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Configuring PIM snooping
This chapter describes PIM snooping, how to configure PIM snooping, configuration examples, and
troubleshooting methods.
Overview
PIM snooping runs on Layer 2 devices. It examines the received PIM messages to determine the
ports that are interested in the multicast data addressed to a multicast group , and adds the ports to
the multicast forwarding entry for the multicast group, so that the multicast data can be forwarded to
only the ports that are interested in the data.
Figure 19 Multicast packet transmission without or with PIM snooping
As shown in
, Source 1 sends multicast data to multicast group G1, and Source 2 sends
multicast data to multicast group G2. Receiver 1 belongs to G1 and Receiver 2 belongs to G2. The
Layer 2 switch's interfaces that connect to the PIM-capable routers are in the same VLAN.
•
When the Layer 2 switch runs only IGMP snooping, it does the following actions:
Multicast packet transmission
when only IGMP snooping runs
Multicast packet transmission when
IGMP snooping and PIM snooping both run
Source 1
Source 2
Receiver 1
Receiver 2
Multicast packets (S1, G1)
Join message (S1, G1)
Layer 2 switch
Source 1
Source 2
Receiver 1
Receiver 2
Layer 2 switch
Multicast packets (S2, G2)
Join message (S2, G2)
PIM
router 3
PIM
router 1
PIM
router 2
PIM
router 4
PIM
router 3
PIM
router 1
PIM
router 2
PIM
router 4