3Com MSR 50 Series Configuration Manual page 1136

1136 C 70: MSDP C
HAPTER
n
ONFIGURATION
An EBGP 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 EBGP 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.
Implementing intra-domain Anycast RP by leveraging MSDP peers
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.
As shown in Figure
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.
Usually Anycast RP address is configured on a logic interface, like a loopback
interface.
Figure 336 Typical network diagram of Anycast RP
RP 1
Source
MSDP peers
SA message
The work process of Anycast RP is as follows:
1 The multicast source registers with the nearest RP. In this example, Source registers
with RP 1, with its multicast data encapsulated in the register message. When the
register message arrives to RP 1, RP 1 decapsulates the message.
2 Receivers send join messages to the nearest RP to join in the RPT rooted as this RP.
In this example, Receiver joins the RPT rooted at RP 2.
3 RPs share the registered multicast information by means of SA messages. In this
example, RP 1 creates an SA message and sends it to RP 2, with the multicast data
336, within a PIM-SM domain, a multicast source sends
Router B
Router A
PIM-SM
RP 2
Receiver