Saturday, June 20, 2009


PIM SSM or Source Specific Multicast, contrary to PIM BiDir, does NOT require the PIM shared tree, and does not use it. No RPS are required and RP protocols such as Auto RP or BSR are not needed. With SSM the SPT is always used.

Like BiDir PIM configuration is pretty straightforward.

The range of multicast groups that are using ssm signaling must be specified on all routers in the mcast domain

To enable pim ssm on the default range of

#conf t
config#ip pim ssm range default

Note for groups in the ssm range no shared trees are allowed and any (*,G) joins will be dropped.

The final step is to enable IGMP version 3 needs on the receiver facing interfaces.

for SW1 TO JOIN for source

config-if#ip igmp version 3
config-if#ip igmp join source

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