Cisco Catalyst 3560-X Series, Software Configuration Manual

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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-25303-03
Chapter 1 Configuring IGMP Snooping and MVR
Configuring IGMP Snooping
You can configure the switch either to snoop on IGMP queries and PIM/DVMRP packets or to listen to
CGMP self-join or proxy-join packets. By default, the switch snoops on PIM/DVMRP packets on all
VLANs. To learn of multicast router ports through only CGMP packets, use the
ip igmp snooping vlan
vlan-id mrouter learn cgmp global configuration command. When this command is entered, the router
listens to only CGMP self-join and CGMP proxy-join packets and to no other CGMP packets. To learn
of multicast router ports through only PIM-DVMRP packets, use the
ip igmp snooping vlan vlan-id
mrouter learn pim-dvmrp global configuration command.
Note
If you want to use CGMP as the learning method and no multicast routers in the VLAN are CGMP
proxy-enabled, you must enter the
ip cgmp router-only command to dynamically access the router. For
more information, see Chapter 1, “Configuring IP Multicast Routing.”
Beginning in privileged EXEC mode, follow these steps to alter the method in which a VLAN interface
dynamically accesses a multicast router:
To return to the default learning method, use the no ip igmp snooping vlan vlan-id mrouter learn cgmp
global configuration command.
This example shows how to configure IGMP snooping to use CGMP packets as the learning method:
Switch# configure terminal
Switch(config)# ip igmp snooping vlan 1 mrouter learn cgmp
Switch(config)#
end
Configuring a Multicast Router Port
To add a multicast router port (add a static connection to a multicast router), use the ip igmp snooping
vlan mrouter global configuration command on the switch.
Note
Static connections to multicast routers are supported only on switch ports.
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 ip igmp snooping vlan vlan-id mrouter
learn { cgmp | pim-dvmrp }
Enable IGMP snooping on a VLAN. The VLAN ID range is 1 to 1001
and 1006 to 4094.
Specify the multicast router learning method:
•
cgmp —Listen for CGMP packets. This method is useful for
reducing control traffic.
• pim-dvmrp —Snoop on IGMP queries and PIM-DVMRP packets.
This is the default.
Step 3 end Return to privileged EXEC mode.
Step 4 show ip igmp snooping Verify the configuration.
Step 5
copy running-config startup-config (Optional) Save your entries in the configuration file.