tn1c

323-1081-543

SDH TRANSMISSION

Nortel TN-1CAlarm Clearing Procedures

Release 2 Standard June 1997

323-1081-543 Release 2 Standard TN-1C Alarm Clearing Procedures

SDH TRANSMISSION

Nortel TN-1C

Alarm Clearing Procedures

Copyright Coypright statement Country of printing NT confidential NTE disclaimer Trademarks

Copyright

1996, 1997 Northern Telecom

The copyright of this document is the property of Northern Telecom. Without the written consent of Northern Telecom, given by contract or otherwise, this document must not be copied, reprinted or reproduced in any material form, either wholly or in part, and the contents of this document, or any methods or techniques available therefrom, must not be disclosed to any other person whatsoever.

Printed in England

NORTHERN TELECOM CONFIDENTIAL:

The information contained in this document is the property of Northern Telecom. Except as specifically authorized in writing by Northern Telecom, the holder of this document shall keep the information contained herein confidential and shall protect same in whole or in part from disclosure and dissemination to third parties and use same for evaluation, operation, and maintenance purposes only.

So far as Northern Telecom is aware the contents of this document are correct. However, such contents have been obtained from a variety of sources and Northern Telecom can give no warranty or undertaking and make no representation as to their accuracy. In particular, Northern Telecom hereby expressly excludes liability for any form of consequential, indirect or special loss, and for loss of data, loss of profits or loss of business opportunity, howsoever arising and whether sustained by the user of the information herein or any third party arising out of the contents of this document.

Document Number: 323-1081-543Document Status: StandardProduct Release Number: Release 2Date: June 1997

iii


Publication history

June 1997

Release 2 Standard.

December 1996

Release 1 Standard.

v

ContentsAbout this document xi

Technical support and information xii

Chapter 1: Introduction 1-1Maintenance philosophy 1-1Alarm indications 1-1Element Controller 1-2Craft access terminal 1-2Unit indications 1-2Alarm masking 1-3Alarm consequences 1-6Beginning fault finding 1-8Responding to logs 1-8Alarm category and severity 1-9

Chapter 2: Clearing equipment alarms 2-1

PS-Power_Fail 2-4

PS-Battery_Low 2-5

INT-NE-SW_Corrupt 2-6

INT-EC-Alarms_Buffer 2-7

NE-Door_Open 2-8

PS-Door_Open 2-9

INT-NE-RAM_Fail 2-11

INT-NE-Config_Corrupt 2-12

NE-Card_Fail 2-14

RS-Loss_of_Signal 2-15

OS-Optical_Power_High 2-18

OS-Laser_Bias_High 2-19


vi

Contents

INT-RS-Tx_Buffer 2-20

INT-HP-Insert_Bus 2-21

RS-Loss_of_Frame 2-22

RS-Realign_Phase 2-25

INT-OS-Laser_Test 2-27

OS-Laser_Shutdown 2-28

MS-Excessive_BER 2-29

MS-Signal_Degrade 2-32

MS-AIS 2-34

MS-FERF 2-36

INT-HP-IP_Buffer 2-37

Qecc-Comms_Fail 2-39

AU-AIS 2-41

HP-TU_Multiframe 2-43

INT-AU-LOP 2-45

INT-AU-AIS 2-47

HP-Excessive_BER 2-49

HP-Signal_Degrade 2-50

HP-FERF 2-51

HP-FEBE 2-52

TU-AIS 2-53

TU-LOP 2-55

HP-Path_Trace 2-57

HP-Signal_Label 2-59

INT-TU-AIS 2-61

INT-TU-LOP 2-62

LP-Excessive_BER 2-63

LP-Signal_Degrade 2-65

TN-1C Alarm Clearing Procedures 323-1081-543 Release 2 Standard

Contents

vii

LP-Signal_Label 2-66

LP-FERF 2-68

LP-FEBE 2-69

INT-LP-OP_Buffer 2-70

PPI-Output_Fail 2-71

PPI-Unexp_Signal 2-72

PPI-Loss_of_Signal 2-73

PPI-Excessive_BER 2-75

PPI-Signal_Degrade 2-76

INT-LP-IP_Buffer 2-77

EA-Ext_inpn 2-78

SYNC-Holdover 2-79

SYNC-SETG_Fail 2-80

NE-Ext_Card_Out 2-81

NE-Wrong_Card 2-82

NE-Unexpected_Card 2-84

NE-Fan_Fail 2-85

NE-High_Temp 2-86

Chapter 3: Common procedures 3-1

Optical connector cleaning 3-2

Optical output power measurement 3-5

Optical input power measurement 3-7

Applying/clearing loopbacks 3-9

Chapter 4: Diagnostic tools 4-1Loopbacks 4-1

STM-1 local loopback (Loop to Mux) 4-1STM-1 remote loopback (Loop to Line) 4-2Tributary local loopback (Loop to Mux) 4-2Tributary remote loopback (Loop to Line) 4-2Simultaneous loopbacks 4-2

2 Mbit/s or 34 Mbit/s test pattern generator and detector 4-4


viii

Contents

Index 5-1

FiguresFigure 1-1 Masking hierarchy (part 1) 1-4Figure 1-2 Masking hierarchy (part 2) 1-5Figure 4-1 TN-1C loopbacks 4-3Figure 4-2 PRBS location 4-4

TablesTable 1-1 Alarm consequences 1-7Table 1-2 Alarm category and alarm severity settings 1-9Table 2-1 List of alarm clearing procedures 2-2

ProceduresProcedure 2-1 PS-Power_Fail alarm clearing 2-4Procedure 2-2 PS-Battery_Low alarm clearing 2-5Procedure 2-3 NE-Door_Open alarm clearing 2-8Procedure 2-4 PS-Door_Open alarm clearing 2-9Procedure 2-5 INT-NE-Config_Corrupt alarm clearing 2-12Procedure 2-6 RS-Loss_of_Signal alarm clearing 2-16Procedure 2-7 RS-Loss_of_Frame alarm clearing 2-23Procedure 2-8 STM-Realign_Phase alarm clearing 2-25Procedure 2-9 MS-Excessive_BER alarm clearing 2-30Procedure 2-10 MS-Signal_Degrade alarm clearing 2-32Procedure 2-11 MS-AIS alarm clearing 2-35Procedure 2-12 MS-FERF alarm clearing 2-36Procedure 2-13 INT-HP-IP_Buffer alarm clearing 2-37Procedure 2-14 Qecc-Comms_Fail alarm clearing 2-39Procedure 2-15 AU-AIS alarm clearing 2-42Procedure 2-16 HP-TU_Multiframe alarm clearing 2-44Procedure 2-17 HP-Excessive_BER alarm clearing 2-49Procedure 2-18 HP-Signal_Degrade alarm clearing 2-50Procedure 2-19 HP-FERF alarm clearing 2-51Procedure 2-20 HP-FEBE alarm clearing 2-52Procedure 2-21 TU-AIS alarm clearing 2-54Procedure 2-22 TU-LOP alarm clearing 2-56Procedure 2-23 HP-Path_Trace alarm clearing 2-58Procedure 2-24 HP-Signal_Label alarm clearing 2-60Procedure 2-25 LP-Excessive_BER alarm clearing 2-64Procedure 2-26 LP-Signal_Degrade alarm clearing 2-65Procedure 2-27 LP_Signal_Label alarm clearing 2-67Procedure 2-28 LP-FERF alarm clearing 2-68Procedure 2-29 LP-FEBE alarm clearing 2-69Procedure 2-30 INT-LP-OP_Buffer alarm clearing 2-70Procedure 2-31 PPI-Output_Fail alarm clearing 2-71Procedure 2-32 PPI-Loss_of_Signal alarm clearing 2-74Procedure 2-33 PPI-Excessive_BER alarm clearing 2-75Procedure 2-34 PPI-Signal_Degrade alarm clearing 2-76Procedure 2-35 INT-LP-IP_Buffer 2-77Procedure 2-36 SYNC-Holdover alarm clearing 2-79Procedure 2-37 SYNC-SETG_Fail alarm clearing 2-80Procedure 2-38 NE-Ext_Card_Out alarm clearing 2-81Procedure 2-39 NE-Wrong_Card alarm clearing 2-82Procedure 2-40 NE-Unexpected_Card alarm clearing 2-84


Contents

ix

Procedure 3-1 Cleaning an optical plug 3-3Procedure 3-2 Cleaning an optical coupler 3-4Procedure 3-3 Optical output power measurement 3-5Procedure 3-4 Optical input power measurements 3-7Procedure 3-5 Applying/removing loopbacks 3-10Procedure 4-1 Applying/stopping a continuity test 4-5


xi

About this documentThis document provides information on the alarm clearing procedures for the TN-1C add/drop multiplexer.

The document is divided into the following chapters:

• Chapter 1: Provides general information regarding the maintenance philosophy and an guide to beginning fault finding.

• Chapter 2: Provides details on each of the alarms generated by the TN-1C and procedures for clearing each fault.

• Chapter 3: Provides details of common procedures used in the alarm clearing procedures.

• Chapter 4: Provides details of diagnostic tools available on the TN-1C which may be used in the alarm clearing procedures.

0

AudienceThis document is intended for:

• Maintenance engineers

• Customer support engineers0

Associated documentsPersonnel must ensure that they are familiar with TN-1C Documentation Overview and Safety, NTP 323-1081-090 which includes essential safety information.

Procedures where the User Interface (UI) for the TN-1C is used require reference to TN-1C User Interface Guide, NTP 323-1081-401.

Procedures for changing field replaceable units are given in TN-1C Equipment Maintenance Procedures, NTP 323-1081-547.


xii

Technical support and informationNortel provides a comprehensive technical support service for its customers. The Nortel Service Desk may be contacted between the hours of 8:30 am and 5:00 pm, Monday to Friday (UK local time), using the following FAX or telephone numbers:

United KingdomFreephone: 0800 626 881Telephone: 0181 361 4693FAX: 0181 945 3456

InternationalTelephone: +44 181 361 4693FAX: +44 181 945 3456

Access to assistance from the Customer Service Desk 24-hour help line can be provided and is subject to a suitable Support Agreement being in place.

To discuss Technical Support services, please contact the Technical Support Hotline on 0181 945 3525.

End of chapter file

This product/product family complies with the provisions of the Low Voltage Directive 73/23/EEC, and with the essential protection requirements of the EMC Directive 89/336/EEC as amended by 92/31/EEC, when it is properly installed and maintained and when it is used for the purposes for which it is intended.


1-1

1

Chapter 1: Introduction

Maintenance philosophyThis chapter provides the field maintenance strategy for locating faulty equipment. The maintenance philosophy is to identify the faulty equipment without the need for extensive on-site maintenance. At all times, the maintenance procedures attempt to avoid disrupting live traffic.

Alarm indicationsWhen a defect is detected, the following occurs:

• When used in a managed environment, the defect is reported to the TN-MS Element Controller (TN-MS EC). The Element Controller provides a consolidated view of the active alarms in the network and provides alarm log facilities. The Element Controller also passes active alarms to the Network Resource Manager (NRM), if applicable, for first-alert functionality.

• The alarm is logged for access by operational personnel via the craft access terminal (CAT). The CAT also provides additional information which may be used in fault diagnosis (alarm logs, performance measurements).

• If the Rack Alarm Adapter is fitted, the appropriate LEDs on the Rack Alarm Adapter are lit and graded alarm extensions are provided to the station alarm system.

• The appropriate LEDs on the TN-1C units are lit.

• Where possible, services are re-established by performing path protection switching.

• When the alarm indicates a path failure or receipt of AIS, an AIS is inserted in all dependent downstream paths and, if appropriate, a remote alarm indication is sent in the opposite direction and is detected by the remote multiplexer.

0

The TN-1C multiplexer performs a degree of alarm correlation (masking) to limit the number of reports to the craft access terminal (see ‘Unit indications’ on page 1-2).


1-2

Introduction

Element ControllerThe TN-MS Element Controller (TN-MS EC) provides all the facilities needed for flexible management of synchronous digital networks based on Nortel’s synchronous multiplexers.

When an TN-1C Network Element (NE) is brought within the TN-MS ECs span of control, a Element Controller Association Session (ECAS) is set up between the TN-1C and the TN-MS EC. This provides a communications channel through which unsolicited event and alarm messages are sent, performance monitoring reports are polled, and NE clocks are aligned. The TM-MS EC also provides access to the user interface (UI) on the TN-1C NE for configuration and monitoring facilities.

When used with the TN-1C, the TN-MS EC provides consolidated alarm reporting for all NEs within its span of control, providing alarm counts according to the severity of the alarms. The TN-MS also provides alarm/event logs which can be viewed, printed and archieved. The TN-MS EC requests performance monitoring reports from the TN-1C NE once every 8 hours which are stored in a daily log. The logs are kept in a comma delimited file which simplifies the exporting to external spreadsheet programs. Viewing, filtering, printing and exporting of performance monitoring reports is carried out outside the TN-MS EC.

Logs are saved for 7 days.

Craft access terminalThe craft access terminal is an IBM-PC compatible ‘Laptop’ computer running VT-100 emulation software. Access with the TN-1C is via an RS232 serial interface port.

The craft access terminal uses the TN-1C multiplexer’s user interface. This interface uses simple commands to display and change configuration data and to view multiplexer status reports (e.g. alarms, performance monitoring).

Details of the craft access facilities are given in the TN-1C User Interface Guide, NTP 323-1081-401.

Unit indicationsThe following indications are provided on the various TN-1C units:

• TN-1C multiplexer unit (not visible when cover is fitted)

— Red FAIL LED (main card). Indicates that a defect has been detected on the unit.

— Red FAIL LED (tributary extension card). Indicates that a NE-Wrong_Card, NE-Unexpected_Card or NE-Card_Fail alarm has been detected on the tributary extension card.

— Green ACTIVE LED. Indicates that the +5 V supply is present on the unit.


Introduction

1-3

1
• Power Supply Unit (on alarm/interface unit, not visible when cover is fitted)
— Red LED. Indicates a low battery voltage and that the batteries have been disconnected from the load.

— Green LED. Indicates that the charger output is within the normal working range of -25.5 V to -30 V d.c.

• Rack Alarm Adapter (optional)

— Red ‘Alarm’ LED.

— Green ‘Receive Att’ LED.

The two LEDs indicate the overall alarm state of the TN-1C as follows:

— Both LEDs off indicates that the subrack has no alarms.

— Red LED only on indicates that the subrack has one or more unacknowledged alarm.

— Green LED only on indicates that an acknowledged alarm has not yet cleared.

— Both LEDs on indicates that an acknowledged alarm has cleared.0

Alarm maskingAlarm masking is the process by which alarm correlation is performed. This ensures that if several related alarms occur, only the highest importance alarm on the same traffic path is reported, all other related alarms are reported as clear. If the high-priority alarm clears, the alarm with the highest priority of the remaining alarms is reported.

For example, if RS-Loss_of_Signal and AU-AIS are both detected, only RS-Loss_of_Signal is reported as AU-AIS is a consequence of RS-Loss_of_Signal, therefore the AU-AIS indication has a high probability of being caused by the RS-Loss_of_Signal.

Figure 1-1 and Figure 1-2 show the masking hierarchy for the TN-1C.


1-4 Introduction

Figure 1-1Masking hierarchy (part 1) 1-1

INT-NE-RAM_Fail

INT-NE- Config_Corrupt

MS-Excessive_BER

Qecc-Comms_Fail

RS-Realign_Phase

MS-Signal_Degrade

AU-AIS

SYNC-Holdover

OS-Laser_Shutdown

INT-EC-Alarms_Buffer

PS-Battery_Low

NE-Card_Fail

RS-Loss_of_Signal

RS-Loss_of_Frame

MS-AISMS-FERF

OS-Laser_Bias_High

INT-OS-Laser_Test

OS-Optical_ Power_High

SYNC-SETG_Fail

EA-Ext_inpn

NE-Door_Open

PS-Door–Open

INT-NE-S/W_Corrupt

PS-Power_Fail

INT-RS-Tx_Buffer

INT-HP-Insert_Bus

A

To Figure 1-2

NE-Fan_High_Temp

NE-Fan_Fail


Introduction 1-5

1
Figure 1-2Masking hierarchy (part 2) 1-2
INT-TU_AIS

LP-Excessive_BER

LP-FERF

LP-FEBE

INT-LP-OP_Buffer

LP-Signal _Degrade

LP-Signal _Label

INT-TU_LOP PPI-Unexp_Signal

PPI-Loss_of _Signal

PPI-Output_Fail

PPI-Excessive_BER

PPI-Signal_Degrade

INT-LP-I/P_Buffer

TU-AIS

TU-LOP

HP-TU_Multiframe

HP-Path_Trace

HP-FERF

HP-FEBE

HP-Excessive_BER

HP-Signal_Degrade

INT-HP-IP_Buffer

INT-AU_LOP

INT-AU_AIS

AFrom Figure 1-1

HP-Signal_ Label

NE-Card_Fail

NE-Unexpected_Card

NE-Wrong_Card

NE-Ext_ Card_Out


1-6 Introduction

Alarm consequencesCertain defects result in automatic consequent actions, namely:

• Injection of a far end receive failure indication (MS-FERF, HP-FERF, or LP-FERF) to the far path/section end. LP-FERF may be discontinued if the path protection switching mechanism re-routes to an alternative valid path.

• Injection of AIS in the outgoing tributary signal (Trib AIS). Injection of tributary AIS may be discontinued if the path protection switching mechanism re-routes to an alternative valid path.

• Injection of low-order AIS towards the STM-1 aggregate port(s). The consequent action can be user configured to send either Tx Trib AIS (standard default) or TU AIS (non-standard). When configured to TU AIS, an indication of the local failure is provided at the far path termination.

• Injection of pass through TU-AIS on TUs that are passed-through the multiplexer.

• For protected paths, path protection switching to an alternative valid path.

• Laser shutdown. This is a safety feature, the laser shutdown is latched and the laser remains switched off until the multiplexer is powered-up.

• Multiplexer restart. The multiplexer restart is performed from the other software bank.

• Configuration switch. The configuration switch is performed using the other configuration data bank, if available and updated. Otherwise software factory-set defaults are used.

0

Table 1-1 details the consequence of each traffic alarm.


Introduction 1-7

1

Note 1: LP-Excessive_BER can be user configured not to cause consequent actions (LP-FERF and Trib AIS) and not to cause a path protection switch simultaneously (consequent actions and path protection switch cannot be disabled individually).

Note 2: The consequent action is dependent on the configuration of Tx Trib AIS or TU AIS. In case of standard configuration (i.e. Tx Trib AIS), the PPI-Unexp_Signal will not cause any consequent action. In case of non-standard configuration (i.e. TU AIS), the PPI-Unexp_Signal will cause TU AIS injection, overriding the unequipped code.

Table 1-1Alarm consequences 1-1

Consequent Action

Alarm

MS

-FE

RF

Pas

s-th

roug

h A

U-A

IS(s

ee N

ote

7)

HP

-FE

RF

LP-F

ER

F

Trib

AIS

Pas

s-th

roug

h T

U A

IS

Tx

Trib

or

TU

AIS

Pat

h P

rote

ctio

nS

witc

h

Lase

rS

hutd

own

Use

oth

er c

onfig

ban

kor

cra

sh d

efau

lts

RS-Loss_of_Signal √ √ √ √ √ √ √

RS-Loss_of_Frame √ √ √ √ √ √ √

MS-AIS √ √ √ √ √ √ √

MS-Excessive_BER √ √ √ √ √ √ √

AU-AIS √ √ √ √ √ √

INT-AU-AIS √ √ √ √ √ √

INT-AU-LOP √ √ √ √ √ √

HP-TU_Multiframe (see Notes 4 & 5)

√ √ √ √

HP-Path_Trace (see Note 3)

√ √ √ √ √

HP-Signal-Label(see Note 3)

√ √ √ √ √

TU-AIS √ √ √ √

TU-LOP √ √ √ √

INT-TU _AIS √ √

INT-TU_LOP √ √

LP-Signal_Label √ √

LP-Excessive_BER (see Note 1)

√ √ √

PPI_Loss_of_Signal √

PPI-Unexp_Signal(see Note 2)

√

OS-Optical_Power_High √

INT-NE-Config_Corrupt √


1-8 Introduction

Note 3: HP-Path_Trace and HP-Signal_Label can be user configured not to cause consequent actions (path protection switch, Trib AIS, HP-FERF and LP-FERF).

Note 4: HP-TU_Multiframe causes LP-FERF, Trib AIS and path protection switching for VC-12s and 2 Mbit/s tributaries only, not for VC-3s and 34/45 Mbit/s tributaries.

Note 5: HP-TU_Multiframe causes pass-through TU AIS for TU-12s only, not for TU-3s.

Note 6: HP-TU_Multiframe monitoring can be disabled by the user.

Note 7: Pass-through AU-AIS is only applicable if a VC-4 through connection is made.

0

Beginning fault findingTo locate and clear a fault in the TN-1C system, it is recommended to proceed as follows:

• Identify the TN-1Cs on which the fault indications are present. This is achieved by:

— On managed systems, using the TN-MS EC to identify the TN-1C with the highest severity alarms. The TN-MS EC can be used to provide a network level alarm status, this may be used to perform some manual network level alarm correlation in order to isolate the cause of the alarm.

— On unmanaged systems, using the CAT to identify the TN-1C with the highest severity alarm.

— If the external output alarm is used to extend the TN-1C alarms to other external equipment, monitor the external equipment for TN-1C alarm conditions.

• Refer to Chapter 2 for detailed, step-by-step procedures for clearing the alarms. When clearing multiple alarms, you should be aware that one alarm can mask or be masked by others (see ‘Alarm masking’ on page 1-3).

0

Responding to logsTN-1C logs are informational messages that are generated by the TN-1C. Logs can be viewed using the CAT and the TN-MS EC.

Often, no action is required on the part of maintenance personnel as a result of log messages. However, some logs are designed to provide supplemental information for certain alarms or trouble-clearing procedure. Copies of the logs may also be useful for Nortel personnel when providing further diagnostic support.


Introduction 1-9

1
Alarm category and severityEach alarm instance is assigned an rack alarm category (prompt, deferred, or in-station) for extension to a rack alarm system. The default alarm categories are given in Table 1-2, these can be changed via the user interface.
Alarm instances are categorised as Critical, Major, or Minor according to the seriousness of their impact (or potential impact). These categories are pre-set for each alarm instance and cannot be changed. The severity settings are given in Table 1-2.

The rack alarm category and alarm severity are included in the TN-1C UI alarm reports. Alarm reports on the Element Controller use only the alarm severity.

Table 1-2Alarm category and alarm severity settings 1-2

Alarm Alarm category Alarm severity

PS-Power_Fail Prompt Critical

PS-Battery_Low Prompt Critical

INT-NE-SW_Corrupt Prompt Critical

INT-EC-Alarms_Buffer Prompt Critical

NE-Door_Open Prompt Critical

PS-Door_Open Prompt Critical

INT-NE-RAM_Fail Prompt Critical

INT-NE-Config_Corrupt Prompt Critical

NE-Card_Fail Prompt Critical

RS-Loss_of_Signal Prompt Critical

OS-Optical_Power_High Prompt Critical

OS-Laser_Bias_High In-station Minor

INT-RS-Tx_Buffer Prompt Critical

INT-HP-Insert_Bus Prompt Critical

RS-Loss_of_Frame Prompt Critical

RS-Realign_Phase Prompt Critical

INT-OS-Laser_Test In-station Minor

OS-Laser_Shutdown In-station Minor

MS-Excessive_BER Prompt Critical

MS-Signal_Degrade Deferred Major

MS-AIS In-station Minor

MS-FERF Deferred Major

INT-HP-IP_Buffer Deferred Major

Qecc-Comms_Fail Prompt Critical

AU-AIS In-station Minor

HP-TU_Multiframe Deferred Major

—continued—


1-10 Introduction

End of chapter file

INT-AU-LOP Deferred Major

INT-AU-AIS In-station Minor

HP-Excessive_BER Prompt Critical

HP-Signal_Degrade Deferred Major

HP-FERF Deferred Major

HP-FEBE Deferred Major

TU-AIS In-station Minor

TU-LOP Deferred Major

HP-Path_Trace Deferred Major

HP-Signal_Label Deferred Major

INT-TU-AIS In-station Minor

INT-TU-LOP Deferred Major

LP-Excessive_BER Deferred Major

LP-Signal_Degrade Deferred Major

LP-Signal_Label Deferred Major

LP-FERF Deferred Major

LP-FEBE Deferred Major

INT-LP-OP_Buffer Deferred Major

PPI-Output_Fail Deferred Major

PPI-Unexp_Signal In-station Minor

PPI-Loss_of_Signal Deferred Major

PPI-Excessive_BER Deferred Major

PPI-Signal_Degrade Deferred Major

INT-LP-IP_Buffer Deferred Major

EA-Ext_inpn (n=1 to 8) Prompt Critical

SYNC-Holdover Prompt Critical

SYNC-SETG_Fail Deferred Major

NE-Ext_Card_Out Prompt Critical

NE-Wrong_Card Prompt Critical

NE-Unexpected_Card In-station Minor

NE-High_Temp Prompt Critical

NE-Fan_Fail Deferred Major

—end—

Table 1-2Alarm category and alarm severity settings (continued) 1-2

Alarm Alarm category Alarm severity


2-12

Chapter 2: Clearing equipment alarmsThis chapter describes how to locate and clear alarms on the TN-1C equipment.

The alarm clearing procedures are based on a TN-1C ring system configuration. If the TN-1C is used in other system configurations, the user should refer to the appropriate equipment handbooks for the appropriate alarm clearing procedures whenever references are made to the far multiplexer.

Table 2-1 provides a list of alarms and the page where the alarm clearing information can be found.

Note: In case where a STM local loopback is performed and passed, it might be helpful to also perform a manual optical loopback (using a fibre pigtail) before investigating the problem in the fibre.


2-2 Clearing equipment alarms

Table 2-1List of alarm clearing procedures 2-1

Alarm Page

‘PS-Power_Fail’ page 2-4

‘PS-Battery_Low’ page 2-5

‘INT-NE-SW_Corrupt’ page 2-6

‘INT-EC-Alarms_Buffer’ page 2-7

‘NE-Door_Open’ page 2-8

‘PS-Door_Open’ page 2-9

‘INT-NE-RAM_Fail’ page 2-11

‘INT-NE-Config_Corrupt’ page 2-12

‘NE-Card_Fail’ page 2-14

‘RS-Loss_of_Signal’ page 2-15

‘OS-Optical_Power_High’ page 2-18

‘OS-Laser_Bias_High’ page 2-19

‘INT-RS-Tx_Buffer’ page 2-20

‘INT-HP-Insert_Bus’ page 2-21

‘RS-Loss_of_Frame’ page 2-22

‘RS-Realign_Phase’ page 2-25

‘INT-OS-Laser_Test’ page 2-27

‘OS-Laser_Shutdown’ page 2-28

‘MS-Excessive_BER’ page 2-29

‘MS-Signal_Degrade’ page 2-32

‘MS-AIS’ page 2-34

‘MS-FERF’ page 2-36

‘INT-HP-IP_Buffer’ page 2-37

‘Qecc-Comms_Fail’ page 2-39

‘AU-AIS’ page 2-41

‘HP-TU_Multiframe’ page 2-43

‘INT-AU-LOP’ page 2-45

‘INT-AU-AIS’ page 2-47

‘HP-Excessive_BER’ page 2-49

‘HP-Signal_Degrade’ page 2-50

‘HP-FERF’ page 2-51

‘HP-FEBE’ page 2-52

‘TU-AIS’ page 2-53

—continued—


Clearing equipment alarms 2-3

2
‘TU-LOP’ page 2-55
‘HP-Path_Trace’ page 2-57

‘HP-Signal_Label’ page 2-59

‘INT-TU-AIS’ page 2-61

‘INT-TU-LOP’ page 2-62

‘LP-Excessive_BER’ page 2-63

‘LP-Signal_Degrade’ page 2-65

‘LP-Signal_Label’ page 2-66

‘LP-FERF’ page 2-68

‘LP-FEBE’ page 2-69

‘INT-LP-OP_Buffer’ page 2-70

‘PPI-Output_Fail’ page 2-71

‘PPI-Unexp_Signal’ page 2-72

‘PPI-Loss_of_Signal’ page 2-73

‘PPI-Excessive_BER’ page 2-75

‘PPI-Signal_Degrade’ page 2-76

‘INT-LP-IP_Buffer’ page 2-77

‘EA-Ext_inpn’ page 2-78

‘SYNC-Holdover’ page 2-79

‘SYNC-SETG_Fail’ page 2-80

‘NE-Ext_Card_Out’ page 2-81

‘NE-Wrong_Card’ page 2-82

‘NE-Unexpected_Card’ page 2-84

‘NE-Fan_Fail’ page 2-85

‘NE-High_Temp’ page 2-86

—end—

Table 2-1List of alarm clearing procedures (continued) 2-1

Alarm Page



PS-Power_Fail

SignificanceThe a.c. mains supply or the external charger to the TN-1C Power Supply Unit has failed (fallen below set level).

Note: This alarm is only applicable when using Nortel’s TN-1C Power Supply Unit.

ImpactNone immediately. Minimum 3 hours of operation is available from battery backup.

Consequent alarms/eventsNone.

Possible causes• a.c. mains failure.

• a.c. fuse blown.

• Input connector not properly connected.

• Faulty TN-1C Power Supply Unit.0

Corrective actionPerform the alarm clearing procedures detailed in Procedure 2-1.

Procedure 2-1PS-Power_Fail alarm clearing 2-1

Step Action

1 Check that the a.c. mains connector is properly connected. Re-connect the connector if required. If alarm still present, proceed to Step 2.

2 Check a.c. fuse, replace if blown.

If fuse blows again, proceed to Step 4.

3 Verify that the a.c. mains supply is present.

If the a.c. mains supply is not present, investigate loss.

If the a.c. mains supply is present, proceed to Step 4.

4 Replace the TN-1C Power Supply Unit. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures.

—end—



2

PS-Battery_Low

SignificanceThe battery voltage has dropped below 21 V ± 0.5 V, indicating that only a few minutes of operation remain.

Note: This alarm is only applicable when using Nortel’s TN-1C Power Supply Unit.

ImpactImminent traffic loss.


Possible causes• a.c. mains failure.

• Input connector not properly connected.

• Faulty power unit.0

Corrective actionPerform the alarm clearing procedures detailed in Procedure 2-2.

Procedure 2-2PS-Battery_Low alarm clearing 2-2

Step Action

1 Check if a ‘PS-Power_Fail’ alarm is present.

If a ‘PS-Power_Fail’ alarm is present, perform the alarm clearing procedure for the ‘PS-Power_Fail’ alarm.

If a ‘PS-Power_Fail’ alarm is not present, proceed to Step 2.

2 Replace the TN-1C Power Supply Unit batteries.

—end—



INT-NE-SW_Corrupt

SignificanceThe checksum of the application code is incorrect.

ImpactNone.


Possible causes• Download failure.

• Spurious software corruption.0

Corrective actionCopy the current good software bank to the corrupted bank using the TN-1C UI (see Software Administration Procedures, NTP 323-1081-303).



2

INT-EC-Alarms_Buffer

SignificanceThe alarm report buffer used for transferring alarm messages to the network management system has overloaded. All current alarm messages in the buffer are removed and an appropriate message is sent to the network management system, which will then request an active alarms report.

ImpactNon-traffic affecting.


Possible causes• Excessive alarm activity on network.

• If single occurrence, probably major network disturbance.

• If persistent, internal fault.0

Corrective actions• Investigate network for major disturbance.

• Investigate local multiplexer for excessive alarm activity.

• Align network management system alarms.



NE-Door_Open

SignificanceThe cover on the TN-1C multiplexer unit has been removed.

Note: The alarm remains active for approximately 5 minutes once the cover is fitted.

ImpactNone.


Possible causes• TN-1C cover removed or not correctly fitted.

• Tab broken on plastic cover.

• Faulty microswitch.

Corrective actionsIf cover removal unauthorised (i.e. no known maintenance activities), or alarm is not cleared within 5 minutes of door closure, perform the alarm clearing procedure given in Procedure 2-3.

Procedure 2-3NE-Door_Open alarm clearing 2-3

Step Action

1 Check that plastic tab is not broken on plastic cover and that the cover is properly fitted.

If the cover is not correctly fitted, refit the cover. If the plastic tab is broken, replace the plastic cover.

If alarm is still present, proceed to Step 2.

2 Check that the microswitch lever is not damaged.

If microswitch is damaged, replace the TN-1C multiplexer.

If microswitch is not damaged, escalate the problem.

—end—



2

PS-Door_Open

SignificanceThe cover on the TN-1C Power Supply Unit (PSU) has been removed.

Note 1: The alarm remains active for approximately 5 minutes once the cover is fitted.

Note 2: On the 16x2 Mbit/s versions of the TN-1C, the alarm will not be raised if the PS-Door_Open jumper is shorted.

ImpactNone.


Possible causes• TN-1C PSU cover removed or not correctly fitted.

• Tab broken on plastic cover.

• Faulty microswitch.

Corrective actions

Note: If the Nortel PSU is not being used, check that the alarm is disabled on the TN-1C (i.e. pins 4 and 9 linked on the power connector).

If cover removal unauthorised (i.e. no known maintenance activities), or alarm is not cleared within 5 minutes of door closure, perform the alarm clearing procedure given in Procedure 2-4.

Procedure 2-4PS-Door_Open alarm clearing 2-4

Step Action

1 Check that plastic tab is not broken on plastic cover and that the cover is properly fitted.

If the cover is not correctly fitted, refit the cover. If the plastic tab is broken, replace the plastic cover.


2 Check that the microswitch lever is not damaged.

If microswitch is damaged, replace the PSU.

If microswitch is not damaged, proceed to Step 3.

—continued—



3 Replace the d.c./alarm cable between the TN-1C and the PSU.

If the alarm clears, no further action is required.

If alarm is still present, replace the PSU.

—end—

Procedure 2-4PS-Door_Open alarm clearing 2-4

Step Action



2

INT-NE-RAM_Fail

SignificanceFailure of the on-board RAM during self-tests which are performed on initialisation and subsequently at regular intervals (approximately every 30 seconds).

ImpactSmall risk of being traffic affecting.


Possible causesRAM failure on TN-1C multiplexer.

Corrective actionReplace the TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures.



INT-NE-Config_Corrupt

SignificanceThe periodic checksum test on the configuration data held in the non-volatile memory has failed.

ImpactIf alternate configuration bank not available, possibly traffic affecting.

Consequent alarms/eventsIf other configuration data bank is available and has been updated, a switch is made to the alternate configuration bank. If alternate configuration data bank not available, factory-set defaults are used.

Possible causesNon-volatile store corrupt.

Corrective actionsPerform the alarm clearing procedure given in Procedure 2-5.

Procedure 2-5INT-NE-Config_Corrupt alarm clearing 2-5

Step Action

1 Use the UI to view the configuration bank status.

If both banks contain the latest correct configuration and the multiplexer is operating correctly, no further action is required.

If only one configuration bank contains the correct configuration, proceed to Step 2.

If the multiplexer is operating from its default settings, proceed to Step 3.

If the alarm is persistent, replace the TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures.

2 Use the UI to commit the configuration to the other bank (see System Administration Procedures, NTP 323-1081-302).

If the commit process fails, replace the TN-1C multiplexer.

Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures.

—continued—



2
3 If a backup configuration is available, download and switch to backup configuration using the UI. If the backup configuration is acceptable, commit the configuration to the other bank. For details of the UI procedures, refer to System Administration Procedures NTP, 323-1081-302.
If the download, restore or commit process fails, replace the TN-1C multiplexer.


—end—

Procedure 2-5INT-NE-Config_Corrupt alarm clearing (continued) 2-5

Step Action



NE-Card_Fail

SignificanceFailure of the on-board ASIC tests or any other hardware tests which are performed on initialisation and subsequently at regular intervals (approximately every 30 seconds).

ImpactMay be traffic affecting, depending on the type of failure.


Possible causes• Failure of the one of the on-board ASICs.

• Hardware checksum failure.

• Phase-Locked Loop problems.0

Corrective actionsIf the alarm is reported for instance ‘S0’ (connector panel), replace TN-1C EMC enclosure.

If the alarm is reported for instance ‘S1’ (main TN-1C ADM card), replace main TN-1C ADM card.

If the alarm is reported for instance ‘S2’ (tributary extension card), replace tributary extension card.




2

RS-Loss_of_Signal

SignificanceThe incoming optical signal has failed or fallen below the threshold level, causing the clock recovery circuit to lose lock, or an all-zeros pattern has been detected for at least 6.5 µs ± 1 µs.

Impact• Traffic affecting on unprotected paths.

• Temporary traffic hit on protected paths if paths switched to aggregate containing alarm.

0

Consequent alarms/eventsLocal • Through paths

— TU-AIS injection on all through paths.

• Protected add/drop TU paths

— Temporary AIS injection on tributary outputs switched to aggregate containing alarm.

— If paths switched to aggregate containing alarm, protection switch to other aggregate (if valid).

• Unprotected add/drop TU paths

— AIS injection on all tributary outputs.

• Laser shutdown.0

HP source— MS-FERF and HP-FERF alarms.

0

LP termination• Protected add/drop TU paths

— TU-AIS alarms.

— If TUs switched to HP containing RS-Loss_of_Signal alarm, protection switch to other aggregate (if valid).


— TU-AIS alarms.0

LP source• Protected add/drop TU paths

— LP-FERF alarms if both paths have failed at local multiplexer.


— LP-FERF alarms.0



Possible causes• Fibre break/bad termination.

• Transmitter failure at far TN-1C multiplexer.

• Receiver failure on local TN-1C multiplexer.0


Procedure 2-6RS-Loss_of_Signal alarm clearing 2-6

Step Action

1 If the route is protected, ensure that the traffic is switched to the other aggregate port.

2 Perform a ‘Local’ loopback on the appropriate aggregate at the local TN-1C multiplexer (see Chapter 3, Common Procedures). Use the UI to issue a laser restart command.

If the alarm is still present, remove the ‘Local’ loopback and replace the local TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures. If the alarm is still present, replace the original TN-1C multiplexer and escalate the problem.

If the alarm clears, remove the ‘Local’ loopback and proceed to Step 3.

3 Clean the receive optical connections at the local TN-1C multiplexer and verify that the received optical power is in the correct range (see Chapter 3, Common Procedures).

If the received optical power is within range, proceed to Step 4.

If the received optical power is not within range, proceed to Step 5.

4 Replace the local TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures.

If the alarm is still present, replace the original TN-1C multiplexer and escalate the problem.

If the alarm clears, the alarm clearing procedures are complete.

—continued—



2
5 Clean the transmit optical connections at the far TN-1C multiplexer and verify that the transmit optical power at the far TN-1C multiplexer is in the correct range (see Chapter 3, Common Procedures).
If the transmit optical power is within range, the fault is associated with the optical fibre. Use appropriate methods to isolate fibre fault.

If the transmit optical power is not within range, proceed to Step 6.

6 Replace the far TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures.

If the alarm is still present, replace the original far TN-1C multiplexer and escalate the problem.

—end—

Procedure 2-6RS-Loss_of_Signal alarm clearing (continued) 2-6

Step Action



OS-Optical_Power_High

SignificanceThe optical output power has exceeded the nominal output level by more than 4 dB, or has exceeded +4 dBm within 600 ms.



0

Consequent alarms/eventsLaser shutdown. This is a safety feature, although the laser output is still within the standard safe range.

Note: The laser shutdown is latched, the laser will remain off until the multiplexer is powered-up.

Possible causesFaulty TN-1C transmit circuit.

Corrective actionsReplace the TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures.



2

OS-Laser_Bias_High

SignificanceThe laser bias current is out-of-limits. Indicates that the laser performance has degraded and that the laser end-of-life is near.

ImpactNon-traffic affecting.

Note: The alarm indicates that a maintenance action is needed, otherwise an Optical Source Low Power condition will occur, which is service affecting.


Possible causesAging of laser.




INT-RS-Tx_Buffer

SignificanceThe DSPI FIFO in the mapping/multiplexing direction is either in the underflow or overflow state.

ImpactTraffic affecting.


Possible causesFaulty local TN-1C multiplexer.

Corrective actionsIf alarm is persistent, replace the TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures.



2

INT-HP-Insert_Bus

SignificanceThe payload data in the mapping/multiplexing direction is errored. The alarm is raised if the AU pointer values are errored in at least eight consecutive frames.







RS-Loss_of_Frame

SignificanceThe frame alignment algorithm has detected loss of frame alignment (loss of framing pattern in the A1 and A2 bytes of the section overhead for three consecutive frames).



0

Consequent alarms/eventsLocal• Through paths






— AIS injection on all tributary outputs.0


0

LP path termination• Protected add/drop TU paths

— TU-AIS alarms.

— If TUs switched to HP containing RS-Loss_of_Frame alarm, protection switch to other aggregate (if valid).


— TU-AIS alarms.0







2

Possible causes• Invalid incoming STM-1 signal.

• Faulty local or remote TN-1C multiplexer.0


Procedure 2-7RS-Loss_of_Frame alarm clearing 2-7

Step Action


2 Perform a ‘Local’ loopback on the appropriate aggregate at the local TN-1C multiplexer (see Chapter 3, Common Procedures).



3 Perform a ‘Local’ loopback on the appropriate aggregate at the far TN-1C multiplexer (see Chapter 3, Common Procedures).

If a RS-Loss_of_Frame alarm is present at the far multiplexer, remove the ‘Local’ loopback and replace the far TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures. If the alarm is still present, replace the original TN-1C multiplexer and escalate the problem.

If a RS-Loss_of_Frame alarm is not present at the far multiplexer, remove the ‘Local’ loopback and proceed to Step 4.




—continued—








—end—

Procedure 2-7RS-Loss_of_Frame alarm clearing 2-7

Step Action



2

RS-Realign_Phase

SignificanceThe STM-1 processor has realigned to a new phase without going out of frame alignment.

ImpactPossible traffic hit.


Possible causesFaulty local or remote TN-1C multiplexer.

Corrective actionsIf the alarm is persistent, perform the alarm clearing procedure given in Procedure 2-8.

Procedure 2-8STM-Realign_Phase alarm clearing 2-8

Step Action


2 Perform a ‘Local’ loopback at the appropriate aggregate at the local TN-1C multiplexer (see Chapter 3, Common Procedures).



3 Perform a ‘Local’ loopback on the appropriate aggregate at the far TN-1C multiplexer (see Chapter 3, Common Procedures).

If a RS-Realign_Phase alarm is present at the far multiplexer, remove the ‘Local’ loopback and replace the far TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures. If the alarm is still present, replace the original TN-1C multiplexer and escalate the problem.

If a RS-Realign_Phase alarm is not present at the far multiplexer, remove the ‘Local’ loopback and proceed to Step 4.

—continued—











—end—

Procedure 2-8STM-Realign_Phase alarm clearing 2-8

Step Action



2

INT-OS-Laser_Test

SignificanceThe automatic laser shutdown (ALS) circuit has been disabled.

ImpactNone.


Possible causesLaser ‘forced_on’ from the TN-1C UI.

Corrective actionsRe-enable ALS by setting laser to ‘normal’ operation from the UI (see User Interface Guide, NTP 323-1081-401). If the alarm is still present, replace the TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures.



OS-Laser_Shutdown

SignificanceThe laser has been shutdown by the automatic laser shutdown (ALS) circuit or by OS-Optical_Power_High alarm.

Note: The OS-Laser_Shutdown alarm remains active during the laser restart pulses (part of the ALS mechanism).



0

Consequent alarms/events• If shutdown by a RS-Loss_of_Signal alarm, automatic laser shutdown

mechanism initiated. Laser restart attempted every 70 seconds until RS-Loss_of_Signal alarm is cleared.

• If shutdown due to an OS-Optical_Power_High alarm, the laser shutdown is latched and the laser will remain off until the multiplexer is powered-up.

Possible causesRS-Loss_of_Signal or OS-Optical_Power_High alarm.

Corrective actionsSend a laser restart command using the UI. If alarm is still present, investigate cause of RS-Loss_of_Signal or OS-Optical_Power_High alarm.



2

MS-Excessive_BER

SignificanceThe BER of the BIP-24 error check has exceeded 10-3.



0









0


— TU-AIS alarms.

— If TUs switched to HP containing MS-Excessive_BER alarm, protection switch to other aggregate (if valid).


— TU-AIS alarms.0







Possible causes• Faulty optical fibre/connections.

• Faulty local TN-1C multiplexer.

• Faulty far end TN-1C multiplexer.0


Procedure 2-9MS-Excessive_BER alarm clearing 2-9

Step Action








4 Apply a manual (external) optical loopback at the local multiplexer.

If the alarm is still present, proceed to Step 5.

If the alarm clears, proceed to Step 7.



If the alarm clears, remove the external optical loopback.The alarm clearing procedures are complete.

—continued—



2
6 Clean the transmit optical connection at the far TN-1C multiplexer and verify that the transmit optical power at the far multiplexer is in the correct range (see Chapter 3, Common Procedures).




—end—

Procedure 2-9MS-Excessive_BER alarm clearing (continued) 2-9

Step Action



MS-Signal_Degrade

SignificanceThe BER of the BIP-24 error check has exceeded the configurable lower threshold (10-5, 10-6, or 10-7, default 10-5).


Consequent alarms/eventsLocal Possible intermittent HP-Signal_Degrade and LP-Signal_Degrade alarms.

HP sourcePossible intermittent HP-FEBE alarms.

LP sourcePossible intermittent LP-FEBE alarms.

Possible causes• Faulty optical fibre/connections.




Procedure 2-10MS-Signal_Degrade alarm clearing 2-10

Step Action





—continued—



2


4 Apply a manual (external) optical loopback at the local multiplexer.


If the alarm clears, proceed to Step 7.



If the alarm clears, remove the external optical loopback. The alarm clearing procedures are complete.

6 Clean the transmit optical connection at the far TN-1C multiplexer and verify that the transmit optical power at the far multiplexer is in the correct range (see Chapter 3, Common Procedures).





—end—

Procedure 2-10MS-Signal_Degrade alarm clearing (continued) 2-10

Step Action



MS-AIS

SignificanceAn AIS has been detected in the K2 byte in the section overhead indicating a failure at the far multiplexer.


• Temporary traffic hit on protected paths.0









0


— TU-AIS alarms.

— If TUs switched to HP path containing MS-AIS alarm, protection switch to other aggregate (if valid).


— TU-AIS alarms.0







2

Possible causesMS AIS generated at far multiplexer or by a regenerator in between (if applicable).

Note: MS AIS is not intentionally generated by the TN-1C multiplexer and should not be raised in a TN-1C to TN-1C system.


Procedure 2-11MS-AIS alarm clearing 2-11

Step Action

1 Check far multiplexer and any intermediate regenerators for cause of AIS.

If cause of AIS found, perform the appropriate alarm clearing procedure.

If cause of alarm not found, proceed to Step 2.

2 If the route is protected, ensure that the traffic is switched to the other aggregate port. Perform a ‘Local’ loopback on the appropriate aggregate at the local TN-1C multiplexer (see Chapter 3, Common Procedures).

If the alarm is still present, remove the ‘Local’ loopback and replace the local TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures.

If the alarm clears, replace the far TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures.

—end—



MS-FERF

SignificanceA FERF indication has been detected in the K2 bytes of the section overhead, indicating that the far multiplexer has detected a fault in the incoming signal.

ImpactNone.


Possible causesRS-Loss_of_Signal, RS-Loss_of_Frame, MS-AIS, or MS-Excessive_BER alarm at the far multiplexer.


Procedure 2-12MS-FERF alarm clearing 2-12

Step Action

1 Check far multiplexer for cause of alarm (RS-Loss_of_Signal, RS-Loss_of_Frame, MS-AIS, or MS-Excessive_BER alarm).

If cause of alarm found, perform the appropriate alarm clearing procedure.





—end—



2

INT-HP-IP_Buffer

SignificanceThe AU FIFO buffer, which allows the incoming STM-1 signal to be aligned to the local frame, has underflowed or overflowed.



Note: If the alarm persists, protected paths may switch due to HP and LP defects.

Possible causes• Synchronisation problems in network.

• Incoming STM-1 signal out-of-limits.

• Faulty local TN-1C multiplexer.0


Procedure 2-13INT-HP-IP_Buffer alarm clearing 2-13

Step Action


2 Isolate the TN-1C from the synchronisation perspective (i.e. remove all external source from the hierarchy so that the TN-1C is operating in the holdover mode).

If the alarm clears, investigate the network for possible synchronisation loops.

If the alarm is still present, return the synchronisation hierarchy to the previous settings and proceed to Step 3.

—continued—




If the alarm is still present, remove the ‘Local’ loopback and replace the local TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures. If the alarm is still present, replace the original local TN-1C multiplexer and escalate the problem.




—end—

Procedure 2-13INT-HP-IP_Buffer alarm clearing (continued) 2-13

Step Action



2

Qecc-Comms_Fail

SignificanceCommunication over the Embedded Control Channel (ECC) has been lost with the adjacent multiplexer on a specific STM-1 link.

Impact• Non-traffic affecting.

• Inter-site data communications are unavailable.


Possible causes• Faulty local or far end TN-1C multiplexer.

• Remote or local aggregate loopback on the local or far end multiplexer.

• If alarm is temporary, cold or warm restart on the local or far TN-1C multiplexer.

Corrective actionsIf the alarm is persistent, perform the alarm clearing procedure given in Procedure 2-14.

Procedure 2-14Qecc-Comms_Fail alarm clearing 2-14

Step Action

1 Disable faulty link at the local TN-1C by disconnecting optical fibres and then reconnecting them.

If alarm clears, report occurrence (no other action is required).


2 Reboot the software using a cold restart from the UI.

If alarm clears, report occurrence (no other action is required).



If alarm still present, replace the original local TN-1C multiplexer and proceed to Step 4.


—continued—





—end—

Procedure 2-14Qecc-Comms_Fail alarm clearing (continued) 2-14

Step Action



2

AU-AIS

SignificanceAn AIS has been detected in the H1 and H2 bytes indicating a failure in the upstream path.










HP source— HP-FERF alarm.

0


— TU-AIS alarms.

— If TUs switched to HP containing AU-AIS alarm, protection switch to other aggregate (if valid).


— TU-AIS alarms.0

LP path source• Protected add/drop TU paths






Possible causesAU AIS being generated by far multiplexer.

Note: AU AIS is not intentionally generated by the TN-1C multiplexer and should not be raised in a TN-1C to TN-1C system.

0


Procedure 2-15AU-AIS alarm clearing 2-15

Step Action

1 Check far multiplexer and any intermediate regenerators for cause of AIS.






—end—



2

HP-TU_Multiframe

SignificanceAn illegal multiframe sequence has been detected in the H4 byte.



0

Consequent alarms/events

Note: When the TN-1C is used in a VC-3 only ring, the HP-TU_Multiframe alarm is not applicable and should be disabled using the UI (see User Interface Guide, NTP 323-1081-401).

Local • Through paths








— TU-AIS alarms.

— If TUs switched to HP path containing HP-TU_Multiframe alarm, protection switch to other aggregate (if valid).


— TU-AIS alarms.0







Possible causes• Line errors.




Procedure 2-16HP-TU_Multiframe alarm clearing 2-16

Step Action


2 Perform a ‘Local’ loopback at the appropriate aggregate at the local TN-1C multiplexer (see Chapter 3, Common Procedures).





—end—



2

INT-AU-LOP

SignificanceThe internal pointer value in the H1 and H2 bytes in the AU pointer has been invalid (i.e. an invalid New Data Flag or size bits) for three consecutive frames.



0









0


— TU-AIS alarms.

— If TUs switched to HP path containing INT-AU-LOP alarm, protection switch to other aggregate (if valid).


— TU-AIS alarms.0








Corrective actionsReplace the local TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures. If the alarm is still present, replace the original local TN-1C multiplexer and escalate the problem.



2

INT-AU-AIS

SignificanceAn internal AIS has been detected internally in the H1 and H2 bytes for three consecutive frames.



0









0


— TU-AIS alarms.

— If TUs switched to HP path containing INT-AU-AIS alarm, protection switch to other aggregate (if valid).


— TU-AIS alarms.0








Corrective actionsReplace the local TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures. If the alarm is still present, replace the original local TN-1C multiplexer and escalate the problem.



2

HP-Excessive_BER

SignificanceThe BER of the VC-4 path (B3) BIP-8 error check has exceeded 10-3.


Consequent alarms/eventsHP sourceHP-FEBE alarm.

LP sourcePossible LP-FEBE alarms.

Possible causes• Faulty local TN-1C multiplexer.

• Faulty far end TN-1C multiplexer.


Procedure 2-17HP-Excessive_BER alarm clearing 2-17

Step Action



If the alarm is still present, remove the ‘Local’ loopback and replace the local TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures. If the alarm is still present, replace the original multiplexer and escalate the problem.



If the alarm is still present, replace the original far TN-1C multiplexer. If the alarm is still present, replace the original far TN-1C multiplexer and escalate the problem.

—end—



HP-Signal_Degrade

SignificanceThe BER of the VC-4 path (B3) BIP-8 error check has exceeded the configurable lower threshold (10-5, 10-6, or 10-7, default 10-5).


Consequent alarms/eventsLocalPossible LP-Signal_Degrade alarms.

HP sourcePossible HP-FEBE alarm.

LP sourcePossible LP-FEBE alarms.


• Faulty far end TN-1C multiplexer.


Procedure 2-18HP-Signal_Degrade alarm clearing 2-18

Step Action


2 Perform a ‘Local’ loopback on the local TN-1C multiplexer (see Chapter 3, Common Procedures).





—end—



2

HP-FERF

SignificanceThe VC-4 Path FERF bit in the VC-4 path status byte (G1) has been set indicating that the HP origin has detected a fault in the incoming HP.

ImpactNone.


Possible causesINT-AU-AIS, HP-Excessive_BER, or INT-AU-LOP alarm at the far multiplexer.


Procedure 2-19HP-FERF alarm clearing 2-19

Step Action

1 Check far multiplexer for cause of alarm (AU-AIS, INT-AU-AIS, INT-AU-LOP, or HP-TU_Multiframe alarm).






—end—



HP-FEBE

SignificanceThe BER of the FEBE bits in the VC-4 path status byte (G1), indicating that the far multiplexer has detected errors in the VC-4 path, has exceeded the configurable threshold of 10-5, 10-6, or 10-7 (default 10-5).

ImpactNone.


Possible causesHP errors on the network.


Procedure 2-20HP-FEBE alarm clearing 2-20

Step Action

1 Check far HP path termination for cause of errors (e.g. HP-Signal_Degrade or HP-Excessive_BER alarm) and carry out fault finding procedures for appropriate alarm.

If cause of errors found, perform the appropriate alarm clearing procedure.

If cause of errors not found, proceed to Step 2.




—end—



2

TU-AIS

SignificanceAn AIS has been detected in the pointer bytes of the TU.



0

Consequent alarms/eventsLocal • Protected add/drop TU path

— Temporary AIS injection on associated tributary output if switched to aggregate containing alarm.


• Unprotected add/drop TU path

— AIS injection on associated tributary output.0

LP source• Protected add/drop TU path

— LP-FERF alarm if both paths have failed at local multiplexer.


— LP-FERF alarm.0

Possible causesTU AIS being generated by another multiplexer on the network.




Procedure 2-21TU-AIS alarm clearing 2-21

Step Action

1 Is traffic expected on the indicated channel.

If traffic is expected, proceed to Step 2.

If traffic is not expected, use the UI to set the channel to ‘Traffic Off’ (this will disable the alarm).

2 Investigate network (LP path source and intermediate locations) for cause of AIS (e.g. PPI-Loss_of_Signal or PPI-Unexp_Signal alarm at far multiplexer or alarms that cause pass-through TU-AIS injection).






—end—



2

TU-LOP

SignificanceThe pointer value in the pointer bytes of the TU is invalid for three consecutive frames.



0

Consequent alarms/eventsLocal • Through path

— TU-AIS injection on associated TU.

• Protected add/drop TU path

— Temporary AIS injection on associated tributary output if switched to aggregate containing alarm.



— AIS injection on associated tributary output.0

LP termination• Protected add/drop TU path

— TU-AIS alarm.

— If TU switched to HP containing TU-LOP alarm, protection switch to other aggregate (if valid).


— TU-AIS alarms.0






• Faulty far TN-1C multiplexer.

• Incorrect connection settings (e.g. VC-3 against a VC-12 connection).




Procedure 2-22TU-LOP alarm clearing 2-22

Step Action


2 Check that the correct network connection settings have been made.

If network connection settings are incorrect, correct as necessary.

If network connection settings are correct, proceed to Step 3.






—end—



2

HP-Path_Trace

SignificanceThe received string of the VC-4 path trace byte (J1) does not match the expected string.

ImpactTraffic affecting if incorrect connection (wrong traffic).


Note: Consequent actions for the HP-Path_Trace alarm can be disabled using the UI (see User Interface Guide, NTP 323-1081-401). The default is for the consequent actions to be disabled.

Local• Through paths








0


— TU-AIS alarms.

— If TUs switched to HP path containing HP-Path_Trace alarm, protection switch to other aggregate (if valid).


— TU-AIS alarms.




— LP-FERF alarms.



Possible causes• Incorrect connection setup.

• Settings incorrectly set during configuration (i.e. receive string or far end transmit string).

• Fibre break if operating in the Single Fibre Working mode.

• Faulty local or far TN-1C multiplexer.0


Procedure 2-23HP-Path_Trace alarm clearing 2-23

Step Action

1 If operating in the Single Fibre Working mode, check for fibre breaks (i.e. output signal is being reflected back to the input of the same TN-1C.

If fibre break detected, perform appropriate actions to repair fibre.

If no fibre break detected, proceed to Step 2.

2 Check that the correct optical connections have been made.

If the optical connections are incorrect, reconnect as required.

If the optical connections are correct, proceed to Step 2.

3 Check the system path trace settings at both ends.

If settings are incorrect, reconfigure as necessary.

If settings are correct, proceed to Step 3.



If the alarm is still present, replace the original local TN-1C multiplexer and proceed to Step 4.



—end—



2

HP-Signal_Label

SignificanceThe value of the signal label code in the C2 byte of the VC-4 does not correspond with the expected value (a value of ‘1’ and ‘2’ is expected).

ImpactTraffic affecting if incorrect connection (wrong traffic).


Note: Consequent actions for the HP-Signal_Label alarm can be disabled using the UI (see User Interface Guide, NTP 323-1081-401). The default is for the consequent actions to be disabled.

Local• Through paths








0


— TU-AIS alarms.

— If TUs switched to HP containing HP-Signal_Label alarm, protection switch to other aggregate (if valid).


— TU-AIS alarms.




— LP-FERF alarms.



Possible causes• Incorrect connection setup.

• Settings incorrectly set during configuration (the settings for the TN-1C are not configurable).



Procedure 2-24HP-Signal_Label alarm clearing 2-24

Step Action

1 Check that the correct optical connections have been made.

If the optical connections are incorrect, reconnect as required.

If the optical connections are correct, proceed to Step 2.

2 If applicable, check the far end HP signal label settings.

If settings are incorrect, reconfigure as necessary.

If settings are correct, proceed to Step 3.



If the alarm is still present, replace the original local TN-1C multiplexer and proceed to Step 4.



—end—



2

INT-TU-AIS

SignificanceAn internal AIS has been detected internally in the pointer bytes of the TU.


Consequent alarms/eventsLocal AIS injection on associated tributary output.

LP sourceLP-FERF alarm.


Corrective actionsReplace local TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures. If alarm still present, replace original local TN-1C multiplexer and escalate problem.



INT-TU-LOP

SignificanceThe internal pointer value in the pointer bytes of the TU is invalid for three consecutive frames.


Consequent alarms/eventsLocal AIS injection on associated tributary output.



Corrective actionsReplace local TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures. If alarm still present, replace original local TN-1C multiplexer and escalate problem.



2

LP-Excessive_BER

SignificanceThe BER of the BIP-2 (VC-12) or BIP-8 (VC-3) error check has exceeded 10-3.



Consequent alarms/eventsLocal • Protected add/drop TU path

— Temporary AIS injection on tributary output if protection switching enabled as a consequent action of an LP-Excessive_BER alarm and path switched to aggregate containing alarm.

— Protection switch to other aggregate (if valid) if protection switching enabled as a consequent action of an LP-Excessive_BER alarm.

— AIS injection on tributary output if LP-Excessive_BER is configured to cause consequent actions and protection switching and LP-Excessive_BER is received on both paths.

Note: If LP-Excessive_BER is received from both paths, path protection switching will be performed every oscillation-guard_time (an event message about path protection switching will only be issued after the first switch).


— AIS injection on associated tributary output if LP-Excessive_BER configured to cause consequent actions.

0

Path source• Protected TU path

— LP-FERF alarm if both paths have failed at local multiplexer.

— LP-FEBE alarm if LP-Excessive_BER is configured not to cause consequent actions.

• Unprotected TU path

— LP-FERF alarm if LP-Excessive_BER configured to cause consequent actions.

— LP-FEBE alarm if LP-Excessive_BER is configured not to cause consequent actions.

Note: LP-FERF as a consequent action of LP-Excessive_BER is configurable by the user (default on).



Possible causes• Errors on network.


• Faulty far TN-1C multiplexer.

Corrective actionsPerform the fault finding procedure given in Procedure 2-25.

Procedure 2-25LP-Excessive_BER alarm clearing 2-25

Step Action

1 Check if there are any MS or HP alarms in the network.

If there are MS or HP alarms in the network, perform recommended actions to clear alarm.

If there are no MS or HP alarms in the network, proceed to Step 2.


If the alarm is still present, replace the original TN-1C multiplexer and replace the far TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures.


—end—



2

LP-Signal_Degrade

SignificanceThe BER of the BIP-2 error check has exceeded the lower configurable threshold:

• 10-4 or 10-5 (default 10-5) for VC-12

• 10-5 or 10-6 or 10-7 (default 10-5) for VC-3.


Consequent alarms/eventsPath source• Possible LP-FEBE alarm (LP-FEBE alarm is not configurable to 10-3

(only 10-4 and 10-5).

Possible causes• Errors in network.



Procedure 2-26LP-Signal_Degrade alarm clearing 2-26

Step Action

1 Check if there are any MS or HP alarms in the network.

If there are MS or HP alarms in the network, perform recommended actions to clear alarm.

If there are no MS or HP alarms in the network, proceed to Step 2.


If the alarm is still present, replace the original TN-1C multiplexer and replace the far TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures.


—end—



LP-Signal_Label

SignificanceThe value of the signal label bits in the V5 byte (VC-12) or C2 byte (VC-3) does not correspond with the expected value as follows:

• for VC-12s a value of ‘1’ or ‘2’ is expected if the traffic is ‘on’, a value of ‘0’ is expected if the traffic is ‘off’.

• for VC-3s a value of ‘1’ or ‘4’ is expected if the traffic is ‘on’, a value of ‘0’ is expected if the traffic is ‘off’.


Consequent alarms/eventsLocalAIS injection on tributary output.


Possible causes• Incorrect traffic settings.

• Incorrect path connection.




2


Procedure 2-27LP_Signal_Label alarm clearing 2-27

Step Action

1 Ensure that the system path configuration at both ends is correct as follows:

VC-12s- if no traffic expected, both ends should be configured to send a value of ‘0’ (traffic-off).

- if traffic is expected, both ends should be configured to send a value of ‘1’ or ‘2’ (traffic-on).

VC-3s- if no traffic expected, both ends should be configured to send a value of ‘0’ (traffic-off).

- if traffic is expected, both ends should be configured to send a value of ‘1’ or ‘4’ (traffic-on).

If the settings are not correct, proceed to Step 2.

2 Verify that the path is correctly connected at all intermediate multiplexers.






—end—



LP-FERF

SignificanceThe VC-12/VC-3 path FERF bit in the incoming VC-12/VC-3 has been set, indicating that a fault has been detected in the receive LP path at the far path termination.

ImpactNone.


Possible causes• If alarm raised for all tributaries, RS-Loss_of_Signal,

RS-Loss_of_Frame, MS-AIS, MS-Excessive_BER, AU-AIS, INT-AU-AIS, INT-AU-LOP, HP-Path_Trace, HP-Signal_Label or HP-TU_Multiframe alarm at the far multiplexer.

• If alarm raised for one tributary only, TU-AIS, TU-LOP, INT-TU-AIS, INT-TU-LOP, LP-Signal_Label or LP-Excessive_BER alarm present at far path termination.


Procedure 2-28LP-FERF alarm clearing 2-28

Step Action

1 Investigate far multiplexer/path termination for cause of alarm and carry out fault finding procedures for appropriate alarm.








—end—



2

LP-FEBE

SignificanceThe BER of the FEBE bits in the V5 byte of the incoming VC-12, indicating that the far station has detected errors in the VC-12 path, has exceeded the configurable threshold of 10-3, 10-4, or 10-5 (default 10-5).

ImpactNone.


Possible causesTU errors on network.


Procedure 2-29LP-FEBE alarm clearing 2-29

Step Action

1 Investigate far path termination for cause of errors and carry out fault finding procedures for appropriate alarm (e.g. LP-Signal_Degrade alarm).








—end—



INT-LP-OP_Buffer

SignificanceThe FIFO in the demapping/demultiplexing direction is either in the underflow or overflow state.



Possible causes• Synchronisation problems in network.



Procedure 2-30INT-LP-OP_Buffer alarm clearing 2-30

Step Action

1 Isolate the TN-1C from the synchronisation perspective (i.e. remove all external sources from the hierarchy so that the TN-1C is operating in the holdover mode).




If the alarm is still present, replace the original local TN-1C multiplexer and escalate the problem.

—end—



2

PPI-Output_Fail

SignificanceThe output tributary signal has fallen below a predefined threshold.

ImpactLoss of 2 Mbit/s or 34/45 Mbit/s traffic output.



Corrective actionsPerform the alarm clearing procedures given in Procedure 2-31.

Procedure 2-31PPI-Output_Fail alarm clearing 2-31

Step Action

1 Ensure that the 2 Mbit/s or 34/45 Mbit/s traffic output cable is properly connected. Re-connect the connector if required. If the alarm is still present, proceed to Step 2.



—end—



PPI-Unexp_Signal

SignificanceA 2 Mbit/s or 34/45 Mbit/s signal has been detected on a tributary which is configured not to expect traffic (i.e. traffic off).

ImpactNone.

Consequent alarms/events• Tx Trib AIS or TU AIS

— If Tx Trib AIS selected as consequent action, no indication will be provided at the far path termination.

— If TU AIS selected as consequent action, TU AIS indication will be provided at far path termination.

Note: Tx Trib AIS/TU AIS is configurable by the user (default Tx Trib AIS).

Possible causesCable mis-connection/system configuration.

Corrective actionsIf a 2 Mbit/s or 34/45 Mbit/s signal is expected on this port, reconfigure system (i.e. turn traffic ‘on’ for port).

If a 2 Mbit/s or 34/45 Mbit/s signal is not expected on this port, check cable connections to ensure that cables are connected to the correct input terminations.



2

PPI-Loss_of_Signal

SignificanceLoss of the tributary input signal, raised if:

• 2 Mbit/s HDB3 tributary: no marks (‘ones’ or violations) are detected for 11 clock periods.

• 34 Mbit/s HDB3 tributary: input is low for 256 bit periods.

• 45 Mbit/s B3ZS tributary: no transitions for 200 bit periods.


Consequent alarms/events• Tx Trib AIS or TU AIS

— If Tx Trib AIS selected as consequent action, no indication will be provided at the far path termination.

— If TU AIS selected as consequent action, TU AIS indication will be provided at far path termination.

Note 1: Tx Trib AIS/TU AIS is configurable by the user (default Tx Trib AIS).

Note 2: If TU AIS is configured as a consequence action of PPI-Loss_of_Signal, TU AIS is transmitted on both aggregates of a protected path. At the far multiplexer, TU AIS may be detected on the working path first, causing a path protection switch on the far multiplexer. Similarly, upon restoration of the tributary signal, the TU AIS may clear on the idle path first, causing a path protection switch at the far multiplexer.

Possible causes• Input connector not properly terminated.

• Preceding equipment failure.




Corrective actionsPerform the fault finding procedure given in Procedure 2-32.

Procedure 2-32PPI-Loss_of_Signal alarm clearing 2-32

Step Action

1 If the tributary is a 2 Mbit/s signal, use the UI to check that the 2 Mbit/s port is configured for the correct impedance (75 Ω or 120 Ω). If the tributary is a 34 Mbit/s or 45 Mbit/s signal, use the UI to check that the port is configured for the correct bit rate (34 Mbit/s or 45 Mbit/s). Refer to the User Interface Guide NTP, 323-1081-401 for details.

If the port is configured incorrectly, reconfigure as appropriate.

If the port is correctly configured, proceed to Step 2.

2 Ensure that the associated input connector is properly connected. Re-connect the connector if required. If the alarm is still present, proceed to Step 3.

3 Verify that a valid tributary signal is present at the output of the cable.

Note: For 2 Mbit/s tributaries, if a spare unused 2 Mbit/s port is available, the 2 Mbit/s signal can be verified by connecting the cable to the spare port. If a signal is present, a ‘PPI-Unexp_Signal’ alarm will be raised for the spare 2 Mbit/s port.

For 34 Mbit/s or 45 Mbit/s tributaries, or if a spare unused 2 Mbit/s port is not available for 2 Mbit/s tributaries, a manual (external) loopback on the affected port can be used to verify that a valid tributary signal is present. If the alarm clears when the loopback is applied, the tributary input signal is invalid.

If a valid signal is not present, check the interconnecting cable and the tributary source equipment.

If a valid signal is present, proceed to Step 4.


If the alarm is still present, replace the original local TN-1C multiplexer and escalate the problem

—end—



2

PPI-Excessive_BER

SignificanceThe BER of the code violations in the incoming tributary signal has exceeded 10-3.



Possible causes• Errored input signal.

• Faulty input circuit on TN-1C multiplexer.0


Procedure 2-33PPI-Excessive_BER alarm clearing 2-33

Step Action

1 Investigate preceding 2 Mbit/s, 34 Mbit/s or 45 Mbit/s equipment for cause of errors.

If errors are intermittent, most likely cause is cabling and the connectors.

If no errors from preceding equipment, proceed to Step 2.

2 Perform a manual (external) loopback on the appropriate tributary port.

If the alarm is still present, remove the external loopback and replace the local TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures. If the alarm is still present, replace the original TN-1C multiplexer and escalate the problem.

If the alarm clears, remove the external loopback and escalate problem.

—end—



PPI-Signal_Degrade

SignificanceThe BER of the code violations in the incoming tributary signal has exceeded 10-5.



Possible causes• Errored input signal.

• Faulty input circuit on TN-1C multiplexer.0

Corrective actionsPerform the alarm clearing procedures given in Procedure 2-34.

Procedure 2-34PPI-Signal_Degrade alarm clearing 2-34

Step Action

1 Investigate preceding 2 Mbit/s, 34 Mbit/s or 45 Mbit/s equipment for cause of errors.

If errors are intermittent, most likely cause is cabling and the connectors.

If no errors from preceding equipment, proceed to Step 2.

2 Perform a manual (external) loopback on the appropriate tributary port.

If the alarm is still present, remove the external loopback and replace the local TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures. If the alarm is still present, replace the original TN-1C multiplexer and escalate the problem.

If the alarm clears, remove the external loopback and escalate problem.

—end—



2

INT-LP-IP_Buffer

SignificanceThe FIFO in the mapping/multiplexing direction is in an underflow or overflow state.



Possible causes• Incoming tributary signal out-of-limits.



Procedure 2-35INT-LP-IP_Buffer 2-35

Step Action

1 Check if tributary input signal is within limits.

If tributary input signal is not within limits, investigate preceding 2 Mbit/s equipment.

If tributary input signal is within limits, proceed to Step 2.

2 Isolate the TN-1C from the synchronisation perspective (i.e. remove all external sources from the hierarchy so that the TN-1C is operating in the holdover mode).





—end—



EA-Ext_inpn

SignificanceThe external alarm n (where n = 1 to 8) is active. The alarms can be assigned names of up to 8 characters.

ImpactDependant on what the alarm represents.


Possible causesExternal device.

Corrective actionsInvestigate external device.



2

SYNC-Holdover

SignificanceThe synchronisation clock has entered the holdover (using last known frequency) or free-run (using internal clock) state. The alarm is not raised during switching between external sources.

Note: The alarm is not raised if the internal clock is selected as the primary source.

ImpactThe multiplexer is not traceable to the network synchronisation, which may cause problems depending on the system synchronisation architecture.


Possible causes• No valid external synchronisation sources available.



Procedure 2-36SYNC-Holdover alarm clearing 2-36

Step Action

1 Check each of the sources in the synchronisation hierarchy for validity (e.g. appropriate alarms).

If any of the sources are invalid, perform the appropriate alarm clearing procedure to clear alarm. If synchronisation is non-revertive, perform a manual switch back to required source.

If the multiplexer cannot synchronise to any valid source, proceed to Step 2.

2 Replace local TN-1C multiplexer. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures.

If alarm still present, replace original local TN-1C multiplexer and escalate problem.

—end—



SYNC-SETG_Fail

SignificanceThe synchronisation source has become invalid.

ImpactNone.


Possible causes• Loss of selected synchronisation signal.

• Receipt of AIS on aggregate selected as synchronisation source.

• Source out-of-limits.

• Excessive BER on selected source (see Note).

• Loss of frame alignment on selected STM signal (see Note).

• HP-Path_Trace alarm present.

Note: Excessive BER, loss of frame alignment, and HP-Path_Trace are user configurable criteria for synchronisation source switching.

0


Procedure 2-37SYNC-SETG_Fail alarm clearing 2-37

Step Action

1 Use the UI (view_status/sync_source_status) to check if the source is out-of-limits (indicated by ‘SS_OUT_OF_LIMITS’ in the report).

If the source is out-of-limits, fix the source frequency, then use the UI to clear the out-of-limits alarm (see User Interface Guide, NTP 323-1081-401).

If the source is not out-of-limits, proceed to Step 2.

2 Investigate the cause of source failure.

If cause identified, perform the alarm clearing procedures for the appropriate alarm. When the synchronisation source is recovered, the SYNC-SETG_Fail alarm clears.

If the alarm is still present, escalate the problem.

—end—



2

NE-Ext_Card_Out

SignificanceThe tributary extension card is provisioned as equipped but is not physically present.

ImpactLoss of tributary traffic carried by tributary extension card.

Consequent alarms/eventsTU-AIS injection on all channels that are connected to the tributary extension card.

Possible causes• Tributary extension card removed.

• System incorrectly configured.



Procedure 2-38NE-Ext_Card_Out alarm clearing 2-38

Step Action

1 Check if tributary extension card is expected.

If tributary extension card is expected, check that the tributary extension card is correctly installed in the TN-1C. If alarm still present, proceed to Step 3.

If the tributary extension card is not expected, proceed to Step 2.

2 Provision the equipment to unequip the tributary extension card (see User Interface Guide, NTP 323-1081-401).

If alarm still present, proceed to Step 3.



—end—



NE-Wrong_Card

Significance• If the alarm is reported with instance ‘S2’, the tributary extension card is

physically present but has been equipped as a different type of tributary extension card.

• If the alarm is reported with instance ‘S0’, the tributary extension card equipped does not correspond to the backplane of the TN-1C. If a 8 x 2 Mbit/s tributary extension card (NTFT08AA) is being fitted, the backplane must be NTFT03AC (part of TN-1C NTFT52AB). If a 34/45 Mbit/s tributary extension card (NTFT31AA) is being fitted, the backplane can be NTFT03AB or NTFT03AC.

Impact• Loss of tributary traffic carried by tributary extension card.

• TU-AIS injection on all channels that are connected to the tributary extension card.


Possible causes• Wrong tributary extension card fitted.




Procedure 2-39NE-Wrong_Card alarm clearing 2-39

Step Action

1 Check what tributary extension card/connector panel should be fitted.

If the correct tributary extension card is not fitted, fit the correct tributary extension card in the TN-1C. If alarm still present, proceed to Step 3.

If the correct tributary extension card is fitted, proceed to Step 2.

2 Provision the equipment to equip the correct tributary extension card (see User Interface Guide, NTP 323-1081-401).


—continued—



2

—end—

Procedure 2-39NE-Wrong_Card alarm clearing 2-39

Step Action



NE-Unexpected_Card

SignificanceThe tributary extension card is physically present but is provisioned as unequipped.

ImpactLoss of tributary traffic carried by tributary extension card.


Possible causes• Tributary extension card incorrectly fitted.




Procedure 2-40NE-Unexpected_Card alarm clearing 2-40

Step Action

1 Check if tributary extension card is expected.

If tributary extension card is not expected, remove the tributary extension card from the TN-1C. If alarm still present, proceed to Step 3.

If the tributary extension card is expected, proceed to Step 2.

2 Provision the equipment to equip the tributary extension card of the correct type (see User Interface Guide, NTP 323-1081-401).




—end—



2

NE-Fan_Fail

SignificanceThe fan has been detected as faulty (i.e. on the first time it is used). The alarm is only cleared when the fan is proved to be operating or is removed.

Note: The NE-Fan_Fail alarm is raised after approximately 30 seconds from detecting the condition and remains active for approximately 30 seconds after the cause is removed.

ImpactPossible overheating of TN-1C.


Possible causes• Faulty fan module.

• Faulty wiring to fan module.

• Faulty -12 V fan power.0

Corrective actionsCheck that the wiring to the fan is correct/not broken. If wiring correct/not broken, replace fan module. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures.



NE-High_Temp

SignificanceThe NE temperature has exceeded 55°C. The alarm is cleared if the temperature falls below 39°C.

ImpactPossible overheating of TN-1C.

Consequent alarms/eventsIf fan is fitted, fan will operate.

Possible causes• Fan module required.

• Faulty fan module.

• Ambient temperature too high.

Corrective actionsIf fan not fitted, fit fan module. Refer to the Installation Procedures, NTP 323-1081-200, for installation procedures.

If fan fitted, use UI to force fan on. If fan does not operate, replace fan module. Refer to the Equipment Maintenance Procedures, NTP 323-1081-547, for replacement procedures.

End of chapter file


3-1

3
Chapter 3: Common procedures
This chapter provides a list of common task procedures to which the user is referred when performing certain alarm clearing procedures.


3-2 Common procedures

Optical connector cleaning

All optical connectors must be treated with the utmost care and a very high standard of cleanliness maintained otherwise their performance may be seriously affected. As soon as a connector is disconnected, the free ends MUST be protected with dust caps.

Materials requiredThe following materials are required for cleaning optical connectors and couplings:

• Microscope with adaptor suitable for connector

• Lint free anti-static lens tissues

• Cotton buds

• Approved cleaning solvent

• Aerosol dust remover (anti-static).

There are two main dirt problems for an optical connector, dust and the grease to which dust can stick. Dust appears as ‘lumps’, ‘flakes’, or even fibres (from clothes or hair). Grease appears as ‘smears’ or ‘blobs’ and is most commonly introduced from the finger tips.

WARNINGDanger from exposure to laser lightAvoid direct exposure to laser beam or fibre. Invisible laser light can blind. Keep all optical connectors capped.

Ensure that the far end of the fibre is disconnected before starting the cleaning procedure.

CAUTIONCleanliness of materialsAlways use new cleaning cloth material and lens tissues to avoid contamination. Never re-use materials. Ensure connector caps are clean and dust free.


Common procedures 3-3

3

The procedures for cleaning optical plugs and optical couplers are described in Procedure 3-1 and Procedure 3-2.

Procedure 3-1Cleaning an optical plug 3-1

Step Action

1 Inspect the connector using the microscope.

Where possible the side as well as the end of the ferrule should be inspected for serious scores or scratches (visible to the naked eye). The ferrule end should then be inspected using a microscope. Particular attention should be paid to the core area of the fibre. The fibre end must be generally smooth and free from cracks. Slight chipping in the cladding is permissible but not obvious cracks or any damage that extends to the core area.

There will invariably be some score marks. Obvious deep score marks are usually evidence of damage by foreign bodies. If these marks are pronounced or extend near to or into the fibre, then the plug should be rejected and the cable reterminated.

2 Blow dust clear using the aerosol dust remover.

3 Inspect again. In the case of persistent dust wipe with clean, dry tissue.

4 Blow dust clear.

5 Inspect again. In the case of persistent dirt or grease (finger marks etc.) apply a small amount of solvent from a solvent dispenser on to a tissue and wipe the plug with the tissue.

6 Blow dry and clear of dust using the aerosol dust remover.

7 Reinspect and repeat the cleaning procedure if necessary.

—end—



Procedure 3-2Cleaning an optical coupler 3-2

Step Action

1 Inspect and, if necessary, proceed with steps 2 to 5

2 Blow dust clear using the aerosol dust remover.

3 Inspect again. In the case of persistent dirt or grease, apply some solvent to the tip of a ‘cotton bud’ and wipe out dirt.

4 Blow dry and clear of dust.

5 Reinspect and repeat the cleaning procedure if necessary.

—end—



3

Optical output power measurement

The procedure for measuring the optical output power is given in Procedure 3-3.


Procedure 3-3Optical output power measurement 3-3

Step Action

1 Connect the Craft Access Terminal to the TN-1C.

2 Open a UI session with the TN-1C.

3 Enter your username after the prompt:<username> ↵

4 Enter your password after the prompt:<password> ↵

The UI main menu is displayed.

5 Turn the laser off (forced_off) by typing:c l o <inst>↵

where <inst> is ‘a’ or ‘b’ (required aggregate).

6 Disconnect the optical patchcord from the optical transmit output.

7 Connect the optical transmit output to the input of an optical power meter using a low loss singlemode optical patchcord.

8 Power down and then power-up the TN-1C. Open a UI session with the TN-1C and enter your username and password (see Steps 2 to 4). Use the UI to turn the laser on (forced_on) within 90 seconds of power-up by typing:

c l f <inst>↵where <inst> is ‘a’ or ‘b’ (required aggregate).

Note: The laser on (forced_on) command can only be issued in the first 90 seconds immediately after power-up.

9 Measure the optical output power of the unit.

Limits: -8 dBm to -15 dBm.

—continued—



10 Use the UI to turn the laser off (forced_off) by typing:c l o <inst>↵


11 Disconnect the optical transmit output from the optical power meter.

12 Connect the optical patchcord to the optical transmit output.

13 Use the UI to return the laser to the normal operating state by typing:c l n <inst>↵


14 Return to the UI main menu by typing:~ ↵


15 Logout from the UI by typing:l ↵

16 Disconnect the Craft Access Terminal to the TN-1C.

—end—

Procedure 3-3Optical output power measurement (continued) 3-3

Step Action



3

Optical input power measurement

The procedure for measuring the optical input power is given in Procedure 3-4.


Procedure 3-4Optical input power measurements 3-4

Step Action

1 Open a UI session with the far TN-1C.




4 Turn the laser off (forced_off) at the far TN-1C by typing:c l o <inst>↵


Note: This requires a technician at the far-end in the case of an unprotected system or if other end is a TN-1X. If the far end is unmanned, do not issue a remote laser off (forced_off) command for the far end otherwise communication will be lost with the far end.

5 Disconnect the receive optical fibre from the receive optical input and connect the optical receive fibre to the input of an optical power meter.

6 Power down and then power-up the TN-1C at the far end. Open a UI session with the far TN-1C and enter your username and password (see Steps 1 to 3). Use the UI to turn the laser on (forced_on) at the far end by typing:

c l f <inst>↵where <inst> is ‘a’ or ‘b’ (required aggregate).

Note: The laser on (forced_on) command can only be issued in the first 90 seconds immediately after power-up.

—continued—



7 Measure the optical input power from the fibre.

Limits: -8 dBm to -28 dBm.

8 Turn the laser off (forced_off) at the far by typing:c l o <inst>↵


9 Disconnect the receive optical fibre from the optical power meter and reconnect the fibre to the receive optical input connector.

10 Use the UI to return the laser at the far end to the normal operating state by typing:

c l n <inst>↵where <inst> is ‘a’ or ‘b’ (required aggregate).




—end—

Procedure 3-4Optical input power measurements (continued) 3-4

Step Action



3

Applying/clearing loopbacks

The TN-1C has a number of loopback facilities which can be used in the alarm clearing/maintenance procedures, see Chapter 4 for details.

The procedure for applying/clearing loopbacks is given in Procedure 3-5.

CAUTIONSTM-1 local loopbackActivating the STM-1 local loopback will cause loss of traffic.

STM-1 loopbacksActivating the STM-1 local or remote loopback on an unprotected STM-1 link (or STM-1 local or remote loopbacks on both aggregates on an protected STM-1 link) will cause subsequent loss of ECC communications. If the loopback(s) is activated remotely, a site visit will be required to de-activate the loopback.



End of chapter file

Procedure 3-5Applying/removing loopbacks 3-5

Step Action

1 Open a UI session with the TN-1C via the CAT or the TN-MS EC.




4 To apply a remote loopback, type the following:d l r <inst> ↵ where <inst> is ‘a’ or ‘b’ for the aggregates or

S<m>-<n> for tributaries<m> is the slot number ‘1’ or ‘2’,<n> is the tributary port ‘1’ to ‘8’ for each tributaryport.

To apply a local loopback, type the following:d l l <inst> ↵ where <inst>is ‘a’ or ‘b’ for the aggregates or


To clear a loopback, type the following:d l c <inst> ↵ where <inst> is ‘a’ or ‘b’ for the aggregates or





—end—


4-1

4

Chapter 4: Diagnostic toolsThis chapter details the diagnostic tools available on the TN-1C multiplexer for maintenance purposes, namely:

• Loopbacks

• Tributary Test Pattern Generator and Detector0

LoopbacksLoopbacks are provided for the user for various test procedures and for assisting in alarm clearing. The loopbacks are initiated from the TN-1C UI.

STM-1 local loopback (Loop to Mux)A local loopback can be activated on either of the aggregates. When activated, the outgoing STM-1 data is routed back to the STM-1 receiver on the same aggregate link, as well as being transmitted towards the line (see Figure 4-1).

Note: When activating the STM-1 local loopback, a temporary RS-Loss_of_Signal alarm will be raised whilst the loopback switch

CAUTIONSynchronisation loopsWhen performing loopbacks, pay attention to avoid synchronisation loops.

CAUTIONSTM-1 local loopbackWhere possible, all traffic should be switched away from the aggregate port before activating the STM-1 local loopback. Activating the STM-1 local loopback will cause loss of traffic on that aggregate.

Activating the STM-1 local loopback on an unprotected STM-1 link (or STM-1 local loopbacks on both aggregates on an protected STM-1 link) will cause subsequent loss of ECC communications. If the loopback(s) is activated remotely, a site visit will be required to de-activate the loopback.


4-2 Diagnostic tools

occurs. If any of the paths are switched to this aggregate, path protection switching will occur for these tributaries.

STM-1 remote loopback (Loop to Line)A remote loopback can be activated on either of the aggregates. When activated, the incoming STM-1 data is routed back to the STM-1 transmitter on the same aggregate link, as well as being transmitted towards the TN-1C (see Figure 4-1).

Note: When activating the STM-1 remote loopback, a temporary RS-Loss_of_Signal alarm will be raised at the far multiplexer whilst the loopback switch occurs. If any of the paths are switched to this aggregate, path protection switching will occur at the far multiplexer for these tributaries.

Tributary local loopback (Loop to Mux)A local tributary loopback (2 Mbit/s or 34/45 Mbit/s) can be activated independently on any of the tributary ports. When activated, the outgoing tributary data is routed back to the tributary receiver on the same link, as well as being transmitted towards the STM-1 line (see Figure 4-1).

Tributary remote loopback (Loop to Line)A remote tributary loopback (2 Mbit/s or 34/45 Mbit/s) can be activated independently on any of the tributary ports. When activated, the incoming tributary data is routed back to the tributary line on the same link, as well as being transmitted towards the tributary receiver (see Figure 4-1).

Simultaneous loopbacksSTM-1 and tributary loopbacks can be performed independently.

On a specific tributary or aggregate, only one direction of loopback (local or remote) is allowed at a given time. If a loopback request is made for one direction whilst the other direction loopback is active, the current loopback is deactivated and the requested loopback is activated.

CAUTIONSTM-1 remote loopbackWhere possible, all traffic should be switched away from the appropriate aggregate port at the far multiplexer before activating the STM-1 remote loopback. Activating the STM-1 remote loopback will cause loss of traffic on that aggregate.

Activating the STM-1 remote loopback on an unprotected STM-1 link (or STM-1 remote loopbacks on both aggregates on an protected STM-1 link) will cause subsequent loss of ECC communications. If the loopback(s) is activated remotely, a site visit will be required to de-activate the loopback.


Diagnostic tools 4-3

4

Figure 4-1TN-1C loopbacks 4-1

Electro-OpticalModule

STM-1SectionTerminationModule

STM-1 local loopback

TribElectricalLine Driver

TribMapper

2 Mbit/sor34/45 Mbit/s

Tributary local loopback

TribElectricalLine Driver

TribMapper

Tributary remote loopback

Electro-OpticalModule

STM-1SectionTerminationModule

STM-1 remote loopback

DSPI

DSPI

2 Mbit/sor34/45 Mbit/s


4-4 Diagnostic tools

2 Mbit/s or 34 Mbit/s test pattern generator and detectorThe TN-1C multiplexer includes an in-built 2 Mbit/s or 34 Mbit/s test pattern generator and detector. The facility allows the bit-error performance to be measured for a selected 2 Mbit/s or 34 Mbit/s channel.

The Pseudo-Random Binary Sequence (PRBS) generator/detector is located between the tributary mapper and the tributary line drivers as shown in Figure 4-2. The PRBS generator/detector is shown for a single tributary, the PRBS generator/detector is common for all tributaries and can be switched to any tributary.

Figure 4-2PRBS location 4-2

Note 1: PRBS should not be injected towards the optical side when the same tributary is in ‘remote’ loopback. The test will fail due to a lack of clock source in that scenario and the test does not provide any value.

Note 2: When the 34 Mbit/s PRBS to line is applied, the downstream traffic (to 34 Mbit/s line) is broken and PRBS is injected instead.

Note 3: For 34 Mbit/s tributaries, PRBS to line does not operate if a PPI-Loss_of_Signal alarm is detected on the tributary.

The test pattern is a PRBS with a pattern length of 215-1 for 2 Mbit/s tributaries and 223-1 for 34/45 Mbit/s tributaries, as defined in ITU-T O.151. The pattern may be injected towards the aggregate on a specific tributary link or towards the tributary line. The pattern overrides the tributary data and framing bits (e.g. for 2 Mbit/s signal all 256 bits per frame carry the test pattern). The pattern detector is connected to the tributary data extracted from the VC-12/VC-3 or from the tributary line. The detector synchronises to the test pattern and then counts the errors between the incoming bit-stream and the expected bit-stream. An indication is provided if synchronisation is lost during the test period. The errors are periodically read and accumulated to derive the test results. The period of test results can be set (1 - 30000 seconds, default 30 seconds).

Note: If the period of test results is too frequent, it will cause fast scrolling on the UI screen, making it hard to read for the user.

Tribelectricalline driver

Tribmapper

PRBSGenerator

PRBSDetector

2 Mbit/sor 34/45 Mbit/s

towardsoptical line


Diagnostic tools 4-5

4

The results are displayed on all open UI sessions. The following is an example of the format of the results:

89, Continuity Test Results891, S1-1, Test_name: Continuity, User name = nortl, 01/08/1995 16:22:58892, S1-1, CT_direction = Fiber, CT_elapsed_time = 00:00:00893, S1-1, CT_stnc_status_since_last_report = NO_sync894, S1-1, CT_error_count = 0, CT_BER = 0.0E+00, *895, End of Test Results;

Note: If an ‘*’ is shown at the end of the PRBS report (as above), it indicates that synchronisation was lost or a counter overflow occurred while the test was running (this invalidates the whole test).

End of chapter file

Procedure 4-1Applying/stopping a continuity test 4-1

Step Action

1 Open a UI session with the TN-1C.




4 To apply a continuity test towards the optical line, type the following:d c f <trib_inst> <RF> ↵

<trib_inst> is S<m>-<n> where<m> is the card number ‘1’ or ‘2’,<n> is the tributary port ‘1’ to ‘8’ for each tributary

<RF> is the report frequency (range 1 to30,000 seconds, in 1 second steps, default 30 seconds)

To apply a continuity test towards the tributary line, type the following:d c l <trib_ inst> <RF> ↵

<trib_inst> is S<m>-<n> where<m> is the card number ‘1’ or ‘2’,<n> is the tributary port ‘1’ to ‘8’ for each tributary

<RF> is the report frequency (range 1 to30,000 seconds, in 1 second steps, default 30 seconds)

To stop a continuity test, type the following:d c s ↵




—end—


5-1

Index 5

5

Numerics2 Mbit/s test pattern 4-434 Mbit/s test pattern 4-4

Aalarm

category 1-9consequences 1-6indications 1-1masking 1-2severity 1-9

associated documents xiAU-AIS 2-41audience xi

Ccleaning

optical connector 3-2craft access terminal 1-2

Ddiagnostic tools 4-1

EEA-Ext-inpn 2-78element controller 1-2

Ffault finding

beginning 1-8

HHP-Excessive_BER 2-49HP-FEBE 2-52HP-FERF 2-51HP-Path_Trace 2-57HP-Signal_Degrade 2-50

HP-Signal_Label 2-59HP-TU_Multiframe 2-43

IINT-AU-AIS 2-47INT-EC-Alarms_Buffer 2-7INT-HP-Insert_Bus 2-21INT-HP-IP_Buffer 2-37INT-LP-IP_Buffer 2-77INT-LP-OP_Buffer 2-70INT-NE-Config_Corrupt 2-12INT-NE-RAM_Fail 2-11INT-NE-SW_Corrupt 2-6INT-OS-Laser_Test 2-27INT-RS-Tx_Buffer 2-20INT-TU-AIS 2-61INT-TU-LOP 2-62

Llogs 1-8loopbacks 4-1

applying/removing 3-9LP-Excessive_BER 2-63LP-FEBE 2-69LP-FERF 2-68LP-Signal_Degrade 2-65LP-Signal_Label 2-66

Mmaintenance

philosophy 1-1masking 1-2measurement

optical input power 3-7optical output power 3-5

MS-AIS 2-34MS-Excessive_BER 2-29MS-FERF 2-36


5-2 Index

MS-Signal_Degrade 2-32

NNE-Card_Fail 2-14NE-Door_Open 2-8NE-Ext_Card_Out 2-81NE-Fail_Fail 2-85NE-High_Temp 2-86NE-Unexpected_Card 2-84NE-Wrong_Card 2-82

Ooptical connector

cleaning 3-2optical input power

measurement 3-7optical output power

measurement 3-5OS-Laser_Bias_High 2-19OS-Laser_Shutdown 2-28OS-Optical_Power_High 2-18

PPPI-Excessive_BER 2-75PPI-Loss_of_Signal 2-73PPI-Output_Fail 2-71PPI-Signal_Degrade 2-76PPI-Unexp_Signal 2-72PS-Battery_Low 2-5PS-Door_Open 2-9PS-Power_Fail 2-4

QQecc-Comms_Fail 2-39

RRS-Loss_of_Frame 2-22RS-Loss_of_Signal 2-15RS-Realign_Phase 2-25

SSYNC-Holdover 2-79SYNC-SETG_Fail 2-80

TTU-AIS 2-53TU-LOP 2-55


Contacts Legal statements Trademarks

International Broadband Networks (Dept. 18600)Nortel plcOakleigh Road SouthLondon, N11 1HB

So far as Northern Telecom is aware the contents of this document are correct. However, such contents have been obtained from a variety of sources and Northern Telecom can give no warranty or undertaking and make no representation as to their accuracy. In particular, Northern Telecom hereby expressly excludes liability for any form of consequential, indirect or special loss, and for loss of data, loss of profits or loss of business opportunity, howsoever arising and whether sustained by the user of the information herein or any third party arising out of the contents of this document.

Family Product Manual Copyright Copyright statement NT confidetial DocNum DocIssue DocStatus Date Publishing statement

SDH TRANSMISSION

Nortel TN-1CAlarm Clearing Procedures

Copyright 1996, 1997 Northern Telecom

The copyright of this document is the property of Northern Telecom. Without the written consent of Northern Telecom, given by contract or otherwise, this document must not be copied, reprinted or reproduced in any material form, either wholly or in part, and the contents of this document, or any methods or techniques available therefrom, must not be disclosed to any other person whatsoever.

NORTHERN TELECOM CONFIDENTIAL: The information contained in this document is the property of Northern Telecom. Except as specifically authorized in writing by Northern Telecom, the holder of this document shall keep the information contained herein confidential and shall protect same in whole or in part from disclosure and dissemination to third parties and use same for evaluation, operation, and maintenance purposes only.

Document Number: 323-1081-543Product Release Number: Release 2Document Status: StandardDate: June 1997Printed in England

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