20082 Loss of E1/T1 Frames (LOF)

Description

A Loss of E1/T1 Frames (LOF) alarm is generated if the E1/T1 port of the BSC does not detect any frame header over a certain period. Then, the BSC sends an RAI signal to the peer NE.

Attribute

Alarm ID	Alarm Severity	Alarm Type
20082	Major	Fault

Parameters

ID	Name	Meaning
1	Subrack No.	Subrack No.
2	Slot No.	Slot No.
3	Cpu No.	CPU No.
4	Port No.	The number of the port
5	Site No.	The IDs of all sites whose OMLs are on the faulty E1/T1. If BTS are cascade connected,a maximum of 4 sites are shown.Only Abis E1/T1 alarm has this parameter.
6	Site Name	The Names of all sites whose OMLs are on the faulty E1/T1. If BTS are cascade connected,a maximum of 4 sites are shown.Only Abis E1/T1 alarm has this parameter.
7	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

If the active board is faulty, the services carried on the port of the board are disrupted.
If the standby board is faulty, the services are not affected.

System Actions

None

Possible Causes

The data configuration of the E1/T1 port of the BSC is inconsistent with that of the E1/T1 port of the peer NE.
The BSC clock is faulty.
The transmission equipment or transmission link between the BSC and the peer NE is faulty.
The clock of the peer NE is faulty.
The BSC interface board is faulty.

Procedure

Check the data configurations of the E1/T1 ports of both the BSC and the peer equipment.
1. Check whether the board that reports the alarm is the Abis interface board or Ater interface board.
  Y => If the board is the Abis interface board, Go to 2. If the board is the Ater interface board, Go to b.
  
  N => The board is not the Abis interface board or the Ater interface board. Go to f.
2. b. Check whether the working modes of the E1/T1 ports of the local and peer GEIUTs are consistent.
  Y => The working modes of the E1/T1 ports of the local and peer GEIUTs are consistent. Go to d.
  
  N => The working modes of the E1/T1 ports of the local and peer GEIUTs are inconsistent. Go to c.
3. Set the working modes of the E1/T1 ports on both ends to the same value. 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. Check whether the frame formats of the E1/T1 ports of the local and peer GEIUTs are consistent.
  Y => The frame formats of the E1/T1 ports are consistent. Go to 2.
  
  N => The frame formats of the E1/T1 ports are inconsistent. Go to e.
5. Set the frame formats for the E1/T1 ports of the local and peer GEIUTs to the same value. 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 2.
6. Contact the maintenance engineers of the peer NE. Check whether the working modes of the E1/T1 ports of the BSC interface board and the peer NE are consistent.
  Y => The working modes of the E1/T1 ports of the BSC interface board and the peer NE are consistent. Go to h.
  
  N => The working modes of the E1/T1 ports of the BSC interface board and the peer NE are inconsistent. Go to g.
7. Set the working modes of the E1/T1 ports of the BSC interface board and the peer NE to the same value. 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 h.
8. Check whether the frame format of the E1/T1 port of the interface board at the peer end is consistent with that of the E1/T1 port of the BSC interface board.
  Y => The frame format of the E1/T1 port of the interface board at the peer end is consistent with that of the E1/T1 port of the BSC interface board. Go to 2.
  
  N => The frame format of the E1/T1 port of the interface board at the peer end is inconsistent with that of the E1/T1 port of the BSC interface board. Go to i.
9. Ensure that the frame formats of the E1/T1 port of the interface board at the peer end is consistent with that of the E1/T1 port of 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. Go to 2.
Check the E1/T1 cable of the BSC interface board.
1. Check whether the E1/T1 cable of the BSC interface board is loosened, or damaged.
  Y => The E1/T1 cable is loosened. Go to b.
  
  N => The E1/T1 cable is normal or damaged. Go to c.
2. Connect both ends of the E1/T1 cable securely. 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. Replace the E1/T1 cable and 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 E1/T1 cable with the original one. Go to 3.
Check the BSC interface board.
1. Perform a local loopback on the E1/T1 port of the BSC interface board. Then, check whether the alarm is cleared.
  Y => The BSC interface board is normal. Go to 4.
  
  N => The BSC interface board is faulty. Go to b.
2. 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 c.
3. Remove and then install 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. Go to d.
4. 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. Replace the BSC interface board with the original one. Go to 4.
Check whether the BSC reports the parent alarms related to the clock.
1. Log in to the LMT and then choose Alarm Maintenance > Browse Alarm. Check whether the BSC reports the following parent alarms related to the clock.
  20016 Faulty 32 MHz Clock from the Backplane
  
  20026 Faulty Phase-Locked Loop of the Board Clock
  
  20044 Unavailable Clock Source
  
  20322 Unavailable Current Clock Reference for GGCU
  
  Y => One of these alarms is reported. Go to b.
  
  N => None of these alarms is reported. Go to 5.
2. Rectify the fault and clear the alarm founding in (a) according to the relevant alarm help. 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 5.
Check the clock of the peer NE.
1. Check the type of board that generates the alarm.
  Y => If the board is an Ater interface board, Go to b. If the board is an Abis interface board, Go to d.
  
  N => The board is of another type. Go to g.
2. Check whether the GEIUT connected to the Ater interface board reports the following alarms related to the clock.
  20016 Faulty 32 MHz Clock from the Backplane
  
  20026 Faulty Phase-Locked Loop of the Board Clock
  
  20044 Unavailable Clock Source
  
  20322 Unavailable Current Clock Reference for GGCU
  
  Y => One of these alarms is reported. Go to c.
  
  N => None of these alarms is reported. Contact Huawei Customer Service Center.
3. Rectify the fault and clear the alarm founding in (b) according to the relevant alarm help. Then, check whether the alarm 20082 Loss of E1/T1 Frames (LOF) is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Contact Huawei Customer Service Center.
4. Query the BTS information according to the alarm location information.
5. Log in to the LMT and then choose Alarm Maintenance > Browse Alarm. Check whether the BTS reports the following alarms related to the clock.
  4120 TRX DBUS Alarm
  
  4154 TRX main clock alarm
  
  4156 TRX slave clock alarm
  
  4184 TRX Clock Critical Alarm
  
  4708 Clock Reference Abnormal Alarm
  
  4732 TMU clock critical alarm
  
  4734 Master TMU clock alarm
  
  4736 Extended TMU clock alarm
  
  4760 13M Maintenance Alarm
  
  Y => One of these alarms is reported. Go to f.
  
  N => None of these alarms is reported. Contact Huawei Customer Service Center.
6. Rectify the fault and clear the alarm founding in (e) according to the relevant alarm help. Then, check whether the alarm 20082 Loss of E1/T1 Frames (LOF) is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm is not cleared. Contact Huawei Customer Service Center.
7. Contact the maintenance engineers of the peer NE. Check whether the clock of the peer NE is normal.
  Y => The clock of the peer NE is normal. Contact Huawei Customer Service Center.
  
  N => The clock of the peer NE is abnormal. Contact the maintenance engineers of the peer equipment. The alarm handling is complete.