Agilent 37717C SDH Concept Guide

HP 37717C Communications Performance Analyzer

SDH Concept Guide

 Copyright HewlettPackard Ltd.1998

Information in this document may apply to modules which use the VxWORKS TM software. The VxWORKS TM software was developed by Wind River Systems, Inc., which has copyright to it.

HP Part No. 37717-90417

First Edition, Feb 98

Printed in U.K.

Warranty

The information contained in this document is subject to change without notice.

Hewlett-Packard mak es no warranty of any kind with regard to this material, including, but not limited to, the implied warranties or merchanability and ﬁtness for a particular purpose.

Hewlett-Packard shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing, performance, or use of this material.

WARNING

Warning Symbols Used on the Product

!

The product is marked with this symbol when the user should refer to the instruction manual in order to protect the apparatus against damage.

The product is marked with this symbol to indicate that hazardous voltages are present

The product is marked with this symbol to indicate that a laser is ﬁtted. The user should refer to the laser safety information in the Calibration Manual.

Hewlett-Packard Limited Telecomms Networks Test Division South Queensferry West Lothian, Scotland EH30 9TG

SDH Concept Guide

HP 37717C Communications Performance Analyzer

About This Book

The information on SDH testing in this book covers the following subjects:

• An Introduction to SDH, the SDH modules and their features.

• Measurement examples.

• Measurement result deﬁnitions

• Logging messages

• Self test error codes

For some operations and measurements, information from one of the associated books listed at the rear of this guide may be required.

iv

Contents

1 Introduction to SDH Testing

Introduction to SDH 2 Option A3R [A3S] SDH Generation and Analysis 4

2 SDH Testing

Add/Drop Multiplexer Testing 6 Alarm Stimulus/Response 11 DCC Testing 15 Desynchroniser Stress 18 Frame Synchronization 21 SDH Jitter Transfer 27 MSP Stimulus/Response 30 Optical Clock Recovery Stress 34 Payload Mapping/Demapping 36 Performance Monitor Stimulus / Response 42 Selective Jitter Transfer Measurement 46 Automatic Alarm and BIP Error Monitoring 50 Automatic Veriﬁcation of ADM Installation 53 Veriﬁcation of Protection Switching 57

3 Result Deﬁnitions

Trouble Scan 62 Error Summary 62 Short Term Results 63 Cumulative Results 64 SDH Error Analysis 65

v

Contents

G.826 Analysis B1 BIP 65 G.826 Analysis B2 BIP 66 G.826 Analysis MS-REI 67 G.826 B3 BIP Analysis 68 G.826 HP-REI Analysis 69 G.826 HP-IEC Analysis 70 G.826 TU BIP Analysis - 34 Mb/s Payload 71 G.826 TU BIP Analysis - 2 Mb/s Payload 72 G.826 LP-REI Analysis - 34 Mb/s Payload 73 G.826 LP-REI Analysis - 2 Mb/s Payload 74

SDH Pointer Value Results 75

SDH Alarm Seconds 76

Frequency Measurement 77 Optical Power 77

4 SDH Logging Messages

Logging Devices 80 Results Logging 81

81 During the Measurement Period 81 At the End of the Measurement Period 86 Bar Graph Logging 87 Graphics Text Results Logging 88 Results Snapshot Logging 89 Overhead Capture Logging 91 Overhead Snapshot Logging 92 SDH Tributary Scan Logging 93 Pointer Graph Logging 94

vi

Contents

5 SDH Self Test Error Codes

6 Terminology

ETSI / ANSI Equivalent Terms 116 Current / Previous Terminology 118

vii

Contents

viii

1

Introduction to SDH page 2 37717C SDH Options page 3

1 Introduction to SDH Testing

Information on SDH in general and the SDH test features of the HP 37717C.

Introduction to SDH Testing

Introduction to SDH

Synchronous Digital Heirarchy (SDH) is an international standard (ETSI) for high speed synchronous optical telecommunications networks.

The concept of a synchronous transport system, based on SDH standards, goes beyond the basic needs of a point to point transmission system. It includes the requirements of telecommunications networking - switching, transmission and network control. These capabilities allow SDH to be used in all three traditional network application areas - Local Network, Inter-exchange Netw ork and Long Haul Network - thus providing a uniﬁed telecommunication network structure.

The SDH standards are based on the principle of direct synchronous multiplexing. This means that individual tributary signals (Payload) may be multiplexed directly into a higher rate SDH signal without intermediate stages of multiplexing. SDH network elements, even those supplied by different manufacturers, can be interconnected directly giving cost and equipment savings.

SDH is capable of transporting all the common tributary signals E1 (2.048 Mb/s), E3 (34.368 Mb/s), E4 (139.264 Mb/s), DS1 (1.544 Mb/s) and DS3 (44.736 Mb/s) currently in use. In addition SDH has the ﬂexibility to readily accommodate any new types of service which are being introduced for example (ATM) or which may be required in the future. Approximately 5% of the SDH signal structure (Overhead) is reserved for network management and maintenance.

This means that SDH can be deployed as an overlay to the existing network thus providing enhanced network ﬂexibility.

The HP 37717C provides comprehensive testing of both payload and overhead at electrical and optical SDHinterfaces.

2

Introduction to SDH Testing

37717C SDH Options

Option A3R [A3S] SDH Generation and Analysis page 4

SDH generation and analysis with STM-0 and STM-1 electrical interfaces, Option A3R.

Additional SDH interface capability is provided by the following Options:: STM-1 Optical Interface, Option UH1. STM-0, STM-1 and STM-4 optical interfaces at 1310nm, Option 131. STM-0, STM-1 and STM-4 optical interfaces at 1310nm and 1550nm, Option 130. STM-0, STM-1, and STM4 binary interfaces, Option 0YH

3

SDH

STM-0/STM-1

2M REF IN

120

Introduction to SDH Testing

Option A3R [A3S] SDH Generation and Analysis

Option A3R [A3S] provides STM-0 and STM-1 Electrical interfaces. When Option UH1 is ﬁtted STM-1 Optical interfaces are provided. When Option 130 or 131 is ﬁtted STM-1 and STM-4 optical interfaces are

provided.

RS449

Ω

When STM1-1 Optical is selected, the STM-1 electrical output is also active. The THRU mode capability allows you to overwrite the TU-2, TU-3, AU-3,

TU12 and AU-4 payloads and the section overhead of the incoming STM-0/ STM-1/STM-4 signal. Frequency offset of the SDH signal of 999 ppm is available.

Bulk Filled and Mixed payloads are available. If Option UKJ, Structured PDH, is ﬁtted, DS1 and DS3 payloads are available and a 2 Mb/s, 34 Mb/s and 140 Mb/s Insert Port is provided. Bit errors can be added to the payload.Errors & Alarms can be added to the SDH signal.

ERROR OUT

OUT IN

Option A3R

AU and TU Pointer Movements can be added to the SDH signal and a Graphical display of Pointer activity is available.

Section and path Overhead bytes are user programmable and can be monitored and displayed in Hexadecimal or as 8 bit bytes. Selected overhead bytes can be transmitted with a programmed sequence of data.

Ω

75

Receive sequences can be captured and displayed. K4 and V5 ov erhead bytes can be accessed.

Allows BER testing of section and path overhead bytes.

Ω

75

Allows testing of MSP Linear and Ring architectures.

Ω

75

DCC Drop and Insert capability is included. Allows Protection Switch time testing if Option UKJ, Structured PDH, is ﬁtted.

Optical Power measurement is available. Optical Clock stress capability at STM-1 and STM-4 is included. Provides SDH Alarm Scan and Tributary Scan.

4

2

Add/Drop Multiplexer Testing page 6 Alarm Stimulus/Response page 11 DCC Testing page 15 Desynchroniser Stress page 18 Frame Synchronization page 21 SDH Jitter Transfer page 27 MSP Stimulus/Response page 30 Optical Clock Recovery Stress page 34 Payload Mapping/Demapping page 36 Performance Monitor Stimulus / Response page 42 Selective Jitter Transfer Measurement page 46 Automatic Alarm and BIP Error Monitoring page 50 Automatic Veriﬁcation of ADM Installation page 53 Veriﬁcation of Protection Switching page 57

2 SDH Testing

This Chapter gives examples of the instrument operation in typical SDH test applications.

SDH Testing

Add/Drop Multiplexer Testing

Application

The insertion of tributary signals into the Add/Drop multiplexer, which are then mapped into the SDH signal, should take place without introducing errors. The insertion and mapping process is tested by adding a test pattern to the tributary inserted at the tributary insert port. At the SDH side of the Add/Drop multiplexer the tributary is demapped by the HP 37717C Communications Performance Analyzer. By using the Optical Splitter, at the optical side of the Add/Drop multiplexer, the Add/Drop multiplexer need not be taken out of service. A Bit error rate (BER) test is performed on the recovered tributary test pattern to determine whether errors have been introduced by the Add/Drop multiplexer.

Default (Known State) Settings

It is advisable to set the HP 37717C to a known state before setting up a measurement. This clears all previous settings and provides a clearly deﬁned instrument state. The default settings are set by selecting

SETTINGS RECALL

STORED SETTING NUMBER 0 and pressing .

OTHER

STORED

Add/Drop Multiplexer Testing Test Setup Procedure

The following Options must be ﬁtted to the HP 37717C to perform this test :

• UKJ [USA]or UKK [USB] - PDH Module

• A3R [A3S] - SDH Module

• 130 or 131 - STM-0/1/4 Optical Interface

In this setup a 2 Mb/s payload, containing a test pattern, is inserted at the tributary insert port of the Add/Drop multiplexer multiplexer. A portion of the STM4 Optical signal is tapped off by the Optical Splitter (approx 10%) and the 2 Mb/s tributary is demapped by the HP 37717C Communications Performance Analyzer.

An Error measurement is performed on the demapped 2 Mb/s tributary test pattern. A SINGLE test period of 24 HOURS is used and the internal printer is enabled to

record results and alarms. The HP 37717C Communications Performance Analyzer GRAPHICS function is

enabled. The graphical results can be viewed on the display

6

GRAPH

SDH Testing

Add/Drop Multiplexer Testing

1. Connect the HP 37717C to the network equipment and set the

SETTINGS CONTROL

Changes made on the display will not affect the display and changes made on the display will not affect the

TRANSMITTER AND RECEIVER to INDEPENDENT.

TRANSMIT

RECEIVE

OTHER

RECEIVE

TRANSMIT

display.

2. Set up the display as shown

TRANSMIT

opposite.

The PAYLOAD TYPE determines the Framing. .

7

SDH Testing

Add/Drop Multiplexer Testing

3. Set up the display as shown

RECEIVE

opposite.

Continuity Check

Before running the test carry out a continuity test to verify the measurement path.

1. Set up the display as shown

RESULTS

opposite.

2. Press to start a

RUN/STOP

measurement.

3. Press error add three times and

SINGLE

check that the errors are recorded on the

RESULTS

display.

3. Check that the errors are recorded on the

RESULTS

4. Press to stop the measurement.

display.

RUN/STOP

Select the required logging DEVICE and set up the display,

OTHER

LOGGING

function, as shown opposite.

8

SDH Testing

Add/Drop Multiplexer Testing

Start the Add/Drop Multiplexer Test

1. Set up the display as shown

RESULTS

opposite.If you do not require stored graphics results select STORAGE [OFF].

Graphics results can be stored to the instrument store - INTERNAL or to DISK.

SHORT TERM PERIOD need only be set if it is intended to view Short Term results.

2. Press to start the

RUN/STOP

measurement.

The measurement results and alarms are available on the display during

RESULTS

the test period. The graphical measurement results and alarms are stored in non volatile memory for viewing later on the GRAPH display.

The test can be halted at any time by pressing

RUN/STOP

9

SDH Testing

Add/Drop Multiplexer Testing

At the End of the Test (Add/Drop Multiplexer Testing)

• The Date and Time the test started and the instrument setup are logged To the

selected logging device.

• Results are logged To the selected logging device at 1 hour intervals if the error

count is greater than 0.

• Any alarms which occur during the test period will be logged To the selected

logging device.

• At the end of the test period a complete set of cumulative results are logged To

the selected logging device.

• A graphical record of the results during the test period can be viewed on the

GRAPH

display. If a printer option is ﬁtted the graph results can be logged to a

printer, at a later date.

• Results and Alarm summaries can be viewed on the display.

GRAPH

The total graphics store capacity is normally 20,000 events. An event is the occurrence of an error or an alarm.

The resolution, determined by the selection made under STORAGE on the

RESULTS

display, affects the ZOOM capability when viewing the bar graphs. If 1 SECOND is selected all resolutions are available under ZOOM. If 1 MIN is selected only 1 MIN/BAR, 15 MINS/BAR and 60 MINS/BAR are available. If 15 MINS is selected only 15 MINS/BAR and 60 MINS/BAR are available. If 1 HOUR is selected only 60 MINS/BAR is available.

Up to 10 sets of graphical results can be stored. If an attempt is made to store more than 10 sets of results, then a ﬁrst in ﬁrst out policy is operated and the oldest set of results will be lost. If graphics are enabled and a test is run which exceeds the remaining storage capacity, then some previously stored graphical results will be lost.

To prevent accidental overwriting of previously stored results the graphics capability should be disabled, when graphical results are not required, by selecting STORAGE [OFF] on the display.

RESULTS

10

SDH Testing

Alarm Stimulus/Response

Application

SDH Network elements transmit alarms in response to certain error/alarm conditions to advise upstream and downstream equipment that these conditions exist. If these alarms are not transmitted in the proper manner, at the proper time, degradations in service will occur.

Alarm testing entails transmitting an alarm signal from the Communications Performance Analyzer and monitoring the network equipment alarm indicators and the upstream or downstream signal for the correct response.

Default (Known State) Settings

It is advisable to set the HP 37717C to a known state before setting up a measurement. This clears all previous settings and provides a clearly deﬁned instrument state. The default settings are set by selecting

SETTINGS RECALL

STORED SETTING NUMBER 0 and pressing .

OTHER

STORED

Alarm Stimulus/Response Test Setup Procedure

The following options must be ﬁtted to the HP 37717C to perform this test:

• A3R [A3S] - SDH module

• UH1, - STM-1 Optical interface or 130 or 131 STM-0/1/4 Optical interface

In this setup the Communications Performance Analyzer transmits MS-AIS Alarm (Line AIS) into the network. The network equipment alarm indicators are monitored for the appropriate alarms. The upstream signal is monitored for occurrences of MSRDI . The downstream signal can be monitored for occurrences of AU-AIS.

A similar procedure can be used for testing all other SDH alarms. See the following tables.

11

SDH Testing

Alarm Stimulus/Response

SDH Alarms

Alarm RSTE MSTE PTE

Down Up Down Up Down Up

Loss Of Signal MS-AIS N/A AU-AIS MS-RDI TU-AIS LP-RDI Loss Of Frame MS-AIS N/A AU-AIS MS-RDI TU-AIS LP-RDI Loss Of Pointer N/A N/A AU-AIS MS-RDI TU-AIS LP-RDI MS-AIS N/A N/A AU-AIS MS-RDI TU-AIS LP-RDI MS-RDI N/A N/A N/A N/A N/A N/A

12

SDH Testing

Alarm Stimulus/Response

1. Set up the ;

CONTROL

Any changes made on the or

RECEIVE

2. Set up the ; display

OTHER

SETTINGS

display as shown opposite.

TRANSMIT

display will affect the other.

TRANSMIT

SDH

as shown opposite.

3. Set up the ; TEST

TRANSMIT

FUNCTION display as shown opposite.

The ERROR ADD TYPE selected does not matter as long as RATE [OFF] is selected.

13

SDH Testing

Alarm Stimulus/Response

4. Set up the display as

RESULTS

shown opposite SHORT TERM PERIOD need only be

set if it is intended to view Short Term results

Start the Alarm Stimulus/Response Test

1. Connect the Communications Performance Analyzer to the upstream port of the network equipment and press on the HP 37717C.

RUN/STOP

2. Check that the network equipment registers MS-AIS and that MS-RDI alarm seconds are recorded on the

RESULTS

display . ALARM SECONDS are displayed but any

of the other results can be selected from the softkey menu without affecting the measurement

The MS-RDI indicator on the front panel in conjunction with will

SHOW HISTORY

also give an indication that the MS-RDI alarm has occurred.

14

SDH Testing

DCC Testing

Application

The section overhead contains two Data Communication Channels (DCC), Regenerator Section DCC at 192 kb/s (overhead bytes D1- D3) and Multiplexer Section DCC at 576 kb/s (overhead bytes D4 - D12). The DCC communicates network management messages between network elements and the network controller via the operations support computer system.

If the DCC is not operating correctly these network management messages will be lost and degradations in network performance will pass unnoticed. This may result in a failure condition.

Full testing of the line and section DCC’s can be carried out using a protocol analyzer connected via the HP 37717C Communications Performance Analyzer to the appropriate overhead bytes. At the far end the HP 37717C Communications Performance Analyzer can drop the selected DCC to the protocol analyzer allowing the DCC integrity to be analyzed.

If you do not have access to a protocol analyzer capable of handling SDH DCC protocol, the DCC integrity can be veriﬁed by a BER test using an HP 37732A, Digital Telecomm/Datacomm Analyzer.

Default (Known State) Settings

It is advisable to set the HP 37717C to a known state prior to setting up a measurement. This clears all previous settings and provides a clearly deﬁned instrument state. The default settings are set by selecting

SETTINGS RECALL

DCC Test Setup Procedure

Alarm Stimulus/Response Test Setup Procedure

The following options must be ﬁtted to the HP 37717C to perform this test:

• A3R [A3S]- SDH module

• UH1, - STM-1 Optical interface or 130 or 131 STM-0/1/4 Optical interface

IIn this procedure the HP 37717C Communications Performance Analyzer accepts a 576 kb/s test pattern via the protocol analyzer port, inserting the test pattern in bytes D4 - D12 of the Multiplexer Section overhead and transmitting an STM-1 optical

STORED SETTING NUMBER 0 and pressing

OTHER

STORED

15

SDH Testing

DCC Testing

signal. The HP 37717C Communications Performance Analyzer receives the STM1 optical signal and drops the Multiplexer Section DCC, via the protocol analyzer port, to the HP 37732A which performs the BER measurement.

1. Connect the HP 37732A and the HP 37717C to the network element, as shown and set up the ;

CONTROL

OTHER

SETTINGS

display as shown opposite.

2. Set up the SDH display as

TRANSMIT

shown opposite.

The CLOCK SYNC selection determines the synchronization source for the

TRANSMIT

clock. If

EXTERNAL MTS

is selected a 2 Mb/s reference must be connected to the front panel 2M REF IN port. The format can be CLOCK or DATA.

16

SDH Testing

DCC Testing

3. Set up the ; TEST

TRANSMIT

FUNCTION display as shown opposite.

4. Set up the ; TEST

RECEIVE

FUNCTION display as shown opposite.

Start the DCC Test

1. Select TEST SELECT DATACOM on the HP 37732A.

2. Set TX Clock Source and RX Clock Source to [INTERF ACE] on the HP 37732A (Clock from HP 37717C protocol port).

3. Select the required pattern and monitor logic errors and frequency to verify the integrity of the DCC.

17

SDH Testing

Desynchroniser Stress

Application

At the boundary of the SDH network the 2 Mb/s or 140 Mb/s payload is demapped from the SDH signal. Pointer adjustments in the signal may cause high levels of tributary jitter in the output payload. Excessive amounts of trib utary jitter will result in errors.

The desynchronizing phase lock loop of the network element should minimize the level of tributary jitter in the payload but correct operation under stress conditions must be veriﬁed. The desynchronizing phase lock loop can be stressed by adding pointer movement sequences (deﬁned in CCITT standard G.783) to the SDH signal such that the test virtual container moves with respect to the SDH frame.

A jitter measurement is made to verify that the desynchroniser output jitter is within the required speciﬁcation.

Default (Known State) Settings

It is advisable to set the HP 37717C to a known state before setting up a measurement. This clears all previous settings and provides a clearly deﬁned instrument state. The default settings are set by selecting

SETTINGS RECALL

STORED SETTING NUMBER 0 and pressing .

OTHER

STORED

Desynchroniser Stress Test Setup Procedure

The following options must be ﬁtted to the HP 37717C to perform this test:

• UKK [USB] or UKJ [USA]- PDH module

• A3L, A3V or A3N - Jitter measurement module

• A3R [A3S]- SDH module

• 130 or 131 STM-0/1/4 Optical interface

The HP 37717C Communications Performance Analyzer transmits an STM-4 optical signal carrying 2 Mb/s payload. Pointer movement sequences are added in a controlled manner. The desynchroniser output is returned to the HP 37717C and a jitter measurement is performed on the demapped 2 Mb/s signal.

18

SDH Testing

Desynchroniser Stress

1. Connect the HP 37717C to the network equipment and set up the ;

display as shown opposite.

SDH

TRANSMIT

The CLOCK SYNC selection determines the synchronization source for the

TRANSMIT

clock. If

EXTERNAL MTS

is selected a 2 Mb/s reference must be connected to the 2M REF IN port. The format can be CLOCK or DATA.

2. Set up the ; TEST

TRANSMIT

FUNCTION display as shown opposite.

Pointer adjustments are made every 10 ms with an extra ADDED adjustment as deﬁned in CCITT standard G.783.

Pointer sequences are started by selecting

STARTED

.

19

SDH Testing

Desynchroniser Stress

3. Set up the ; JITTER

RECEIVE

PDH

display as shown opposite. SHORT TERM PERIOD need only be set

if it is intended to view Short Term results

4. Set up the display as

RESULTS

shown opposite. .

Start the Desynchroniser Stress Test

1. Press to start the Jitter

RUN/STOP

measurement. Jitter Hits or any other result can also be

viewed without affecting the measurement

20

SDH Testing

Frame Synchronization

Application

A network element should maintain synchronization even in the presence of some frame errors. If the number of frame errors exceeds the speciﬁed threshold for 3 ms, the network element will lose frame synchronization causing a new search for frame alignment to begin.

The frame synchronization process of the network element can be stressed by injecting frame errors, into the A1 and A2 framing bytes of the Regenerator Section overhead. As the frame error injection rate is increased to the frame synchronization threshold, the network element should indicate Out Of Frame (OOF) and Loss Of Frame (LOF) conditions. As the frame error injection rate is decreased again, the network element should regain frame synchronization.

Default (Known State) Settings

It is advisable to set the HP 37717C to a known state before setting up a measurement. This clears all previous settings and provides a clearly deﬁned instrument state. The default settings are set by selecting

SETTINGS RECALL

STORED SETTING NUMBER 0 and pressing .

OTHER

STORED

Frame Synchronization Test Setup Procedure Frame Error Add Test Function In this setup the HP 37717C Communications

Performance Analyzer is used to insert frame errors in the A1 and A2, framing bytes of the Regenerator section overhead of an STM-1 optical signal. The STM-1 optical signal is transmitted to the network equipment. The network equipment OOF and LOF alarms are monitored as the frame error add rate is increased and decreased.

Sequence Generation Test Function

In this setup procedure the HP 37717C Communications Performance Analyzer generates a sequence of errored framing bytes to test the OOF and LOF alarm threshold criteria. The upstream STM-1 optical signal is monitored for occurrences of Multiplexer Section FERF. The downstream STM-1 optical signal can be monitored for AIS.

21

SDH Testing

Frame Synchronization

1. Connect the HP 37717C to the network

equipment and set up the ;

SETTINGS CONTROL

OTHER

display as shown

opposite.

2. Set up the ; display

TRANSMIT

SDH

as shown opposite. The CLOCK SYNC selection determines

the synchronization source for the

TRANSMIT

clock. If

EXTERNAL MTS

is selected a 2 Mb/s reference must be connected to the front panel 2M REF IN port. The format can be CLOCK or DATA.

22

SDH Testing

Frame Synchronization

3. Set up the display as

RESULTS

shown opposite SHORT TERM PERIOD need only be

set if it is intended to view Short Term results.

4,.ALARM SECONDS are displayed but any of the other results can be selected from the softkey menu without affecting the measurement

The MS-RDI indicator on the front panel in conjunction with will

SHOW HISTORY

also give an indication that the MS-RDI alarm has occurred.

5. Set up the ; TEST

TRANSMIT

FUNCTION display as shown opposite.

23

SDH Testing

Frame Synchronization

Start the Frame Synchronization Test (Frame Error Add)

1. Check that the Loss Of Frame (LOF) alarm indicator on the network element remains unlit and no occurrences of MS-RDI are recorded.

2. Increase the Frame Error Add Rate to 2 IN 4 and check that the Loss Of Frame (LOF) alarm indicator on the network element remains unlit and no occurrences of MS-RDI are recorded.

3. Increase the Frame Error Add Rate to 3 IN 4 and check that the Loss Of Frame (LOF) alarm indicator on the network element remains unlit and no occurrences of MS-RDI are recorded.

4. Increase the Frame Error Add Rate to 4 IN 4 and check that the OOF and LOF alarm indicators on the network equipment are lit and occurrences of MS-RDI are recorded.

5. Decrease the Frame Error Add Rate to 3 IN 4 and check that the OOF and LOF alarm indicators on the network equipment remain lit and occurrences of MS-RDI are still being recorded.

6. Decrease the Frame Error Add Rate to 2 IN 4 and check that the OOF and LOF alarm indicators on the network equipment go off, and no further occurrences of MS-RDI are recorded.

Sequence Generation Test Function

1. Connect the HP 37717C to the network equipment and set up the

SETTINGS CONTROL

OTHER

display as shown

opposite.

24

SDH Testing

Frame Synchronization

2. Set up the ; display as

TRANSMIT

SDH

shown opposite.

The CLOCK SYNC selection determines the synchronization source for the clock. If is selected a 2

EXTERNAL MTS

TRANSMIT

Mb/s reference must be connected to the front panel 2M REF IN port. The format can be CLOCK or DATA.

3. Set up the display as

RESULTS

shown opposite SHORT TERM PERIOD need only be

set if it is intended to view Short Term results.

4..ALARM SECONDS are displayed but any of the other results can be selected from the softkey menu without affecting the measurement.

25

SDH Testing

Frame Synchronization

Start the Frame Synchronization Test (Sequence Test)

1. Set up the TEST

TRANSMIT

FUNCTION display as shown opposite.

2. Press on the

STARTED

TRANSMIT

TEST FUNCTION display to start the sequence. As a result of this sequence one OOF alarm second and one LOF alarm second should occur every two seconds.

3. Check that the network element OOF and LOF alarm indicators cycle ON and OFF and that an occurrence of MS-RDI is recorded every two seconds.

3. Press to stop the sequence and set up the TEST

STOPPED

TRANSMIT

FUNCTIONdisplay as shown opposite.

4. Press on the

STARTED

TRANSMIT

TEST FUNCTIONdisplay to start the sequence. As a result of this sequence one OOF alarm second should occur every two seconds but LOF should not occur.

5. Check that the network element OOF alarm indicator cycles ON and OFF. The LOF alarm should not occur and no occurrences of MS-RDI should be recorded.

26

SDH Testing

SDH Jitter Transfer

Digital transmission systems use Regenerators to transport the signal over long distances. These Regenerators are cascaded together and it is important that each regenerator adds minimal amounts of jitter to the signal.

It is necessary during installation and maintenance to measure the degree to which jitter present at the input is ampliﬁed or attenuated by the network elements (Jitter Gain/Transfer).

The jitter transfer measurement entails measuring the input and output jitter at selected jitter frequencies within the jitter bandwidth. The jitter gain is calculated : Jitter Gain (dB) = 20 Log {Jitter out \\over Jitter in}

When the network equipment meets CCITT speciﬁcation G.823 it should be possible to connect network elements without incurring bit errors.

Default (Known State) Settings

It can be advisable to set the HP 37717C to a known state prior to setting up to make a measurement. This clears all previous settings and provides a clearly deﬁned instrument state. The default settings are set by selecting

SETTINGS RECALL

Test Setup Procedure (Jitter Transfer Test)

The following Options must be ﬁtted to the HP 37717C to perform this test :

• A3K - Jitter and Wander Generation

STORED SETTING NUMBER 0 and pressing .

OTHER

STORED

27

SDH Testing

SDH Jitter Transfer

• A3V or A3N- SDH Jitter Measurement

• A3R [A3S] - SDH Module

This setup procedure is based on 155.52 Mb/s (STM-1), 140 Mb/s payload, PRBS test data with jitter. The Jitter frequenc y is v aried within the jitter bandwidth and the received jitter is measured to allow calculation of the jitter gain.

1. Set up the OTHER SETTINGS CONTROL display as shown opposite.

Any SDH settings change made on the

TRANSMIT

or displays will

RECEIVE

automatically occur on the other.

2. Connect the HP 37717C to the line

equipment, select ; and

TRANSMIT

SDH

set up the display as shown opposite.

3. Select ; JITTER and set up

TRANSMIT

the display as shown opposite. Select the required Jitter MODULATING

FREQUENCY and AMPLITUDE.

28

SDH Testing

SDH Jitter Transfer

4. Setup the ;

RECEIVE

SDH JITTER

display as shown opposite. If Jitter ﬁltering is required select from the

softkey menu.

Run the Test (Jitter Transfer)

1. Select and set up the

RESULTS

display as shown opposite. SHORT TERM PERIOD need only be

set if it is intended to view Short Term results.

2.Press to start the

RUN/STOP

measurement.

3. Record the Jitter Amplitude result from the display.

RESULTS

4. Select each jitter Modulating Frequency and Amplitude in turn on the display, press twice and

RUN/STOP

TRANSMIT

record the Jitter Amplitude result from the RESULTSdisplay.

5. Calculate the Jitter gain for each frequency selected.

Jitter Gain (dB) = 20 Log {Jitter out / Jitter in}. Where Jitter In is the AMPLITUDE selected on the display.

TRANSMIT

29

SDH Testing

MSP Stimulus/Response

Application

Multiplexer Section Protection (MSP) is an optional feature for SDH Multiplexer Section Terminating Equipment (MSTE). For those MSTE’s, in which it is provided, the MSP system is standardized to ensure the interworking of MSP between MSTE’s from different suppliers.

Standard messages, carried in the K1 and K2 bytes of the SDH signal transport overhead, indicate the state of the MSP.

Switching to the protection line occurs when one of the following conditions exists for a speciﬁed length of time :

• Loss Of Signal (LOS)

• Loss Of Frame (LOF)

• Signal Fail - Bit Error Ratio > 1 X 10

-3

• Signal Degrade - Bit Error Ratio programmable

• MS-AIS

The Signal Degrade Bit Error Ratio threshold is normally programmable in the range 1 X 10-5to 1 X 10-9.

The HP 37717C Communications Performance Analyzer can be used to test Multiplexer Section Protection switching by :

Generating the switching conditions listed above. Transmitting and monitoring the K1 K2 messages.

MSP Stimulus/Response 1+1 Architecture Test Setup Procedure

In this setup the HP 37717C PDH/SDH test set, inserted in the working line, generates B2 BIP errors in sufﬁcient quantity to violate the Signal Degrade threshold of the Multiplexer Section Protection. The network equipment Service Terminal indicates that switching to the standby line has occurred. The activity on the K1 K2 bytes can be monitored on the TRANSMIT TEST FUNCTION MSP Messages display.

30

SDH Testing

MSP Stimulus/Response

1. Set up the ; display

TRANSMIT

SDH

as shown opposite.

The CLOCK SYNC selection determines the synchronization source for the

TRANSMIT

clock. If

EXTERNAL MTS

is selected a 2 Mb/s reference must be connected to the front panel 2M REF IN port. The format can be CLOCK or DATA.

31

SDH Testing

MSP Stimulus/Response

2. Set up the ; TEST

TRANSMIT

FUNCTION display as shown opposite.

1530 B2 BIP errors in 1 second corresponds to a BER of 1 in 10-5. The Service terminal should indicate switching to standby within 1 second.

MSP Stimulus/Response 1:N Architecture

The HP 37717C Communications Performance Analyzer ;TEST FUNCTION ; can be used to transmit and monitor the K1 K2

MSP MESSAGES

TRANSMIT

messages.

The MSP Messages are transmitted when

DOWNLOAD

is pressed.

Two displays of K1 and K2 are provided :

1. Current TX - Values of K1 and K2 bytes which are currentlybeing transmitted.

2. Current RX - Values of K1 and K2 bytes which are currentlybeing received.

K1 Bits 1 ->4 Selects the MSP message to be transmitted.

Table 1 K1 Bits 1 - >4

Selection Message Selection Message

0000 NO REQUEST 1000 MANUAL SWITCH 0001 DO NOT REVERT 1001 NOT USED 0010 REVERSE REQUEST 1010 SD - Low Priority 0011 NOT USED 1011 SD - High Priority

32

SDH Testing

MSP Stimulus/Response

Table 1 K1 Bits 1 - >4

Selection Message Selection Message

0100 EXERCISE 1100 SF - Low Priority 0101 NOT USED 1101 SF - High Priority 0110 WAIT TO RESTORE 1110 FORCED SWITCH 0111 NOT USED 1111 LOCKOUT OF PROT

SD - High Priority and SF - High Priority are only available when K2 bit 5 is set to 1 ( 1 : N architecture).

K1 Bits 5 ->8 Selects the channel used by the MSP Messages.

Table 2 K1 Bits 5 - >8

Selection Message Selection Message

0000 NULL CHANNEL 1000 WORKING CHANNEL #8 0001 WORKING CHANNEL #1 1001 WORKING CHANNEL #9 0010 WORKING CHANNEL #2 1010 WORKING CHANNEL #10 0011 WORKING CHANNEL #3 1011 WORKING CHANNEL #11 0100 WORKING CHANNEL #4 1100 WORKING CHANNEL #12 0101 WORKING CHANNEL #5 1101 WORKING CHANNEL #13 0110 WORKING CHANNEL #6 1110 WORKING CHANNEL #14 0111 WORKING CHANNEL #7 1111 EXTRA TRAFFIC CHANNEL

WORKING CHANNEL #2 through WORKING CHANNEL #14 and EXTRA TRAFFIC CHANNEL are only available when K2 Bit 5 is set to 1 : N architecture. If K1 bits 1 >4 are set to 1111 LOCKOUT OF PR OT then K1 bits 5 ->8 are ﬁxed at 0000 NULL CHANNEL.

K2 bits 1 - >4 Selects the bridged channel used by the MSP Messages. Can be

set in the range 0000 to 1111.

K2 bit 5 Determines the automatic protection switch architecture.

0 (1 + 1 architecture), 1 (1 : N architecture)

33

SDH Testing

Optical Clock Recovery Stress

K2 bits 6 ->8 Selects the reserved bits. Can be set in the range 000 to 101.

Optical Clock Recovery Stress

Application

Ideally the clock recovery circuits in the network equipment optical interfaces should recover a clock even in the presence of long strings of 0’s.

The optical clock recovery performance of the network equipment can be measured by increasing the length of a zero substitution block until errors occur.

Default (Known State) Settings

It is advisable to set the HP 37717C to a known state before setting up a measurement. This clears all previous settings and provides a clearly deﬁned instrument state. The default settings are set by selecting

SETTINGS RECALL

Optical Clock Recovery Stress Test Setup Procedure

In this setup procedure the HP 37717C Communications Performance Analyzer transmits an STM-1 optical signal with zero’s substituted into the payload data pattern. The length of the block of zero’s is increased until the network equipment alarms are triggered.

STORED SETTING NUMBER 0 and pressing .

OTHER

STORED

34

SDH Testing

Optical Clock Recovery Stress

1. Connect the HP 37717C to the network

equipment and set up the ;

display as shown opposite.

SDH

TRANSMIT

The CLOCK SYNC selection determines the synchronization source for the

TRANSMIT

clock. If

EXTERNAL MTS

is selected a 2 Mb/s reference must be connected to the front panel 2M REF IN port. The format can be CLOCK or DATA.

2. Set up the ; TEST

TRANSMIT

FUNCTION display as shown opposite G.958 Test Pattern consists of consecutive

blocks of four types of data : All 1’s PRBS All 0’s a data block consisting of the ﬁrst row of section overhead bytes.

Start the Optical Clock Recovery Stress Test

Increase the Block Length until the network equipment alarms are triggered.

35

SDH Testing

Payload Mapping/Demapping

Application

The mapping and demapping of a 2 Mb/s or 140 Mb/s payload into/from the appropriate SDH containers should take place without introducing errors.

The mapping process is tested by inserting a test pattern in the 2 Mb/s or 140 Mb/s payload at the low-rate side of the terminal multiplexer. On the high-rate side of the terminal multiplexer, the payload is demapped from the SDH signal by the HP 37717C Communications Performance Analyzer.

The demapping process is tested by transmitting a SDH signal to the high-rate side of the multiplexer . On the lo w-rate side of the multiple x er the payload is recei ved by the HP 37717C Communications Performance Analyzer.

A Bit error rate (BER) test is performed on the recovered payload test pattern to determine whether errors have been introduced by the mapping process.

Default (Known State) Settings

It is advisable to set the HP 37717C to a known state before setting up a measurement. This clears all previous settings and provides a clearly deﬁned instrument state. The default settings are set by selecting

SETTINGS RECALL

STORED SETTING NUMBER 0 and pressing .

OTHER

STORED

Payload Mapping/Demapping Test Setup Procedure

The following Options must be ﬁtted to the HP 37717C to perform this test :

• UKJ or UKK - PDH Module

• A3R [A3S] - SDH Module

• UH1, 130 or 131 - STM-1/STM-4 Optical Interface

For mapping a 140 Mb/s payload, containing a test pattern, is transmitted into the low-rate side of the terminal multiplexer. The 140 Mb/s payload is demapped from the STM-4 Optical signal at the high-rate side of the terminal multiplexer.

For demapping an STM-4 Optical signal is transmitted into the high-rate side of the Add Drop multiplexer. The 140 Mb/s signal, on the low-rate side of the Add Drop multiplexer , is recei v ed by the HP 37717C Communications Performance Analyzer.

A BER measurement is performed on the demapped 140 Mb/s payload test pattern.

36

SDH Testing

Payload Mapping/Demapping

A SINGLE test period of 24 HOURS is used and the internal printer is enabled to record results and alarms.

The HP 37717C Communications Performance Analyzer GRAPHICS function is enabled. The graphical results can be viewed on the GRAPH display

Payload Mapping

Payload Demapping

t

tttt

37

SDH Testing

Payload Mapping/Demapping

1. Connect the HP 37717C to the network equipment and set up the

SETTINGS CONTROL

OTHER

display as shown

opposite.

2. For Mapping set up the

TRANSMIT

display as shown opposite.

2a. For Demapping set up the display as shown opposite.

TRANSMIT

38

SDH Testing

Payload Mapping/Demapping

3. For Mapping set up the

RECEIVE

display as shown opposite.

3a. For Demapping set up the display as shown opposite.

RECEIVE

4. Set up the display,

OTHER

LOGGING

function, as shown opposite. All results are logged to the selected

logging device at 1 hour intervals. Any alarms which occur during the test period will be logged To the selected logging device.

39

SDH Testing

Payload Mapping/Demapping

Start the Payload Mapping/Demapping Test

1. Set up the display as

RESULTS

shown opposite. If you do not require stored graphics results select STORAGE [OFF].

SHORT TERM PERIOD need only be set if it is intended to view Short Term results.

2. Press to start the

RUN/STOP

measurement.

The measurement results and alarms are available on the RESULTS display during the test period.

The graphical measurement results and alarms are stored in non volatile memory for viewing later on the display.

GRAPH

The test can be halted at any time by pressing .

RUN/STOP

40

SDH Testing

Payload Mapping/Demapping

At the End of the Test (Payload Mapping/Demapping)

• The Date and Time the test started and the instrument setup are logged to the

selected logging device.

• All results are logged to the selected logging device at 1 hour intervals.

• Any alarms which occur during the test period will be logged to the selected

logging device.

• At the end of the test period a complete set of cumulative results are logged to the

selected logging device.

• A graphical record of the results during the test period can be viewed on the

GRAPH display. If a printer option is ﬁtted the graph results can be logged to a printer, at a later date.

• Results and Alarm summaries can be viewed on the display.

GRAPH

The total graphics store capacity is normally 20,000 events. An event is the occurrence of an error or an alarm.

The resolution, determined by the selection made under STORAGE on the

RESULTS

display, affects the ZOOM capability when viewing the bar graphs. If 1 SECOND is selected all resolutions are available under ZOOM. If 1 MIN is selected only 1 MIN/BAR, 15 MINS/BAR and 60 MINS/BAR are available. If 15 MINS is selected only 15 MINS/BAR and 60 MINS/BAR are available. If 1 HOUR is selected only 60 MINS/BAR is available.

Up to 10 sets of graphical results can be stored. If an attempt is made to store more than 10 sets of results, then a ﬁrst in ﬁrst out policy is operated and the oldest set of results will be lost. If graphics are enabled and a test is run which exceeds the remaining storage capacity, then some previously stored graphical results will be lost.

T o prev ent accidental overwriting of pre viously stored results the graphics capability should be disabled, when graphical results are not required, by selecting STORAGE [OFF] on the display.

RESULTS

41

SDH Testing

Performance Monitor Stimulus / Response

Application

Performance monitors built into the SDH network equipment count BIP errors, and communicate the results to the network controller via the Data Communication Channel (DCC). Performance monitors in Path Terminating Equipment (PTE) also communicate with the upstream equipment.

If the performance monitors are not operating correctly, degradations in network performance will pass unnoticed and may result in a failure condition.

The performance monitors can be tested by the Communications Performance Analyzer transmitting BIP errors in the appropriate byte of the overhead and monitoring upstream for the correct response :

Regenerator Section (RS) - B1 Byte of regenerator section overhead Multiplexer Section (MS) - B2 Bytes of multiplexer section overhead PATH B3 - B3 Byte of path overhead

Default (Known State) Settings

It is advisable to set the HP 37717C to a known state before setting up a measurement. This clears all previous settings and provides a clearly deﬁned instrument state. The default settings are set by selecting

SETTINGS RECALL

Performance Monitor Stimulus/Response Test Setup Procedure

The following Options must be ﬁtted to the HP 37717C to perform this test :

• A3R - SDH Module

• UH1,130 or 131 - STM-1/STM-4 Optical Interface

In this setup the HP 37717C Communications Performance Analyzer inserts “PATH” B3 BIP errors in byte B3 of the path overhead of the SDH signal. The upstream signal is monitored to provide a measure of the FEBE (Far End Block Error) count.

42

STORED SETTING NUMBER 0 and pressing .

OTHER

STORED

SDH Testing

Performance Monitor Stimulus / Response

1. Connect the HP 37717C to the network equipment and set up the ;

SETTINGS CONTROL

OTHER

display as shown

opposite.

2. Set up the ; display

TRANSMIT

SDH

as shown opposite.

The CLOCK SYNC selection determines the synchronization source for the

TRANSMIT

clock.

43

SDH Testing

Performance Monitor Stimulus / Response

3. Set up the display as

RESULTS

shown opposite. SHORT TERM PERIOD need only be

set if it is intended to view Short Term results

HP-REI ERROR RESULTS are displayed but any of the other results can be selected from the softkey menu without affecting the measurement.

4. Set up the ; TEST

TRANSMIT

FUNCTION display as shown opposite. The ERROR RATE required can be selected

from the softkey menu.

44

SDH Testing

Performance Monitor Stimulus / Response

Start the Performance Monitor Stimulus/Response Test

1. Press on the HP 37717C Communications Performance Analyzer.

RUN/STOP

2. Check that the HP-REI error rate is the same as the generated B3 BIP rate. All the measurement results are available, throughout the test, on the

RESULTS

display .

At the end of the test :

• the cumulative measurement results are available on the display.

RESULTS

45

SDH Testing

Selective Jitter Transfer Measurement

The problem with many SDH jitter analyzers is the fact that their receivers are wideband receivers and are not able to measure within a sufﬁciently narrow bandwidth. The reason is that these instruments are designed to measure peak to peak jitter in the transmission network for troubleshooting purposes and are not designed to make selective jitter measurements. The jitter analyzer just measures the peak-peak value of the incoming jitter over a wide frequency range. The problem occurs when testing the jitter transfer of real network equipment i.e. SDH regenerators.

The regenerator produces intrinsic jitter and this disturbs the measurement as the jitter receiver cannot determine whether it is measuring the jitter produced by the jitter analyzers transmitter or the intrinsic jitter which is generated, at a different frequency , by the re generator . The problem is greatest at the higher jitter modulating frequencies when the amount of jitter generated, as per ITU-T G.958, is much smaller. The measurement is corrupted by the higher amplitude intrinsic jitter generated by the regenerator at lower frequencies and incorrectly measured by the analyzer.

The accurate method for measuring jitter transfer requires a selective measurement. One such method is to use a network analyzer in conjunction with the HP 37717C. The network analyzer provides the capability to measure jitter selectively and has increased sensitivity.

Default (Known State) Settings

It can be advisable to set the HP 37717C to a known state prior to setting up to make a measurement. This clears all previous settings and provides a clearly deﬁned instrument state. The default settings are set by selecting

SETTINGS RECALL

Test Setup Procedure (Jitter Transfer Test)

The following Options must be ﬁtted to the HP 37717C to perform this test:

• A3K - Jitter Generation

• A3L or A3V or A3N - SDH Jitter Measurement

• A3R [A3S] - SDH Module

• UH1, 130 or 131 - STM-1/4 Optical interface

46

STORED SETTING NUMBER 0 and pressing .

OTHER

STORED

SDH Testing

Selective Jitter Transfer Measurement

This setup procedure is based on 155.52 Mb/s (STM-1), 140 Mb/s payload, PRBS test data with jitter. The jitter modulation is provided by the network analyzer. The HP 37717C demodulated jitter output is returned to the network analyzer for measurement. Before connecting to the regenerator to be tested the HP 37717C is looped back to back and the network analyzer is programmed to sweep over the required frequency range at the required amplitude. This provides a reference trace and removes the inaccuracies of the of the test conﬁguration (inaccuracies of the HP 37717C and the Network Analyzer). The HP 37717C is connected to the regenerator and the network analyzer sweep is repeated. The difference between the two traces is the jitter transfer result.

TEST SET

Selective Jitter Transfer Test

1. Set up the OTHER SETTINGS CONTROL display as shown opposite.

Any SDH settings change made on the

TRANSMIT

or displays will

RECEIVE

automatically occur on the other.

47

SDH Testing

Selective Jitter Transfer Measurement

2. Connect the HP 37717C to the network analyzer as shown. Connect STM-1/STM4 IN to STM-1/STM-4 OUT. Select

SDH and set up the

TRANSMIT

SDH

display as shown opposite.

3. Select

TRANSMIT

SDH

JITTER

and set up the display as shown opposite.

4. Setup the

RECEIVE

SDH JITTER

display as shown opposite. If Jitter ﬁltering is required select from

the softkey menu.

48

SDH Testing

Selective Jitter Transfer Measurement

5. Select and set up the

RESULTS

display as shown opposite. Press to start the

RUN/STOP

measurement.

6. Adjust the network analyzer output level until the display records the

RESULTS

required peak-peak jitter value.

7. Press to stop the

RUN/STOP

measurement.

0.01

8. Start the network analyzer sweep and store the resultant "reference trace"

9. Connect the HP 37717C to the regenerator as shown (loopback removed) and repeat the network analyzer sweep.

The difference between the two traces is the Jitter Transfer result.

49

SDH Testing

Automatic Alarm and BIP Error Monitoring

Application

Problems in the network at all levels in the hierarchy can be detected by the occurrence of alarms or BIP errors in each tributary of SDH systems. Since an STM-4 ﬁbre contains up to 252 TU-12 tributaries, checking each tributary individually is time consuming and laborious.

Using the HP 37717C in a receive only mode, each tributary is scanned and any alarm or BIP occurrence is ﬂagged on the display. If the ﬁbre contains an unknown signal structure (mixed payloads) the HP 37717C will quickly determine and scan that structure.

Default (Known State) Settings

It can be advisable to set the HP 37717C to a known state prior to setting up to make a measurement. This clears all previous settings and provides a clearly deﬁned instrument state. The default settings are set by selecting

STORED SETTINGS

STORED SETTING NUMBER 0 and pressing .

RESULTS

OTHER

RECALL

Test Setup Procedure (Alarm Monitoring)

The following Options must be ﬁtted to the HP 37717C to perform this test:

• UKJ or UKK - PDH Module

• A3R [A3S] - SDH Module

• 130 or 131 - STM-1/4 Optical Interface

This setup procedure is based on STM-4 line trafﬁc with mixed payload. The instrument is used in a receive only mode to monitor Loss of Pointer, AU-AIS,

HP-RDI, H4 Loss of Multiframe, TU-Loss Of Pointer, TU-AIS, LP-RDI alarms and BIP errors in AU-4, AU-3, TU-3, TU-2 and TU-12 payloads.

50

SDH Testing

Automatic Alarm and BIP Error Monitoring

HP 15774B

SDH

Optical Splitter

90%

PDH

Alarm Monitoring

1. Connect the HP 37717C to the Network equipment via the optical splitter and set up the display as

RECEIVE

SDH

shown opposite. The MAPPING and TU PAYLOAD

selections are only important if the Alarm Scan is to be carried out on the RX SETTINGS.

2. Set up the display as shown opposite.

SCAN

RESULTS

SDH ALM

10%

TEST SET

STM-1/STM-4 IN

conﬁgures the HP 37717C to

AUTO

determine the received payload structure and carry out an Alarm Scan in each tributary.

BIP [>0] conﬁgures the 37717C to detect any occurrence of a BIP error . A choice of BIP [>1E-3] or [>1E-6] or [OFF] is also available.

51

SDH Testing

Automatic Alarm and BIP Error Monitoring

Start the Test (Alarm Monitoring)

1. Select on the display.

START

RESULTS

SDH ALM SCAN

If any of the alarms, Loss of Pointer, AU-AIS, HP-RDI, H4 Loss of Multiframe, TU Loss of Pointer, TU-AIS or LP-RDI has occurred the appropriate point in the hierarchy will be highlighted.

If a BIP error has occurred in the AU-4, AU-3, TU-3, TU-2 or TU-12 payload the appropriate point in the hierarchy will be highlighted.

If Unequiped is identiﬁed, the apropriate point in the hierarchy will be changed to U. The test can be halted at any time by selecting on the

SDH ALM SCAN

display.

STOP

RESULTS

52

SDH Testing

Automatic Veriﬁcation of ADM Installation

Application

An important part of the ADM installation process is the veriﬁcation of path routing through an ADM (or Digital Cross Connect). In order to verify the routing of VC-n paths which are terminated by the network element, the mapped payload, dropped to a PDH tributary port, must be looped back at the digital distribution frame and mapped into the VC-n at the PDH tributary insert port. VC-n paths which are not terminated must be looped back at the STM-n level. Since an STM-1 contains 63 VC-12’s and a STM-4 contains 252 VC-12’s, manually checking each path is time consuming and laborious.

Using the HP 37717C Tributary Scan feature the installation of ADM’s can be automated and any Bit errors or Pattern Sync Loss will be ﬂagged on the display.

Default (Known State) Settings

It can be advisable to set the HP 37717C to a known state prior to setting up to make a measurement. This clears all previous settings and provides a clearly deﬁned instrument state. The default settings are set by selecting

STORED SETTINGS

STORED SETTING NUMBER 0 and pressing .

OTHER

RESULTS

RECALL

Test Setup Procedure (Alarm Monitoring)

The following Options must be ﬁtted to the HP 37717C to perform this test:

• UKJ or UKK - PDH Module

• A3R [A3S]- SDH Module

• 130 or 131 - STM-1/4 Optical Interface

This setup procedure is based on STM-4 with 252 TU-12 payloads. The instrument generates a STM-4 signal with 252 TU-12 tributaries. The

tributaries are mapped into the STM-4 received signal and scanned by the Tributary Scan for bit errors and Pattern Sync Loss.

The Parallel printer port is enabled and the Tributary Scan results are logged to a Centronics printer

53

SDH Testing

Automatic Veriﬁcation of ADM Installation

TEST SET

ADM Installation

1. Connect the HP 37717C to the ADM and set up the display as shown

OTHER

opposite. Any changes made on the or

RECEIVE

display will affect the other.

TRANSMIT

2. Connect a Centronics printer to the HP 37717C Parallel printer port.

3. Set up the display as shown below.

TRANSMIT

SDH

The MAPPING and TU PAYLOAD selections should reﬂect the mapping and TU payload employed in the ADM

54

SDH Testing

Automatic Veriﬁcation of ADM Installation

4. Set up the TEST

TRANSMIT

FUNCTION display as shown opposite. The BIT ERROR THRESHOLD setting

has three choices:

- Any bit error will highlight the

> 0

tributary in error.

- Bit error rate greater than 1 in

>1E-6

106will highlight the tributary in error.

- Bit error rate greater than 1 in

>1E-3

103will highlight the tributary in error.

TEST TIMING determines the time taken to verify each tributary. If 10 seconds is selected, in this example 252 TU-12 tributaries, the test will take approximately 55 minutes.

Start the Test (ADM Installation)

1. Select on the

SDH TRIB SCAN

START

RESULTS

display.

The "ﬂashing" message on the status line indicates that the SDH Tributary Scan is active.

For STM-4 signals only one STM-1 is displayed at a time. To view the other STM-1’s select the required number 1, 2, 3 or 4 on the

RESULTS

SDH TRIB SCAN

display.

A PRBS is inserted in each tributary. If Pattern Synchronization is not achieved in 3 seconds the relevant tributary is highlighted. A Bit error measurement is performed in each tributary. The timing of the measurement is determined by the TEST TIMING selection made on the TEST FUNCTION display, in this

TRANSMIT

example 10 Seconds. If the Bit error rate exceeds the BIT ERROR THRESHOLD selected on the TEST FUNCTION display the relevant tributary is

TRANSMIT

highlighted.

55

SDH Testing

Automatic Veriﬁcation of ADM Installation

2. Set up the

OTHER

LOGGING

display as shown opposite. PRINTER TYPE allows selection of HP

printer or Alternative suppliers printer. If [ALT. PRINTER] is selected a choice of

NORMAL COMPRESS

(80 column) or

(40 column) is provided.

3. Set up the

OTHER

LOGGING

display as shown opposite. LOG ON DEMAND [TRIB SCAN]

ensures that the SDH Tributary Scan is logged to the Centronics printer when

PRINT NOW

is pressed.

At the end of the SDH Tributary Scan (the status line message is no longer "ﬂashing")

PRINT NOW

press to log the results of all four STM-1’s on the Centronics printer.

56

SDH Testing

Veriﬁcation of Protection Switching

Application

An important part of the installation process is the veriﬁcation of protection switching mechanisms. Switching veriﬁcation ensures that data integrity is maintained and revenue protected when equipment failure or ﬁbre cuts occur. Measuring the speed of the network elements protection switch mechanism ensures data loss is minimized. The protection switch can be invok ed by either removing the STM-n ﬁbre or using the network management system to make the switch.

The protection switch times can then be measured using the HP 37717C’s Service Disruption Time measurement. The measurement is made at the Path or Payload level carrying the actual service and therefore provides a real indication of the time the network takes to self heal.

Capability is also provided to inv oke protection switching at the Multiplex er Section level using the K1K2 byte textual decodes otherwise known as MSP Message Generation. Both Linear Architecture MSP Messages as described in ITU-T G.783 and Ring Architecture MSPRing Messages as described in ITU-T G.841 are provided.

Default (Known State) Settings

It can be advisable to set the HP 37717C to a known state prior to setting up to make a measurement. This clears all previous settings and provides a clearly deﬁned instrument state. The default settings are set by selecting

STORED SETTINGS

Test Setup Procedure (Veriﬁcation of Protection Switching)

The following Options must be ﬁtted to the HP 37717C to perform this test:

• UKJ or UKK - PDH Module

• A3R [A3S] - SDH Module

• 130 or 131 - STM-1/4 Optical Interface

This setup procedure is based on STM-1 with Structured PDH payload.

STORED SETTING NUMBER 0 and pressing .

OTHER

RECALL

57

SDH Testing

Veriﬁcation of Protection Switching

The instrument generates a STM-1 signal with a structured payload with PRBS pattern. This is inserted into the network element. The Receiver locks on to the PRBS pattern. The management system is used to invoke the protection switching. At the time of switching, pattern synchronization will be lost and will not be regained until the standby line is in place. The time interval between pattern sync loss and pattern sync gain is a measure of the disruption of service due to protection switching. This is measured by the HP 37717C.

TEST SET

Protection Switching Veriﬁcation

58

SDH Testing

Veriﬁcation of Protection Switching

1. Connect the HP 37717C to the ADM

and set up the display as shown

OTHER

opposite. Any changes made on the or

RECEIVE

2. Set up the display

display will affect the other.

TRANSMIT

SDH

as shown opposite.

3. Set up the

TRANSMIT

STRUCTURED PAYLOAD display as shown opposite.

59

SDH Testing

Veriﬁcation of Protection Switching

Start the Test (Protection Switch Veriﬁcation)

Press to start the test.

RUN/STOP

Check that pattern synchronization is achieved (no errors). Invoke the protection switch using the network management system. Set up the display as shown

RESULTS

opposite. The Service Disruption result is displayed

when pattern synchronization is regained. LONGEST - Longest burst of errors

during measurement. SHORTEST - Shortest burst of errors during measurement. LAST - Length of last burst of errors detected during measurement.

60

3

3 Result Deﬁnitions

Information about SDH resuilts.

Result Deﬁnitions

Trouble Scan

All possible error sources and alarms are scanned simultaneously. If an y error counts are not zero then these are displayed. Up to 4 non-zero error counts are displayed in priority order

Error Count Priority

UPDH (Option UKK[USB]

CRC BIT CODE FRAME REBE

SDH (Option A3R [A3S] SPDH

RS B1 BIP or B1 BIP MS B2 BIP or B2 BIP Path B3 BIP or B3 BIP VC3 PATH BIP TU2 BIP TU12 BIP A1A2 FRAME MS FEBE or MS REI PATH FEBE or HP REI PATH IEC or HP IEC VC3 PATH FEBE or HP REI TU2 FEBE or LP REI TU12 FEBE or LP REI BIT

(Option UKJ[USA] )

CRC BIT CODE FAS 140M FAS 34M FAS 8M FAS 2M REBE

ATM (Option UKN) + SDH

B1 BIP (SDH only) B2 BIP (SDH only) B3 BIP (SDH only) Non Corrected HEC Corrected HEC Lost Cells Misinserted Cells Path FEBE or REI Bit Errored Cells

If any alarms are active "ALARMS ACTIVE" is displayed.

SHOW HISTORY

and the alarm led’s can be used to determine which alarms are

active. If no alarms are active and no non-zero error counts are detected then "NO

TROUBLE" is displayed.

Error Summary

ATM (Option UKN) + SPDH

EM BIP Non Corrected HEC Corrected HEC Lost Cells Misinserted Cells EM FEBE Bit Errored Cells

A summary of the short term / cumulative results as counts or ratios and optical power on one display.

62

Result Deﬁnitions

Short Term Results

Displays period results obtained during the measurement. The period is user-deﬁned under SHORT TERM PERIOD on the display. Many result parameters are presented in two forms: a count of error events (EC or COUNT) and a ratio of the number of errors to the total possible in the time period (ER or RATIO).

Error Count and Error Ratio results for the following error sources are available: A1A2 FRAME Compares the received Framing bytes with the known value.

(Option A1T[A1U] only)

B1 BIP Compares the received B1 with the recalculated value. B2 BIP Compares the received B2 with the recalculated value. MS-REI Calculated from the REI bits in the received M1 overhead byte.

(Option A1T[A1U] only)

B3 BIP Compares the received B3 with the recalculated value. HP-REI Calculated from the REI bits in the received G1 overhead byte. HP-IEC Calculated from the IEC bits in the received Z5 Path overhead

byte. (Option A1T[A1U] only)

RESULTS

If a Payload of 34 Mb/s is selected, Error Count and Error Ratio results for the following additional error sources are also available:

TU BIP Compares the received VC3, B3 with the recalculated value. LP-REI Calculated from the FEBE bits in the received VC3, G1 over-

head byte.

If a Payload of 2 Mb/s is selected, Error Count and Error Ratio results for the following additional error sources are also available:

TU BIP Compares the received V5, BIP-2 in the TU12 selected for test

with the recalculated value.

LP-REI Calculated from the FEBE bits in the V5 overhead byte of the

TU12 selected for test.

63

Result Deﬁnitions

Cumulative Results

Provides a cumulative display of the results during the measurement period. Many result parameters are presented in two forms: a count of error events (EC or COUNT) and a ratio of the number of errors to the total possible in the time period (ER or RATIO).

Error Count and Error Ratio results for the following error sources are available: A1A2 FRAME Compares the received Framing bytes with the known value.

(Option A1T[A1U] only)

B1 BIP Compares the received B1 with the recalculated value. B2 BIP Compares the received B2 with the recalculated value. MS-REI Calculated from the REI bits in the received M1 overhead byte.

(Option A1T[A1U] only)

B3 BIP Compares the received B3 with the recalculated value. HP-REI Calculated from the REI bits in the received G1 overhead byte. HP-IEC Calculated from the PIEC bits in the received Z5 Path ov erhead

byte. (Option A1T[A1U] only)

If a Payload of 34 Mb/s is selected, Error Count and Error Ratio results for the following additional error sources are also available:

TU BIP Compares the received VC3, B3 with the recalculated value. LP-REI Calculated from the FEBE bits in the received VC3, G1 over-

head byte.

If a Payload of 2 Mb/s is selected, Error Count and Error Ratio results for the following additional error sources are also available:

TU BIP Compares the received V5, BIP-2 in the TU12 selected for test

with the recalculated value.

LP-REI Calculated from the FEBE bits in the V5 overhead byte of the

TU12 selected for test.

64

Result Deﬁnitions

SDH Error Analysis

Analysis results are calculated for the following error sources: B1 BIP; B2 BIP; MS-REI; B3 BIP; HP-REI and HP-IEC. If a Payload of 34 Mb/s

or 2 Mb/s is selected additional error sources of TU BIP and LP-REI are also available.

G.826 Analysis B1 BIP

These calculations are based on "Errored Blocks". A Block is a set of consecutive bits associated with the Path. Each bit belongs to one and only one block. If an STM-4 interface is selected an errored block is a BIP with one or more bits in error .

Table 3-1 G.826 Analysis B1 BIP

Display Deﬁnition

ES Errored Seconds - Cumulative count of 1 second periods that contain at least 1 Errored

Block. EB Errored Block count - cumulative count of errored blocks. SES Severely errored Seconds - Cumulative count of 1 second periods with >= 2400 Errored

Blocks, or containing a "defect". Defects are LOS and LOF. UNAV Unavailability - Cumulative count of unavailab le seconds. A period of unav ailability begins

at the start of 10 or more consecutive severely errored seconds, and ends at the start of

10 or more consecutive non severely errored seconds. ESR Error Second Ratio - The ratio of errored seconds to the total seconds of available time. A

period of unavailability begins at the start of 10 or more consecutive Severely Errored

Seconds, and ends at the start of 10 or more non Severely Errored Seconds. SESR Severely Errored Second Ratio - The ratio of severely errored seconds to the total

seconds of available time. BBEC Background Block error count - Cumulative count of errored blocks which occur outwith a

severely errored second. BBER Background Block error Ratio - The ratio of errored blocks to total blocks.Total blocks

excludes severely errored seconds and periods of unavailability.

65

Result Deﬁnitions

SDH Error Analysis

G.826 Analysis B2 BIP

These calculations are based on "Errored Blocks". A Block is a set of consecutive bits associated with the Path. Each bit belongs to one and only one block. If an STM-4 interface is selected an errored block is a BIP with one or more bits in error .

Table 3-2 G.826 Analysis MS B2 BIP

Display Deﬁnition

ES Errored Seconds - Cumulative count of 1 second periods that contain at least 1 Errored

EB Errored Block count - cumulative count of errored blocks. SES Severely errored Seconds - Cumulative count of 1 second periods with >= 2400 Errored

UNAV Unavailability - Cumulative count of unavailab le seconds. A period of unav ailability begins

ESR Error Second Ratio - The ratio of errored seconds to the total seconds of available time. A

SESR Severely Errored Second Ratio - The ratio of severely errored seconds to the total

BBEC Background Block error count - Cumulative count of errored blocks which occur outwith a

BBER Background Block error Ratio - The ratio of errored blocks to total blocks.Total blocks

Block.

Blocks, or containing a "defect". Defects are LOS, LOF and MS-AIS.

at the start of 10 or more consecutive severely errored seconds, and ends at the start of 10 or more consecutive non severely errored seconds.

period of unavailability begins at the start of 10 or more consecutive Severely Errored Seconds, and ends at the start of 10 or more non Severely Errored Seconds.

seconds of available time.

severely errored second.

excludes severely errored seconds and periods of unavailability.

66

Result Deﬁnitions

SDH Error Analysis

G.826 Analysis MS-REI

These calculations are based on "Errored Blocks". A Block is a set of consecutive bits associated with the Path. Each bit belongs to one and only one block. If an STM-4 interface is selected an errored block is a REI with one or more bits in error .

Table 3-3 G.826 Analysis MS-REI

Display Deﬁnition

ES Errored Seconds - Cumulative count of 1 second periods that contain at least 1 Errored

EB Errored Block count - cumulative count of errored blocks. SES Severely errored Seconds - Cumulative count of 1 second periods with >= 2400 Errored

UNAV Unavailability - Cumulative count of unavailab le seconds. A period of unav ailability begins

ESR Error Second Ratio - The ratio of errored seconds to the total seconds of available time. A

SESR Severely Errored Second Ratio - The ratio of severely errored seconds to the total

BBEC Background Block error count - Cumulative count of errored blocks which occur outwith a

BBER Background Block error Ratio - The ratio of errored blocks to total blocks.Total blocks

Block.

Blocks, or MS-RDI.

at the start of 10 or more consecutive severely errored seconds, and ends at the start of

10 or more consecutive non severely errored seconds.

period of unavailability begins at the start of 10 or more consecutive Severely Errored

Seconds, and ends at the start of 10 or more non Severely Errored Seconds.

seconds of available time.

severely errored second.

excludes severely errored seconds and periods of unavailability.

NOTE Near End Failures of LOS, LOF and MS-AIS produce "dead time" in the MS-REI

measurement such that result accumulation is suspended.

67

Result Deﬁnitions

SDH Error Analysis

G.826 B3 BIP Analysis

These calculations are based on "Errored Blocks". A Block is a set of consecutive bits associated with the Path. Each bit belongs to one and only one block.

Table 3-4 G.826 Analysis B3 BIP

Display Deﬁnition

ES Errored Seconds - Cumulative count of 1 second periods that contain at least 1 Errored

EB Errored Block count - cumulative count of errored blocks. SES Severely errored Seconds - Cumulative count of 1 second periods with >= 2400 Errored

UNAV Unavailability - Cumulative count of unavailab le seconds. A period of unav ailability begins

ESR Error Second Ratio - The ratio of errored seconds to the total seconds of available time. A

SESR Severely Errored Second Ratio - The ratio of severely errored seconds to the total

BBEC Background Block error count - Cumulative count of errored blocks which occur outwith a

BBER Background Block error Ratio - The ratio of errored blocks to total blocks.Total blocks

PUAS Path Unavailable Second count - Logical OR of the Near and Far end unavailable

Block.

Blocks, or containing a "defect". Defects are LOS, LOF, MS-AIS, LOP and AU-AIS.

at the start of 10 or more consecutive severely errored seconds, and ends at the start of 10 or more consecutive non severely errored seconds.

period of unavailability begins at the start of 10 or more consecutive Severely Errored Seconds, and ends at the start of 10 or more non Severely Errored Seconds.

seconds of available time.

severely errored second.

excludes severely errored seconds and periods of unavailability.

seconds.

68

Result Deﬁnitions

SDH Error Analysis

G.826 HP-REI Analysis

These calculations are based on "Errored Blocks". A Block is a set of consecutive bits associated with the Path. Each bit belongs to one and only one block.

Table 3-5 G.826 Analysis HP-REI

Display Deﬁnition

ES Errored Seconds - Cumulative count of 1 second periods that contain at least 1 Errored

EB Errored Block count - cumulative count of errored blocks. SES Severely errored Seconds - Cumulative count of 1 second periods with >= 2400 Errored

UNAV Unavailability - Cumulative count of unavailab le seconds. A period of unav ailability begins

ESR Error Second Ratio - The ratio of errored seconds to the total seconds of available time. A

SESR Severely Errored Second Ratio - The ratio of severely errored seconds tot he total

BBEC Background Block error count - Cumulative count of errored blocks which occur outwith a

BBER Background Block error Ratio - The ratio of errored blocks to total blocks.Total blocks

PUAS Path Unavailable Second count - Logical OR of the Near and Far end unavailable

Block.

Blocks, or HP-RDI.

at the start of 10 or more consecutive severely errored seconds, and ends at the start of

10 or more consecutive non severely errored seconds.

period of unavailability begins at the start of 10 or more consecutive Severely Errored

Seconds, and ends at the start of 10 or more non Severely Errored Seconds.

seconds of available time.

severely errored second.

excludes severely errored seconds and periods of unavailability.

seconds.

NOTE Near End Failures of LOS, LOF, MS-AIS, AU-LOP and AU-AIS produce "dead

time" in the HP-REI measurement such that result accumulation is suspended.

69

Result Deﬁnitions

SDH Error Analysis

G.826 HP-IEC Analysis

These calculations are based on "Errored Blocks". A Block is a set of consecutive bits associated with the Path. Each bit belongs to one and only one block.

Table 3-6 G.826 Analysis HP-IEC