Cisco Systems 78-11741-02 manual Igmp Features Configuration Task List, IPC-409

Configuring IP Multicast Routing

IGMP Features Configuration Task List

IGMP Features Configuration Task List

To configure IGMP features, perform the tasks described in the following sections. The tasks in the first section are required; the tasks in the remaining sections are optional.

•Configuring a Router to Be a Member of a Group (Required)

•Controlling Access to IP Multicast Groups (Optional)

•Changing the IGMP Version (Optional)

•Modifying the IGMP Host-Query Message and Query Timeout Intervals (Optional)

•Configuring IGMP Version 3 (Optional)

•Changing the Maximum Query Response Time (Optional)

•Configuring the Router as a Statically Connected Member (Optional)

•Configuring IGMP Leave Latency (Optional)

For information about configuring IGMP unidirectional link routing (UDLR), see the chapter “Configuring Unidirectional Link Routing” in this document.

Configuring a Router to Be a Member of a Group

Cisco routers can be configured to be members of a multicast group. This strategy is useful for determining multicast reachability in a network. If a device is configured to be a group member and supports the protocol that is being sent to the group, it can respond (to the ping EXEC command, for example). The device responds to ICMP echo request packets addressed to a group of which it is a member. Another example is the multicast traceroute tools provided in the Cisco IOS software.

To have the router join a multicast group and enable IGMP, use the following command in interface configuration mode:

Command	Purpose
Router(config-if)# ip igmp join-groupgroup-address	Joins a multicast group.

Controlling Access to IP Multicast Groups

Multicast routers send IGMP host query messages to determine which multicast groups have members in the attached local networks of the router. The routers then forward to these group members all packets addressed to the multicast group. You can place a filter on each interface that restricts the multicast groups that hosts on the subnet serviced by the interface can join.

To filter multicast groups allowed on an interface, use the following command in interface configuration mode:

Command	Purpose
Router(config-if)#ip igmp access-group access-list	Controls the multicast groups that hosts on the subnet serviced
	by an interface can join.

Cisco IOS IP Configuration Guide

IPC-409