Pim Overview; Introduction To Pim-Dm - 3Com MSR 50 Series Configuration Manual

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PIM Overview

Introduction to PIM-DM

PIM C
ONFIGURATION
When configuring PIM, go to these sections for information you are interested in:
"PIM Overview" on page 1161
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"Configuring PIM-DM" on page 1173
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"Configuring PIM-SM" on page 1176
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"Configuring PIM-SSM" on page 1185
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"Configuring PIM Common Information" on page 1187
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"Displaying and Maintaining PIM" on page 1192
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"PIM Configuration Examples" on page 1193
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"Troubleshooting PIM Configuration" on page 1205
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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. For
more information about RPF, refer to
Configuration" on page
Based on the forwarding mechanism, PIM falls into two modes:
Protocol Independent Multicast-Dense Mode (PIM-DM), and
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Protocol Independent Multicast-Sparse Mode (PIM-SM).
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n
To facilitate description, a network comprising PIM-capable routers is referred to
as a "PIM domain" in this document.
PIM-DM is a type of dense mode multicast protocol. It uses the "push mode" for
multicast forwarding, and is suitable for small-sized networks with densely
distributed multicast members.
The basic implementation of PIM-DM is as follows:
"Multicast Routing and Forwarding
1097.