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Catalyst 2950 Desktop Switch Software Configuration Guide
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Chapter 17 Configuring IGMP Snooping and M V R Configuring IGMP Snooping
Beginning in privileged EXEC mode, follow these steps to alter the method in which a VLAN interface
dynamically accesses a multicast router:
This example shows how to configure IGMP sno oping to use C GMP packets as t he learni ng method :
Switch# configure terminal
Switch(config)# ip igmp snooping vlan 1 mrouter learn cgmp
Switch(config)# end
Switch# show ip igmp snooping vlan 1
vlan 1
----------
IGMP snooping is globally enabled
IGMP snooping is enabled on this Vlan
IGMP snooping immediate-leave is disabled on this Vlan
IGMP snooping mrouter learn mode is cgmp on this Vlan
IGMP snooping is running in IGMP_ONLY mode on this Vlan
To retur n to the defaul t learning method, use the no ip ig mp snooping vlan vlan -id mr outer learn cgmp
global configurat ion comm and.

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 c onfigura tion c om mand on the swit ch.
Beginning in privileged EXEC mode, follow these steps to enable a static connection to a multicast
router:
Command Purpose
Step 1 configure terminal Enter g lo bal c onfigurat ion m ode.
Step 2 ip igmp snooping vlan vlan-id mrouter
learn {cgmp | pim-dvmrp}Enable IGMP snooping on a VL AN .The VLAN ID range is 1 to 1005
when the standard software image (SI) is installed and 1 to 4094 when
the enhanced software image (EI) is installed (or when running on an
Catalys t 2950 LRE switc h); do not en ter leadin g zeros.
Specify th e multi cast ro uter lear ning met hod:
•cgmp—Listen for CGMP packets. This method is useful for
reduci ng co n trol tr affic.
•pim-dvmrp—Snoop on IGM P queri es a nd PIM-DVMRP
packets. This is the default.
Step 3 end Return to privileged EXEC mode.
Step 4 show ip igmp snooping Verify the configurat ion.
Step 5 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Step 1 configure terminal Enter globa l configurati on mode.
Step 2 ip igmp snooping vlan vlan-id mrouter
interface interface-id Specify the multicast router VLAN ID and specify the interface
to the multicast router. For the VLAN ID, the range is 1 to 1005
when the SI is insta lled and 1 t o 4094 when the E I is install ed; do
not enter leading zeros.