C H A P T E R
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Cisco ME 3800X and 3600X Switch Software Configuration Guide
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Configuring IGMP Snooping
This chapter describes how to configure Internet Group Management Protocol (IGMP) snooping on the
Cisco ME 3800X and ME 3600X switch. It also includes procedures for controlling multicast group
membership by using IGMP filtering and procedures for configuring the IGMP throttling action.
Note
For complete syntax and usage information for the commands used in this chapter, see the switch
command reference for this release and the “IP Multicast Routing Commands” section in the Cisco IOS
IP Command Reference, Volume 3 of 3:Multicast, Release 12.2.
•
Understanding IGMP Snooping, page 18-1
•
Configuring IGMP Snooping, page 18-6
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Displaying IGMP Snooping Information, page 18-12
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Configuring IGMP Filtering and Throttling, page 18-13
•
Displaying IGMP Filtering and Throttling Configuration, page 18-18
Note
You can either manage IP multicast group addresses through features such as IGMP snooping or you can
use static IP addresses.
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,
the switch adds the host port number to the forwarding table entry; when it receives an IGMP Leave
Group message from a host, it removes the host port from the table entry. It also periodically deletes
entries if it does not receive IGMP membership reports from the multicast clients.
Note
For more information on IP multicast and IGMP, see RFC 1112 and RFC 2236.