Msdp - Avaya 8800 Planning And Engineering, Network Design

Multicast network design
• One switch has a single SSM range.
• You can have different SSM ranges on different switches.
Configure the core switches that relay multicast traffic so that they cover all of these groups in
their SSM range, or use PIM-SM.
Note:
On the ERS 8800/8600 with IGMPv3, note that receivers on the same switch cannot join flows
from different sources in the same group since the IGMPv3 channel table currently allows only
one entry per group. It does not matter whether the sources are on different switches or not
because the PIM state machine can manage multiple sources per group.
For more information about PIM-SSM scaling, see

MSDP

Multicast Source Discovery Protocol (MSDP) allows rendezvous point (RP) routers to share source
information across Protocol Independent Multicast Sparse-Mode (PIM-SM) domains. RP routers in
different domains use MSDP to discover and distribute multicast sources for a group.
MSDP-enabled RP routers establish MSDP peering relationships with MSDP peers in other
domains. The peering relationship occurs over a TCP connection. When a source registers with the
local RP, the RP sends out Source Active (SA) messages to all of its MSDP peers. The Source
Active message identifies the address of the source, the multicast group address, and the address
of the RP that originates the message.
Each MSDP peer that receives the SA floods it to all MSDP peers that are downstream from the
originating RP. To prevent loops, each receiving MSDP peer examines the routing table (of the
protocol used) to determine which peer is the next hop towards the RP that originated the SA. This
peer is the Reverse Path Forwarding (RPF) peer. Each MSDP peer drops any SAs that are received
on interfaces other than the one connecting to the RPF peer.
MSDP is similar to BGP and in deployments it usually follows BGP peering.
When receivers in a domain belong to a multicast group whose source is in a remote domain, the
normal PIM-SM source-tree building mechanism delivers multicast data over an interdomain
distribution tree. However, with MSDP, group members continue to obtain source information from
their local RP. They are not directly dependent on the RPs in other domains.
The following figure shows an example MSDP network.
June 2016
PIM-SM and PIM-SSM scalability
Planning and Engineering — Network Design
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