In a ring WDM configuration network, customer lost management between two sites and after verifying the status of the IP over DCC and services they were found ok.
Put a physical loop between the client interface (TX/RX) in the corresponding OTU board.
Management of this equipments is not through OSC board (SC1 or SC2). These NEs are managed by using a WDM channel in the system, by an OTU board.
As in some point in the network, two equipments were connected without using IFU and OSC boards, management was design to be through an OTU interface.
So in order to transmit the signal, it is necessary to put a loop in the client interface.
After checking the fiber connection in the site, we asked customer about this configuration and he confirmed he remove the physical loop in the board.