20-22
Catalyst 3550 Multilayer Switch Software Configuration Guide
78-11194-09
Chapter 20 Configuring IGMP Snooping and MVR
Configuring IGMP Filtering and Throttling
With the IGMP throttling feature, you can also 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 remove a randomly selected multicast entry in the
forwarding table and then to add the IGMP group in the report to the table.
These sections describe how to configure IGMP filtering and throttling:
• Default IGMP Filtering and Throttling Configuration, page 20-22
• Configuring IGMP Profiles, page 20-22 (optional)
• Applying IGMP Profiles, page 20-23 (optional)
• Setting the Maximum Number of IGMP Groups, page 20-24 (optional)
• Configuring the IGMP Throttling Action, page 20-25 (optional)
Default IGMP Filtering and Throttling Configuration
Table 20-7 shows the default IGMP filtering configuration.
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 “Configuring the IGMP Throttling Action”
section on page 20-25.
Configuring IGMP Profiles
To configure an IGMP profile, use the ip igmp profile global configuration command with a profile
number to create an IGMP profile and to enter IGMP profile configuration mode. From this mode, you
can specify the parameters of the IGMP profile to be used for filtering IGMP join requests from a port.
When you are in IGMP profile configuration mode, you can create the profile by using these commands:
• deny: Specifies that matching addresses are denied; this is the default condition.
• exit: Exits from igmp-profile configuration mode.
• no: Negates a command or sets its defaults.
• permit: Specifies that matching addresses are permitted.
• range: Specifies a range of IP addresses for the profile. You can enter a single IP address or a range
with a start and an end address.
The default is for the switch to have no IGMP profiles configured. When a profile is configured, if
neither the permit nor deny keyword is included, the default is to deny access to the range of IP
addresses.
Table 20-7 Default IGMP Filtering Configuration
Feature Default Setting
IGMP filters None applied
IGMP Maximum number of IGMP groups No maximum set
IGMP profiles None defined
IGMP profile action Deny the range addresses
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