Edison Ortiz Thu, 08/30/2007 - 13:53
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It's a Source-Specific Multicast Distribution Tree.

SSM delivery datagrams are based on (S,G) where the source sends the data directly to the multicast group, not to the RP (*,G).

Mohamed Sobair Fri, 08/31/2007 - 14:08
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adding the following to SSM:

In SSM, delivery of datagrams is based on (S,G) . Traffic for one (S,G) channel consists of datagrams with an IP unicast source address S and the multicast group address G as the IP destination address.

Receivers will receive this traffic by becoming members of the (S, G). In both SSM no signalling is required to become a source. However, in SSM, receivers must subscribe or unsubscribe to (S, G) channels to receive or not receive traffic from specific sources. In other words, receivers can receive traffic only from (S, G) channels that they are subscribed to, whereas in ISM, receivers need not know the IP addresses of sources from which they receive their traffic. The proposed standard approach for channel subscription signalling utilizes IGMP INCLUDE mode membership reports, which are only supported in Version 3 of IGMP.


Mohamed Sobair


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