Multicast And Multi-Link Trunking Considerations - Avaya 8800 Planning And Engineering, Network Design

Multicast network design

Multicast and Multi-Link Trunking considerations

Multicast traffic distribution is important because the bandwidth requirements can be substantial
when a large number of streams are employed. The Avaya Ethernet Routing Switch 8800/8600 can
distribute IP multicast streams over links of a multilink trunk. If you need to use several links to share
the load of several multicast streams between two switches, use one of the following:
• DVMRP or PIM route tuning to load share streams
• Multicast flow distribution over MLT
DVMRP or PIM route tuning to load share streams
You can use Distance Vector Multicast Routing Protocol (DVMRP) or Protocol Independent
Multicast (PIM) routing to distribute multicast traffic. With this method, you must distribute sources of
multicast traffic on different IP subnets and configure routing metrics so that traffic from different
sources flows on different paths to the destination groups.
The following figure illustrates one way to distribute multicast traffic sourced on different subnets
and forwarded on different paths.
Figure 82: Traffic distribution for multicast data
The multicast sources S1 to S4 are on different subnets; use different links for every set of sources
to send their multicast data. In this case, S1 and S2 send their traffic on a common link (L1) and S3
and S4 use another common link (L2). These links can be MLT links. Unicast traffic is shared on the
MLT links, whereas multicast traffic only uses one of the MLT links. Receivers can be located
anywhere on the network. This design can be worked in parallel with unicast designs and, in the
case of DVMRP, does not impact unicast routing.
In this example, sources must be on the VLAN that interconnects the two switches. In more generic
scenarios, you can design the network by changing the interface cost values to force some paths to
be taken by multicast traffic.
June 2016
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Planning and Engineering — Network Design
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