Design Reference

Figure 72: Receivers on interconnected VLANs
IGMP reports that the messages that the receiver sends are forwarded to the DR, and both A and B
create (*,G) records. Switch A receives duplicate data through the path from C to A, and through the
second path from C to B to A. Switch A discards the data on the second path (assuming the
upstream source is A to C).
To avoid this waste of resources, Avaya recommends that you do not place receivers on V1. This
configuration guarantees that no traffic flows between B and A for receivers attached to A. In this
case, the existence of the receivers is only learned through PIM join messages to the RP [for (*,G)]
and of the source through SPT joins.
PIM network with non-PIM interfaces
For proper multicast traffic flow in a PIM-SM domain, as a general rule, enable PIM-SM on all
interfaces in the network (even if paths exist between all PIM interfaces). Enable PIM on all
interfaces because PIM-SM relies on the unicast routing table to determine the path to the RP, BSR,
and multicast sources. Ensure that all routers on these paths have PIM-SM enabled interfaces.
The following figure provides an example of this situation. If A is the RP, then initially the receiver
receives data from the shared tree path (that is, through switch A).
Protocol Independent Multicast-Sparse Mode guidelines
June 2015 Network Design Reference for Avaya VSP 4000 Series 143
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