20321 Unavailable Clock Reference for GGCU

Description

The clock reference of GGCU board is in unusable state.

Attribute

Alarm ID	Alarm Severity	Alarm Type
20321	Minor	Fault

Parameters

ID	Name	Meaning
1	Subrack No.	Subrack No.
2	Slot No.	Slot No.
3	Cpu No.	CPU No.
4	Source Index No.	The Index in Source table of lost source
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

None.

System Actions

If the GGCU is in automatic switch mode and there are other available clock sources when the current clock source is unavailable, then the GGCU switches to other available clock source.
If the GGCU is in automatic switch mode and there are no available clock sources when the current clock source is unavailable, then the phase-lock loop of the GGCU enters self-oscillation state or remains unchanged.
If the GGCU is in manual switch mode and the current clock source is unavailable, then the phase-lock loop of the GGCU enters self-oscillation state or remains unchanged.
No alarm handling for other cases.

Possible Causes

The input signal for the clock reference is lost.
The frequency offset for the input signal of the reference source is abnormal, that is, the frequency offset is greater than that being introduced.
The board is faulty.

Procedure

As the handling procedures vary for different clock reference, please specify the type of the clock reference in advance by the values of parameter 4.
If the type of the faulty clock reference is 2 MHz or 2 MBPS:
1. Secure the clock cable of the GGCU that connects the clock source, and then check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm persists. Go to b.
2. Replace the clock cable, and then check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm persists. Go to c.
3. Check whether the frequency offset output from the clock source is normal by using relevant equipment.
  Y => The frequency offset is normal. Go to d.
  
  N => The frequency offset is abnormal. Go to e.
4. Replace the board, and then check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm persists. Please contact Huawei Customer Service Center.
5. Check whether the clock source is of BITS clock.
  Y => Contact the maintenance engineer concerning the BITS clock to solve the problem. The alarm handling is complete.
  
  N => The clock source is from the interface board of the BSC. Go to f.
6. The interface board that output the clock source is faulty. Clear the relevant fault, and then check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm persists. Please contact Huawei Customer Service Center.
If the type of the faulty clock reference is 8K:
1. Secure the GGCU and the interface board that output the clock source, and then check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm persists. Go to b.
2. Check whether there are clock-related alarms with the interface board that output the clock source.
  Y => There are clock-related alarms. Go to c.
  
  N => There is no clock-related alarm. Go to d.
3. Clear the clock alarm of the interface board according to its relevant handling suggestions, and then check whether the alarm of the board is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm persists. Go to d.
4. Replace the faulty GGCU board, and then check whether the alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  
  N => The alarm persists. Please contact Huawei Customer Service Center.