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Catalyst 3560 Switch Software Configuration Guide
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Chapter 23 Configuring IGMP Snooping and MVR
Configuring IGMP Snooping
Beginning in privileged EXEC mode, follow these steps to enable IGMP snooping on a VLAN interface:
To disable IGMP snooping on a VLAN interface, use the no ip igmp snooping vlan vlan-id global
configuration command for the specified VLAN number.
Setting the Snooping Method
Multicast-capable router ports are added to the forwarding table for every Layer 2 multicast entry. The
switch learns of such ports through one of these methods:
Snooping on IGMP queries, Protocol Independent Multicast (PIM) packets, and Distance Vector
Multicast Routing Protocol (DVMRP) packets
Listening to Cisco Group Management Protocol (CGMP) packets from other routers
Statically connecting to a multicast router port with the ip igmp snooping mrouter global
configuration command
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 44, “Configuring IP Multicast Routing.”
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 ip igmp snooping vlan vlan-id Enable IGMP snooping on the VLAN interface.The VLAN ID range
is 1 to 1001 and 1006 to 4094.
Note IGMP snooping must be globally enabled before you can
enable VLAN snooping.
Step 3 end Return to privileged EXEC mode.
Step 4 copy running-config startup-config (Optional) Save your entries in the configuration file.