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Each PIM router in the VLAN, whether interested in the multicast data or not, can receive all
multicast data and all PIM messages except PIM hello messages.
•
When the Layer 2 switch runs both IGMP snooping and PIM snooping, it performs the following
actions:
d.
Examines whether a PIM router is interested in the multicast data addressed to a multicast
group according to the received PIM messages that the router sends.
e.
Adds only the ports that connect to the router and are interested in the data to a PIM
snooping routing entry.
f.
Forwards PIM messages and multicast data to only the routers that are interested in the
data, which saves network bandwidth.
For more information about IGMP snooping and the router port, see "Configuring IGMP snooping."
PIM snooping can run in PIM-SM and PIM-SSM networks. Do not configure PIM snooping in
PIM-DM or BIDIR-PIM networks. For more information about PIM, see "Configuring PIM."
Configuring PIM snooping
IMPORTANT:
•
Do not configure PIM snooping in secondary VLANs because PIM snooping does not take effect on
secondary VLANs. For more information about secondary VLANs, see
Layer 2—LAN Switching
Configuration Guide
.
•
Make sure the maximum size of a PIM join or prune message is smaller than the path MTU of devices
connected to PIM snooping devices. Otherwise, fragmented PIM join or prune messages prevent PIM
snooping from correctly forwarding multicast data. For more information about setting the maximum size of
a join or prune message, see "Configuring PIM."
To configure PIM snooping for a VLAN or VSI, you must enable IGMP snooping globally on the Layer
2 device, and then enable IGMP snooping and PIM snooping for the VLAN or VSI.
After you enable PIM snooping for a VLAN, PIM snooping works only on the member interfaces of
the VLAN.
To configure PIM snooping:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable IGMP snooping
globally and enter
IGMP-snooping view.
igmp-snooping
By default, IGMP snooping is
disabled.
3.
Return to system view.
quit
N/A
4.
Enter VLAN view or VSI
view.
•
Enter VLAN view:
vlan vlan-id
•
Enter VSI view:
vsi
vsi-name
N/A
5.
Enable IGMP snooping for
the VLAN or VSI.
igmp-snooping enable
By default, IGMP snooping is
disabled in a VLAN or VSI.
6.
Enable PIM snooping for the
VLAN or VSI.
pim-snooping enable
By default, PIM snooping is disabled
in a VLAN or VSI.
7.
(Optional.) Set the aging
time for global neighbor
ports on the new master
device after a
master/subordinate
pim-snooping
graceful-restart
neighbor-aging-time
seconds
The default setting is 105 seconds.
A global neighbor port is a Layer 2
aggregate interface, AC, N-PW, or
U-PW that acts as a neighbor port.