Thursday, October 16, 2008

Multicast Routing - Part II Statically Connected Member

If there is a requirement for a host on a segment to receive multicast traffic but the host is unable to request membership itself via igmp this initially poses a problem. To get around this the connected switch interface can request multicast traffic on behalf of the host.

Such a configuration effectively makes the host on the segment a statically connected member of the group. Two commands are available, and differ in the respect of how the switch forwards the multicast traffic.

#int fa0/23
config-if#ip igmp join-group {group address}

This command forces the switch to accept the multicast stream and forward out of the interface via process switching.

#int fa0/23
config-if#ip igmp static-group {group address}

With this command the switch does NOT accept the multicast stream itself but simply forwards them out of the specified interface. This forwarding is done by fast switching, as opposed to process switching when the previous command is used

As with all 3560 multicast commands they can be found on the doc cd under the IP multicast routing section.

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