Pim Overview; Pim Configuration - 3Com 5500-EI PWR Install Manual

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PIM Configuration

When configuring PIM, go to these sections for information you are interested in:

PIM Overview

Configuring PIM-DM
Configuring PIM-SM
Configuring Common PIM Parameters
Displaying and Maintaining PIM
PIM Configuration Examples
Troubleshooting PIM
In this manual, the term "router" refers to a router in the generic sense or a Layer 3 Ethernet switch
running an IP multicast protocol.
PIM Overview
Protocol Independent Multicast (PIM) provides IP multicast forwarding by leveraging static routes or
unicast routing tables generated by any unicast routing protocol, such as Routing Information Protocol
(RIP), open shortest path first (OSPF), Intermediate System to Intermediate System (IS-IS), or Border
Gateway Protocol (BGP). Independent of the unicast routing protocols running on the device, multicast
routing can be implemented as long as the corresponding multicast routing entries are created through
unicast routes. PIM uses the Reverse Path Forwarding (RPF) mechanism to implement multicast
forwarding. When a multicast packet arrives on an interface of the device, it is subject to an RPF check.
If the RPF check succeeds, the device creates the corresponding routing entry and forwards the packet;
if the RPF check fails, the device discards the packet.
Based on the forwarding mechanism, PIM falls into two modes:
Protocol Independent Multicast–Dense Mode (PIM-DM), and
Protocol Independent Multicast–Sparse Mode (PIM-SM).
To facilitate description, a network comprising PIM-capable routers is referred to as a "PIM domain" in
this document.
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