Multicast Source Discovery Protocol (Msdp); Protocol Overview - Dell Force10 S4810P Configuration Manual

Multicast Source Discovery Protocol (MSDP)

Multicast Source Discovery Protocol (MSDP)

Protocol Overview

Multicast Source Discovery Protocol (MSDP) is a Layer 3 protocol that connects IPv4 PIM-SM domains.
A domain in the context of MSDP is contiguous set of routers operating PIM within a common boundary
defined by an exterior gateway protocol, such as BGP.
Each RP peers with every other RP via TCP. Through this connection, peers advertise the sources in their
domain.
1. When an RP in a PIM-SM domain receives a PIM register message from a source it sends a
Source-Active (SA) message
2. Each MSDP peer receives and forwards the message to its peers away from the originating RP.
3. When an MSDP peer receives an SA message, it determines if there are any group members within the
domain interested in any of the advertised sources. If there are, the receiving RP sends a join message
to the originating RP, creating an SPT to the source.
Figure 31-1. Multicast Source Discovery Protocol
AS X
Area 0
1/21
1/2
R1
1/1
PC 1
Receiver
(Figure
PC 2
Source
2/1
R2
2/11
RP1
is supported on platform
31-1) to MSDP peers.
PC 3
Receiver
3/21
3/41
R3
RP
Multicast Source Discovery Protocol (MSDP) | 665
31
e
and
4/1
R4
4/31
.
AS Y
Area 0