Cisco Nexus 7000 Series NX-OS Multicast Routing Configuration Guide
Configuring IGMP Snooping
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Configuring IGMP Snooping

Configuring IGMP Snooping

This chapter describes how to configure Internet Group Management Protocol (IGMP) snooping on a Cisco NX-OS device.

Information About IGMP Snooping


Note


We recommend that you do not disable IGPM snooping on the device. If you disable IGMP snooping, you might see reduced multicast performance because of excessive false flooding within the device.


IGMP snooping software examines Layer 2 IP multicast traffic within a VLAN to discover the ports where interested receivers reside. Using the port information, IGMP snooping can reduce bandwidth consumption in a multiaccess LAN environment to avoid flooding the entire VLAN. IGMP snooping tracks which ports are attached to multicast-capable routers to help the routers forward IGMP membership reports. The IGMP snooping software responds to topology change notifications. By default, IGMP snooping is enabled on the device.

This figure shows an IGMP snooping switch that sits between the host and the IGMP router. The IGMP snooping switch snoops the IGMP membership reports and leave messages and forwards them only when necessary to the connected IGMP routers.

Figure 1. IGMP Snooping Switch

The IGMP snooping software operates upon IGMPv1, IGMPv2, and IGMPv3 control plane packets where Layer 3 control plane packets are intercepted and influence the Layer 2 forwarding behavior.

For more information about IGMP, see Configuring IGMP.

The Cisco NX-OS IGMP snooping software has the following proprietary features:

  • Source filtering that allows forwarding of multicast packets based on destination and source IP.
  • Multicast forwarding based on IP addresses rather than MAC addresses.
  • Beginning with Cisco Release 5.2(1) for the Nexus 7000 Series devices, multicast forwarding alternately based on the MAC address
  • Optimized multicast flooding (OMF) that forwards unknown traffic to routers only and performs no data-driven state creation.

For more information about IGMP snooping, see RFC 4541.

IGMPv1 and IGMPv2

Both IGMPv1 and IGMPv2 support membership report suppression, which means that if two hosts on the same subnet want to receive multicast data for the same group, then the host that receives a member report from the other host suppresses sending its report. Membership report suppression occurs for hosts that share a port.

If no more than one host is attached to each VLAN switch port, you can configure the fast leave feature in IGMPv2. The fast leave feature does not send last member query messages to hosts. As soon as the software receives an IGMP leave message, the software stops forwarding multicast data to that port.

IGMPv1 does not provide an explicit IGMP leave message, so the software must rely on the membership message timeout to indicate that no hosts remain that want to receive multicast data for a particular group.


Note


The software ignores the configuration of the last member query interval when you enable the fast leave feature because it does not check for remaining hosts.


IGMPv3

The IGMPv3 snooping implementation on Cisco NX-OS supports full IGMPv3 snooping, which provides constrained flooding based on the (S, G) information in the IGMPv3 reports. This source-based filtering enables the device to constrain multicast traffic to a set of ports based on the source that sends traffic to the multicast group.

By default, the software tracks hosts on each VLAN port. The explicit tracking feature provides a fast leave mechanism. Because every IGMPv3 host sends membership reports, report suppression limits the amount of traffic that the device sends to other multicast-capable routers. When report suppression is enabled, and no IGMPv1 or IGMPv2 hosts requested the same group, the software provides proxy reporting. The proxy feature builds the group state from membership reports from the downstream hosts and generates membership reports in response to queries from upstream queriers.

Even though the IGMPv3 membership reports provide a full accounting of group members on a LAN segment, when the last host leaves, the software sends a membership query. You can configure the parameter last member query interval. If no host responds before the timeout, the software removes the group state.

IGMP Snooping Querier

When PIM is not enabled on an interface because the multicast traffic does not need to be routed, you must configure an IGMP snooping querier to send membership queries. You define the querier in a VLAN that contains multicast sources and receivers but no other active querier.

The querier can be configured to use any IP address in the VLAN.

As a best practice, a unique IP address, one that is not already used by the switch interface or the HSRP VIP, should be configured so as to easily reference the querier.


Note


The IP address for the querier should not be a broadcast IP, multicast IP, or 0(0.0.0.0).


When an IGMP snooping querier is enabled, it sends out periodic IGMP queries that trigger IGMP report messages from hosts that want to receive IP multicast traffic. IGMP snooping listens to these IGMP reports to establish appropriate forwarding.

The IGMP snooping querier performs querier election as described in RFC 2236. A querier election occurs in the following configurations:

  • When there are multiple switch queriers configured with the same subnet on the same VLAN on different switches.
  • When the configured switch querier is in the same subnet as with other Layer 3 SVI queriers.

Static Multicast MAC Address

Beginning with the Cisco Release 5.2(1) for the Nexus 7000 Series devices, you configure an outgoing interface statically for a multicast MAC address. Also, you can configure the IGMP snooping to use a MAC-based lookup mode.

Previously, the system performs the lookup on a Layer 2 multicast table using the destination IP address rather than the destination MAC address. However, some applications share a single unicast cluster IP and multicast cluster MAC address. The system forwards traffic destined to the unicast cluster IP address by the last-hop router with the shared multicast MAC address. This action can be accomplished by assigning a static multicast MAC address for the destination IP address for the end host or cluster.

The default lookup mode remains IP, but you can configure the lookup type to MAC address-based. You can configure the lookup mode globally or per VLAN:

  • If the VDC contains ports from only an M-Series module and the global lookup mode is set to IP, VLANs can be set to either one of the two lookup modes. But, if the global lookup mode is set to a MAC address, the operational lookup mode for all the VLANs changes to MAC-address mode.
  • If the VDC contains ports from both an M-Series module and an F-Series module and if you change the lookup mode to a MAC address in any VLAN, the operation lookup mode changes for all of the VLANs to a MAC-address based. With these modules in the chassis, you have the same lookup mode globally and for the VLANs. Similarly, if the global lookup mode is MAC-address based, the operational lookup mode for all VLAN is also MAC-address based.

    Note


    Changing the lookup mode is disruptive. Multicast forwarding is not optimal until all multicast entries are programmed with the new lookup mode. Also, when 32 IP addresses are mapped to a single MAC address, you might see suboptimal forwarding on the device.


IGMP Snooping with VDCs and VRFs

A virtual device context (VDC) is a logical representation of a set of system resources. Within each VDC, you can define multiple virtual routing and forwarding (VRF) instances. One IGMP process can run per VDC. The IGMP process supports all VRFs in that VDC and performs the function of IGMP snooping within that VDC.

You can use the show commands with a VRF argument to provide a context for the information displayed. The default VRF is used if no VRF argument is supplied.

For information about configuring VDCs, see the Cisco Nexus 7000 Series NX-OS Virtual Device Context Configuration Guide.

For information about configuring VRFs, see the Cisco Nexus 7000 Series NX-OS Unicast Routing Configuration Guide.

IGMP Snooping across VPLS Domains

Beginning with Cisco Release 6.2(2) for the Nexus 7000 Series devices, IGMP snooping can be configured across Virtual Private LAN Service (VPLS) domains. The IGMP Snooping across VPLS Domains feature enables snooping of the IGMP packets on the pseudowire and on the Layer 2 side of the network for optimal delivery of the multicast packets.

A pseudowire is a point-to-point connection between pairs of Provider Edge (PE) devices. A pseudowire emulates services like Ethernet over an underlying core multiprotocol label switching (MPLS) network through encapsulation into a common MPLS format. A pseudowire allows carriers to converge their services to an MPLS network by encapsulating services into a common MPLS format.

By snooping IGMP packets received on a link, the device sends multicast packets only to interested end points. Once an IGMP packet going over the Layer 2 link is snooped, it is passed to the control plane. The control plane will add the link on which it was received to the multicast group. The IGMP packets coming on the pseudowire are also snooped and sent to the control plane. The control plane then adds the pseudowire to the multicast group. When a multicast packet is received, it will be sent only to the multicast group instead of flooding the VLAN.

Licensing Requirements for IGMP Snooping

Product

License Requirement

Cisco NX-OS

IGMP snooping requires no license. Any feature not included in a license package is bundled with the Cisco NX-OS system images and is provided at no extra charge to you. For a complete explanation of the Cisco NX-OS licensing scheme, see Cisco NX-OS Licensing Guide.

Prerequisites for IGMP Snooping

IGMP snooping has the following prerequisites:

  • You are logged onto the device.
  • You are in the correct virtual device context (VDC). A VDC is a logical representation of a set of system resources. You can use the switchto vdc command with a VDC number.
  • For global commands, you are in the correct virtual routing and forwarding (VRF) mode. The default configuration mode shown in the examples in this chapter applies to the default VRF.

Guidelines and Limitations for IGMP Snooping

IGMP snooping has the following guidelines and limitations:

  • You must disable IGMP optimized multicast flooding (OMF) for IPv6 multicast networks that require multicast forwarding over a layer 2 network.
  • You must disable IGMP optimized multicast forwarding on VLANs that require forwarding of IPv6 packets.
  • If you are configuring vPC peers, the differences in the IGMP snooping configuration options between the two devices have the following results:
    • If IGMP snooping is enabled on one device but not on the other, the device on which snooping is disabled floods all multicast traffic.
    • A difference in multicast router or static group configuration can cause traffic loss.
    • The fast leave, explicit tracking, and report suppression options can differ if they are used for forwarding traffic.
    • If a query parameter is different between the devices, one device expires the multicast state faster while the other device continues to forward. This difference results in either traffic loss or forwarding for an extended period.
    • If an IGMP snooping querier is configured on both devices, only one of them will be active because an IGMP snooping querier shuts down if a query is seen in the traffic.
  • You must enable ip igmp snooping group-timeout when you use ip igmp snooping proxy general-queries. We recommend to set it to "never." If this is not done you might have multicast packet loss.
  • Network applications that use unicast destination IP addresses with multicast destination MAC addresses might require the configuration of IGMP snooping to use MAC-based forwarding lookups on the switch. If the destination MAC address used for this kind of applications is a non-IP multicast MAC address, use the mac address-table multicast command to statically configure the port membership. If the destination MAC address is in the IP multicast range, 0100.5E00.0000 to 0100.5E7F.FFFF, use static IGMP snooping membership entries for the corresponding Layer 3 IP multicast address to configure the port membership. For example, if the application uses destination MAC address 0100.5E01.0101, configure a static IGMP snooping membership entry for an IP multicast address that maps to that MAC address. An example of this is ip igmp snooping static-group 239.1.1.1.

Default Settings for IGMP Snooping

This table lists the default settings for IGMP snooping parameters.

Parameters

Default

IGMP snooping

Enabled

Explicit tracking

Enabled

Fast leave

Disabled

Last member query interval

1 second

Snooping querier

Disabled

Report suppression

Enabled

Link-local groups suppression

Enabled

IGMPv3 report suppression for the entire device

Disabled

IGMPv3 report suppression per VLAN

Enabled

Configuring IGMP Snooping Parameters


Note


If you are familiar with the Cisco IOS CLI, be aware that the Cisco NX-OS commands for this feature might differ from the Cisco IOS commands that you would use.



Note


You must enable IGMP snooping globally before any other commands take effect.


Configuring Global IGMP Snooping Parameters

To affect the operation of the IGMP snooping process globally, you can configure the optional IGMP snooping parameters described in the following table:

Parameter

Description

IGMP snooping

Enables IGMP snooping on the active VDC. The default is enabled.

Note   

If the global setting is disabled, all VLANs are treated as disabled, whether they are enabled or not.

Event history

Configures the size of the IGMP snooping history buffers. The default is small.

Group timeout

Configures the group membership timeout for all VLANs on the device.

Link-local groups suppression

Configures link-local groups suppression on the device. The default is enabled.

Optimise-multicast-flood

Configures Optimized Multicast Flood (OMF) on all VLANs on the device. The default is enabled.

Proxy

Configures IGMP snooping proxy for the device. The default is 5 seconds.

Report suppression

Limits the membership report traffic sent to multicast-capable routers on the device. When you disable report suppression, all IGMP reports are sent as is to multicast-capable routers. The default is enabled.

IGMPv3 report suppression

Configures IGMPv3 report suppression and proxy reporting on the device. The default is disabled.

Notes for IGMP Snooping Parameters

The following are additional notes about some of the IGMP snooping parameters.

  • IGMP Snooping Proxy parameter To decrease the burden placed on the snooping switch during each IGMP general query (GQ) interval, Cisco NX-OS provides a way to decouple the periodic general query behavior of the IGMP snooping switch from the query interval configured on the multicast routers. Beginning with Cisco NX-OS release 5.2(1), a configuration option became available to enable the Cisco Nexus 7000 switch to consume IGMP general queries from the multicast router, rather than flooding the general queries to all the switchports. When receiving a general query, the switch produces proxy reports for all currently active groups and distributes the proxy reports over the period specified by the MRT that is specified in the router query. At the same time, independent of the periodic general query activity of the multicast router, the switch sends an IGMP general query on each port in the VLAN in a round-robin fashion. It cycles through all the interfaces in the VLAN at the rate given by the following formula. Rate = {number of interfaces in VLAN} * {configured MRT} * {number of VLANS} When running queries in this mode, the default MRT value is 5,000 milliseconds (5 seconds), which means that in a switch that has 500 switchports in a VLAN, it would take 2,500 seconds (40 minutes) to cycle through all the interfaces in the system. This is also true when the Cisco Nexus 7000 switch itself is the querier. This behavior ensures that only one host responds to a general query at a given time and it keeps the simultaneous reporting rate below the packet-per-second IGMP capability of the switch (approximately 3,000 to 4,000 pps).

    Note


    When using this option, you must change the ip igmp snooping group-timeout parameter to a high value or to never time out.


    The ip igmp snooping proxy general-queries[mrt] command causes the snooping function to proxy reply to general queries from the multicast router, while also sending round-robin general queries on each switchport with the specified MRT value (the default MRT value is 5 seconds).
  • IGMP Snooping Group-timeout parameter Configuring the group-timeout parameter disables the behavior of expiring membership based on three missed general queries. The group membership remains on a given switchport until the switch receives an explicit IGMP leave on that port. The ip igmp snooping group-timeout {timeout|never} command modifies or disables the behavior of an expiring IGMP snooping group membership after three missed general queries.
Procedure
     Command or ActionPurpose
    Step 1config t


    Example:
    switch# config t
    switch(config)#
     

    Enters global configuration mode.

     
    Step 2
    Option Description
    ip igmp snooping
    switch(config)# ip igmp snooping
    

    Enables IGMP snooping for the device. The default is enabled.

    Note   

    If the global setting is disabled with the no form of this command, IGMP snooping on all VLANs is disabled, whether IGMP snooping is enabled on a VLAN or not. If you disable IGMP snooping, Layer 2 multicast frames flood to all modules.

    Note   

    IGMP snooping can be configured across Virtual Private LAN Service (VPLS) domains.

    ip igmp snooping event-history {igmp-snoop-internal | mfdm | mfdm-sum | rib | vlan | vlan-events | vpc} size {disabled | large | medium | small}
    switch(config)# ip igmp snooping event-history igmp-snoop-internal size large

    Configures the size of the event history buffer. The default is small.

    ip igmp snooping group-timeout{minutes|never}
    switch(config)# ip igmp snooping group-timeout never
    

    Configures the group membership timeout value for all VLANs on the device.

    ip igmp snooping link-local-groups-suppression
    switch(config)# ip igmp snooping link-local-groups-suppression
    

    Configures link-local groups suppression for the entire device. The default is enabled.

    ip igmp snooping optimise-multicast-flood
    switch(config)# ip igmp snooping optimise-multicast-flood
    

    Optimizes OMF on all VLANs on the device. The default is enabled.

    ip igmp snooping proxy general-queries [mrt seconds]
    switch(config)# ip igmp snooping proxy general-queries

    Configures IGMP snooping proxy for the device. The default is 5 seconds.

    ip igmp snooping v3-report-suppression
    switch(config)# ip igmp snooping v3-report-suppression
    

    Limits the membership report traffic sent to multicast-capable routers. When you disable report suppression, all IGMP reports are sent as is to multicast-capable routers. The default is enabled.

    ip igmp snooping report-suppression
    switch(config)# ip igmp snooping report-suppression
    

    Configures IGMPv3 report suppression and proxy reporting. The default is disabled.

    ip igmp snooping max-gq-miss count
    switch(config)# ip igmp snooping max-gq-miss 5
    

    Configures the maximum number of general query misses permitted. The range is 3 to 5 queries. The default is 3 queries.

     

    The following commands can be used to configure the IGMP snooping.

     
    Step 3copy running-config startup-config


    Example:
    switch(config)# copy running-config startup-config
     

    (Optional) Saves configuration changes.

     

    Configuring IGMP Snooping Parameters per VLAN

    To affect the operation of the IGMP snooping process per VLAN, you can configure the optional IGMP snooping parameters described in this table.

    Parameter

    Description

    IGMP snooping

    Enables IGMP snooping on a per-VLAN basis. The default is enabled.

    Note   

    If the global setting is disabled, all VLANs are treated as disabled, whether they are enabled or not.

    Explicit tracking

    Tracks IGMPv3 membership reports from individual hosts for each port on a per-VLAN basis. The default is enabled.

    Fast leave

    Enables the software to remove the group state when it receives an IGMP leave report without sending an IGMP query message. This parameter is used for IGMPv2 hosts when no more than one host is present on each VLAN port. The default is disabled.

    Group timeout

    Configures the group membership timeout for the specified VLANs.

    Last member query interval

    Sets the interval that the software waits after sending an IGMP query to verify that no hosts that want to receive a particular multicast group remain on a network segment. If no hosts respond before the last member query interval expires, the software removes the group from the associated VLAN port. Values range from 1 to 25 seconds. The default is 1 second.

    Optimise-multicast-flood

    Configures Optimized Multicast Flood (OMF) on specified VLANs. The default is enabled.

    Proxy

    Configures IGMP snooping proxy for the specified VLANs. The default is 5 seconds.

    Snooping querier

    Configures a snooping querier on an interface when you do not enable PIM because multicast traffic does not need to be routed. You can also configure the following values for the snooping querier:

    • timeout—Timeout value for IGMPv2
    • interval—Time between query transmissions
    • maximum response time—MRT for query messages
    • startup count—Number of queries sent at startup
    • startup interval—Interval between queries at startup

    Robustness variable

    Configures the robustness value for the specified VLANs.

    Report suppression

    Limits the membership report traffic sent to multicast-capable routers on a per-VLAN basis. When you disable report suppression, all IGMP reports are sent as is to multicast-capable routers. The default is enabled.

    Multicast router

    Configures a static connection to a multicast router. The interface to the router must be in the selected VLAN.

    Static group

    Configures a Layer 2 port of a VLAN as a static member of a multicast group.

    Link-local groups suppression

    Configures link-local groups suppression on a per-VLAN basis. The default is enabled.

    IGMPv3 report suppression

    Configures IGMPv3 report suppression and proxy reporting on a per-VLAN basis. The default is enabled per VLAN.

    Version

    Configures the IGMP version number for the specified VLANs.


    Note


    Beginning with Cisco Release 5.1(1), step 3 in the following procedure changed from vlan to vlan configuration vlan-id. You configure the IP IGMP snooping parameters that you want by using this configuration mode; however, the configurations apply only after you specifically create the specified VLAN. See the Cisco Nexus 7000 Series NX-OS Layer 2 Switching Configuration Guide for information on creating VLANs.


    Procedure
       Command or ActionPurpose
      Step 1 config t


      Example:
      switch# config t
      switch(config)#
       

      Enters global configuration mode.

       
      Step 2ip igmp snooping


      Example:
      switch(config)# ip igmp snooping
       

      Enables IGMP snooping for the current VDC. The default is enabled.

      Note   

      If the global setting is disabled with the no form of this command, IGMP snooping on all VLANs is disabled, whether IGMP snooping is enabled on a VLAN or not. If you disable IGMP snooping, Layer 2 multicast frames flood to all modules.

       
      Step 3
      Option Description
      vlan vlan-id
      switch(config)# vlan 2
      switch(config-vlan)#

      Enters VLAN configuration mode.

      vlan configurationvlan-id
      switch(config)# vlan configuration 2
      switch(config-vlan-config)#

      Beginning with Cisco Release 5.1(1), use this command to configure the IGMP snooping parameters you want for the VLAN. These configurations do not apply until you create the specified VLAN.

       

      Depending on your release of Cisco NX-OS, use one of the commands in the table.

       
      Step 4
      Option Description
      ip igmp snooping
      switch(config-vlan-config)# ip igmp snooping

      Enables IGMP snooping for the current VLAN. The default is enabled.

      ip igmp snooping explicit-tracking
      switch(config-vlan-config)# ip igmp snooping explicit-tracking

      Tracks IGMPv3 membership reports from individual hosts for each port on a per-VLAN basis. The default is enabled on all VLANs.

      ip igmp snooping fast-leave
      switch(config-vlan-config)# ip igmp snooping fast-leave

      Supports IGMPv2 hosts that cannot be explicitly tracked because of the host report suppression mechanism of the IGMPv2 protocol. When you enable fast leave, the IGMP software assumes that no more than one host is present on each VLAN port. The default is disabled for all VLANs.

      ip igmp snooping group-timeout {minutes |never}
      switch(config-vlan-config)# ip igmp snooping group-timeout never

      Configures the group membership timeout for the specified VLANs.

      ip igmp snooping last-member-query-interval seconds
      switch(config-vlan-config)# ip igmp snooping last-member-query-interval 3

      Removes the group from the associated VLAN port if no hosts respond to an IGMP query message before the last member query interval expires. Values range from 1 to 25 seconds. The default is 1 second.

      ip igmp snooping optimise-multicast-flood
      switch(config-vlan-config)# ip igmp snooping optimise-multicast-flood

      Optimizes OMF on selected VLANs. The default is enabled.

      ip igmp snooping proxy general-queries mrt seconds
      switch(config-vlan-config)# ip igmp snooping proxy general-queries

      Configures an IGMP snooping proxy for specified VLANs. The default is 5 seconds.

      ip igmp snooping querier ip-address
      switch(config-vlan-config)# ip igmp snooping querier 172.20.52.106

      Configures a snooping querier when you do not enable PIM because multicast traffic does not need to be routed. The IP address is used as the source in messages.

      ip igmp snooping querier-timeout seconds
      switch(config-vlan-config)# ip igmp snooping querier-timeout 300

      Configures a snooping querier timeout value for IGMPv2 when you do not enable PIM because multicast traffic does not need to be routed. The default is 255 seconds.

      ip igmp snooping query-interval seconds
      switch(config-vlan-config)# ip igmp snooping query-interval 120

      Configures a snooping query interval when you do not enable PIM because multicast traffic does not need to be routed. The default value is 125 seconds.

      ip igmp snooping query-max-response-time seconds
      switch(config-vlan-config)# ip igmp snooping query-max-response-time 12

      Configures a snooping MRT for query messages when you do not enable PIM because multicast traffic does not need to be routed. The default value is 10 seconds.

      ip igmp snooping startup-query-count value
      switch(config-vlan-config)# ip igmp snooping startup-query-count 5

      Configures snooping for a number of queries sent at startup when you do not enable PIM because multicast traffic does not need to be routed.

      ip igmp snooping startup-query-interval seconds
      switch(config-vlan-config)# ip igmp snooping startup-query-interval 15000

      Configures a snooping query interval at startup when you do not enable PIM because multicast traffic does not need to be routed.

      ip igmp snooping robustness-variable value
      switch(config-vlan-config)# ip igmp snooping robustness-variable 5

      Configures the robustness value for the specified VLANs. The default value is 2.

      ip igmp snooping report-suppression
      switch(config-vlan-config)# ip igmp snooping report-suppression

      Limits the membership report traffic sent to multicast-capable routers. When you disable report suppression, all IGMP reports are sent as is to multicast-capable routers. The default is enabled.

      ip igmp snooping mrouter interface interface
      switch(config-vlan-config)# ip igmp snooping mrouter interface ethernet 2/1

      Configures a static connection to a multicast router. The interface to the router must be in the selected VLAN. You can specify the interface by the type and the number, such as ethernet slot/port.

      ip igmp snooping static-group [group-ip-addr ]source [source-ip-addr] interface interface
      switch(config-vlan-config)# ip igmp snooping static-group 230.0.0.1 interface ethernet 2/1

      Configures a Layer 2 port of a VLAN as a static member of a multicast group. You can specify the interface by the type and the number, such as ethernet slot/port.

      ip igmp snooping link-local-groups-suppression
      switch(config-vlan-config)# ip igmp snooping link-local-groups-suppression

      Configures link-local groups suppression for the specified VLANs. The default is enabled.

      ip igmp snooping v3-report-suppression
      switch(config-vlan-config)# ip igmp snooping v3-report-suppression

      Configures IGMPv3 report suppression and proxy reporting for the specified VLANs. The default is enabled per VLAN.

      ip igmp snooping version value
      switch(config-vlan-config)# ip igmp snooping version 2

      Configures the IGMP version number for the specified VLANs.

       

      These commands configure IGMP snooping parameters.

       
      Step 5copy running-config startup-config


      Example:
      switch(config)# copy running-config startup-config
       

      (Optional) Saves configuration changes.

       

      Changing the Lookup Mode

      Beginning with Cisco Release 5.2(1) for the Nexus 7000 Series chassis, you can configure the lookup mode to be based on the MAC address either globally or per VLAN.

      Procedure
         Command or ActionPurpose
        Step 1config t


        Example:
        switch# config t
        switch(config)#
         

        Enters global configuration mode.

         
        Step 2layer-2 multicast lookup mac


        Example:
        
        
        switch(config)# layer-2 multicast lookup mac
        
         

        Globally changes the lookup mode to be based on the MAC address. To return to the default IP lookup mode, use the no form of this command.

         
        Step 3vlan vlan-id


        Example:
        
        
        switch(config)# vlan 5
        switch(config-vlan)#
        
        layer-2 multicast lookup mac
        
        
        
        switch(config-vlan)# layer-2 multicast lookup mac
        switch(config-vlan)#
        
         

        Changes the lookup mode to be based on the MAC address for the specified VLANs. To return to the default IP lookup mode for these VLANs, use the no form of this command.

         
        Step 4exit


        Example:
        switch(config)# exit
        switch#
         

        Exits configuration and/or VLAN configuration mode.

         
        Step 5show ip igmp snooping lookup-mode vlan [vlan-id]

        Example:
        
        
        switch# show ip igmp snooping lookup-mode
        
         

        (Optional) Displays the IGMP snooping lookup mode.

         
        Step 6copy running-config startup-config


        Example:
        switch# copy running-config startup-config
         

        (Optional) Copies the running configuration to the startup configuration.

         

        Configuring a Static Multicast MAC Address

        Beginning with Cisco Release 5.2(1) for the Nexus 7000 Series chassis, you can configure an outgoing interface statically for a multicast MAC address.

        Procedure
           Command or ActionPurpose
          Step 1config t


          Example:
          switch# config t
          switch(config)#
           

          Enters global configuration mode.

           
          Step 2mac address-table multicast multicast-mac-addr vlan vlan-id interface slot/port


          Example:
          
          
          switch(config)# mac address-table multicast 01:00:5f:00:00:00 vlan 5 interface ethernet 2/5
          
           

          Configures the specified outgoing interface statically for a multicast MAC address.

           
          Step 3exit


          Example:
          switch(config)# exit
          switch#
           

          Exits configuration and/or VLAN configuration mode.

           
          Step 4show ip igmp snooping mac-oif [detail | vlan vlan-id [detail]]


          Example:
          
          
          switch# show feature-set
          
           

          (Optional) Displays the IGMP snooping static MAC addresses.

           
          Step 5copy running-config startup-config


          Example:
          switch# copy running-config startup-config
           

          (Optional) Copies the running configuration to the startup configuration.

           

          Verifying IGMP Snooping Configuration

          To display the IGMP configuration information, perform one of the following tasks:

          Command or Action

          Purpose

          show ip igmp snooping [vlan vlan-id]

          Displays the IGMP snooping configuration by VLAN.

          show ip igmp snooping groups [source [group] | group | [source] | [ vlan vlan-id] [detail]

          Displays IGMP snooping information about groups by VLAN.

          show ip igmp snooping querier [ vlan vlan-id]

          Displays IGMP snooping queriers by VLAN.

          show ip igmp snooping mroute [ vlan vlan-id]

          Displays multicast router ports by VLAN.

          show ip igmp snooping explicit-tracking [ vlan vlan-id]

          Displays IGMP snooping explicit tracking information by VLAN.

          show ip igmp snooping lookup-mode [ vlan vlan-id]

          Displays the IGMP snooping lookup mode.

          show ip igmp snooping mac-oif [ detail | vlan vlan-id[ detail]]

          Displays IGMP snooping static MAC addresses.

          show ip igmp snooping pw vlan brief

          Displays VLANs, which have pseudowire interfaces that are operationally up.

          Displaying IGMP Snooping Statistics

          Use the show ip igmp snooping statistics vlan command to display IGMP snooping statistics. You can see the virtual port channel (vPC) statistics in this output.

          Use the clear ip igmp snooping statistics vlan command to clear IGMP snooping statistics.

          For detailed information about using these commands, see the Cisco Nexus 7000 Series NX-OS Multicast Routing Command Reference.

          Configuration Example for IGMP Snooping

          This example shows how to configure the IGMP snooping parameters:

          
          switch# config t
          switch# ip igmp snooping
          switch# vlan 2
          switch# ip igmp snooping
          switch# ip igmp snooping explicit-tracking
          switch# ip igmp snooping fast-leave
          switch# ip igmp snooping last-member-query-interval 3
          switch# ip igmp snooping querier 172.20.52.106
          switch# ip igmp snooping report-suppression
          switch# ip igmp snooping mrouter interface ethernet 2/1
          switch# ip igmp snooping static-group 230.0.0.1 interface ethernet 2/1
          switch# ip igmp snooping link-local-groups-suppression
          switch# ip igmp snooping v3-report-suppression
          
          
          

          This example shows how to configure the IGMP snooping parameters beginning with Cisco Release 5.1(1):

          
          switch# config t
          switch# ip igmp snooping
          switch# vlan configuration 2
          switch# ip igmp snooping
          switch# ip igmp snooping explicit-tracking
          switch# ip igmp snooping fast-leave
          switch# ip igmp snooping last-member-query-interval 3
          switch# ip igmp snooping querier 172.20.52.106
          switch# ip igmp snooping report-suppression
          switch# ip igmp snooping mrouter interface ethernet 2/1
          switch# ip igmp snooping static-group 230.0.0.1 interface ethernet 2/1
          switch# ip igmp snooping link-local-groups-suppression
          switch# ip igmp snooping v3-report-suppression
          
          
          

          The following example shows how to configure IGMP Snooping across VPLS Domains:

          switch# configure terminal
          switch(config)# ip igmp snooping
          switch(config)# ip igmp snooping event-history igmp-snoop-internal size large
          switch(config)# ip igmp snooping group-timeout never
          switch(config)# ip igmp snooping link-local-groups-suppression
          switch(config)# ip igmp snooping optimise-multicast-flood
          switch(config)# ip igmp snooping proxy general-queries
          switch(config)# ip igmp snooping report-suppression
          switch(config)# ip igmp snooping v3-report-suppression
          
          
          

          These configurations do not apply until you specifically create the VLAN. See the Cisco Nexus 7000 Series NX-OS Layer 2 Switching Configuration Guide for information on creating VLANs.

          Related Documents

          Related Topic

          Document Title

          VDCs

          Cisco Nexus 7000 Series NX-OS Virtual Device Context Configuration Guide

          CLI commands

          Cisco Nexus 7000 Series NX-OS Multicast Routing Command Reference

          Standards

          Standards

          Title

          No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

          Feature History for IGMP Snooping in CLI

          Feature Name

          Releases

          Feature Information

          ip igmp snooping max-gq-miss count

          6.2(2)

          Command added to allow you to configure the maximum number of general query misses permitted.

          IGMP Snooping across VPLS domains

          6.2(2)

          The IGMP Snooping across VPLS Domains feature enables snooping of the IGMP packets on the pseudowire as well as on the Layer 2 side of the network for optimal delivery of the multicast packets.

          The following command was introduced:

          show ip igmp snooping pw vlan brief

          Configuring lookup mode to MAC and assigning a static MAC address

          5.2(1)

          You can configure IGMP snooping to use the forwarding lookup mode as MAC-based, as well as assign a static MAC address.

          vlan configuration vlan-id

          5.1(1)

          Command added to allow you to configure a VLAN before you actually create the VLAN.

          vPC

          4.1(3)

          List of guidelines and limitations that apply to a vPC.

          Display vPC statistics with the show ip igmp snooping statistics vlan command.

          The following sections provide information about this feature:

          • Guidelines and Limitations for IGMP Snooping
          • Displaying IGMP Snooping Statistics