Control channels are classified into control channels inside and outside fibers. The control channels inside fibers use D4-D12 bytes to transmit the check information. The control channels outside fibers are seldom used.
Common Causes for Impassable Control Channels
Possible causes for impassable control channels are listed below:
- The opposite NE is a traditional NE.
- The LMP protocol of the optical interface is manually disabled.
- No DCC is allocated to the optical interface.
- The ECC is not passable because of bit errors.
- Alarms such as R_LOS or R_LOF are raised at the optical interface.
- The board is not in position.
Procedure
- Check the type of the opposite NE. If the opposite NE is a traditional NE, the control channel of the local NE is not passable.
- Check the state of the LMP protocol at the optical interface. If the state of the protocol at the optical interface is Disabled, the LMP protocol is manually disabled. Enable the LMP protocol at the optical interface again.
- Check DCC state of the optical interface. If no DCC is allocated to the optical interface, shut down the DCC of the optical interface that does not require ECC communication.
NOTE: Only the DCC of the optical interface that does not require ECC communication can be shut down. Make sure that ECC communication is not necessary for the optical interface before shutting down the DCC.
- Check the bit errors of the optical interface. If there is any bit error, clear them.
- Check the alarms at the optical interface. If there are alarms such as R_LOS and R_LOF, clear the alarms.
- Check the state of the physical board.
- If the physical board is not in position, remove it and then insert it again. Add the logical board correctly.
- If the physical board is faulty, replace it.
- Disable LMP of the optical interfaces at the two ends of the control channel. Then enable LMP of the optical interfaces at the two ends of the control channel.