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Configuring IGMP Snooping

With IGMP snooping enabled, a switch monitors the IGMP (Internet Group Management Protocol) traffic between hosts and multicast routers and uses what it learns to forward multicast traffic to only the downstream interfaces that are connected to interested receivers. This conserves bandwidth by allowing the switch to send multicast traffic to only those interfaces that are connected to devices that want to receive the traffic (instead of flooding the traffic to all the downstream VLAN interfaces).

Note: You cannot configure IGMP snooping on a secondary VLAN.

To enable IGMP snooping and configure individual options as needed for your network by using the CLI:

  1. Enable IGMP snooping on a VLAN:
    [edit protocols]
    user@switch# set igmp-snooping vlan employee-vlan
  2. Configure the switch to immediately remove group membership from interfaces on a VLAN when it receives a leave message through that VLAN, and have it not forward any membership queries for the multicast group to the VLAN (IGMPv2 only):
    [edit protocols]
    user@switch# set igmp-snooping vlan vlan-name immediate-leave
  3. Configure an interface to belong to a multicast group:
    [edit protocols]
    user@switch# set igmp-snooping vlan-name interface interface-name static group group-address
  4. Configure an interface to forward IGMP queries received from multicast routers.
    [edit protocols]
    user@switch# set igmp-snooping vlan vlan-name interface interface-name multicast-router-interface
  5. Configure the switch to wait for four timeout intervals before timing out a multicast group on a VLAN:
    [edit protocols]
    user@switch# set igmp-snooping vlan vlan-name robust-count 4
  6. If you want the switch to act as an IGMP querier, enter the following:
    [edit protocols]
    user@switch# set igmp-snooping vlan vlan-name l2-querier source-address source address

    The switch uses the address that you configure as the source address in the IGMP queries that it sends. If there are any multicast routers on the same local network, make sure the source address for the IGMP querier is greater (a higher number) than the IP addresses for those routers on the network. This ensures that switch is always the IGMP querier on the network.

    Note: The igmp-querier statement is not supported on QFabric systems.

 

Related Documentation

 

Published: 2014-10-14

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