooping........................................... 38
Enabling PIM SM snooping on a VLAN............................................ 39
Disabling PIM SM snooping on a VLAN............................................39
PIM SM snooping show commands..............................................................39
Displaying PIM SM snooping information......................................... 39
Displaying PIM SM snooping information on a Layer 2 switch......... 40
Displaying PIM SM snooping information for a specific group or
source group pair.........................................................................41
IPv6 Multicast Traffic Reduction............................................................................................ 43
IPv6 Multicast Traffic Reduction....................................................................43
MLD snooping overview................................................................................43
Support for MLD snooping and Layer 3 IPv6 multicast routing
together on the same device....................................................... 44
Forwarding mechanism in hardware.................................................45
Hardware resources for MLD and PIMv6 SM snooping....................45
MLD snooping configuration notes and feature limitations............... 46
MLD snooping-enabled queriers and non-queriers...........................47
MLD and VLAN configuration............................................................48
MLDv1 with MLDv2...........................................................................48
MLD snooping configuration......................................................................... 48
Configuring the hardware and software resource limits....................49
Configuring the global MLD mode.....................................................49
Modifying the age interval................................................................. 50
Modifying the query interval (active MLD snooping mode only)....... 50
Configuring the global MLD version..................................................50
Configuring report control..................................................................51
Modifying the wait time before stopping traffic when receiving a
leave message............................................................................ 51
Modifying the multicast cache aging time......................................... 51
Disabling error and warning messages.............................................52
Configuring the MLD mode for a VLAN.............................................52
Disabling MLD snooping for the VLAN..............................................52
Configuring the MLD version for the VLAN.......................................52
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Configuring the MLD version for individual ports................................ 53
Configuring static groups.................................................................... 53
Configuring static router ports............................................................. 53
Disabling static group proxy................................................................ 53
Enabling MLDv2 membership tracking and fast leave for the
VLAN............................................................................................. 54
Configuring fast leave for MLDv1........................................................54
Enabling fast convergence .................................................................55
Displaying MLD snooping information.............................................................55
Displaying MLD snooping error information........................................ 55
Displaying MLD group information...................................................... 56
Displaying MLD snooping mcache information................................... 57
Displaying status of MLD snooping traffic........................................... 59
Displaying MLD snooping information by VLAN................................. 60
Clearing MLD snooping counters and mcache............................................... 61
Clearing MLD counters on all VLANs..................................................61
Clearing the mcache on all VLANs..................................................... 61
Clearing the mcache on a specific VLAN............................................61
Clearing traffic counters on a specific VLAN.......................................61
Disabling the flooding of unregistered IPv6 multicast frames in an MLD-
snooping-enabled VLAN............................................................................62
PIM6 SM traffic snooping overview.................................................................62
Application examples of PIM6 SM traffic snooping............................. 62
Configuration notes and limitations for PIM6 SM snooping................ 64
PIM6 SM snooping configuration.................................................................... 65
Enabling or disabling PIM6 SM snooping........................................... 65
Enabling PIM6 SM snooping on a VLAN............................................ 66
Disabling PIM6 SM snooping on a VLAN............................................66
PIM6 SM snooping show commands..............................................................66
Displaying PIM6 SM snooping information......................................... 66
Displaying PIM6 SM snooping for a VLAN..........................................67
IPv4 Multicast Protocols..........................................................................................................69
Supported IPv4 Multicast Protocols features.................................................. 69
Overview of IP multicasting.............................................................................71
Multicast terms.................................................................................... 71
Support for Multicast Multi-VRF...................................................................... 71
system-max command changes......................................................... 71
Show and clear command support......................................................72
Changing global IP multicast parameters....................................................... 72
Concurrent support for multicast routing and snooping...................... 72
Defining the maximum number of PIM cache entries......................... 73
Defining the maximum number of IGMP group addresses................. 73
Changing IGMP V1 and V2 parameters..............................................74
Adding an interface to a multicast group.........................................................75
Multicast non-stop routing............................................................................... 76
Configuration considerations...............................................................76
Configuring multicast non-stop routing................................................76
Displaying the multicast NSR status................................................... 77
Passive multicast route insertion ....................................................................78
Configuring PMRI................................................................................79
Displaying hardware-drop................................................................... 79
IP multicast boundaries...................................................................................79
Configuration considerations...............................................................79
Configuring multicast boundaries........................................................80
Displaying multicast boundaries..........................................................80
PIM Dense ..................................................................................................... 81
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Initiating PIM multicasts on a network...............................................82
Pruning a multicast tree.................................................................... 82
Grafts to a multicast tree...................................................................84
PIM DM versions...............................................................................85
Configuring PIM DM .........................................................................85
Failover time in a multi-path topology............................................... 88
Configuring a DR priority...................................................................89
Displaying basic PIM Dense configuration information.....................89
Displaying all multicast cache entries in a pruned state................... 90
Displaying all multicast cache entries............................................... 90
PIM Sparse .................................................................................................. 95
PIM Sparse device types.................................................................. 95
RP paths and SPT paths...................................................................96
Configuring PIM Sparse....................................................................96
ACL based RP assignment.............................................................101
PIM Passive................................................................................................ 102
Multicast Outgoing Interface (OIF) list optimization.................................... 102
Displaying system values............................................................................103
Displaying PIM resources........................................................................... 103
Displaying PIM Sparse configuration information and statistics................. 105
Displaying basic PIM Sparse configuration information..................105
Displaying a list of multicast groups................................................107
Displaying BSR information............................................................ 108
Displaying candidate RP information.............................................. 110
Displaying RP-to-group mappings.................................................. 111
Displaying RP Information for a PIM Sparse group........................ 112
Displaying the RP set list................................................................ 112
Displaying multicast neighbor information.......................................113
Displaying the PIM multicast cache................................................ 114
Displaying the PIM multicast cache for DIT.................................... 117
Clearing the PIM forwarding cache.............................................................118
Displaying PIM traffic statistics....................................................................118
Clearing the PIM message counters...........................................................120
Displaying PIM RPF....................................................................................121
Configuring Multicast Source Discovery Protocol (MSDP)......................... 121
Peer Reverse Path Forwarding (RPF) flooding...............................122
Source Active caching.....................................................................122
Configuring MSDP.......................................................................... 123
Disabling an MSDP peer.................................................................124
Designating the interface IP address as the RP IP address........... 124
Filtering MSDP source-group pairs.................................................125
Filtering incoming and outgoing Source-Active messages............. 125
Filtering advertised Source-Active messages.................................127
Displaying MSDP information......................................................... 127
Displaying MSDP RPF-Peer........................................................... 133
Displaying MSDP Peer....................................................................134
Displaying MSDP VRF RPF-Peer...................................................134
Clearing MSDP information.............................................................134
Configuring MSDP mesh groups ................................................................135
Configuring MSDP mesh group...................................................... 136
MSDP Anycast RP......................................................................................137
Configuring MSDP Anycast RP.......................................................137
Example.......................................................................................... 138
PIM Anycast RP..........................................................................................141
Configuring PIM Anycast RP...........................................................141
Static multicast routes.................................................................................143
IGMP Proxy.................................................................................................144
IGMP proxy configuration notes......................................................144
4
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IGMP proxy limitations...................................................................... 144
Configuring IGMP Proxy................................................................... 144
Filtering groups in proxy report messages........................................ 145
Displaying IGMP Proxy information.................................................. 145
IGMP V3........................................................................................................147
Default IGMP version........................................................................ 148
Compatibility with IGMP V1 and V2.................................................. 148
Globally enabling the IGMP version .................................................149
Enabling the IGMP version per interface setting ..............................149
Enabling the IGMP version on a physical port within a virtual
routing interface ..........................................................................149
Enabling membership tracking and fast leave.................................. 150
Creating a static IGMP group............................................................151
Setting the query interval.................................................................. 151
Setting the group membership time.................................................. 152
Setting the maximum response time.................................................152
Displaying IGMPv3 information.........................................................152
Clearing the IGMP group membership table ....................................154
Displaying static IGMP groups.......................................................... 154
Clearing IGMP traffic statistics ......................................................... 156
Source-specific multicast.................................................................. 158
Configuring PIM SSM group range................................................... 158
Configuring multiple SSM group ranges........................................... 159
IGMPv2 SSM mapping......................................................................160
IPv6 Multicast Protocols....................................................................................................... 163
Supported IPv6 Multicast Features............................................................... 163
IPv6 PIM Sparse .......................................................................................... 164
PIM Sparse router types................................................................... 164
RP paths and SPT paths...................................................................165
RFC 3513 and RFC 4007 compliance for IPv6 multicast scope-
based forwarding......................................................................... 165
Configuring PIM Sparse.................................................................... 165
IPv6 PIM-Sparse mode..................................................................... 166
Configuring IPv6 PIM-SM on a virtual routing interface.................... 166
Enabling IPv6 PIM-SM for a specified VRF...................................... 166
Configuring BSRs .............................................................................167
Enabling Source-specific Multicast................................................... 174
Configuring a DR priority...................................................................174
Passive Multicast Route Insertion..................................................... 175
Displaying system values..................................................................176
Displaying PIM Sparse configuration information and statistics........176
Clearing the IPv6 PIM forwarding cache...........................................191
Clearing the IPv6 PIM message counters.........................................191
Updating PIM Sparse forwarding entries witha new RP
configuration................................................................................ 191
Clearing the IPv6 PIM traffic ............................................................ 192
Defining the maximum number of IPv6 PIM cache entries............... 192
Configuring a static multicast route within a VRF..............................193
Configuring the route precedence by specifying the route types...... 193
PIM Anycast RP............................................................................................ 194
Configuring PIM Anycast RP.............................................................194
Multicast Listener Discovery and source-specific multicast protocols...........196
Enabling MLDv2................................................................................197
Configuring MLD parameters for default and non-default VRFs....... 197
Configuring MLD parameters at the interface level...........................200
Displaying MLD information.............................................................. 201
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Clearing IPv6 MLD traffic................................................................ 206
Clearing the IPv6 MLD group membership table cache................. 206
IPv6 Multicast Boundaries...........................................................................206
Configuration considerations...........................................................207
Configuring multicast boundaries....................................................207
Displaying multicast boundaries......................................................208
IP Multicast Commands......................................................................................................209
clear ip mroute............................................................................................ 209
clear ipv6 mroute.........................................................................................210
ip max-mroute............................................................................................. 211
ip mroute..................................................................................................... 211
ip mroute (next hop)....................................................................................212
ip mroute next-hop-enable-default.............................................................. 213
ip mroute next-hop-recursion...................................................................... 214
ip multicast disable-flooding........................................................................214
ipv6 max-mroute......................................................................................... 215
ipv6 mroute................................................................................................. 215
ipv6 mroute (next hop)................................................................................ 216
ipv6 mroute next-hop-enable-default.......................................................... 217
ipv6 mroute next-hop-recursion.................................................................. 218
ipv6 multicast disable-flooding.................................................................... 218
route-precedence........................................................................................219
route-precedence admin-distance.............................................................. 220
show ip mroute............................................................................................220
show ip multicast optimization ...............................................................222
show ip static mroute.................................................................................. 222
show ipv6 mroute........................................................................................223
show ipv6 multicast optimization ...........................................................224
show ipv6 static mroute...............................................................................225
Index..................................................................................................................................227
6
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Preface
● Document conventions......................................................................................................7
● Brocade resources............................................................................................................ 9
● Getting technical help........................................................................................................9
● Document feedback........................................................................................................ 10
Document conventions
The document conventions describe text formatting conventions, command syntax conventions, and
important notice formats used in Brocade technical documentation.
Text formatting conventions
Text formatting conventions such as boldface, italic, or Courier font may be used in the flow of the text
to highlight specific words or phrases.
Format
bold text
italic text
Courier font
Description
Identifies command names
Identifies keywords and operands
Identifies the names of user-manipulated GUI elements
Identifies text to enter at the GUI
Identifies emphasis
Identifies variables and modifiers
Identifies paths and Internet addresses
Identifies document titles
Identifies CLI output
Identifies command syntax examples
Command syntax conventions
Bold and italic text identify command syntax components. Delimiters and operators define groupings of
parameters and their logical relationships.
Convention
bold text Identifies command names, keywords, and command options.
italic text Identifies a variable.
Description
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Notes, cautions, and warnings
Convention Description
value In Fibre Channel products, a fixed value provided as input to a command
option is printed in plain text, for example, --show WWN.
[ ]
{ x | y | z }
x | y
< >
...
\
Syntax components displayed within square brackets are optional.
Default responses to system prompts are enclosed in square brackets.
A choice of required parameters is enclosed in curly brackets separated by
vertical bars. You must select one of the options.
In Fibre Channel products, square brackets may be used instead for this
purpose.
A vertical bar separates mutually exclusive elements.
Nonprinting characters, for example, passwords, are enclosed in angle
brackets.
Repeat the previous element, for example, member[member...].
Indicates a “soft” line break in command examples. If a backslash separates
two lines of a command input, enter the entire command at the prompt without
the backslash.
Notes, cautions, and warnings
Notes, cautions, and warning statements may be used in this document. They are listed in the order of
increasing severity of potential hazards.
NOTE
A note provides a tip, guidance, or advice, emphasizes important information, or provides a reference
to related information.
ATTENTION
An Attention statement indicates potential damage to hardware or data.
CAUTION
A Caution statement alerts you to situations that can be potentially hazardous to you or cause
damage to hardware, firmware, software, or data.
DANGER
A Danger statement indicates conditions or situations that can be potentially lethal or
extremely hazardous to you. Safety labels are also attached directly to products to warn of
these conditions or situations.
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Brocade resources
Visit the Brocade website to locate related documentation for your product and additional Brocade
resources.
You can download additional publications supporting your product at www.brocade.com.
• Adapter documentation is available on the Downloads and Documentation for Brocade Adapters
page. Select your platform and scroll down to the Documentation section.
• For all other products, select the Brocade Products tab to locate your product, then click the
Brocade product name or image to open the individual product page. The user manuals are
available in the resources module at the bottom of the page under the Documentation category.
To get up-to-the-minute information on Brocade products and resources, go to MyBrocade. You can
register at no cost to obtain a user ID and password.
Release notes are available on MyBrocade under Product Downloads.
White papers, online demonstrations, and data sheets are available through the Brocade website.
Brocade resources
Getting technical help
You can contact Brocade Support 24x7 online, by telephone, or by e-mail.
For product support information and the latest information on contacting the Technical Assistance
Center, go to http://www.brocade.com/services-support/index.html.
Use one of the following methods to contact the Brocade Technical Assistance Center.
Online Telephone E-mail
Preferred method of contact for nonurgent issues:
• My Cases through MyBrocade
• Software downloads and
licensing tools
• Knowledge Base
Required for Sev 1-Critical and Sev
2-High issues:
• Continental US:
1-800-752-8061
• Europe, Middle East, Africa,
and Asia Pacific: +800-AT
FIBREE (+800 28 34 27 33)
• For areas unable to access toll
free number: +1-408-333-6061
• Toll-free numbers are available
in many countries.
support@brocade.com
Please include:
• Problem summary
• Serial number
• Installation details
• Environment description
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Document feedback
Document feedback
To send feedback and report errors in the documentation you can use the feedback form posted with
the document or you can e-mail the documentation team.
Quality is our first concern at Brocade and we have made every effort to ensure the accuracy and
completeness of this document. However, if you find an error or an omission, or you think that a topic
needs further development, we want to hear from you. You can provide feedback in two ways:
• Through the online feedback form in the HTML documents posted on www.brocade.com.
• By sending your feedback to documentation@brocade.com.
Provide the publication title, part number, and as much detail as possible, including the topic heading
and page number if applicable, as well as your suggestions for improvement.
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About This Guide
● Introduction..................................................................................................................... 11
● What’s new in this document.......................................................................................... 11
● How command information is presented in this guide.....................................................12
Introduction
This guide includes procedures for configuring the software. The software procedures show how to
perform tasks using the CLI. This guide also describes how to monitor Brocade products using statistics
and summary screens.
Supported hardware
This guide supports the following product families from Brocade:
• FastIron X Series devices (chassis models):
‐ FastIron SX 800
‐ FastIron SX 1600
• Brocade FCX Series (FCX) Stackable Switch
• Brocade ICX™ 6610 (ICX 6610) Stackable Switch
• Brocade ICX 6430 Series (ICX 6430)
• Brocade ICX 6450 Series (ICX 6450)
• Brocade ICX 6650 Series (ICX 6650)
• Brocade ICX7750 Series (ICX7750)
NOTE
The Brocade ICX 6430-C switch supports the same feature set as the Brocade ICX 6430 switch unless
otherwise noted.
NOTE
The Brocade ICX 6450-C12-PD switch supports the same feature set as the Brocade ICX 6450 switch
unless otherwise noted.
What’s new in this document
Support is added for static mroute.
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How command information is presented in this guide
How command information is presented in this guide
For all new content, command syntax and parameters are documented in a separate command
reference section at the end of the publication.
In an effort to provide consistent command line interface (CLI) documentation for all products, Brocade
is in the process of preparing standalone Command References for the IP platforms. This process
involves separating command syntax and parameter descriptions from configuration tasks. Until this
process is completed, command information is presented in two ways:
• For all new content included in this guide, the CLI is documented in separate command pages.
The new command pages follow a standard format to present syntax, parameters, usage
guidelines, examples, and command history. Command pages are compiled in alphabetical order
in a separate command reference chapter at the end of the publication.
• Legacy content continues to include command syntax and parameter descriptions in the chapters
where the features are documented.
If you do not find command syntax information embedded in a configuration task, refer to the
command reference section at the end of this publication for information on CLI syntax and usage.
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IPv4 Multicast Traffic Reduction
● Supported IPv4 Multicast Traffic Reduction.................................................................... 13
● IGMP snooping overview................................................................................................ 13
● IGMP snooping configuration..........................................................................................17
● IGMP snooping show commands................................................................................... 26
● Clear commands for IGMP snooping.............................................................................. 34
● Disabling the flooding of unregistered IPv4 multicast frames in an IGMP-snooping-
enabled VLAN...............................................................................................................35
● PIM SM traffic snooping overview...................................................................................35
● PIM SM snooping configuration...................................................................................... 38
● PIM SM snooping show commands................................................................................39
Supported IPv4 Multicast Traffic Reduction
The following table lists the individual Brocade FastIron switches and the IPv4 multicast traffic reduction
features they support. These features are supported in the Layer 2 and Layer 3 software images,
except where explicitly noted.
Feature ICX 6430 ICX 6450 FCX ICX 6610 ICX 6650 FSX 800
FSX 1600
IGMP v1/v2/v3 snooping (global and
local)
IGMP fast leave for v2 08.0.01 08.0.01 08.0.01 08.0.01 08.0.01 08.0.01 08.0.10
IGMP membership tracking and fast
leave for v3
PIM-SM v2 Snooping 08.0.01 08.0.01 08.0.01 08.0.01 08.0.01 08.0.01 08.0.10
Static IGMP groups with support for
proxy
IGMP static group traffic filtering 08.0.01 08.0.01 08.0.01 08.0.01 08.0.01 No No
08.0.01 08.0.01 08.0.01 08.0.01 08.0.01 08.0.01 08.0.10
08.0.01 08.0.01 08.0.01 08.0.01 08.0.01 08.0.01 08.0.10
08.0.01 08.0.01 08.0.01 08.0.01 08.0.01 08.0.01 08.0.10
ICX 7750
IGMP snooping overview
When a device processes a multicast packet, by default, it broadcasts the packets to all ports except
the incoming port of a VLAN. Packets are flooded by hardware without going to the CPU. This behavior
causes some clients to receive unwanted traffic.
IGMP snooping provides multicast containment by forwarding traffic to only the ports that have IGMP
receivers for a specific multicast group (destination address). A device maintains the IGMP group
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Queriers and non-queriers
membership information by processing the IGMP reports and leave messages, so traffic can be
forwarded to ports receiving IGMP reports.
An IPv4 multicast address is a destination address in the range of 224.0.0.0 to 239.255.255.255.
Addresses of 224.0.0.X are reserved. Because packets destined for these addresses may require
VLAN flooding, devices do not snoop in the reserved range. Data packets destined to addresses in the
reserved range are flooded to the entire VLAN by hardware, and mirrored to the CPU. Multicast data
packets destined for the non-reserved range of addresses are snooped. A client must send IGMP
reports in order to receive traffic.
An IGMP device's responsibility is to broadcast general queries periodically, and to send group queries
when receiving a leave message, to confirm that none of the clients on the port still want specific traffic
before removing the traffic from the port. IGMP V2 lets clients specify what group (destination address)
will receive the traffic but not to specify the source of the traffic. IGMP V3 is for source-specific
multicast traffic, adding the capability for clients to INCLUDE or EXCLUDE specific traffic sources. An
IGMP V3 device port state could be INCLUDE or EXCLUDE, and there are different types of group
records for client reports.
The interfaces respond to general or group queries by sending a membership report that contains one
or more of the following records associated with a specific group:
• Current-state record that indicates from which sources the interface wants to receive and not
• Filter-mode-change record. If the interface state changes from IS_IN to IS_EX, a TO_EX record is
• An IGMP V2 leave report is equivalent to a TO_IN (empty) record in IGMP V3. This record means
• An IGMP V2 group report is equivalent to an IS_EX (empty) record in IGMP V3. This record
• Source-list-change record. If the interface wants to add or remove traffic sources from its
IGMP protocols provide a method for clients and a device to exchange messages, and let the device
build a database indicating which port wants what traffic. The protocols do not specify forwarding
methods. They require IGMP snooping or multicast protocols such as PIM to handle packet
forwarding. PIM can route multicast packets within and outside a VLAN, while IGMP snooping can
switch packets only within a VLAN.
If a VLAN is not IGMP snooping-enabled, it floods multicast data and control packets to the entire
VLAN in hardware. When snooping is enabled, IGMP packets are trapped to the CPU. Data packets
are mirrored to the CPU in addition to being VLAN flooded. The CPU then installs hardware resources,
so that subsequent data packets can be switched to desired ports in hardware without going to the
CPU. If there is no client report or port to queriers for a data stream, the hardware resource drops it.
receive traffic. This record contains the source address of interfaces and whether or not traffic will
be included (IS_IN) or not excluded (IS_EX) from this source.
included in the membership report. Likewise, if the interface state changes from IS_EX to IS_IN, a
TO_IN record appears in the membership report.
that no traffic from this group will be received regardless of the source.
means that all traffic from this group will be received regardless of source.
membership report, the report can contain an ALLOW record, which includes a list of new sources
from which the interface wishes to receive traffic. It can also contain a BLOCK record, which lists
the current traffic sources from which the interface wants to stop receiving traffic.
Queriers and non-queriers
An IGMP snooping-enabled Brocade device can be configured as a querier (active) or non-querier
(passive). An IGMP querier sends queries; a non-querier listens for IGMP queries and forwards them
to the entire VLAN. VLANs can be independently configured to be queriers or non-queriers. If a VLAN
has a connection to a PIM-enabled port on another router, the VLAN must be configured as a nonquerier. When multiple IGMP snooping devices are connected together, and there is no connection to
a PIM-enabled port, one of the devices must be configured as a querier. If multiple devices are
configured as queriers, after these devices exchange queries, then all except the winner stop sending
queries. The device with the lowest address becomes the querier. Although the system will work when
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VLAN-specific configuration
multiple devices are configured as queriers, Brocade recommends that only one device (preferably the
one with the traffic source) is configured as a querier.
The non-queriers always forward multicast data traffic and IGMP messages to router ports which
receive IGMP queries or PIM hellos. Brocade recommends that you configure the device with the data
traffic source (server) as a querier. If a server is attached to a non-querier, the non-querier always
forwards traffic to the querier regardless of whether there are any clients on the querier.
NOTE
In a topology of one or more connecting devices, at least one device must be running PIM configured as
active. Otherwise, none of the devices can send out queries, and traffic cannot be forwarded to clients.
VLAN-specific configuration
IGMP snooping can be enabled on some VLANs or on all VLANs. Each VLAN can be independently
configured to be a querier or non-querier and can be configured for IGMP V2 or IGMP V3. In general,
the ip multicast commands apply globally to all VLANs except those configured with VLAN-specific
multicast commands. The VLAN-specific multicast commands supersede the global ip multicast
commands.
IGMP snooping can be configured for IGMP V2 or IGMP V3 on individual ports of a VLAN. An interface
or router sends the queries and reports that include its IGMP version specified on it. The version
configuration only applies to sending queries. The snooping device recognizes and processes IGMP V2
and IGMP V3 packets regardless of the version configuration.
To avoid version deadlock, an interface retains its version configuration even when it receives a report
with a lower version.
Tracking and fast leave
Brocade devices support fast leave for IGMP V2, and tracking and fast leave for IGMP V3. Fast leave
stops the traffic immediately when the port receives a leave message. Tracking traces all IGMP V3
clients. Refer to Enabling IGMP V3 membership tracking and fast leave for the VLAN on page 24 and
Enabling fast leave for IGMP V2 on page 25.
Support for IGMP snooping and Layer 3 multicast routing together on the same device
The Brocade device supports global Layer 2 IP multicast traffic reduction (IGMP snoopoing) and Layer
3 multicast routing (PIM-Sparse or PIM-Dense) together on the same device in the full Layer 3 software
image, as long as the Layer 2 feature configuration is at the VLAN level.
Forwarding mechanism in hardware
IP-based forwarding implementation on FCX and ICX devices
The following information about *,G or S,G fdb-based implementation is specific to FCX, ICX 6610, ICX
6430, and ICX 6450 devices.
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MAC-based forwarding implementation on FastIron X Series devices
On both switch and router software images, IGMP snooping is either *,G based or S,G based. The
hardware can either match the group address only (* G), or both the source and group (S, G) of the
data stream. This is 32-bit IP address matching, not 23-bit multicast MAC address 01-00-5e-xx-xx-xx
matching.
When any port in a VLAN is configured for IGMP v3, the VLAN matches both source and group (S, G)
in hardware switching. If no ports are configured for IGMP v3, the VLAN matches group only (* G).
Matching (S, G) requires more hardware resources than matching (* G) when there are multiple
servers sharing the same group. For example, two data streams from different sources to the same
group require two (S, G) entries in IGMP v3, but only one (* G) entry in IGMP v2.
To conserve resources, IGMP v3 must be used only in source-specific applications. When VLANs are
independently configured for versions, some VLANs can match (* G) while others match (S, G).
MAC-based forwarding implementation on FastIron X Series devices
On both switch and router software images, IGMP snooping is MAC-based. This differs from IGMP
snooping on the BigIron router images, which match on both IP source and group (S,G) entries
programmed in the Layer 4 CAM.
This differs from IGMP snooping on the FastIron FCX/ICX router images, which match on both IP
source and group (S,G) entries. In contrast, the FastIron X Series images match on Layer 2 23-bit
multicast MAC address i.e. 01-00-5e-xx-xx-xx (*,G) entries.
In addition, the lowest 23 bits of the group address are mapped to a MAC address. In this way,
multiple groups (for example, 224.1.1.1 and 225.1.1.1) have the same MAC address. Groups having
the same MAC address are switched to the same destination ports, which are the superset of
individual group output ports. Thus, the use of Layer 2 CAM might cause unwanted packets to be sent
to some ports. However, the switch generally needs far less layer 2 mac entries than it does for IPbased forwarding, which is required for each stream with a different source and group.
Hardware resources for IGMP and PIM-SM snooping
Brocade devices allocate/program fdb/mac entries and application VLAN (vidx) to achieve multicast
snooping in hardware. If a data packet does not match any of these resources, it might be sent to the
CPU, which increases the CPU burden. This can happen if the device runs out of hardware resources,
or is unable to install resources for a specific matching address due to a hashing collision.
The hardware hashes addresses into available fdb/mac entries, with some addresses hashed into the
same entry. If the collision number in an entry is more than the hardware chain length, the resource
cannot be installed.
Configuration notes and feature limitations for IGMP snooping and Layer 3 multicast routing
The following notes apply to all devices:
• Layer 2 IGMP multicast is automatically enabled with Layer 3 multicast routing. If Layer 3
multicast routing is enabled on your system, do not attempt to enable Layer 2 IGMP snooping.
• The default IGMP version is V2.
• A user can configure the maximum numbers of group address entries.
• An IGMP device can be configured to rate-limit the forwarding IGMP V2 membership reports to
queriers.
• The device supports static groups. The device acts as a proxy to send IGMP reports for the static
groups when receiving queries.
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IGMP snooping configuration
• A user can configure static router ports to force all multicast traffic to these specific ports.
• If a VLAN has a connection to a PIM-enabled port on another router, the VLAN must be configured
as a non-querier (passive). When multiple snooping devices connect together and there is no
connection to PIM ports, one device must be configured as a querier (active). If multiple devices
are configured as active (queriers), only one will keep sending queries after exchanging queries.
• The querier must configure an IP address to send out queries.
• IGMP snooping requires hardware resource. Hardware resource is installed only when there is data
traffic. If resource is inadequate, the data stream without a resource is mirrored to the CPU in
addition to being VLAN flooded, which can cause high CPU usage. Brocade recommends that you
avoid global enabling of snooping unless necessary.
• IGMP snooping requires clients to send membership reports in order to receive data traffic. If a
client application does not send reports, you must configure static groups on the snooping VLAN to
force traffic to client ports. Note that servers (traffic sources) are not required to send IGMP
memberships.
• Support for VSRP together with IGMP snooping on the same interface.
• When VSRP or VSRP-aware is configured on a VLAN, only IGMP version 2 is recommended;
IGMP version 3 is not recommended.
• Each VLAN can independently enable or disable IGMP, or configure IGMP v2 or IGMP v3.
• IGMP/PIM-SM snooping over Multi-Chassis Trunking is supported on ICX 6650, ICX 7750, and X
series devices.
The following details apply to FCX, ICX 6610, ICX 6430, ICX 6450, and ICX 6650 devices:
• Using the drop option, you can configure a static group that can discard multicast data packets to a
specified group in hardware, including addresses in the reserved range.
The following details apply to FastIron X Series devices:
• High CPU utilization occurs when IGMP Snooping and PIM routing are enabled simultaneously,
and if the ingressing VLAN of the snooping traffic has "router-interface" configuration. With this
configuration, IP Multicast data packets received in the snooping VLANs are forwarded to client
ports via the hardware; however, copies of these packets are received and dropped by the CPU.
IGMP snooping configuration
Configuring IGMP snooping on a Brocade device consists of the following global, VLAN-specific, and
port-specific tasks:
Perform the following global IGMP snooping tasks:
• Configuring the IGMP V3 snooping software resource limits
• Enabling IGMP snooping globally on the device
• Configuring the global IGMP mode
• Configuring the global IGMP version
• Modifying the age interval for group membership entries
• Modifying the query interval (active IGMP snooping mode only)
• Modifying the maximum response time
• Configuring report control (rate limiting)
• Modifying the wait time before stopping traffic when receiving a leave message
• Modifying the multicast cache age time
• Enabling or disabling error and warning messages
Perform the following VLAN-specific IGMP snooping tasks:
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IGMP snooping mcache entries and group addresses
• Configuring the IGMP mode for a VLAN (active or passive)
• Disabling IGMP snooping on a VLAN
• Configuring the IGMP version for a VLAN
• Configuring static router ports
• Turning off static group proxy
• Enabling IGMP V3 membership tracking and fast leave for the VLAN
• Enabling fast leave for IGMP
• Enabling fast convergence
Perform the following port-specific IGMP snooping task:
• Configuring the IGMP version for individual ports in a VLAN
IGMP snooping mcache entries and group addresses
An IGMP snooping group address entry is created when an IGMP join message is received for a
group. An IGMP snooping mcache entry is created when data traffic is received for that group. Each
mcache entry represents one data stream, and multiple mcache entries (up to 32) can share the same
hardware (MAC) address entry. The egress port list for the mcache entry is obtained from the IGMP
group address entry. If there is no existing IGMP group address entry when an mcache entry is
created, data traffic for that multicast group is dropped in hardware. If there is an existing IGMP group
address entry when an mcache is created, data traffic for that multicast group is switched in hardware.
The following describes the IGMP snooping software resource limits for Brocade devices:
• FCX, FSX, ICX 6610, and ICX 6450 devices support up to a maximum of 8192 IGMP snooping
multicast cache (mcache) entries and a maximum of 8192 IGMP group addresses.
• ICX 6430 devices support up to 2048 IGMP snooping multicast cache (mcache) entries and a
maximum of 4096 IGMP group addresses.
• ICX 6650 devices support 8192 IGMP snooping mcache entries and 8192 IGMP groups
addresses.
• ICX 7750 switches support 8192 IGMP snooping mcache entries and 8192 IGMP group
addresses.
• ICX 7750 routers support 6K IGMP snooping mcache entries and 8192 IGMP group addresses.
The default for IGMP snooping mcache entries is 512, with the exception of ICX 6430 devices where
the default is 256.
Changing the maximum number of supported IGMP snooping mcache entries
You can configure the system-max igmp-snoop-mcache command to change the maximum number
of IGMP snooping cache entries supported on a device.
Device(config)#system-max igmp-snoop-mcache 2000
Syntax: [no] system-max igmp-snoop-mcache num
The num variable is a value from 256 through 8192. The default is 512.
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Setting the maximum number of IGMP group addresses
Setting the maximum number of IGMP group addresses
The configured number of IGMP group addresses is the upper limit of an expandable database. Client
memberships exceeding the group limit are not processed. Configure the system-max igmp-snoop-
group-addr command to define the maximum number of IGMP group addresses.
Device(config)#system-max igmp-snoop-group-addr 1600
Syntax: [no] system-max igmp-snoop-group-addr num
The num variable is a value from 256 to 8192. The default for IGMP snooping group addresses is 4096,
except for ICX 6430 devices where the default is 1024.
Enabling IGMP snooping globally on the device
When you globally enable IGMP snooping, you can specify IGMP V2 or IGMP V3. The ip multicast
version command enables IGMP V3.
device(config)#ip multicast version 3
Syntax: [no] ip multicast version [2 | 3]
If you do not specify a version number, IGMP V2 is assumed.
Configuration notes for Layer 3 devices
• If Layer 3 multicast routing is enabled on your system, do not attempt to enable Layer 2 IGMP
snooping. Layer 2 IGMP snooping is automatically enabled with Layer 3 multicast routing.
• If the "route-only" feature is enabled on the Layer 3 Switch, then IP multicast traffic reduction will
not be supported.
• IGMP snooping is not supported on the default VLAN of Layer 3 Switches.
Configuring the IGMP mode
You can configure active or passive IGMP modes on the Brocade device. The default mode is passive.
If you specify an IGMP mode for a VLAN, it overrides the global setting.
• Active - When active IGMP mode is enabled, a Brocade device actively sends out IGMP queries to
identify multicast groups on the network, and makes entries in the IGMP table based on the group
membership reports it receives.
NOTE
Routers in the network generally handle this operation. Use the active IGMP mode only when the
device is in a stand-alone Layer 2 Switched network with no external IP multicast router attachments. In
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Configuring the global IGMP mode
this case, enable the active IGMP mode on only one of the devices and leave the other devices
configured for passive IGMP mode.
• Passive - When passive IGMP mode is enabled, it forwards reports to the router ports which
receive queries. IGMP snooping in the passive mode does not send queries. However, it forwards
queries to the entire VLAN.
Configuring the global IGMP mode
To globally set the IGMP mode to active, enter the following command.
device(config)#ip multicast active
Syntax: [no] ip multicast [ active | passive ]
If you do not enter either active or passive, the passive mode is assumed.
Configuring the IGMP mode for a VLAN
If you specify an IGMP mode for a VLAN, it overrides the global setting.
To set the IGMP mode for VLAN 20 to active, enter the following commands.
device(config)#vlan 20
device(config-vlan-20)#multicast active
Syntax: [no] multicast [ active | passive]
Configuring the IGMP version
Use the procedures in this section to specify the IGMP version.
Configuring the global IGMP version
To globally specify IGMP V2 or IGMP V3, refer to Enabling IGMP snooping globally on the device on
page 19.
Configuring the IGMP version for a VLAN
You can specify the IGMP version for a VLAN. For example, the following commands configure VLAN
20 to use IGMP V3.
device(config)#vlan 20
device(config-vlan-20)#multicast version 3
Syntax: [no] multicast version [2 | 3 ]
If no IGMP version is specified, then the globally-configured IGMP version is used. If an IGMP version
is specified for individual ports, those ports use that version, instead of the VLAN version.
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Configuring the IGMP version for individual ports in a VLAN
Configuring the IGMP version for individual ports in a VLAN
You can specify the IGMP version for individual ports in a VLAN. For example, the following commands
configure ports 4, 5, and 6 to use IGMP V3. The other ports either use the IGMP version specified with
the multicast version command, or the globally-configured IGMP version.
device(config)#vlan 20
device(config-vlan-20)#multicast port-version 3 ethernet 2/4 to 2/6
Syntax: [no] multicast port-version [2 | 3 ] ethernetport [ethernet port | toport ]
To specify a list of ports, enter each port as ethernetport followed by a space. For example, ethernet
1/24 ethernet 6/24 ethernet 8/17.
To specify a range of ports, enter the first port in the range as ethernetport followed by the last port in
the range. For example, ethernet 1/1 to 1/8 .
You can combine lists and ranges in the same command. For example: enable ethernet 1/1 to 1/8
ethernet 1/24 ethernet 6/24 ethernet 8/17.
Configuring static groups to specific ports
A snooping-enabled VLAN cannot forward multicast traffic to ports that do not receive IGMP
membership reports. If clients cannot send reports, you can configure a static group which applies to
specific ports. The static group allows packets to be forwarded to the static group ports even though
they have no client membership reports.
device(config)#vlan 20
device(config-vlan-20)#multicast static-group 224.1.1.1 count 2 ethernet 0/1/3
ethernet 0/1/5 to 0/1/7
Information specific to FCX and ICX devices
The following information about the drop option is specific to FCX, ICX 6610, ICX 6430, ICX 6450, and
ICX 6650 devices.
The static group drop option discards data traffic to a group in hardware. The group can be any
multicast group including groups in the reserved range of 224.0.0.X. The drop option does not apply to
IGMP packets, which are always trapped to CPU when snooping is enabled. The drop option applies to
the entire VLAN, and cannot be configured for a port list. When the drop option is not specified, the
group must exist outside the reserved range.
device(config-vlan-20)#multicast static-group 239.1.1.1 count 3 drop
Syntax: [no] multicast static-group ipv4-address [count num] [port-numbers | drop]
The ipv4-address parameter is the address of the multicast group.
The count is optional, which allows a contiguous range of groups. Omitting the count num is equivalent
to the count being 1.
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Disabling IGMP snooping on a VLAN
Disabling IGMP snooping on a VLAN
When IGMP snooping is enabled globally, you can still disable it for a specific VLAN. For example, the
following commands cause IGMP snooping to be disabled for VLAN 20. This setting overrides the
global setting.
device(config)#vlan 20
device(config-vlan-20)#multicast disable-multicast-snoop
Syntax: [no] multicast disable-multicast-snoop
Modifying the age interval for group membership entries
When the device receives a group membership report, it makes an entry for that group in the IGMP
group table. The age interval specifies how long the entry can remain in the table before the device
receives another group membership report. When multiple devices connect together, all devices must
be configured for the same age interval, which must be at least twice the length of the query interval,
so that missing one report won't stop traffic. Non-querier age intervals must be the same as the age
interval of the querier.
To modify the age interval, enter the following command.
device(config)#ip multicast age-interval 280
Syntax: [no] ip multicast age-interval interval
The interval parameter specifies the aging time. You can specify a value from 20 through 26000
seconds. The default is 260 seconds.
Modifying the query interval (active IGMP snooping mode only)
If IP multicast traffic reduction is set to active mode, you can modify the query interval to specify how
often the device sends general queries. When multiple queriers connect together, they must all be
configured with the same query interval.
To modify the query interval, enter the following command.
device(config)#ip multicast query-interval 120
Syntax: [no] ip multicast query-intervalinterval
The interval parameter specifies the time between queries. You can specify a value from 10 through
3600 seconds. The default is 125 seconds.
Modifying the maximum response time
The maximum response time is the number of seconds that a client can wait before responding to a
query sent by the switch.
To change the maximum response time, enter the following command.
device(config)#ip multicast max-response-time 5
Syntax: [no] ip multicast max-response-time interval
For interval , enter a value from 1 through 10 seconds. The default is 10 seconds.
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Configuring report control
Configuring report control
A device in passive mode forwards reports and leave messages from clients to the upstream router
ports that are receiving queries.
You can configure report control to rate-limit report forwarding within the same group to no more than
once every 10 seconds. This rate-limiting does not apply to the first report answering a group-specific
query.
NOTE
This feature applies to IGMP V2 only. The leave messages are not rate limited.
IGMP V2 membership reports of the same group from different clients are considered to be the same
and are rate-limited.
Use the ip multicast report-control command to alleviate report storms from many clients answering
the upstream router query.
device(config)#ip multicast report-control
Syntax: [no] ip multicast-report-control
The original command, ip igmp-report-control , has been renamed to ip multicast report-control .
The original command is still accepted; however, it is renamed when you configure a show
configuration command.
Modifying the wait time before stopping traffic when receiving a leave message
You can define the wait time before stopping traffic to a port when a leave message is received. The
device sends group-specific queries once per second to ask if any client in the same port still needs this
group. Due to internal timer granularity, the actual wait time is between n and (n+1) seconds (n is the
configured value).
device(config)#ip multicast leave-wait-time 1
Syntax: [no] ip multicast leave-wait-timenum
num is the number of seconds from 1 through 5. The default is 2 seconds.
Modifying the multicast cache age time
You can set the time for an mcache to age out when it does not receive traffic. The traffic is hardware
switched. One minute before aging out an mcache, the device mirrors a packet of this mcache to CPU
to reset the age. If no data traffic arrives within one minute, this mcache is deleted. A lower value
quickly removes resources consumed by idle streams, but it mirrors packets to CPU often. A higher
value is recommended only data streams are continually arriving.
device(config)#ip multicast mcache-age 180
Syntax: [no] ip multicast mcache-age num
num is the number of seconds from 60 through 3600. The default is 60 seconds.
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Enabling or disabling error and warning messages
Enabling or disabling error and warning messages
The device prints error or warning messages when it runs out of software resources or when it
receives packets with the wrong checksum or groups. These messages are rate-limited. You can turn
off these messages by entering the following command.
device(config)#ip multicast verbose-off
Syntax: [no] ip multicast verbose-off
Configuring static router ports
The Brocade device forwards all multicast control and data packets to router ports which receive
queries. Although router ports are learned, you can force multicast traffic to specified ports even
though these ports never receive queries. To configure static router ports, enter the following
commands.
device(config)#vlan 70
device(config-vlan-70)#multicast router-port ethernet 4 to 5 ethernet 8
Syntax: [no] multicast router-port ethernet port [ethernet port | to port]
To specify a list of ports, enter each port as ethernetport followed by a space. For example, ethernet
1/24 ethernet 6/24 ethernet 8/17.
To specify a range of ports, enter the first port in the range as ethernetport followed by the last port in
the range. For example, ethernet 1/1 to 1/8 .
You can combine lists and ranges in the same command. For example: enable ethernet 1/1 to 1/8
ethernet 1/24 ethernet 6/24 ethernet 8/17.
Turning off static group proxy
If a device has been configured for static groups, it acts as a proxy and sends membership reports for
the static groups when it receives general or group-specific queries. When a static group configuration
is removed, it is deleted from the active group table immediately. However, leave messages are not
sent to the querier, and the querier must age out the group. Proxy activity can be turned off. The
default is on. To turn proxy activity off for VLAN 20, enter the following commands.
device(config)#vlan 20
device(config-vlan-20)#multicast proxy-off
Syntax: [no] multicast proxy-off
Enabling IGMP V3 membership tracking and fast leave for the VLAN
IGMP V3 gives clients membership tracking and fast leave capability. In IGMP V2, only one client on
an interface needs to respond to a router's queries. This can leave some clients invisible to the router,
making it impossible to track the membership of all clients in a group. When a client leaves the group,
the device sends group-specific queries to the interface to see if other clients on that interface need
the data stream of the client who is leaving. If no client responds, the device waits a few seconds
before it stops the traffic. You can configure the wait time using the ip multicast leave-wait-time
command.
IGMP V3 requires every client to respond to queries, allowing the device to track all clients. When
tracking is enabled, and an IGMP V3 client sends a leave message and there is no other client, the
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Enabling fast leave for IGMP V2
device immediately stops forwarding traffic to the interface. This feature requires the entire VLAN be
configured for IGMP V3 with no IGMP V2 clients. If a client does not send a report during the specified
group membership time (the default is 260 seconds), that client is removed from the tracking list.
Every group on a physical port keeps its own tracking record. However, it can only track group
membership; it cannot track by (source, group). For example, Client A and Client B belong to group1
but each receives traffic streams from different sources. Client A receives a stream from (source_1,
group1) and Client B receives a stream from (source_2, group1). The device still waits for the
configured leave-wait-time before it stops the traffic because these two clients are in the same group. If
the clients are in different groups, then the waiting period is not applied and traffic is stopped
immediately.
To enable the tracking and fast leave feature for VLAN 20, enter the following commands.
device(config)#vlan 20
device(config-vlan-20)#multicast tracking
Syntax: [no] multicast tracking
The membership tracking and fast leave features are supported for IGMP V3 only. If any port or any
client is not configured for IGMP V3, then the multicast tracking command is ignored.
Enabling fast leave for IGMP V2
When a device receives an IGMP V2 leave message, it sends out multiple group-specific queries. If no
other client replies within the waiting period, the device stops forwarding traffic. When fast-leave-v2 is
configured, and when the device receives a leave message, it immediately stops forwarding to that port.
The device does not send group specific-queries. When fast-leave-v2 is configured on a VLAN, you
must not have multiple clients on any port that is part of the VLAN. In a scenario where two devices
connect, the querier device should not be configured for fast-leave-v2 because the port might have
multiple clients through the non-querier. The number of queries, and the waiting period (in seconds) can
be configured using the ip multicast leave-wait-time command. The default is 2 seconds.
To configure fast leave for IGMP V2, enter the following commands.
device(config)#vlan 20
device(config-vlan-20)#multicast fast-leave-v2
Syntax: [no] multicast fast-leave-v2
Enabling fast convergence
In addition to sending periodic general queries, an active device sends general queries when it detects
a new port. However, because the device does not recognize the other device's port up event, multicast
traffic might still require up to the query-interval time to resume after a topology change. Fast
convergence allows the device to listen to topology change events in Layer 2 protocols such as
spanning tree, and then send general queries to shorten the convergence time.
If the Layer 2 protocol cannot detect a topology change, fast convergence may not work in some cases.
For example, if the direct connection between two devices switches from one interface to another, the
rapid spanning tree protocol (802.1w) considers this optimization, rather than a topology change. In this
example, other devices will not receive topology change notifications, and will be unable to send queries
to speed up the convergence. Fast convergence works well with the regular spanning tree protocol in
this case.
To enable fast-convergency, enter the following commands.
device(config)#vlan 70
device(config-vlan-70)#multicast fast-convergence
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IGMP snooping show commands
Syntax: multicast fast-convergence
IGMP snooping show commands
This section describes the show commands for IGMP snooping.
Displaying the IGMP snooping configuration
To display the global IGMP snooping configuration, enter the show ip multicast command at any
level of the CLI.
device#show ip multicast
Summary of all vlans. Please use "sh ip mu vlan vlan-id" for details
Version=2, Intervals: Query=125, Group Age=260, Max Resp=10, Other Qr=260
VL10: cfg V3, vlan cfg passive, , pimsm (vlan cfg), 1 grp, 0 (SG) cache, no rtr port
To display the IGMP snooping information for a specific VLAN, enter the following command.
device#show ip multicast vlan 10
Version=3, Intervals: Query=10, Group Age=260, Max Resp=10, Other Qr=30
VL10: cfg V3, vlan cfg passive, , pimsm (vlan cfg), 3 grp, 1 (SG) cache, no rtr port,
e2 has 3 groups, non-QR (passive), default V3
**** Warning! has V2 client (life=240),
group: 239.0.0.3, life = 240
group: 224.1.1.2, life = 240
group: 224.1.1.1, life = 240
e4 has 0 groups, non-QR (passive), default V3
Syntax: show ip multicast vlan vlan-id
If you do not specify a vlan-id , information for all VLANs is displayed.
The following table describes the information displayed by the show ip multicast vlan command.
Field Description
Version The global IGMP version. In this example, the device is configured for IGMP version 2.
Query How often a querier sends a general query on the interface. In this example, the general queries are
sent every 125 seconds.
Group Age The number of seconds membership groups can be members of this group before aging out.
Max Resp The maximum number of seconds a client waits before replying to a query.
Other Qr How long it took a switch with a lower IP address to become a new querier. This value is 2 x Query +
Max Resp.
cfg The IGMP version for the specified VLAN. In this example, VL10: cfg V3 indicates that VLAN 10 is
configured for IGMP V3.
vlan cfg The IGMP configuration mode, which is either passive or active.
pimsm Indicates that PIM SM is enabled on the VLAN.
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Displaying IGMP snooping errors
Field Description
rtr port The router ports, which are the ports receiving queries.
Displaying IGMP snooping errors
To display information about possible IGMP errors, enter the show ip multicast error command.
device#show ip multicast error
snoop SW processed pkt: 173, up-time 160 sec
Syntax: show ip multicast error
The following table describes the output from the show ip multicast error command.
Field Description
SW processed pkt The number of multicast packets processed by IGMP snooping.
up-time The time since the IGMP snooping is enabled.
Displaying IGMP group information
To display default, maximum, current, and configured values for system maximum parameters, use the
show default values command. The following output example does not show complete output; it
shows only IGMP group values.
device(config)#show default values
System Parameters Default Maximum Current Configured
igmp-snoop-group-add 4096 8192 5000 5000
To display information about IGMP groups, enter the show ip multicast group command.
device#show ip multicast group
p-:physical, ST:static, QR:querier, EX:exclude, IN:include, Y:yes, N:no
VL70 : 3 groups, 4 group-port, tracking_enabled
group p-port ST QR life mode source
1 224.1.1.2 1/33 no yes 120 EX 0
2 224.1.1.1 1/33 no yes 120 EX 0
3 226.1.1.1 1/35 yes yes 100 EX 0
4 226.1.1.1 1/33 yes yes 100 EX 0
In this example, an IGMP V2 group is in EXCLUDE mode with a source of 0. The group only excludes
traffic from the 0 (zero) source list, which actually means that all traffic sources are included.
To display detailed IGMP group information for a specific group, enter the show ip multicast group
detail command.
device#show ip multicast group 226.1.1.1 detail
Display group 226.1.1.1 in all interfaces in details.
p-:physical, ST:static, QR:querier, EX:exclude, IN:include, Y:yes, N:no
VL70 : 1 groups, 2 group-port, tracking_enabled
group p-port ST QR life mode source
1 226.1.1.1 1/35 yes yes 120 EX 0
group: 226.1.1.1, EX, permit 0 (source, life):
life=120, deny 0:
group p-port ST QR life mode source
2 226.1.1.1 1/33 yes yes 120 EX 0
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Displaying IGMP snooping mcache information
group: 226.1.1.1, EX, permit 0 (source, life):
life=120, deny 0:
If the tracking and fast leave features are enabled, you can display the list of clients that belong to a
particular group by entering the following command.
device#show ip multicast group 224.1.1.1 tracking
Display group 224.1.1.1 in all interfaces with tracking enabled.
p-:physical, ST:static, QR:querier, EX:exclude, IN:include, Y:yes, N:no
VL70 : 1 groups, 1 group-port, tracking_enabled
group p-port ST QR life mode source
*** Note: has 1 static groups to the entire vlan, not displayed here
1 224.1.1.1 1/33 no yes 100 EX 0
receive reports from 1 clients: (age)
(10.2.100.2 60)
Syntax: show ip multicast group [group-address [detail] [tracking]]
If you want a report for a specific multicast group, enter that group's address for group-address .
Enter detail to display the source list of a specific VLAN.
Enter tracking for information on interfaces that have tracking enabled.
The following table describes the information displayed by the show ip multicast group command.
Field Description
group The address of the group (destination address in this case, 224.1.1.1)
p-port The physical port on which the group membership was received.
ST Yes indicates that the IGMP group was configured as a static group; No means the address was learned
from reports.
QR Yes means the port is a querier port; No means it is not. A port becomes a non-querier port when it
receives a query from a source with a lower source IP address than the device.
life The number of seconds the group can remain in EXCLUDE mode. An EXCLUDE mode changes to
INCLUDE mode if it does not receive an "IS_EX" or "TO_EX" message during a certain period of time.
The default is 260 seconds. There is no life displayed in INCLUDE mode.
mode Indicates current mode of the interface: INCLUDE or EXCLUDE. If the interface is in INCLUDE mode, it
admits traffic only from the source list. If an interface is in EXCLUDE mode, it denies traffic from the
source list and accepts the rest.
source Identifies the source list that will be included or excluded on the interface.
For example, if an IGMP V2 group is in EXCLUDE mode with a source of 0, the group excludes traffic
from the 0 (zero) source list, which actually means that all traffic sources are included.
Displaying IGMP snooping mcache information
To display default, maximum, current, and configured values for system maximum parameters, use
the show default values command. The following output example does not show complete output; it
shows only IGMP mcache values.
device(config)#show default values
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