802.3ah is a link level Metro Ethernet OAM which is used for the last mile monitoring purpose. It cannot scale more than a single hop. It can transmit at max rate of 10 frames per second which is equivalent to 100ms transmission time for single frame. At least we need 3 frames to detect the link loss with high cpu usage which will contribute almost 300ms to acheive only link level convergence time.

Functions:-
OAM discovery
Remote Failure Indication remote loopback
Port Level Loopback
Fault Isolation
Perfomrance and Status Monitoring