Advanced RANOP Chapter 8 - Alarm Interpretation and Monitoring PFF

5/21/2018 Advanced RANOP Chapter 8 - Alarm Interpretation and Monitoring PFF

1/201 NOKIA Training Center / RDM

Chapter 8: Alarm Interpretation andMonitoring



Objectives

Objectives: Describes the Nokia Alarm Monitoring and Alarm Interpretation

References:

Tuan Vo



Contents

Alarm Monitoring Basics

Alarm Interpretation



MML Commands for Alarms

There are basically two levels of alarm monitoring: BSC and BTS Both levels allow for the output of active alarms or a history of alarms BTS alarms are reported on a BCF level

So itsimportant to know the BCF ID of a particular site

The alarm handling MML commands are as follows:

Alarm Output MML CommandBSC Active ZAHO;

BSC History ZAHP:[obj]:[NR=Alarm Number]:[yyyy-mm-dd];

BTS Active ZEOL:bcf_id;

BTS History ZEOH:[yyyy-mm-dd]:BCF=bcf_id,[NR=Alarm Number];



Alarm Reference

Nokia Electronic Documentation (NED) is an invaluable reference tool

for understanding alarms NED contains the following alarm information:

Meaning Supplementary Information Fields Instructions Canceling



Reading Alarm Info

Heresan example of an active BTS Alarm

MML Command for active

BTS alarms on BCF-118

Alarm Number

Alarm NameAdditional and supplementary

alarm information (use NED to find

the meaning of the info)

Network Element

InformationAlarm Timestamp

Alarm Level: Critical,

Major, Minor



Alarm Number Structure

There is a numbering structure to the alarms that will help in

understanding which network element is affected

Alarm Number Category

0 - 999 Notices

1000 - 1999 Disturbance Printouts

2000 - 3999 Failure Printouts and Diagnostics Reports7000 - 7999 Base Station Alarms

8000 - 8999 Transmission Equipment Alarms



Contents

Alarm Monitoring Basics

Alarm Interpretation



BSC Alarms

In general BSC level alarms are usually monitored by an operators

switching or core group Alarms on the BSC level are usually BSC elements (i.e. TCSM, BCSU, PCU,

etc) There are a few alarms that require RF planning assistance to resolve, e.g.

2720 TELECOM LINK OVERLOAD 2725 ADJACENT CELL IDENTIFIER CONFIGURATION ERROR



BSC Alarm2720 Telecom Link Overload

This alarm usually is a sign that the FXC card needs to be replaced

when the following is observed: TBF Success Rate degrades significantly on affected BTSs Supplementary information shows that the LAPD link is overloaded All BTSs in the same cabinet have the alarm at some point (i.e. check the BSC

alarm history)

01 signifies LAPD overload and 72d

means that BTS-72 is affected



BSC Alarm2725 Adjacent Cell Identifier Configuration Error

This alarm may signify an incorrect LAC/CI combination in the MSC

An audit of the LAC/CI in the MSC vs. the BSC should be performed The specific neighbor source-target information is provided in the supplementary

information



BTS Alarms

A cells performance can be significantly degraded by hardware or

transmission issues

There are a number of performance metrics that will point to apossible HW or transport problem, for example:

TCH drop causes of LAPD, BTS Fail, or Transcoder Failure Drop in average available TCHs, spike in blocking or TCH failures Quality degradation on specific TRXs Almost 100% incoming handover failures

In many cases when HW or transport is suspected, checking theactive alarms on a cell may not be enough

For example, a site may be falling in and out of service and the instance that theactive alarms are checked may be the instance that the site is on air

An alarm history would clearly show that the cell is periodically falling in and out ofservice



High TCH Drops

TCH Drop Distribution

0

500

1000

1500

2000

2500

01/30 01/28 01/26 01/24 01/22 01/20 01/18 01/15 01/13 01/11 01/08 01/06 01/04

tch_radio_fail tch_rf_old_ho tch_abis_fail_call tch_abil_fail_old tch_a_if_fail_call

tch_a_if_fail_old tch_tr_fail tch_tr_fail_old tch_user_act tch_netw_act

tch_lapd_fail tch_bts_fail tch_bcsu_reset tch_act_fail_call

In the case of a spike in TCH drops, the drop causes should be investigated

If the drops are mainly from LAPD, BTS, and/or Transcoder, then the BTS alarms shouldbe checked A high drop cause of transcoder failure that is localized to an individual site is usually

caused from transport issues A true transcoder hardware failure would be spread across the BSC

An alarm history would generally show a combination that includes the following alarms: 7767 BCCH MISSING 7706 BTS O&M LINK FAILURE 7704 PCM FAILURE 7705 LAPD FAILURE

TCH Drop Distribution

0

50

100

150

200

250

300

01/30 01/28 01/26 01/24 01/22 01/20 01/18 01/16 01/14 01/12 01/10 01/08 01/06 01/04

Retainab

ility

tch_radio_fail tch_rf_old_ho tch_abis_fail_call tch_abil_fail_old tch_a_if_fail_call

tch_a_if_fail_old tch_tr_fail tch_tr_fail_old tch_user_act tch_netw_act

tch_lapd_fail tch_bts_fail tch_bcsu_reset tch_act_fail_call



High TCH Access Failures

In the case of a spike in TCH access failures, the cause could be a

radio or an ET/PCM thats out of service An alarm check could show any of the following alarms:

7606 TRX FAULTY 7705 LAPD FAILURE 7704 PCM FAILURE 7745 CHANNEL FAILURE RATE ABOVE DEFINED THRESHOLD

TCH Access Failures

0

1000

2000

3000

4000

5000

6000

01/30 01/28 01/26 01/24 01/21 01/19 01/17 01/15 01/13 01/11 01/09 01/07 01/05 01/03

TCH Cong (#) TCH Setup Fail (#)



TRX HW Issues

At times, a TRX may need to be replaced

Usually a TRX faulty alarm is generated, but sometimes a channel failure rate threshold alarmis generated instead The alarms in conjunction with TRX quality and BTS performance reports can show which TRX(s)

need to be replaced

The performance degradation to look for can be individual TRX quality, handovers, drops,and/or access failures

The TRX alarms that may be triggered are the following and may be confined to a single TRXon a cell:

7745 CHANNEL FAILURE RATE ABOVE DEFINED THRESHOLD 7743 MEAN HOLDING TIME BELOW DEFINED THRESHOLD 7606 TRX FAULTY

LSVGNVL050Y - Incoming HO Failures

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

09/23 09/30 10/07 10/14 10/21

IncomingHOS

uc

cessRat

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

IncomingHO

Failure

Inc oming HO Failures Inc oming HO Suc ces s Rate



7740 Beating BTS Alarms

A beating BTS alarm is an alarm that is triggered when the same alarm has triggered

20 times consecutively Its important to check the alarm indicated by the 7740 alarm

This alarm could point to issues with the transport of a site

The alarm can be cancelled if the issue has already been resolved

8172 Yellow Alarm

Occurred

- Check the alarm history to

see if the alarm is still anissue


17/20

17 NOKIA Training Center / RDM

Testing The ET

ETs with errors will usually have the 8102 RECEIVED BIT ERROR RATIO (BER) >

1E-6 alarm To remotely check for slips or errors on the ET, use the following MML commands:

ZYMO:ET,et_id;

1. 8102 Alarm

2. BCF-41 has 3ETs (125, 164,163)

3. All 3 ETs aretested and ET-163 is found tohave errors andslips


18/20


Dumping All Alarms

There may be times when all of the active BTS alarms on a BSC need

to be captured

The MML commands are simply: ZEOL; for all active BTS alarms ZEOH; for all BTS alarms triggered and cancelled starting from the previous

midnight

For example: ZEOH; run at 8am will contain all BTS alarms and alarmcancellations from the 8 hour period of 12am to 8am

ZEOH:yyyy-mm-dd:BCF=bcf_id; to dump the alarm history of an individual BCF


19/20


Some Common Alarms

AlarmNo.

Alarm Description PerformanceImpact

Solution

7606 TRX Faulty Critical fault hasoccurred in the TRX and

is blocked by system

Blocking Depends on typeof fault

7607 TRX/BTS OperationDegraded

Critical fault hasoccurred in the TRX/BTS

Supplementaryinfo gives nature

of the fault

7616 Oscillator AdjustingTemporarily Interrupted

The Abis frequency istoo high or low, or keeps

fluctuating

Drop calls Check Abisconnection.

7704 PCM Failures The LAPD links haveproblems

Drop calls.Site may go

down

Check ET forerrors and reset

T17705 LAPD Failures The LAPD of a particular

TRX has problemsDrop calls Check the LAPD


20/20


Some Common Alarms

AlarmNo.

Alarm Description PerformanceImpact

Solution

7740 Beating BTS Alarm The same alarm hastriggered or cancelled 20

times

Depends onthe alarm

Correct alarmcause

7745 Channel Failure RateAbove Defined

Threshold

The call rate terminatingin failure on a channel isabove the set threshold

Drop calls Faulty channelsare identified in

the supplementary

fields

7767 BCCH Missing The BSC cannotconfigure a BCCH to the

BTS

No service Check BTS

7995 Mains Breakdown with

battery back-up

Power is lost in a site No site,

eventually

Restore power.

8112 Frequency Error Frequency error hasbeen detected in input

signal

Drop calls Supplementaryfields provide

more information

Documents

Advanced RANOP Chapter 8 - Alarm Interpretation and Monitoring PFF