Smlt And Multicast Traffic Issues - Avaya 8800 Planning And Engineering, Network Design

SMLT and multicast traffic issues

This section describes potential traffic issues that can occur in multicast/SMLT networks.
When PIM-SM or other multicast protocols are used in an SMLT environment, the protocol should
be enabled on the IST. Although, in general, routing protocols should not run over an IST, multicast
routing protocols are an exception.
In a single PIM domain with an MBR (Multicast Border Router), Avaya does not support a
configuration of DVMRP in a triangle SMLT and PIM-SM in a square SMLT.
When you use PIM and a unicast routing protocol, ensure that the unicast route to the BSR and RP
has PIM active and enabled. If multiple OSPF paths exist, and PIM is not active on each path, the
BSR is learned on a path that does not have PIM active. The unicast route issue can be described
as follows. In the network shown in the following figure, the switches are configured with the
following:
• 5510A VLAN is VLAN 101.
• 5510B VLAN is VLAN 102.
• BSR is configured on 8600B.
• Both Avaya Ethernet Routing Switch 8800/8600s have OSPF enabled, and PIM is enabled and
active on VLAN 101.
• Both Avaya Ethernet Routing Switch 8800/8600s have OSPF enabled, and PIM is either
disabled or passive on VLAN 102.
Figure 106: Unicast route example
In this example, the unicast route table on 8600A learns the BSR on 8600B through VLAN 102 via
OSPF. The BSR is either not learned or does not provide the RP to 8600A.
Another traffic issue can occur when the path to a source network on the aggregation switches is
the same for both switches. When the path is the same, duplicate traffic can result. The following
figure illustrates the issue and the solution.
June 2016 Planning and Engineering — Network Design
Comments on this document? infodev@avaya.com
Multicast and SMLT guidelines
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