Cisco WS-C3750-48PS-S Software Configuration Manual page 472

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 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.
If you want to use CGMP as the learning method and no multicast routers in the VLAN are CGMP
Note
proxy-enabled, you must enter the ip cgmp router-only command to dynamically access the router. For
more information, see
Beginning in privileged EXEC mode, follow these steps to alter the method in which a VLAN interface
dynamically accesses a multicast router:
Command
Step 1 configure terminal
Step 2 ip igmp snooping vlan vlan-id mrouter
learn {cgmp | pim-dvmrp}
Step 3
end
Step 4 show ip igmp snooping
Step 5 copy running-config startup-config
Catalyst 3750 Switch Software Configuration Guide
23-8
Chapter 36, "Configuring IP Multicast Routing."
Purpose
Enter global configuration mode.
Enable IGMP snooping on a VLAN. The VLAN ID range is 1 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.
Return to privileged EXEC mode.
Verify the configuration.
(Optional) Save your entries in the configuration file.
Chapter 23 Configuring IGMP Snooping and MVR
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