The value of msapAtmPlcyOamPeriodicLoopback specifies if the
MSAP will run periodic OAM loopbacks.
If enabled, an ATM OAM loopback cell will be transmitted every period
as configured in tAtmSysOamLoopbackPeriod; if a response is not
received and tAtmSysOamRetryDown consecutive retries also result
in failure, the endpoint will transition to the eteAisLoc state;
once in the eteAisLoc state, an ATM OAM loopback cell will be
transmitted every period as configured in tAtmSysOamLoopbackPeriod;
if a response is received for the periodic loopback and
tAtmSysOamRetryUp consecutive retries also each receive a response,
the endpoint will transition back to the up state.