How Msdp Works - H3C S7500E Series Operation Manual

Operation Manual – Multicast
H3C S7500E Series Ethernet Switches
Caution:
MSDP is applicable only if the intra-domain multicast protocol is PIM-SM.
MSDP is meaningful only for the any-source multicast (ASM) model.

6.1.2 How MSDP Works

I. MSDP peers
With one or more pairs of MSDP peers configured in the network, an MSDP
interconnection map is formed, where the RPs of different PIM-SM domains are
interconnected in series. Relayed by these MSDP peers, an SA message sent by an
RP can be delivered to all other RPs.
Figure 6-1 Where MSDP peers are in the network
As shown in
peers created on PIM-SM routers that assume different roles function differently.
1) MSDP peers on RPs
Source-side MSDP peer: the MSDP peer nearest to the multicast source (Source),
typically the source-side RP, like RP 1. The source-side RP creates SA messages
and sends the messages to its remote MSDP peer to notify the MSDP peer of the
locally registered multicast source information. A source-side MSDP must be
created on the source-side RP; otherwise it will not be able to advertise the
multicast source information out of the PIM-SM domain.
Receiver-side MSDP peer: the MSDP peer nearest to the receivers, typically the
receiver-side RP, like RP 3. Upon receiving an SA message, the receiver-side
MSDP peer resolves the multicast source information carried in the message and
joins the SPT rooted at the source across the PIM-SM domain. When multicast
Figure 6-1, an MSDP peer can be created on any PIM-SM router. MSDP
6-2
Chapter 6 MSDP Configuration