Load distribution over ISAs in static 1:1 NAT

For best traffic distribution over ISAs, the value of the classic-lsn-max-subscriber-limit max parameter should be set to 1.

config
   router / service vprn X
      nat
         inside 
             deterministic
               classic-lsn-max-subscriber-limit  <num>

This mean that traffic is load balanced over ISAs based on inside IP addresses. In static 1:1 NAT this is certainly possible because the subscriber-limit parameter at the pool level is preset to a fixed value of 1.

However, if 1:1 static NAT is simultaneously used with regular (many-to-one) deterministic NAT where the subscriber-limit parameter can be set to a value greater than 1, then the classic-lsn-max-subscriber-limit parameter also has to be set to a value that is greater than 1. The consequence of this is that the traffic is load balanced based on the consecutive blocks of IP addresses (subnets) instead of individual IP addresses. See Deterministic NAT for information about Deterministic NAT behavior.