HP MSR2003 Configuration Manual page 151

The subsequent multicast data flows to RP 2 along the SPT, and from RP 2 to the receiver-side
DR along the RPT. After receiving the multicast data, the receiver-side DR determines whether
to initiate an RPT-to-SPT switchover process based on its configuration.
If no receivers exist in the domain, RP 2 neither creates an (S, G) entry nor sends a join message
toward the multicast source.
In inter-domain multicasting using MSDP, once an RP gets information about a multicast source in another
PIM-SM domain, it no longer relies on RPs in other PIM-SM domains. The receivers can override the RPs
in other domains and directly join the multicast SPT rooted at the source.
Anycast RP through MSDP
PIM-SM requires only one active RP to serve each multicast group. If the active RP fails, the multicast traffic
might be interrupted. The Anycast RP mechanism enables redundancy backup between two or more RPs
by configuring multiple RPs with the same IP address for one multicast group. A multicast source registers
with the nearest RP or a receiver joins the nearest RP to implement source information synchronization.
Anycast RP has the following benefits:
Optimal RP path—A multicast source registers with the nearest RP to build an optimal SPT. A
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receiver joins the nearest RP to build an optimal RPT.
Redundancy backup among RPs—When an RP fails, the RP-related sources and receiver-side DRs
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will register with or join their nearest available RPs. This achieves redundancy backup among RPs.
Anycast RP is implemented by using either of the following methods:
Anycast RP through PIM-SM—In this method, you can configure multiple RPs for one multicast group
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and add them to an Anycast RP set. For more information about Anycast RP through PIM-SM, see
"Configuring PIM."
• Anycast RP through MSDP—In this method, you can configure multiple RPs with the same IP address
for one multicast group and configure MSDP peering relationships between the RPs.
As shown in
multicast group G, and the receiver joins the multicast group.
To implement Anycast RP through MSDP:
a. Configure the same IP address (known as Anycast RP address, typically a private address) to
an interface on Router A and Router B.
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b. Configure the interfaces as C-RPs.
c. Establish an MSDP peering relationship between Router A and Router B.
An MSDP peer address must be different from the Anycast RP address.
Figure 50, within a PIM-SM domain, a multicast source sends multicast data to
An Anycast RP address is usually configured on a logical interface, such as a loopback
interface.
Make sure the Anycast RP address is a host address (with the subnet mask
255.255.255.255).
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