46-40
Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter46 Configuring IP Multicast Routing
Configuring Optional IGMP Features
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.
To disable groups on an interface, use the no ip igmp access-group interface configuration command.
This example shows how to configure hosts attached to a port as able to join only group 255.2.2.2:
Switch(config)# access-list 1 255.2.2.2 0.0.0.0
Switch(config)# interface gigabitethernet1/0/1
Switch(config-if)# ip igmp access-group 1
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 interface interface-id Specify the interface to be configured, and enter interface
configuration mode.
Step3 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.
Step4 exit Return to global configuration mode.
Step5 access-list access-list-number {deny |
permit} source [source-wildcard]
Create a standard access list.
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.
Step6 end Return to privileged EXEC mode.
Step7 show ip igmp interface [interface-id] Verify your entries.
Step8 copy running-config startup-config (Optional) Save your entries in the configuration file.