HP A8800 Configuration Manual page 203

5. When RP 7 receives the SA message from RP 6, because the SA message is from a static RPF peer
(RP 6), RP 7 accepts the SA message and forwards it to other peer (RP 8).
6. When RP 8 receives the SA message from RP 7, a BGP or MBGP route exists between two MSDP
peers in different ASs. Because the SA message is from an MSDP peer (RP 7) in a different AS, and
the MSDP peer is the next hop on the BGP or MBGP route to the source-side RP, RP 8 accepts the
message and forwards it to its other peer (RP 9).
7. When RP 9 receives the SA message from RP 8, because RP 9 has only one MSDP peer, RP 9
accepts the SA message.
SA messages from other paths than described above will not be accepted nor forwarded by MSDP
peers.
Intra-domain Anycast RP through MSDP
Anycast RP refers to such an application that enables load balancing and redundancy backup between
two or more RPs within a PIM-SM domain by configuring the same IP address for, and establishing MSDP
peering relationships between, these RPs.
The significance of Anycast RP is as follows:
Optimal RP path: A multicast source registers with the nearest RP so that an SPT with the optimal
•
path is built; a receiver joins the nearest RP so that an RPT with the optimal path is built.
• Load balancing between RPs: Each RP just needs to maintain part of the source/group information
within the PIM-SM domain and forward part of the multicast data, thus achieving load balancing
between different RPs.
Redundancy backup between RPs: When an RP fails, the multicast source previously registered on
•
it or the receivers previous joined it will register with or join another nearest RP, thus achieving
redundancy backup between RPs.
As shown in
group G, and Receiver is a member of the multicast group. To implement Anycast RP, configure the same
IP address (known as Anycast RP address, typically a private address) on Router A and Router B,
configure these interfaces as C-RPs, and establish an MSDP peering relationship between Router A and
Router B.
NOTE:
Usually an Anycast RP address is configured on a logic interface, like a loopback interface.
Figure 58 Intra-domain Anycast RP through MSDP
Figure 58, within a PIM-SM domain, a multicast source sends multicast data to multicast
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