3com S7906E Installationsanweisungen

 

1-3 

2)  MSDP peers created on common PIM-SM routers (other than RPs)  

Router A and Router B are MSDP peers on common multicast routers. Such MSDP peers just forward 

received SA messages.  

 

In a PIM-SM network running the BSR mechanism, the RP is dynamically elected from C-RPs. To 

enhance network robustness, a PIM-SM network typically has more than one C-RP. As the RP election 

result is unpredictable, MSDP peering relationships should be built among all C-RPs so that the winner 

C-RP is always on the "MSDP interconnection map”, while loser C-RPs will assume the role of common 

PIM-SM routers on the “MSDP interconnection map”.  

 

As shown in 

, an active source (Source) exists in the domain PIM-SM 1, and RP 1 has 

learned the existence of Source through multicast source registration. If RPs in PIM-SM 2 and PIM-SM 

3 also wish to know the specific location of Source so that receiver hosts can receive multicast traffic 

originated from it, MSDP peering relationships should be established between RP 1 and RP 3 and 

between RP 3 and RP 2 respectively.  

Figure 1-2 MSDP peering relationships 

PIM-SM 1

PIM-SM 3

PIM-SM 2

PIM-SM 4

MSDP peers

SA message

Join message

Multicast packets

Register message

 

 

The process of implementing inter-domain multicast delivery by leveraging MSDP peers is as follows:  

1)  When the multicast source in PIM-SM 1 sends the first multicast packet to multicast group G, DR 1 

encapsulates the multicast data within a register message and sends the register message to RP 1. 

Then, RP 1 gets aware of the information related to the multicast source.