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    Configuring Multicast Groups for IGMP

    You can configure multicast groups for IGMP using the following tasks:

    Specifying Multicast Groups

    You can use a standard-format or extended-format IP access list to specify the multicast groups that a host can join.

    1. Configure the host on a subnetwork to join only multicast groups that appear on the specified IP access list.
      host1:boston(config-if)#ip igmp access-group boston-list
    2. Configure the host on a subnetwork to become a member of only those (S,G) pairs (also known as channels) which are included on the specified IP access list.
      host1:boston(config-if)#ip igmp access-source-group dallas-list

    Assigning a Multicast Group to an Interface

    You can assign an interface to send and receive all traffic for a particular multicast group. This feature enables you to control the IGMP traffic and to test the behavior of multicast protocols in the network.

    To send and receive all traffic for a multicast group from a specific interface:

    • Issue the ip igmp static-group command in Interface Configuration mode.
      host1:boston(config-if)#ip igmp static-group 225.1.2.3

    You can use the no version to stop the interface from sending all traffic for the group. The interface sets no timers for this group.

    Configuring Group Outgoing Interface Mapping

    You can configure an IGMP interface to use a different outgoing interface (OIF) for multicast-data-forwarding by applying an OIF map. When you configure an OIF map on an IGMP interface, the map is applied to all IGMP membership requests that the interface receives.

    To configure OIF mapping on an interface:

    1. Create an OIF map using the ip igmp oif-map command at the global level.
      host1(config)#ip igmp oif-map OIFMAP atm 3/0.1 232.0.0.1/32 51.0.0.1/32 host1(config)#ip igmp oif-map OIFMAP atm 3/0.2 232.0.0.1/32 51.0.0.2/32 host1(config)#ip igmp oif-map OIFMAP atm 3/0.3 233.0.0.1/32 host1(config)#ip igmp oif-map OIFMAP atm 3/0.4 233.0.0.0/24 51.0.0.1/32 host1(config)#ip igmp oif-map OIFMAP atm 3/0.5 233.0.0.0/24 51.0.0.2/32 host1(config)#ip igmp oif-map OIFMAP self 0.0.0.0/0 51.0.0.0/24
    2. Apply the OIF map to an interface using the ip igmp apply-oif-map command.
      host1(config-subif)#ip igmp apply-oif-map OIFMAP

    To properly configure an interface used in the OIF map for multicast-data-forwarding capability, you must configure the interface version as passive with the ip igmp version command. You can either specify a passive interface as the OIF or specify the OIF as self (to use the IGMP interface as the OIF) in the ip igmp oif-map command.

    Published: 2014-08-19