Square And Full-Mesh Topology Multicast Guidelines; Smlt And Multicast Traffic Issues - Avaya 8800 Planning And Engineering

Multicast network design
Always place any multicast receivers and senders on the core switches on VLANs different
from those that span the IST.

Square and full-mesh topology multicast guidelines

In a square design, you connect a pair of aggregation switches to another pair of aggregation
switches. If you connect the aggregation switches in a full-mesh, it is a full-mesh design. Prior to
release 4.1.1, the full-mesh design does not support SMLT and IP multicast. Releases 4.1.1
and later support Layer 3 IP multicast (PIM-SM only) over a full-mesh SMLT or Routed SMLT
(RSMLT) configuration. The Avaya Ethernet Routing Switch 8800/8600 does not support
DVMRP in SMLT full-mesh designs.
In a square design, you must configure all switches with PIM-SM. Avaya recommends that you
place the BSR and RP in one of the four core switches. For both full-mesh and square
topologies that use multicast, you must set the multicast square-smlt flag.

SMLT and multicast traffic issues

This section describes potential traffic issues that can occur in multicast/SMLT networks.
When PIM-SM or other multicast protocolsare used in an SMLT environment, the protocol
should be enabled onthe IST. Although, in general, routing protocols should not run overan
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.
200 Planning and Engineering — Network Design November 2010