H3C S9500 Series Operation Manual page 4

Operation Manual – MSDP
H3C S9500 Series Routing Switches
message. Besides, the RP in domain 1 encapsulates the first received multicast data
into this SA message.
If there is any group member in the domain of an MSDP peer (in the figure, it is PIM-SM
domain 3), the RP in this domain sends the multicast data encapsulated in the SA
message to group members along the RPT and the join message to multicast source.
After the reverse forwarding path is created, the multicast source data is sent directly to
the RP in domain 3, and then the RP forwards the data along the RPT. In this case, the
last hop router connected with the group member in domain 3 can choose whether to
switch to SPT.
II. Message forwarding and RPF check between MSDP peers
As shown in
D to domain 2, and Switch E and Switch F to domain 3. MSDP peer relationship is
established between them, indicated with bi-directional arrows in the figure. Among
them, Mesh Group is created among Switch B, Switch C and Switch D.
Switch E
Switch F
Figure 1-2 MSDP working principles (II)
The SA message forwarding and RPF check among these MSDP peers are illustrated
as follows:
If the SA message is from a MSDP peer that is the RP of the multicast source, it is
received and forwarded to other peers (for example, from Switch A to Switch B).
If the SA message is from a MSDP peer that has only one peer, it is received (for
example, from Switch B to Switch A).
If the SA message is from a static RPF peer, it is received and forwarded to other peers
(for example, from Switch D to Switch E).
If the SA message is from a MSDP peer in Mesh Group, it is received and forwarded to
the peers outside the Mesh Group (for example, from Switch B to Switch D).
Figure 1-2, Switch A belongs to domain 1, Switch B, Switch C, and Switch
AS 1
Switch A
Source
AS 2
AS 3
Static Peer
Switch D
Switch B
Mesh Group
Switch C
1-3
Chapter 1 MSDP Configuration