The following table describes the flags that you can include. That is, IGMP snooping and multicast forwarding will proceed independently in each learning domain in the bridge. The configuration could not be easier for newer Catalyst or Nexus product switches. During the snooping process, the switch listens for IGMP messages from both routers and hosts. Snooping makes multicasting more efficient in these devices. This enables the Layer 2 device to keep track of the multicast groups and associated member ports.

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You can specify which trace operations are logged by including specific tracing flags. Bridge or VPLS instance interfaces are either multicast-router interfaces or host-side interfaces. Query—All general and group-specific IGMP query messages received on a multicast-router interface are forwarded to all other interfaces both multicast-router interfaces and host-side interfaces on the bridge. If there is only one host and it leaves the multicast group, the switch immediately sends a group mrouter latest version message to the upstream router.

Report—IGMP reports received on any interface of the bridge are forwarded toward other multicast-router interfaces. That is, IGMP snooping and multicast forwarding will proceed independently in each learning domain in the bridge. Using the show ip igmp snooping groups command, we can also see the entry in the switch, as demonstrated in Mrouter latest version Also, a group timer is set for the group on that interface.


Statically configure IGMP group membership on a port. Switches learn about routers using several mechanisms: By default, the query interval is seconds.

Look carefully at the output in Example This example shows how to configure IGMP snooping. Here is the best part—it is on by default and obviously not necessary to type the previous command.

The following example requires mrouter latest version to navigate various levels in the configuration hierarchy. An interface on the bridge is considered a multicast-router interface if it meets at least one of the following criteria: A multicast-router interface is an interface in the direction of a multicasting router. By default, the robust count is 2. The Layer 2 device uses this information to make intelligent decisions and to forward multicast traffic to only the intended destination hosts.

When a host connected to the switch wants to join a multicast stream, it sends an IGMP membership report. The status of the group remains the same from the router’s point of view.

RFC – Internet Group Management Protocol, Version 2

You configure IGMP mrouter latest version for each bridge on the router. By default, the query response interval is 10 seconds. To verify the configuration, run the following commands: Configure an interface to be an exclusively host-facing interface to drop IGMP query messages.


You can wait more intervals if subnet packet loss is high and IGMP report messages might be lost. Only group-specific queries mrkuter generated by IGMP snooping directly.

Example: Configuring IGMP Snooping

Also, all reports generated by IGMP snooping are sent with 0. By default, IGMP snooping is not enabled. One of the interesting aspects of this message is that the switch spoofs the Mrokter address of the last client. About Affiliates Cisco Systems, Inc.

Snooping > Network Access and Layer 2 Multicast

Using the debug ip igmp snooping group command, we can monitor the activity. There are currently no related articles. The switch does not notify the router of any additions or removals to the group, with the exception of the last host. To configure IGMP snooping: