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CHAPTER
17-1
Catalyst 2950 Desktop Switch Software Configuration Guide
78-14982-01
17
Configuring IGMP Snooping and MVR
This chapter describes how to configure Internet Group Management Protocol (IGMP) snooping on your
switch, including an application of local IGMP snooping, Multicast VLAN Registration (MVR). It also
includes procedures for controlling multicast group membership by using IGMP filtering.
Note For complete syntax and usage information for the commands used in this chapter, refer to the switch
command reference for this release and the Cisco IOS Release Network Protocols Command Reference,
Part 1, for Release 12.1.
This chapter consists of these sections:
• Understanding IGMP Snooping, page 17-1
• Configuring IGMP Snooping, page 17-5
• Displaying IGMP Snooping Information, page 17-11
• Understanding Multicast VLAN Registration, page 17-13
• Configuring MVR, page 17-15
• Displaying MVR Information, page 17-19
• Configuring IGMP Filtering, page 17-20
• Displaying IGMP Filtering Configuration, page 17-24
Note For MAC addresses that map to IP multicast groups, you can either manage them through features such
as IGMP snooping and MVR, or you can use static MAC addresses. However, you cannot use both
methods simultaneously. Therefore, before using IGMP snooping or MVR, you should remove all
statically configured MAC addresses that map to IP multicast groups.
Understanding IGMP Snooping
Layer 2 switches can use IGMP snooping to constrain the flooding ofmulticast traffic by dynamically
configuring Layer 2 interfaces so that multicast traffic is forwarded to only those interfaces associated
with IP multicast devices. As the name implies, IGMP snooping requires the LAN switch to snoop on
the IGMP transmissions between the host and the router and to keep track of multicast groups and
member ports. When the switch receives an IGMP report from a host for a particular multicast group,