402 Switchback after BCCH Mutual Aid in a Cell

Description

[1]This alarm is reported when the BCCH is switched back to the initial TRX under the following conditions: the BSC detects that the initial TRX that carries the BCCH resumes to normal operation, and the management status of the main BCCH is Unlocked, and the switchback is allowed in the cell. [2]This alarm is also reported when a forced switchback occurs due to data configuration.

Attribute

Alarm ID	Alarm Severity	Alarm Type
402	Major	Event

Parameters

ID	Name	Meaning
1	Cell Index.	Index of the cell where the main BCCH is switched between two TRXs
2	Cause	0: Fourth level BTS reset; 1: Fourth level cell reset; 2: Current BCCH deleted; 3: Original BCCH restored; 4: TRX mutual aid disabled; 5: Rollback due to inconsistent internal resources; 6: BCCH modified; 7: Mutual aid on current BCCH disabled.
3	Cell Name	Name of the cell where the main BCCH is switched between two TRXs
4	Cell CGI	Cell Global Identifier of the cell where the main BCCH is switched between two TRXs
5	Site No.	Number of the site where the cell generating an alarm is located
6	Site Name	Name of the site where the cell generating an alarm is located
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

The cell is reinitialized. The BCCH is switched back to the initial TRX. The services provided by this cell are interrupted and then restored within 10 seconds.

System Actions

When the initial TRX that carries the main BCCH resumes to normal operation and the management status of the main BCCH is Unblocked, a switchback occurs if the cell allows switchback. The alarm is then reported and the cell is re-initialized.
If the switchback occurs due to data configuration, the alarm is reported and the cell is re-initialized.

Possible Causes

The faults of the former TRX which carries the BCCH are rectified.
The BCCH TRX is manually unblocked. The BCCH is switched back to the initial TRX.
The BCCH is manually unblocked. The BCCH is switched back to the initial TRX.
The switchback occurs due to data configuration.

Procedure

Check whether the forced switchback is caused by data configuration.
Y=> No handling is required.

N=> Go to 2.
Check whether the switchback is caused by manual troubleshooting.
Y=> Go to 4.

N=> This indicates that the initial TRX is unstable or has transient faults. Go to 3.
Check whether the primary BCCH is idle after the BCCH mutual aid.
Y=> The primary BCCH is idle. Go to 4.

N=> The primary BCCH is not idle. The switchover of the main BCCH fails. Please contact Huawei Customer Service Center andreplace the faulty TRX.
Wait for 15 minutes and then launch the LMT. Check whether the alarm 401 BCCH Mutual Aid in a Celloccurs.
Y=> The alarm 401 BCCH Mutual Aid in a Cell occurs. Clear alarm 401 BCCH Mutual Aid in a Cell according to its relevant handling suggestions. In addition, the occurrence of the mutual aid and switchback shows that the BCCH-carried TRX is unstable. Please contactHuawei Customer Service Center and replace the faulty TRX.

N=> The alarm 401 BCCH Mutual Aid in a Cell does not occur. Go to 5.
Check whether the switchback of the BCCH is caused by manual operation.
Y=> The BCCH is switched back to the initial TRX intentionally. The alarm handling is complete.

N=> Please contact Huawei Customer Service Centerand replace the faulty TRX.