712
Configuring IP Multicast Routing
Configuring Optional IGMP Features
Modifying the PIM Router-Query Message Interval
PIM routers and multilayer switches send PIM router-query messages to find which device will be the DR for each LAN
segment (subnet). The DR is responsible for sending IGMP host-query messages to all hosts on the directly connected
LAN.
With PIM DM operation, the DR has meaning only if IGMPv1 is in use. IGMPv1 does not have an IGMP querier election
process, so the elected DR functions as the IGMP querier. With PIM SM operation, the DR is the device that is directly
connected to the multicast source. It sends PIM register messages to notify the RP that multicast traffic from a source
needs to be forwarded down the shared tree. In this case, the DR is the device with the highest IP address.
Follow this procedure to modify the router-query message interval. This procedure is optional.
BEFORE YOU BEGIN
Review the Information About PIM, page 677.
DETAILED STEPS
To return to the default setting, use the no ip pim query-interval [seconds] interface configuration command.
EXAMPLE
The following example shows how to set the PIM hello interval to 45 seconds:
interface FastEthernet0/1
ip pim query-interval 45
Configuring Optional IGMP Features
This section includes the following topics:
Default IGMP Configuration, page 713
Configuring the Switch as a Member of a Group, page 713 (optional)
Controlling Access to IP Multicast Groups, page 714 (optional)
Command Purpose
1. configure terminal Enter global configuration mode.
2. interface interface-id Specify the interface to be configured, and enter interface
configuration mode.
3. no shutdown Enable the port, if necessary. By default, UNIs and ENIs are
disabled, and NNIs are enabled.
4. ip pim query-interval seconds Configure the frequency at which the switch sends PIM
router-query messages.
The default is 30 seconds. The range is 1 to 65535.
5. end Return to privileged EXEC mode.
6. show ip igmp interface
[interface-id]
Verify your entries.
7. copy running-config
startup-config
(Optional) Save your entries in the configuration file.
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