Protocol-Independent Multicast: Difference between revisions

Revision as of 10:16, 3 November 2023

Revision as of 14:04, 6 November 2023

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'''Dense mode multicast''' is one mode that [[multicast]] can use to construct a [[Tree (data structure)|tree]] for sending [[Packet (information technology)|packet]]s to the multicast subscribers. It is an alternative to sparse mode.

The basic assumption behind dense mode is that the multicast packet stream has receivers at most locations. Sparse mode assumes relatively fewer receivers. Dense mode is ideal for groups where many of the nodes will subscribe to receive the multicast packets, so that most of the [[router (computing)|router]]sands must receive and forward these packets (groups of a high density).

This difference shows up in the initial behavior and mechanisms of the two protocols. Dense Mode uses a fairly simple approach to handle [[IP multicast]] routing. The source initially [[Broadcasting (networking)|broadcast]]s to every [[router (computing)|router]] directly connected to it. These neighboring routers further forward the data to their neighbors. When a router does not wish to receive this group's data (if no other neighboring PIM routers are present and no host is interested in the group), it sends a Prune message to indicate its lack of interest. Upon receiving a Prune message, the router will modify its state so that it will not forward those packets out that [[Interface (computer science)|interface]]. If every interface on a router is pruned, the router will also be pruned.<ref name=CiscoPIM/>