HP A6600 Configuration Manual page 108

Figure 35 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:
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 with the highest IP address wins.
3.
The hashing algorithm used for RP calculation is:
Value (G, M, C ) = (1103515245 * ( (1103515245 * (G & M) + 12345) XOR C
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Table 8 Values in the hashing algorithm
Value Description
Value Hash value
G IP address of the multicast group
M Hash mask length
C IP address of the C-RP
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& 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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) + 12345) mod 2 31
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