The C-RP priority parameter determines an active RP for a group. The hash values for different RPs are only compared for RPs with the highest priority. Among the RPs with the highest priority value and the same hash value, the C-RP with the highest RP IP address is chosen as the active RP.
You cannot configure the C-RP priority. Each RP has a default C-RP priority value of 0, and the algorithm uses the RP if the group address maps to the grp-prefix that you configure for that RP. If a different router in the network has a C-RP priority value greater than 0, the switch uses this part of the algorithm in the RP election process.
Currently, you cannot configure the hash mask used in the hash algorithm. Unless you configure a different PIM BSR in the network with a nondefault hash mask value, the default hash mask of 255.255.255.252 is used. Static RP configurations do not use the BSR hash mask; they use the default hash mask.
For example:
RP1 = 128.10.0.54 and RP2 = 128.10.0.56. The group prefix for both RPs is 238.0.0.0/255.0.0.0. Hash mask = 255.255.255.252.
The hash function assigns the groups to RPs in the following manner:
The group range 238.1.1.40 to 238.1.1.51 (12 consecutive groups) maps to 128.10.0.56. The group range 238.1.1.52 to 238.1.1.55 (4 consecutive groups) maps to 128.10.0.54. The group range 238.1.1.56 to 238.1.1.63 (8 consecutive groups) maps to 128.10.0.56.