Pim-Sm Overview - Huawei Quidway s3700 series Configuration Manual

Quidway S3700 Series Ethernet Switches
Configuration Guide - Multicast

7.1 PIM-SM Overview

In a PIM-SM network, group members are sparsely distributed and almost all the network
segments do not have group members resided. Therefore, an RP is a forwarding core of the PIM-
SM network. All PIM devices in the PIM-SM network must know the location of the RP and
the RP collects information about both group members and multicast sources.
The Protocol Independent Multicast (PIM) indicates that any unicast routing protocol, such as
static route, RIP, OSPF, IS-IS, or BGP, can provide the routing information for IP multicast.
multicast routing is independent of unicast routing protocols, except that the unicast routing table
is used to generated multicast routing entries.
PIM forwards multicast packets by using the Reverse Path Forwarding (RPF) mechanism. The
RPF mechanism is used to create the multicast forwarding tree through the existing unicast
routing information. When a multicast packet arrives at a switch, the switch performs the RPF
check on the packet. If the RPF check succeeds, a multicast routing entry is created for
forwarding the multicast packet. If the RPF check fails, the packet is discarded.
The working process of the Protocol Independent Multicast-Sparse Mode (PIM-SM) consists
of neighbor discovery, assert, DR election, RP discovery, join, prune, register, and SPT
switchover.
As shown in
group members.
Figure 7-1 Application of PIM-SM a the multicast network
Source
Server
Issue 01 (2011-10-26)
NOTE
The S3700SI does not support PIM-SM.
NOTE
For details of RPF, refer to the chapter
Figure 7-1, PIM-SM is used in a large-scale network with sparsely distributed
PIM-SM
Multicast
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IPv4 Multicast Routing
Receiver
UserA
IGMP
PIM-SM
PIM-SM
PIM-SM
PIM-SM
PIM-SM
PIM-SM
7 PIM-SM (IPv4) Configuration
Management.
Receiver
IGMP
UserB
Receiver
IGMP
UserC
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