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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter11 Configuring IGMP Snooping and MVR
Configuring IGMP Filtering
Configuring IGMP Filtering
In some environments, for example metropolitan or multiple-dwelling unit (MDU) installations, an
administrator might want to control the set of multicast groups to which a user on a switch port can
belong. This allows the administrator to control the distribution of multicast services, such as IP/TV,
based on some type of subscription or service plan. With the IGMP f ilte ring fea ture , you c an fi lter
multicast joins on a per-port basis by configuring IP multicast profiles and associating them with
individual switch ports. An IGMP profile can contain one or more multicast groups and specifies
whether access to the group is permitted or denied. If an IGMP profile denying access to a multicast
group is applied to a switch port, the IGMP join report requ esting t he str eam of I P mu ltic ast tra ffic is
dropped, and the port is not allowed to receive IP multicast traffic from that group. If the filtering action
permits access to the multicast group, the IGMP report from the port is forwarded for normal processing.
IGMP filtering controls only IGMP membership join reports and has no relationship with the function
that directs the forwarding of IP multicast traffic. The filtering feature operates in the same manner
whether CGMP or MVR is used to forward the multicast traffic.
You can also set the maximum number of IGMP groups that a Layer 2 interface can join.

Default IGMP Filtering Configuration

Table11-5 shows the def ault IGM P f ilte ring conf igur ati on.

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 andto enter IGMP profile configuratio n 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 u sing 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 en ter a si ngl e IP addr ess or a rang e
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.
Table11-7 Default MVR 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