H3C Technologies H3C S10500 Series Switches - Manual (Page 223)

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3. When RP 4 and RP 5 receive the SA message from RP 3:
Because the SA message is from an MSDP peer (RP 3) in the same mesh group, RP 4 and RP 5 both
accept the SA message, but they do not forward the message to other members in the mesh group.
Instead, they forward it to other MSDP peers (RP 6 in this example) out of the mesh group.
4. When RP 6 receives the SA messages from RP 4 and RP 5 (suppose RP 5 has a higher IP address):
Although RP 4 and RP 5 are in the same AS (AS 3) and both are MSDP peers of RP 6, because RP
5 has a higher IP address, RP 6 accepts only the SA message from RP 5.
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 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 by configuring the same IP address for, and establishing MSDP
peering relationships between, these RPs.
As shown in
Figure 61 , 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, 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 61 Intra-domain Anycast RP through MSDP
SA message
Source Receiver
Router A Router B
RP 1 RP 2
PIM-SM
MSDP peers