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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
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Chapter 21 Configuring IGMP Snooping and MVR
Configuring IGMP Snooping
To disable IGMP Immediate-Leave on a VLAN, use the no ip igmp snooping vlan vlan-id
immediate-leave global configuration command.
This example shows how to enable IGMP immediate-leave processing on VLAN 130:
Switch# configure terminal
Switch(config)# ip igmp snooping vlan 130 immediate-leave
Switch(config)# end
Disabling IGMP Report Suppression
IGMP report suppression is enabled by default. When it is enabled, the switch forwards only one IGMP
report per multicast router query. When report suppression is disabled, all IGMP reports are forwarded
to the multicast routers.
Note IGMP report suppression is supported only when the multicast query has IGMPv1 and IGMPv2 reports.
This feature is not supported when the query includes IGMPv3 reports.
Beginning in privileged EXEC mode, follow these steps to disable IGMP report suppression:
To re-enable IGMP report suppression, use the ip igmp snooping report-suppression global
configuration command.
Disabling IP Multicast-Source-Only Learning
The IP multicast-source-only learning method is enabled by default. The switch learns the IP multicast
group from the IP multicast data stream and only forwards traffic to the multicast router ports.
If IP multicast-source-only learning is disabled by using the no ip igmp snooping source-only-learning
global configuration command, the switch floods unknown multicast traffic to the VLAN and sends the
traffic to the CPU until the traffic becomes known. When the switch receives an IGMP report from a host
for a particular multicast group, the switch forwards traffic from this multicast group only to the
multicast router ports.
To disable multicast router discovery by PIMv2 packets, you should also enter the no ip igmp snooping
mrouter learn pim v2 global configuration command.
Step 4
show ip igmp snooping vlan vlan-id Verify that Immediate Leave is enabled on the VLAN.
Step 5
copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
no ip igmp snooping report-suppression Disable IGMP report suppression.
Step 3
end Return to privileged EXEC mode.
Step 4
show ip igmp snooping Verify that IGMP report suppression is disabled.
Step 5
copy running-config startup-config (Optional) Save your entries in the configuration file.