Configuring Igmp Snooping And Mvr; Understanding Igmp Snooping - Cisco Catalyst 2950 Software Configuration Manual

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 2950 Desktop 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:
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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

Internet Group Management Protocol (IGMP) snooping constrains the flooding of multicast traffic by
dynamically configuring the interfaces so that multicast traffic is forwarded only to those interfaces
associated with IP multicast devices. The LAN switch snoops on the IGMP traffic between the host and
the router and keeps track of multicast groups and member ports. When the switch receives an IGMP
join report from a host for a particular multicast group, the switch adds the host port number to the
associated multicast forwarding table entry. When it receives an IGMP Leave Group message from a
78-11380-04
Understanding IGMP Snooping, page 16-1
Configuring IGMP Snooping, page 16-5
Displaying IGMP Snooping Information, page 16-10
Understanding Multicast VLAN Registration, page 16-11
Configuring MVR, page 16-13
Displaying MVR Information, page 16-17
Configuring IGMP Filtering, page 16-18
Displaying IGMP Filtering Configuration, page 16-22
C H A P T E R
Catalyst 2950 Desktop Switch Software Configuration Guide
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16-1