SMC Networks SMC6724L3 manual 223, Configuring Global Dvmrp Settings

MULTICAST ROUTING

to build up a source-rooted multicast delivery tree that allows it to prevent looping and determine the shortest path to the source of this multicast traffic.

source

branch

leaf leaf

When this router receives the multicast message, it checks its unicast routing table to locate the port that provides the shortest path back to the source. If that path passes through the same port on which the multicast message was received, then this router records path information for the concerned multicast group in its routing table and forwards the multicast message on to adjacent routers, except for the port through which the message arrived. This process eliminates potential loops from the tree and ensures that the shortest path (in terms of hop count) is always used.

Configuring Global DVMRP Settings

DVMRP is used to route multicast traffic to nodes which have requested a specific multicast service via IGMP. This router uses Reverse Path Forwarding (RPF) to build a shortest-path delivery tree that begins at the source and spreads out to reach group members through the network. RPF uses three different techniques to dynamically reconfigure the multicast spanning tree: broadcasting, pruning, and grafting.

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