Multicast Routing And Switch Stacks - Cisco WS-CBS3032-DEL Software Configuration Manual

Multicast Routing and Switch Stacks

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.
CGMP is mutually exclusive with HSRPv1. You cannot enable CGMP leaving processing and HSRPv1
at the same time. However, you can enable CGMP and HSRPv2 at the same time. For more information,
see the
Multicast Routing and Switch Stacks
For all multicast routing protocols, the entire stack appears as a single router to the network and operates
as a single multicast router.
In a switch stack, the routing master (stack master) performs these functions:
•
•
•
The stack members perform these functions:
•
•
Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
45-10
"HSRP Versions" section on page
It is responsible for completing the IP multicast routing functions of the stack. It fully initializes and
runs the IP multicast routing protocols.
It builds and maintains the multicast routing table for the entire stack.
It is responsible for distributing the multicast routing table to all stack members.
They act as multicast routing standby devices and are ready to take over if there is a stack master
failure.
If the stack master fails, all stack members delete their multicast routing tables. The newly elected
stack master starts building the routing tables and distributes them to the stack members.
Note If a stack master running the IP services feature set fails and if the newly elected stack master
is running the IP base feature set, the switch stack loses its multicast routing capability.
For information about the stack master election process, see
They do not build multicast routing tables. Instead, they use the multicast routing table that is
distributed by the stack master.
Chapter 45
41-3.
Chapter 7, "Managing Switch Stacks."
Configuring IP Multicast Routing
OL-13270-06