H3C Technologies H3C SecPath F1000-E - Manual (Page 67)

6
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 4 , 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 4 Typical network diagram of Anycast RP
SA message
Source Receiver
Router A Router B
RP 1 RP 2
PIM-SM
MSDP peers
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 at RP
1, RP 1 de-encapsulates 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 from Source encapsulated in
the SA message. When the SA message reaches RP 2, RP 2 de-encapsulates the message.
4. Receivers receive the multicast data along the RPT and directly join the SPT rooted at the multicast
source. In this example, RP 2 forwards the multicast data down the RPT. When Receiver receives
the multicast data from Source, it directly joins the SPT rooted at Source.
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.