HP MSR ASM Configuration Manual page 313

specified on each router in the IPv6 PIM-SM domain. An RP can serve multiple IPv6 multicast groups, but
a given IPv6 multicast group can have only one RP to serve it at a time.
In most cases, however, an IPv6 PIM-SM network covers a wide area and a huge amount of IPv6
multicast traffic must be forwarded through the RP. To lessen the RP burden and optimize the topological
structure of the RPT, you can configure multiple C-RPs in an IPv6 PIM-SM domain. Among them, an RP is
dynamically elected through the bootstrap mechanism. Each elected RP serves a different multicast group
range. For this purpose, you must configure a BSR.
A BSR serves as the administrative core of the IPv6 PIM-SM domain. An IPv6 PIM-SM domain can have
only one BSR, but can have multiple C-BSRs. If the BSR fails, a new BSR is automatically elected from the
C-BSRs to avoid service interruption. A device can serve as a C-RP and a C-BSR at the same time.
As shown in Figure 85, each C-RP periodically unicasts its advertisement messages (C-RP-Adv messages)
to the BSR. A C-RP-Adv message contains the address of the advertising C-RP and the IPv6 multicast
group range it serves.
The BSR collects these advertisement messages and chooses the appropriate C-RP information for each
multicast group to form an RP-set, which is a database of mappings between IPv6 multicast groups and
RPs. The BSR then encapsulates the RP-set in the bootstrap messages it periodically originates and floods
the BSMs to the entire IPv6 PIM-SM domain.
Figure 85 BSR and C-RPs
Based on the information in the RP-sets, all routers in the network can calculate the location of the
corresponding RPs based on the following rules:
1. The C-RP with the highest priority wins.
2. If all the C-RPs have the same priority, their hash values are calculated through the hashing
algorithm. The C-RP with the largest hash value wins.
3. If all the C-RPs have the same priority and hash value, the C-RP that has the highest IP address wins.
The hashing algorithm used for RP calculation is "Value (G, M, C
& M) + 12345) XOR C
Table 25 Values in the hashing algorithm
Value Description
Value Hash value.
) + 12345) mod 2 ."
31
i
301
) = (1 103515245 * ( (1 103515245 * (G
i