Restrictions For Cgmp; Information About Cgmp; Enabling Cgmp Server Support - Cisco Catalyst 2960-XR Configuration Manuals

Restrictions for CGMP

Restrictions for CGMP

The following are the restrictions for CGMP:
• CGMP is mutually exclusive with HSRPv1. You cannot enable CGMP leaving processing and HSRPv1

Information About CGMP

This software release provides Cisco Group Management Protocol or CGMP-server support on your switch;
no client-side functionality is provided. The switch serves as a CGMP server for devices that do not support
IGMP snooping but have CGMP-client functionality.
CGMP is a protocol used on Cisco routers and multilayer switches connected to Layer 2 Catalyst switches to
perform tasks similar to those performed by IGMP. CGMP permits Layer 2 group membership information
to be communicated from the CGMP server to the switch. The switch can then learn on which interfaces
multicast members reside instead of flooding multicast traffic to all switch interfaces. (IGMP snooping is
another method to constrain the flooding of multicast packets.)
CGMP is necessary because the Layer 2 switch cannot distinguish between IP multicast data packets and
IGMP report messages, which are both at the MAC level and are addressed to the same group address.

Enabling CGMP Server Support

The switch serves as a CGMP server for devices that do not support IGMP snooping but have CGMP client
functionality. CGMP is a protocol used on Cisco routers and multilayer switches connected to Layer 2 Catalyst
switches to perform tasks similar to those performed by IGMP. CGMP is necessary because the Layer 2 switch
cannot distinguish between IP multicast data packets and IGMP report messages, which are both at the MAC
level and are addressed to the same group address.
When multiple Cisco CGMP-capable devices are connected to a switched network and the ip cgmp proxy
command is needed, we recommend that all devices be configured with the same CGMP option and have
precedence for becoming the IGMP querier over non-Cisco routers.
This procedure is optional.
SUMMARY STEPS
1. configure terminal
2. interface interface-id
3. ip cgmp [proxy | router-only]
4. end
5. show running-config
6. copy running-config startup-config
Catalyst 2960-XR Switch IP Multicast Routing Configuration Guide, Cisco IOS Release 15.0(2)EX1
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at the same time. However, you can enable CGMP and HSRPv2 at the same time.
Configuring CGMP
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