Changing The Cgmp Router Hold-Time; Removing Multicast Groups - Cisco WS-C2955T-12 Software Manual

Configuring CGMP

Changing the CGMP Router Hold-Time

The router hold-time is the number of seconds the switch waits before removing (aging) a router entry
and ceasing to exchange messages with the router. If it is the last router entry in a VLAN, all CGMP
groups on that VLAN are removed. You can thus enter a lower router hold-time to accelerate the removal
of CGMP groups.
You can remove router ports before the router hold-time has expired.
Note
Beginning in privileged EXEC mode, follow these steps to change the router hold-time:
Command
Step 1
configure terminal
Step 2
cgmp holdtime 400
Step 3
end
Step 4 show running-config

Removing Multicast Groups

You can reduce the forwarding of IP multicast packets by removing groups from the Current Multicast
Groups table. Each entry in the table consists of the VLAN, IGMP multicast address, and ports.
You can use the CLI to clear all CGMP groups, all CGMP groups in a VLAN, or all routers, their ports,
and their expiration times. Beginning in privileged EXEC mode, follow these steps to remove all
multicast groups:
Command
Step 1 clear cgmp group
Step 2
show cgmp
Catalyst 2900 Series XL and Catalyst 3500 Series XL Software Configuration Guide
6-22
Purpose
Enter global configuration mode.
Configure the number of seconds the switch waits before dropping a router
entry.
Return to privileged EXEC mode.
Verify your entry.
Purpose
Clear all CGMP groups on all VLANs on the switch.
Verify your entry by displaying CGMP information.
Chapter 6 Configuring the System
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