Huawei quidway s7700 - PIM-DM Overview

5.1 PIM-DM Overview
In the network where multicast group members are densely distributed and each network
segment may have multicast group members, PIM-DM builds a unidirectional and loop-free
SPT from the multicast source to the group member through periodical flooding and pruning.
CAUTION
This chapter is concerned only about the PIM-DM configuration in an IPv4 network.
The Protocol Independent Multicast (PIM) is a multicast protocol that is independent of unicast
routing protocol such as static route, RIP, OSPF, IS-IS, and BGP. Multicast routing is
independent of unicast routing protocols, except that unicast routing protocols are used to
generate related multicast routing entries.
Based on the Reverse Path Forwarding (RPF), PIM transmits multicast data across a network.
RPF constructs a multicast forwarding tree by using the existing unicast routing information.
When a multicast packet reaches a switch, the switch performs the RPF check first. If the packet
does not pass the RPF check, the switch directly discards the packet.
NOTE
For details about RPF, see IPv4 Multicast Routing Management.
The Protocol Independent Multicast-Dense Mode (PIM-DM) is applicable to a small-scale
network with densely-distributed members.
The functions and location of PIM-DM in a multicast network are shown in Figure 5-1.
Figure 5-1 Location of PIM-DM on the multicast network
Receiver
UserD
Source
Multicast
Server
Receiver
UserB
Receiver
UserC
Receiver
UserA
IGMP
PIM-DM
PIM-DM
PIM-DM
IGMP
Quidway S7700 Smart Routing Switch
Configuration Guide - Multicast 5 PIM-DM (IPv4) Configuration
Issue 01 (2011-07-15) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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