Pim General Requirements - Avaya 8800 Planning And Engineering, Network Design

Multicast network design
Interfaces that run PIM must also use a unicast routing protocol (PIM uses the unicast routing table),
which puts stringent requirements on the system. As a result, 1500 interfaces are not supported in
some scenarios, especially if the number of routes and neighbors is high. With a high number of
interfaces, take special care to reduce the load on the system.
Use few active IP routed interfaces. You can use IP forwarding without a routing protocol enabled
on the interfaces, and enable only one or two with a routing protocol. You can configure proper
routing by using IP routing policies to announce and accept routes on the switch. Use PIM passive
interfaces on the majority of interfaces. Avaya recommends a maximum of ten active PIM interfaces
on a switch when the number of interfaces exceeds 300. The PIM passive interface has the same
uses and advantages as the DVMRP passive interface. For more information, see
interfaces on page 196.
Important:
Avaya does not support more than 80 interfaces and recommends the use of not more than 10
PIM active interfaces in a large-scale configuration of more than 500 VLANs. If you configure
more interfaces, they must be passive.
When using PIM-SM, the number of routes can scale up to the unicast route limit because PIM uses
the unicast routing table to make forwarding decisions. For higher route scaling, Avaya recommends
that you use OSPF rather than PIM.
As a general rule, a well-designed network should not have many routes in the routing table. For
PIM to work properly, ensure that all subnets configured with PIM are reachable and that PIM uses
the information in the unicast routing table. For the RPF check, to correctly reach the source of any
multicast traffic, PIM requires the unicast routing table. For more information, see
non-PIM interfaces
Avaya recommends that you limit the maximum number of active multicast (S,G) pairs to 2000.
Ensure that the number of source subnets times the number of receiver groups does not exceed
500.

PIM general requirements

Avaya recommends that you design simple PIM networks where VLANs do not span several
switches.
PIM relies on unicast routing protocols to perform its multicast forwarding. As a result, your PIM
network design should include a unicast design where the unicast routing table has a route to every
source and receiver of multicast traffic, as well as a route to the Rendezvous Point (RP) router and
Bootstrap router (BSR) in the network. Ensure that the path between a sender and receiver contains
PIM-enabled interfaces. Receiver subnets may not always be required in the routing table.
Avaya recommends that you follow these guidelines:
• Ensure that every PIM-SM domain is configured with a RP and a BSR.
• Ensure that every group address used in multicast applications has an RP in the network.
• As a redundancy option, you can configure several RPs for the same group in a PIM domain.
June 2016
on page 212.
Planning and Engineering — Network Design
Comments on this document? infodev@avaya.com
DVMRP passive
PIM network with
198