20222 Loss of Signals on the Optical Port (RLOS)

Description

The Loss of Signals on the Optical Port (RLOS) alarm is generated when the optical port of the BSC interface board fails to detect the optical signal or detects that the optical signals are at a low level within a certain time.

Attribute

Alarm ID	Alarm Severity	Alarm Type
20222	Major	Fault

Parameters

ID	Name	Meaning
1	Subrack No.	Subrack No.
2	Slot No.	Slot No.
3	Cpu No.	CPU No.
4	Optical Interface No.	Optical interface No.
5	Alarm Attribute	0=Normal, Alarms period are longer than the Transient Threshold. 1=Transient Count, The times and the period of the alarms whose periods are shorter than the Transient Threshold are summed up. If the sum result is longer than the Alarm Occurrence Period Threshold or Alarm Occurrence Times Threshold, an alarm so called Transient Count Alarm is triggered. Because Transient Count Alarm is based on accumulative result, the recovery of the alarm may occur at least one Summing Cycle later. The Summing Cycle can be query by MML "LST STATSLDWIN".

Impact on the System

The services carried on the optical port are disrupted.

System Actions

When the active interface board is faulty, an active/standby switchover is performed if the standby board allows a switchover. Otherwise, no handling is performed.
When the standby interface board is faulty, no handling is performed.
When the faulty interface board works in independent mode, no handling is performed.

Possible Causes

The connection of the optical cable between the BSC and the peer equipment is abnormal.
The transmission line or transmission device is faulty.
The optical module is faulty.
The BSC interface board is faulty.
The peer NE is faulty.

Procedure

Check the optical cable connected to the BSC interface board.
1. Check whether the optical cable is correctly connected.
  Y => The optical cable is correctly connected. Go to c.
  
  N => The optical cable is incorrectly connected. Go to b.
2. Connect the optical cable correctly. Then, check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Go to c.
3. Reinsert the connectors of the optical cable, and secure the connectors at both ends. Then, check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Go to d.
4. Identify the first connection point (such as the ODF) connected to the BSC and perform a loopback on the TX and RX of the BSC. Then, check whether the alarm is cleared.
  Y => The alarm is cleared. Go to 3.
  
  N => The alarm is not cleared. Go to e.
5. Perform a loopback on the optical port of the BSC interface board and then check whether the alarm is cleared.
  Y => The alarm is cleared. The BSC interface board and the optical module are normal. Reconnect the optical cable to the optical port, and Go to f.
  
  N => The alarm is not cleared. The BSC interface board is faulty or the optical module is faulty. Reconnect the optical cable to the optical port, and Go to 2.
6. Remove the connectors of the optical cable and use the absorbent cotton saturated with the absolute alcohol to clean the connectors. Reinsert the connectors, and then check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Go to g.
7. Replace the optical cable. Then, check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Replace the optical cable with the original one. Go to 3.
Check the BSC interface board and the optical module.
1. Remove and the install the optical module. Check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Go to b.
2. Replace the optical module and check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is cleared.
  
  N => The alarm is not cleared. Replace the optical module with the original one. Go to c.
3. Reset the BSC interface board. Wait five to ten minutes. Then, check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Go to d.
4. Reinsert the BSC interface board. Wait five to ten minutes after the board is started. Then, check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Go to e.
5. Replace the BSC interface board. Then, check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Contact Huawei Customer Service Center.
Check whether the transmission equipment exists between the BSC and the peer NE.
Y => The transmission equipment exists between the BSC and the peer NE. Contact the transmission engineers to troubleshoot the transmission network problems. The alarm handling is complete.

N => There is no transmission equipment between the BSC and the peer NE. Go to 4.
Check the optical cable connected to the interface board of the peer NE.
1. Check the type of the peer NE.
  Y => If the peer NE is the GMPS/GEPS/GTCS or the BTS, Go to b.
  
  N => If the peer NE is not the GMPS/GEPS/GTCS or the BTS, contact the maintenance engineers of the peer NE. The alarm handling is complete.
2. Remove and reinsert the connectors of the optical cable connected to the interface board of the peer NE and secure the connectors of the optical cable at both ends. Then, check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Go to c.
3. Remove the connectors of the optical cable to interface board of the peer NE. Use the absorbent cotton saturated with the absolute alcohol to clean the connectors. Then, reinsert the connectors, and check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Go to d.
4. Replace the optical cable connected to the interface board of the peer NE. Check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Replace the optical cable with the original one. Go to 5.
Check the interface board and the optical module of the peer NE.
1. Remove and then reinstall the optical module. Then, check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Go to b.
2. Replace the optical module and check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Replace the optical module with the original one. Go to c.
3. Reset the interface board of the peer NE. Wait five to ten minutes after the board is started. Then, check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Go to d.
4. Reinsert the interface board of the peer NE. Wait five to ten minutes after the board is started. Then, check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Contact Huawei Customer Service Center.
5. Replace the interface board of the peer NE. Then, check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Contact Huawei Customer Service Center.