196
4.
When RP 6 receives the SA messages from RP 4 and RP 5 (suppose RP 5 has a higher IP
address):
RP 4 and RP 5 are in the same AS (AS 3) and both are MSDP peers of RP 6. RP 6 accepts only
the SA message from RP 5, because RP 5 has a higher IP address.
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. 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. Therefore, 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 paths other than those described previously are not accepted or forwarded by
MSDP peers.
Intra-domain Anycast RP through MSDP
Anycast RP refers to an application that enables load balancing and redundancy backup between
two or more RPs within a PIM-SM domain. Anycast RP is implemented by configuring the same IP
address for, and establishing MSDP peering relationship between, these RPs.
As shown in
, within a PIM-SM domain, a multicast source sends multicast data to multicast
group G, and Receiver is a member of the multicast group.
To implement Anycast RP:
1.
Configure the same IP address (known as Anycast RP address, typically a private address) on
Router A and Router B.
2.
Configure these interfaces as C-RPs.
3.
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 61 Intra-domain Anycast RP through MSDP
The working process of Anycast RP is as follows:
