Cisco Systems 3750E Changing the Igmp Query Timeout for IGMPv2, Ip igmp query-interval seconds

Chapter 42 Configuring IP Multicast Routing

Configuring Optional IGMP Features

The switch elects a PIM designated router (DR) for the LAN (subnet). The DR is the router or multilayer switch with the highest IP address for IGMPv2. For IGMPv1, the DR is elected according to the multicast routing protocol that runs on the LAN. The designated router is responsible for sending IGMP host-query messages to all hosts on the LAN. In sparse mode, the designated router also sends PIM register and PIM join messages toward the RP router.

Beginning in privileged EXEC mode, follow these steps to modify the host-query interval. This procedure is optional.

	Command	Purpose
Step 1
	configure terminal	Enter global configuration mode.
Step 2
	interface interface-id	Specify the interface to be configured, and enter interface configuration
		mode.
Step 3
	ip igmp query-interval seconds	Configure the frequency at which the designated router sends IGMP
		host-query messages.
		By default, the designated router sends IGMP host-query messages
		every 60 seconds to keep the IGMP overhead very low on hosts and
		networks. The range is 1 to 65535.
Step 4
	end	Return to privileged EXEC mode.
Step 5
	show ip igmp interface [interface-id]	Verify your entries.
Step 6
	copy running-config startup-config	(Optional) Save your entries in the configuration file.

To return to the default setting, use the no ip igmp query-intervalinterface configuration command.

Changing the IGMP Query Timeout for IGMPv2

If you are using IGMPv2, you can specify the period of time before the switch takes over as the querier for the interface. By default, the switch waits twice the query interval controlled by the ip igmp query-intervalinterface configuration command. After that time, if the switch has received no queries, it becomes the querier.

You can configure the query interval by entering the show ip igmp interface interface-idprivileged EXEC command.

Beginning in privileged EXEC mode, follow these steps to change the IGMP query timeout. This procedure is optional.

	Command	Purpose
Step 1
	configure terminal	Enter global configuration mode.
Step 2
	interface interface-id	Specify the interface to be configured, and enter interface configuration
		mode.
Step 3
	ip igmp querier-timeout seconds	Specify the IGMP query timeout.
		The default is 60 seconds (twice the query interval). The range is 60
		to 300.
Step 4
	end	Return to privileged EXEC mode.

	Catalyst 3750-E and 3560-E Switch Software Configuration Guide
42-32	OL-9775-02