Chapter 15
Configuring IGMP Snooping
IGMP filtering controls only group-specific query and membership reports, including join and leave
reports. It does not control general IGMP queries. IGMP filtering has no relationship with the function
that directs the forwarding of IP multicast traffic. The filtering feature uses CGMP to forward the
multicast traffic.
IGMP filtering is applicable only to the dynamic learning of IP multicast group addresses, not static
configuration.
With the IGMP throttling feature, you can set the maximum number of IGMP groups that a Layer 2
interface can join. If the maximum number of IGMP groups is set, the IGMP snooping forwarding table
contains the maximum number of entries, and the interface receives an IGMP join report, you can
configure an interface to drop the IGMP report or to replace the randomly selected multicast entry with
the received IGMP report.
Note
IGMPv3 join and leave messages are not supported on switches running IGMP filtering.
These sections contain this configuration information:
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•
•
•
•
Default IGMP Filtering and Throttling Configuration
Table 15-5
Table 15-5
Feature
IGMP filters
IGMP maximum number of IGMP groups
IGMP profiles
IGMP profile action
When the maximum number of groups is in forwarding table, the default IGMP throttling action is to
deny the IGMP report. For configuration guidelines, see the
section on page 15-20.
OL-19808-01
shows the default IGMP filtering configuration.
Default IGMP Filtering Configuration
Configuring IGMP Filtering and Throttling
(optional)
(optional)
(optional)
(optional)
Default Setting
None applied
No maximum set
None defined
Deny the range addresses
"Configuring the IGMP Throttling Action"
Catalyst 2360 Switch Software Configuration Guide
15-17