Reference Guide

724 | PIM Sparse-Mode
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Similarly, in Figure 37-1, when PIM-SM snooping is enabled and multicast data is sent to VLAN members
of group G, the switches forward the data traffic from the server attached to Router B only to the router
(Router A) in the multicast group that should receive it. Without PIM-SM snooping, the switches would
flood the data to all connected routers, including Routers C and D.
Figure 37-2. PIM-SM Snooping: Data Forwarding
PIM-SM Snooping Configuration
You can enable PIM-SM snooping globally on a switch or on individual VLANs. PIM-SM snooping is not
enabled by default and does not require an IP address, PIM-DM, or PIM-SM.
PIM-SM snooping and PIM multicast routing are mutually exclusive: PIM-SM snooping cannot be
enabled on a switch/router if PIM-SM or PIM-DM is enabled.
If enabled at the global level, PIM-SM snooping is automatically enabled on all VLANs on the switch
unless the
no ip pim snooping command has been entered on a VLAN interface.
If enabled at the VLAN level, PIM-SM snooping requires that you also enter the
no shutdown command to
enable the interface.
Router A
Router B
RP Source
Router C
Router D
Data
G Traffic
Layer 2 Network
with PIM Snooping