For the legacy network PDH/DSn, SDH/SONET circuits, normally operators will do in-service test; out-of-service; and round-trip-delay test. The test solution for OTN network is similar to SDH/SONET circuits. Basically operators will also do the similar test as SDH/SONET.
Out of Service Test
End to End error free transmission verfication;
Automatic protection switching verfication;
SDH/SONET mapping verfication down to VC12/VT1.5.
In Service Test
In service monitoring protected monitoring points or optical splitters;
Overhead bytes monitoring and decoding;
Round Trip Delay Test