Posts Tagged ‘PIM SSM’

Basic Multicast part 5 – PIM SSM and SSM mapping

November 28, 2012 3 comments

Continuing with Multicast topic I will talk this time about PIM SSM (Source Specific Multicast RFC 3569) and SSM mapping. In my previous posts on Multicast I demonstrated how to configure PIM DM/SM which uses IGMPv2 for host to router signaling. PIM DM and SM are known as “Any Source Multicast” or ASM. The receivers are willing to receive multicast from any source which is why a RP is needed in order to allow the receivers to discover new sources. With PIM SSM the concept is different as the receivers signal which source they want receive multicast traffic from by using IGMPv3 which means that RPs are not needed and the multicast routers in the multicast domain will only build shortest-path trees (SPT).

 For this post I will use the same topology as the other multicast posts:

Scenario: The Multicast source will send two streams, one for the multicast group and one for the multicast group The first group ( will be running PIM SM and R4 will be the RP for this group. The second multicast group ( will be running PIM SSM. The receiver will act as an IGMPv2/v3 receiver. In the second part of this post I will demonstrate how to configure SSM mapping where the receiver will not be IGMPv3 capable.

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