1000 LAPD OML Fault

Description

The data link layer protocol between the BSC and the BTS is the LAPD protocol. To enable the communication between the data link layers of the BSC and the BTS through the LAPD protocol, the LAPD link should be established. The link carries operation and maintenance information is called OML, or LAPD_OML. This alarm is generated when the BSC detects the LAPD_OML disconnection between the BSC and the BTS or the BSC detects that the handshake with the BTS times out.

Attribute

Alarm ID	Alarm Severity	Alarm Type
1000	Critical	Fault

Parameters

ID	Name	Meaning
1	Site No.	Number of the site where the OML link is disconnected.
2	BoxNo	Number of the BSC Subrack where the OML link is disconnected.
3	SlotNo	Number of the BSC Slot where the OML link is disconnected.
4	Port NO.	Number of the E1 where the OML link is disconnected.
5	Site Name	Site Name
6	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

All the BTS services are disrupted when the LAPD_OML is disconnected.
Fifteen minutes after the LAPD_OML is disconnected, the corresponding BTS will be reset automatically.

System Actions

The BSC sends handshake messages to the BTS periodically, trying to reestablish the connection.

Possible Causes

The transmission device or transmission link between the BSC and the BTS is faulty.
The Abis interfaced board of the BSC is faulty.
The BTS experiences power failure.
The TMU board or E1 lightning protection board of the BTS is faulty.

Procedure

Check the trunk parent alarms.
1. Check whether the upper-layer equipment of the BTS, as indicated by the Site No. carried in the alarm location information, is the BSC.
  Y=> The upper-layer equipment of the BTS is the BSC. Go to b.
  N=> The upper-layer equipment of the BTS is the BTS. Go to d.
2. Log in to the LMT and then choose Alarm Maintenance > Browse Alarm. Check whether the BSC reports the following trunk parent alarms.
  408 Automatic Loading and Activation of BTS TMU Version
  20081 Loss of E1/T1 Signals (LOS)
  20082 Loss of E1/T1 Frames (LOF)
  20083 Remote E1/T1 Alarm (RAI)
  20084 E1/T1 Alarm Indication Signal (AIS)
  20085 Loss of E1/T1 Multiframes (LOM)
  20086 E1/T1 Link Loopback
  20087 High BER over the E1/T1 Link
  20221 Loss of Clock on the Optical Port (RLOC)
  20222 Loss of Signals on the Optical Port (RLOS)
  20223 Loss of Received Signal Frames on the Optical Port (RLOF)
  20224 Out-of-Synchronization of Received Signal Frames on the Optical Port (ROOF)
  20226 Regenerator Section Signal Failure (RSF)
  20227 Regenerator Section Signal Deteriorated (RSD)
  20228 Multiplex Section Alarm Indication Signal (MAIS)
  20229 Multiplex Section Remote Defect Indication (MRDI)
  20230 Loopback on the Optical Port
  20231 Administration Unit Alarm Indication Signal (AUAIS)
  20232 Loss of Administration Unit Pointer (AULOP)
  20233 Service Unequipped on the High-Order Path of the Optical Port (HPUNEQ)
  20235 High-Order Path Signal Label Byte Mismatch (HPSLM)
  20236 High-Order Path Signal Failure (HPSF)
  20237 High-Order Path Signal Deteriorated (HPSD)
  20238 Remote Defect Indication on the High-Order Path of the Optical Port (HPRDI)
  20239 Loss of Tributary Unit Multi-frames (TULOM)
  20240 Tributary Unit Alarm Indication Signal (TUAIS)
  20241 Loss of Tributary Unit Pointer (TULOP)
  20242 Service Unequipped on the Lower-Order Path of the Optical Port (LPUNEQ)
  20244 Signal Flag Mismatch on the Low-Order Path of the Optical Port (LPSLM)
  20245 Low-Order Path Remote Failure Indicaton (LPRFI)
  20246 Low-Order Path Remote Defect Indication (LPRDI)
  20247 Tributary Unit Type Mismatch (TUSIZEERR)
  20248 Loss of Tributary Signals (LOS)
  20249 Tributary Alarm Indication Signal (AIS)
  20250 Loss of Tributary Frames (LOF)
  20251 Remote Alarm Indication over the Tributary (RAI)
  20254 Tributary Loopback Alarm
  20255 Optical Module Fault
  20969 Ethernet Link failure
  20972 Ethernet Link Loop
  20977 Failure of High-Speed Communication Link on the Backplane of Service Boards
  20978 Software Abnormal
  20980 Ethernet Port Band Width Change
  20981 Ethernet Port Duplex Mode Change
  Y => Any of the previous alarms is reported. Go to c.
  N => The alarm is not reported. Go to 2.
3. Rectify the fault according to the alarm help. After the trunk parent alarm is cleared, check whether this alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  N => The alarm is not cleared. Go to 2.
4. Check whether the upper-layer BTS reports the following parent alarms:
  4102 TRX LAPD Link Interrupt Alarm or other associated alarms
  4714 E1/T1 Local Alarm or Other Alarms Related to Transmission on the Abis Interface on the BTS Side.
  Y => Any of the previous alarms is reported. Go to e.
  N => The alarm is not reported. Go to 2.
5. Rectify the fault according to the alarm help. After the LAPD Alarm or E1 Local Alarm is cleared, check whether this alarm is cleared.
  Y => The alarm is cleared. The alarm handling is complete.
  N => The alarm is not cleared. Go to 2.
Check the Abis interface board of the BSC.
1. Check whether the Abis interface board of the BSC is in normal state.
  Y => Go to 3.
  N => Go to b.
2. Reinsert the interface board, 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 c.
3. Replace the Abis 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 3.
Check the BTS power supply.
1. Contact the maintenance engineer on the BTS side and check whether the BTS is equipped with batteries.
  Y=> The BTS is equipped with batteries. Go to b.
  Y=> The BTS is not equipped with batteries. Go to d.
2. Log in to the LMT, and choose Alarm Maintenance > Browse Alarm. Check whether the BTS reports the 5886 No Mains Supply Alarm or other associated alarms.
  Y => Any of the previous alarms is reported. Go to c.
  N => The alarm is not reported. Go to 4.
3. Rectify the fault according to the 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 4.
4. Check whether the BTS experiences power failure on the BTS side.
  Y=> The BTS experiences power failure. Go to e.
  N=> The BTS does not experience power failure. Go to 4.
5. Power the BTS, 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 4.
Based on the Site No. carried in the alarm location information, check the E1 lightning protection board.
1. Reinsert the E1 lightning protection board, 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 b.
2. Replace the E1 lightning protection 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 5.
Check whether the faulty BTS is in IP transmission mode.
Y => Go to 6.
N => Go to 7.
Check whether a cable is improperly connected to the E1 Signal Lightning-Protection Card
panel.
1. Check whether an E1 cable is connected to the E1 Signal Lightning-Protection Card panel.
  Y => Remove the E1 cable from the E1 Signal Lightning-Protection Card panel. Go to b.
  N => Go to 7.
2. Check whether the alarm is cleared.
  Y=> The alarm is cleared. The alarm handling is complete.
  N => The alarm is not cleared. Go to 7.
Based on the Site No. carried in the alarm location information, check the TMU board.
1. Reinsert the TMU board, 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 b.
2. Replace the TMU. 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.