HP A6600 Configuration Manual page 313

A router can server as a C-RP and a C-BSR at the same time.
As shown in Figure 88, 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 bootstrap messages (BSMs) to the entire IPv6 PIM-SM domain.
Figure 88 BSR and C-RPs
C-RP
Bootstrap message
Advertisement message
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:
The C-RP with the highest priority wins.
1.
If all the C-RPs have the same priority, their hash values are calculated through the hashing
2.
algorithm. The C-RP with the largest hash value wins.
If all the C-RPs have the same priority and hash value, the C-RP has the highest IP address wins.
3.
The hashing algorithm used for RP calculation is "Value (G, M, C
(G & M) + 12345) XOR C
Table 13 Values in the hashing algorithm
Value Description
Value Hash value
The digest from the XOR operation between the 32-bit segments of the IPv6 multicast
G group address. For example, if the IPv6 multicast address is FF0E:C20:1A3:63::101, G
= 0xFF0E0C20 XOR 0x01A30063 XOR 0x00000000 XOR 0x00000101
M Hash mask length
The digest from the XOR operation between the 32-bit segments of the C-RP IPv6
C address. For example, if the IPv6 address of the C-RP is 3FFE:B00:C18:1::10, C
i
0x3FFE0B00 XOR 0x0C180001 XOR 0x00000000 XOR 0x00000010
& Logical operator of "and"
XOR Logical operator of "exclusive-or"
mod Modulo operator, which gives the remainder of an integer division
IPv6 PIM-SM
BSR
C-RP
) + 12345) mod 2 31 ".
i
302
C-RP
C-BSR
) = (1103515245 * ( (1103515245 *
i
=
i