Split-Subnet And Multicast; Layer 2 Multicast Features - Avaya 8800 Planning And Engineering, Network Design

Figure 86: Applying IP multicast access policies for DVMRP
The following rules and limitations apply to IGMP access policy parameters when used with IGMP
versus DVMRP and PIM:
• The static member parameter applies to IGMP snooping, DVMRP, and PIM on both
interconnected links and edge ports.
• The Static Not Allowed to Join parameter applies to IGMP snooping, DVMRP, and PIM on both
interconnected links and edge ports.
• For multicast access control, the denyRx parameter applies to IGMP snooping, DVMRP, and
PIM. The DenyTx and DenyBoth parameters apply only to IGMP snooping.

Split-subnet and multicast

The split-subnet issue arises when a subnet is divided into two unconnected sections in a network.
This results in the production of erroneous routing information about how to reach the hosts on that
subnet. The split-subnet problem applies to any type of traffic. However, it has a larger impact on a
PIM-SM network.
To avoid the split-subnet problem in PIM networks, ensure that the Rendezvous Point (RP) router is
not located in a subnet that can become a split subnet. Also, avoid having receivers on this subnet.
Because the RP is an entity that must be reached by all PIM-enabled switches with receivers in a
network, placing the RP on a split-subnet can impact the whole multicast traffic flow. Traffic can be
affected even for receivers and senders that are not part of the split-subnet.

Layer 2 multicast features

On Layer 2 VLANs, the Avaya Ethernet Routing Switch 8800/8600 provides the following features to
support multicast traffic.
• IGMP snoop and proxy
June 2016
on page 188
Planning and Engineering — Network Design
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Layer 2 multicast features
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