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20-12
Catalyst 3550 Multilayer Switch Software Configuration Guide
78-11194-09
Chapter 20 Configuring IGMP Snooping and MVR
Displaying IGMP Snooping Information
Configuring the Aging Time
You can set the aging time for forwarding-table entries that the switch learns by using the IP
multicast-source-only learning method.
Beginning in privileged EXEC mode, follow these steps to configure the aging time:
To disable the aging of the forwarding table entries, enter the ip igmp snooping source-only-learning
age-timer 0 global configuration command.
Displaying IGMP Snooping Information
You can display IGMP snooping information for dynamically learned and statically configured router
ports and VLAN interfaces. You can also display MAC address multicast entries for a VLAN configured
for IGMP snooping.
To display IGMP snooping information, use one or more of the privileged EXEC commands in
.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode
Step 2
ip igmp snooping source-only learning age-timer
time
Set the aging time. The range is from 0 to 2880 seconds. The
default is 600 seconds (10 minutes).
Step 3
end
Return to privileged EXEC mode.
Step 4
show running-config | include
source-only-learning
Verify the aging time.
Step 5
copy running-config startup-config
(Optional) Save your entries in the configuration file.
Table 20-4 Commands for Displaying IGMP Snooping Information
Command
Purpose
show ip igmp snooping [vlan vlan-id]
Display the snooping configuration information for all VLANs on the
switch or for a specified VLAN.
(Optional) Enter vlan vlan-id to display information for a single VLAN.
show ip igmp snooping group [vlan vlan-id]
Display information about the IGMP multicast groups, the compatibility
mode, and the ports that are associated with each group.
(Optional) Enter vlan vlan-id to display information for a single VLAN.
show ip igmp snooping mrouter [vlan vlan-id]
Display information on dynamically learned and manually configured
multicast router interfaces.
Note
When you enable IGMP snooping, the switch automatically
learns the interface to which a multicast router is connected.
These are dynamically learned interfaces.
(Optional) Enter vlan vlan-id to display information for a single VLAN.