The value of tmnxNatPlcySessionResvCount specifies,
for each NAT subscriber associated with this policy,
the number of sessions that are reserved within its allocation
allowed by the value of tmnxNatPlcySessionLimit.
The value obtained by subtracting the tmnxNatPlcySessionResvCount from
the tmnxNatPlcySessionLimit is a soft session limit; this soft limit
can only be exceeded by sessions that belong to one of the
forwarding classes specified by the value of
tmnxNatPlcyPrioSessionFcSet.
The value of tmnxNatPlcySessionResvCount must be smaller than the
value of tmnxNatPlcySessionLimit.