Users Guide

Table Of Contents
IPv4 and IPv6 Multicast 1599
PIM-SM Protocol Operation
This section describes the workings of PIM-SM protocol per RFC 4601. The
protocol operates essentially in three phases, as explained in the following
sections.
Phase-1: RP Tree
Figure 46-1. PIM-SM Shared Tree Join
In this example, an active receiver (attached to leaf router at the bottom of
the drawing) has joined multicast group “G”.
The leaf router (labeled DR above) knows the IP address of the
Rendezvous Point (RP) for group G and sends a (*, G) Join for this group
towards the RP.
This (*, G) Join travels hop-by-hop to the RP, building a branch of the
Shared Tree that extends from the RP to the last-hop router directly
connected to the receiver.
At this point, group “G” traffic can flow down the Shared Tree to the
receiver.