Redundancy For Multicast Traffic - Cisco WS-C6506 Software Manual

Chapter 51 Configuring Multicast Services

Redundancy for Multicast Traffic

Redundancy for multicast traffic requires the following conditions:
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Unicast routing protocol such as OSPF or EIGRP
PIM uses RPF checks on the unicast routing table to determine the proper paths for multicast data
to traverse. If a unicast routing path changes, PIM relies upon the unicast routing protocol (OSPF)
to properly converge, so that the RPF checks used by PIM continue to work and show valid unicast
paths to and from the source IP address of the server sourcing the multicast stream.
PIM configured on all related Layer 3 interfaces
The unicast routing table is used to do path selection for PIM. PIM uses RPF checks to ultimately
determine the shortest path tree (SPT) between the client (receiver VLAN) and the source (multicast
VLAN). Therefore, the objective of PIM is to find the shortest unicast path between the receiver
subnet and the source subnet. You do not need to configure anything else for multicast when the
unicast routing protocol is working as expected and PIM is configured on all the Layer 3 links
associated with the unicast routing protocol.
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
Understanding How Multicasting Works
51-9