Msdp Support For Vpns; Protocols And Standards - HP MSR2003 Configuration Manual

Figure 51 MSDP peer-RPF forwarding
The process of peer-RPF forwarding is as follows:
1. RP 1 creates an SA message and forwards it to its peer RP 2.
2. RP 2 determines that RP 1 is the RP that creates the SA message because the RP address in the SA
message is the same as that of RP 1. Then, RP 2 accepts and forwards the SA message.
3. RP 2 and RP 3 reside in the same AS, and RP 2 is the next hop of RP 3 to RP 1. RP 3 accepts and
forwards the SA message.
4. RP 4 and RP 5 accept the SA message, because RP 3 is in the same mesh group with them. Then,
RP 4 and RP 5 forward the SA message to their peer RP 6 rather than other members of the mesh
group.
5. RP 4 and RP 5 reside in the closest AS in the route to RP 1. However, RP 6 accepts and forwards
only the SA message from RP 5, because the IP address of RP 5 is higher than that of RP 4.
6. RP 7 accepts and forwards the SA message, because RP 6 is its static RPF peer.
7. RP 8 accepts and forwards the SA message, because RP 7 is the eBGP or MBGP next hop of the
peer-RPF route to RP 1.
8. RP 9 accepts the SA message, because RP 8 is the only RP of RP 9.

MSDP support for VPNs

Interfaces on the multicast routers in a VPN can set up MSDP peering relationships with each other. With
the SA messages exchanged between MSDP peers, the multi-instance VPN implements the forwarding of
multicast data across different PIM-SM domains.
To support MSDP for VPNs, a multicast router that runs MSDP maintains an independent set of MSDP
mechanism for each VPN that it supports. These mechanisms include SA message cache, peering
connection, timers, sending cache, and cache for exchanging PIM messages.
One VPN is isolated from another, and MSDP and PIM-SM messages can be exchanged only within the
same VPN.

Protocols and standards

RFC 3618, Multicast Source Discovery Protocol (MSDP)
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