Cisco Systems 3750E manual Controlling Access to IP Multicast Groups, 42-30

Chapter 42 Configuring IP Multicast Routing

Configuring Optional IGMP Features

	Command	Purpose
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 cancel membership in a group, use the no ip igmp join-groupgroup-addressinterface configuration command.

This example shows how to enable the switch to join multicast group 255.2.2.2:

Switch(config)# interface gigabitethernet1/0/1

Switch(config-if)#ip igmp join-group 255.2.2.2

Controlling Access to IP Multicast Groups

The switch sends IGMP host-query messages to find which multicast groups have members on attached local networks. The switch then forwards to these group members all packets addressed to the multicast group. You can place a filter on each interface to restrict the multicast groups that hosts on the subnet serviced by the interface can join.

Beginning in privileged EXEC mode, follow these steps to filter multicast groups allowed on an interface. 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 access-group access-list-number		Specify the multicast groups that hosts on the subnet serviced by an
			interface can join.
			By default, all groups are allowed on an interface.
			For access-list-number, specify an IP standard access list number.
			The range is 1 to 99.
Step 4	exit		Return to global configuration mode.
Step 5	access-listaccess-list-number {deny		Create a standard access list.
	permit} source [source-wildcard]		• For access-list-number, specify the access list created in Step 3.
			• The deny keyword denies access if the conditions are matched.
			The permit keyword permits access if the conditions are
			matched.
			• For source, specify the multicast group that hosts on the subnet
			can join.
			• (Optional) For source-wildcard, enter the wildcard bits in dotted
			decimal notation to be applied to the source. Place ones in the bit
			positions that you want to ignore.
			Recall that the access list is always terminated by an implicit deny
			statement for everything.
Step 6	end		Return to privileged EXEC mode.
		Catalyst 3750-E and 3560-E Switch Software Configuration Guide
42-30			OL-9775-02