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    Blocking Mroutes

    By default, when an interface that is configured with one or more multicast protocols (for example, PIM or IGMP) receives multicast traffic, even when the scope of that traffic exceeds link-local, the virtual router creates an mroute. You can use the ip block-multicast-sources command to block all multicast traffic with a scope larger than link-local (for example, global) and prevent mroute creation under these conditions.

    Note: Issuing this command does not affect reception of link-local multicast packets.

    To prevent mroute creation by blocking multicast traffic that has a scope larger than link-local (for example, global):

    • Issue the ip block-multicast-sources command in Interface Configuration mode:
      host1(config-if)#ip block-multicast-sources

    You can use the no version to restore the default behavior of creating mroutes on received multicast packets.

    Published: 2014-08-20