H3C Technologies H3C S10500 Series Switches - Manual (Page 71)

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PIM snooping configuration
PIM snooping overview
Protocol Independent Multicast (PIM) snooping runs on Layer 2 devices. It determines which ports are
interested in multicast data by analyzing the received PIM messages, and adds the ports to a multicast
forwarding entry to ensure that 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
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
As shown in Figure 19 , 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 maintains the router ports according to the
received PIM hello messages that PIM-capable routers send, broadcasts all other types of received