This selects which end of the circuit actually transmits the OAM loopback test cell, the near end's port if set to local, or the far end's port if set to remote, which determines exactly which half of the circuit path the resulting loopback test actually exercises. An admin isolating a fault to one side of a circuit would run the test with cktOamLoopbackDirection set to remote first to check the far segment, then local to check the near segment. For example, a successful remote-direction loopback combined with a failing local-direction one would tell the admin the fault is specifically in the near-end segment of the circuit.