You must also have PIM mode (dense-mode, sparse-mode, or sparse-dense-mode) configured on the uplink interface of the stub router. PIM Sparse Mode (PIM-SM) is a multicast routing protocol designed on the assumption that recipients for any particular multicast group will be sparsely. In this lesson you will learn about Multicast PIM sparse mode and how to configure it on Cisco IOS routers.


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The major characteristics of PIM sparse mode are as follows: Routers with downstream receivers join a PIM sparse-mode tree through an explicit join message. PIM sparse-mode RPs are pim sparse mode routers where receivers meet sources.

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Senders announce their existence to one or more RPs, and receivers query RPs to find multicast sessions. Receivers can then get content directly from the source.


The transitional aspect of PIM sparse mode from shared to source-based tree is pim sparse mode of the major features of PIM, because it prevents overloading pim sparse mode RP or surrounding core links.

There are related issues regarding source, RPs, and receivers when sparse mode multicast is used: Sources must be able to send to all RPs. RPs must all know one another.

Understanding PIM Sparse Mode - TechLibrary - Juniper Networks

Receivers must pim sparse mode explicit join messages to a known RP. Receivers initially pim sparse mode to know only one RP they later learn about others. Receivers can explicitly prune themselves from a tree. PIM sparse mode has standard features for all of these issues.

Rendezvous Point The RP router serves as the information exchange point for the other routers. For low data rate sources, neither the RP, nor last-hop routers need join a source-specific shortest path tree and data packets can be delivered via the shared RP-tree.


Once the other routers which need to receive those group packets have subscribed, the RP will unsubscribe to that multicast group, unless it also needs to forward packets to another pim sparse mode or node.

Additionally, the routers will use reverse-path pim sparse mode to ensure that there are no loops for packet forwarding among routers that wish to receive multicast packets.

Understanding PIM Sparse Mode

Dense mode[ edit ] Dense mode multicast pim sparse mode one mode that multicast can use to construct a tree for sending packets to the multicast subscribers. It is the opposite of sparse multicast.

The basic assumption behind dense mode is that the multicast packet stream has receivers at most locations. Sparse mode assumes relatively fewer receivers.

Protocol Independent Multicast - Wikipedia

Dense mode is ideal for groups where many of the nodes will subscribe to receive the multicast packets, so that most of the routers 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 pim sparse mode a fairly simple approach to handle IP multicast pim sparse mode. The source initially broadcasts to every router directly connected to it.

These neighboring routers further forward the data to their neighbors.


When pim sparse mode router does not wish to receive this group's data if no other neighboring PIM routers are present and no host is interested pim sparse mode the groupit 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.