Design Reference

4. The RP sends join messages towards the source DR on the reverse path.
5. After the source DR receives the join messages, it sends native multicast traffic.
6. After SW_B or SW_D receives multicast traffic from upstream, it forwards the traffic on the
vIST as well as on the SMLT link. Other aggregation switches drop multicast traffic received
over the vIST at egress. This action provides fast failover for multicast traffic. Both SW_D
and SW_E (Aggregation switches) have similar (S,G) records.
7. In case of SW_D or RP failure, SW_B changes only the next-hop interface towards SW_E.
Because the circuitless IP (CLIP) RP address is the same, SW_B does not flush (S,G)
entries and achieves fast failover.
Related Links
Layer 3 switch clustering and multicast SMLT on page 62
Multicast triangle topology
A triangle design is an SMLT configuration that connects edge switches or SMLT clients to two
aggregation switches. Connect the aggregation switches together with a vIST that carries all the
SMLT trunks configured on the switches.
Virtual Services Platform 4000 supports the following triangle configurations:
• a configuration with Layer 3 PIM-SM routing on both the edge and aggregation switches
• a configuration with Layer 2 snooping on the client switches and Layer 3 routing with PIM-SM
on the aggregation switches
To avoid using an external query device to provide correct handling and routing of multicast traffic to
the rest of the network, use the triangle design with IGMP Snoop at the client switches. Use
multicast routing at the aggregation switches as shown in the following figure.
Layer 3 switch clustering and multicast SMLT
64 Network Design Reference for Avaya VSP 4000 Series June 2015
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