C H A P T E R
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Catalyst 3550 Multilayer Switch Software Configuration Guide
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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
Catalyst 3550 Multilayer 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 11-1
•
Configuring IGMP Snooping, page 11-5
•
Displaying IGMP Snooping Information, page 11-9
•
Understanding Multicast VLAN Registration, page 11-12
•
Configuring MVR, page 11-14
•
Displaying MVR Information, page 11-18
•
Configuring IGMP Filtering, page 11-20
•
Displaying IGMP Filtering Configuration, page 11-24
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 of multicast 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,
