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.

Related Documentation

• Monitoring Multicast Forwarding Entries
• Monitoring Active Multicast Routes
• Monitoring Multicast Entries in a Source or Group
• Monitoring Multicast Routes When OIF Mapping Is Configured
• Monitoring Multicast Statistics
• Monitoring Summary Information of Multicast Routes
• Monitoring Multicast Protocols Enabled on the Router
• ip block-multicast-sources