Symptom
On a network built with the OptiX OSN 6800, optical cables are cut. During the process of testing WDM-side optical power on the ODF, optical power can be detected on WDM-side fibers for transmitting and receiving signals. The transmit optical power is -15 dBm and the receive optical power is -21 dBm. During the process of testing optical power on the FIU board at an upstream station, optical power can be detected at the IN and OUT ports on the FIU board. The transmit optical power at the OUT port is +4 dBm and the transmit optical power at the IN port is -2 dBm. It is incorrect that optical power can be detected at the IN port.
Cause analysis
Possible causes of the problem are as follows:
- Connections of fiber patch cords at the optical port on the FIU board are incorrect.
Procedure
- The FIU board and SCA board are passive components and cannot emit light by themselves. Therefore, optical power at the IN and OUT ports must be the optical power of lights at other optical ports.
- According to the functional block diagram of the FIU board, the IN port and OUT port belong to two independent modules. The two modules are passive optical components similar to fiber patch cords. Therefore, the optical power at the IN and OUT ports are from two different optical channels.
- According to the previous analysis, besides the IN and OUT ports, the RC optical port on the FIU board can receive service channel signals and the RM optical port on the FIU board can receive supervisory channel signals. The transmit optical power of the IN port is -2 dBm, which is close to that of the SC2 board. Therefore, it is determined that the OUT port transmits service channel signals and the IN port transmits supervisory channel signals.
- Services on the ring network are switched because of line faults. The fiber patch cord is removed from the RC port and then the FIU board is tested. The OUT port does not transmit optical signals and the transmit optical power of the IN port is -2 dBm. After the fiber patch cord is installed to the RC port and the fiber patch cord of TM port is removed, the IN port does not transmit optical signals and the transmit optical power of the OUT port is +4 dBm.
- Check connections of the fiber patch cords according to the connection diagram. Connections of the fiber patch cords for service channels are correct but those for supervisory channels are incorrect.
- Change the connection according to the connection diagram. Then the problem is resolved.
Reference Information
- If fiber patch cords are inversely connected, the multiplexing/demultiplexing module can still separate optical signals. Make sure that the SC2 boards at both ends can transmit and receive optical signals normally.
- For passive optical components, after the optical power of proper wavelengths is received at one end, the optical power must be output from the other end. Therefore, there is no difference between the optical power at the IN and OUT ports.
