EXFO ETS-1000G - Manual (Page 70)

OAM
60 ETS-1000G
6. Open the Remote Device menu. Information about the remote device
should be displayed in the screen.
7. Press (LB up). The Loopback mode will be enabled for the data
link layer (L2) on the remote device (traffic will be redirected without
the swapping of MAC addresses).
To disable the Loopback mode, press (LB down).
Mode The possible OAM states are:

Active – the active mode. In this mode the port can send
the commands to detect devices and to enable the
Loopback feature on the remote device, and also respond
to the Ethernet OAM commands received from the remote
device.

Passive – the passive mode. In this mode the port cannot
initiate enabling the Loopback feature, it can only respond
to the Ethernet OAM commands received from the remote
device.

Off – OAM is disabled.