The value of tmnxNatGrpCfgSessionResvCount specifies,
for each MDA in this ISA group,
the number of sessions that are reserved for prioritized sessions.
The value obtained by subtracting the tmnxNatGrpCfgSessionResvCount
from the maximum number of sessions supported by each MDA
is a soft session limit; this soft limit can only be exceeded
by prioritized sessions.