Configuration Guide User guide

1560 FastIron Configuration Guide
53-1002494-02
Multicast Source Discovery Protocol (MSDP)
FIGURE 176 PIM Sparse domains joined by MSDP routers
In this example, the source for PIM Sparse multicast group 232.0.1.95 is in PIM Sparse domain 1.
The source sends a packet for the group to its directly attached DR. The DR sends a Group
Advertisement message for the group to the domain RP. The RP is configured for MSDP, which
enables the RP to exchange source information with other PIM Sparse domains by communicating
with RPs in other domains that are running MSDP.
The RP sends the source information to each of its peers by sending a Source Active message. The
message contains the IP address of the source, the group address to which the source is sending,
and the IP address of the RP interface with its peer. By default, the IP address included in the RP
address field of the SA message is the IP address of the originating RP. However, if MSDP is
instructed to use a specific address as the IP address of the RP in a Source Address message (CLI
command originator-id <type> <number>), the Source Active message can be the IP address of any
interface on the originating RP. The interface is usually a loopback interface.
In this example, the Source Active message contains the following information:
• Source address: 206.251.14.22
• Group address: 232.1.0.95
• RP address: 206.251.17.41
Rendezvous Point (RP)
PIM Sparse Domain 3
Rendezvous Point (RP)
Receiver for
Group
232.1.0.95
PIM Sparse Domain 4
Rendezvous Point (RP)
PIM Sparse Domain 2
Source for
Group
232.1.0.95
PIM Sparse Domain 1
Designated Router (DR)
206.251.14.22
Source Advertisement message
1. DR receives traffic from source
and registers source with RP.
2. RP sends SA message
through MSDP to its MSDP
peers in other PIM Sparse
domains.
4. When SA caching is enabled,
the RP immediately responds to
Join messages from receivers.
Otherwise, the RP and receiver
must wait for the next SA message
for the group.
3. RP that receives the SA
floods the SA to all its MSDP
peers, except the one that sent
the SA.
Rendezvous Point (RP)
206.251.17.41