117
messages (BSMs) that it periodically originates and floods the bootstrap messages to the entire PIM-SM
domain.
Figure 39 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
i
) = (1103515245 * ( (1103515245 *
(G & M) + 12345) XOR C
i
) + 12345) mod 2
31
.
Table 7 Values in the hashing algorithm
Value Descri
tion
Value Hash value
G IP address of the multicast group
M Hash mask length
C
i
IP address of the C-RP
& Logical operator of “and”
XOR Logical operator of “exclusive-or”
Mod Modulo operator, which gives the remainder of an integer division
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