The Protocol Independent Multicast (PIM) protocol is a family of IP multicast protocols. PIM does not
rely on any particular routing protocol for creating its network topology state. Instead, PIM uses routing
information supplied by other traditional routing protocols such as the Routing Information Protocol,
Open Shortest Path First, Border Gateway Protocol, and Multicast Source Discovery Protocol.

PIM messages are sent encapsulated in an IP packet with the IP protocol field set to 103. Depending on
the type of message, the packet is either sent to the PIM All-Router-Multicast address (224.0.0.13) or
sent as unicast to a specific host.

As with IP multicast, the main use case of PIM is for the source to be able to send the same information
to multiple receivers by using a single stream of traffic. This helps minimize the processing load on the
source as it needs to maintain only one session irrespective of the number of actual receivers. It also
minimizes the load on the IP network since the packets are sent only on links which lead to an
interested receiver.

Several types of PIM exist, but in this release Brocade supports only PIM Sparse Mode (PIM-SM). PIM-
SM explicitly builds unidirectional shared trees rooted at a rendezvous point (RP) per group, and
optionally creates shortest-path trees per source.

Important notes

• PIM can be enabled on the Brocade VDX 6740 and VDX 8770 series platforms only.
• PIM-SM can be used in VCS mode only.

PIM Sparse Mode

PIM-SM (Sparse Mode) is the most commonly deployed flavor of PIM. PIM-SM is most effective in large
networks sparsely populated with hosts interested in multicast traffic. It is assumed that most hosts
within a network are not interested in all multicast data streams.

Network OS Administrator’s Guide

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