The value of tmnxOtuIfSmTtiExpMode specifies the type of expected
Trail Trace Identifier (TTI) for the Section Monitoring (SM) in
the OTU overhead.
Specifying a tmnxOtuIfSmTtiExpMode value of 'auto (0)' along with
tmnxOtuIfSmTtiExp set with a single octet of '0xFF' will revert the
SM-TTI to the default which is 'all zeros' in tmnxOtuIfSmTtiExp.