Agilent 37717C PDH Concept Guide

HP 37717C Communications Performance Analyzer

PDH 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. 37717-90407

First edition, March 98

Printed in U.K.

Documentation 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 merchantability 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 Telecommunications Networks Test Division South Queensferry West Lothian, Scotland EH30 9TG

PDH Concept Guide

HP 37717C Communications Performance Analyzer

About This Book

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

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

• Measurement examples.

• Measurement result deﬁnitions

• Logging messages

Contents

1 Introduction to PDH Testing

Introduction to PDH / DSn 2 Unstructured PDH Generation and Measurement. Option UKK (USB) 3 Structured PDH Generation and Measurement. Options UKJ (USA) and UKN (USE) 4 Binary Interfaces. Option UH3 (US7) 5 Multiple PDH Outputs. Option UHC (US6) 6 DS1, DS3, E1 and E3 Transmit and Receive Interfaces for PDH/DSn Payloads. Option 110 7

2 PDH / DSn Testing

Alarm Monitoring 10 Analysis of N x 64 kb/s 13 BERT Testing 17 Cross Multiplexer Testing 22 FAS Monitoring 28 Frequency Measurement 32 Frequency Offset Tolerance 35 Multiplexer Testing 39 Round Trip Delay 44 M.2100, M.2110, M.2120 Analysis 47

3 Result Deﬁnitions

Trouble Scan 52 Short Term Results 53

Contents

Cumulative Results 54 PDH Error Analysis G.821, G.826, M.2100, M.2110, M.2120 55 Alarm Seconds 70 Frequency Measurement 71

4 PDH Logging Messages

Logging Devices 74 Results Logging 75

Introduction to PDH / DSn page 2 Unstructured PDH Generation and Measurement. Option UKK (USB) page 3 Structured PDH Generation and Measurement. Options UKJ (USA) and UKN (USE) page 4 Binary Interfaces. Option UH3 (US7) page 5 Multiple PDH Outputs. Option UHC (US6) page 6 DS1, DS3, E1 and E3 Transmit and Receive Interfaces for PDH/DSn Payloads. Option 110

page 7

1 Introduction to PDH Testing

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

Introduction to PDH Testing

Introduction to PDH / DSn

The Plesiochronous Digital Hierarchy (PDH / DSn) is still the dominant technology in most existing telecommunications networks throughout the world, although it is being replaced in many networks by Synchronous Digital Hierarchy (SDH) or SONET networks. PDH / DSn networks were developed at a time when point-to-point transmission was the predominant network requirement. To support this requirement, the standard approach to network management and maintenance was to use manual distribution frames for access to individual signals. This is now considered out of date and consequently SDH / SONET is now the preferred network topology for new installations.

However PDH / DSn networks will exist for a long time to come even in networks where SDH /SONET is the preferred technology. PDH is the ETSI international standard, based on 2 Mb/s, deﬁned by the ITU-T, and covers the hierarchal transmission rates of 2 Mb/s, 8 Mb/s, 34 Mb/s and 140 Mb/s. DSn is the ANSI standard covering transmission rates of 1.544 Mb/s (DS1) and 44.736 Mb/s (DS3). PDH is asynchronous at 8 Mb/s, 34 Mb/s and 140 Mb/s. In order to access a signal, for rerouting or test purposes, the whole line signal structure must be demultiplexed step by step down to the 2 Mb/s level, because of the asynchronous nature of the multiplexing.

At each multiplexing step, the bit rate of the individual tributary signals is controlled within speciﬁed limits and is not synchronized with the multiplex equipment. Because the bit rates of the individual tributaries are controlled within speciﬁc limits this type of multiplexing is referred to as Plesiochronous i.e. nearly synchronous. The individual tributaries are synchronized with the equipment at each multiplex step by the process of positive bit stufﬁng justiﬁcation.

In new SDH / SONET networks, PDH / DSn signals are mapped into virtual containers / tributaries before being transported as part of the SDH / SONET payload. The SDH / SONET payload must then be demapped into a PDH / DSn tributary signal.

Therefore all PDH / DSn, SDH / SONET and mixed PDH/SDH DSn / SONET networks require test sets which have PDH / DSn interfaces and PDH / DSn test capability.

Introduction to PDH Testing

Unstructured PDH Generation and Measurement. Option UKK (USB)

Option UKK (USB), Unstructured PDH, provides generation and measurement of unstructured PDH at interface rates of 704 kb/s,

2.048 Mb/s, 8.448 Mb/s, 34.368 Mb/s and 139.264 Mb/s Allows the addition of Frequency Offset to the PDH signal Provides 75 Ω unbalanced or 120 Ω balanced input and output

interfaces. Allows selection of PRBS, WORD or USER patterns Allows selection of Line Code AMI, HDB3 or CMI Provides an ECL pulse each time an error occurs (Error Out)

Option UKK [USB]

Introduction to PDH Testing

Structured PDH Generation and Measurement. Options UKJ (USA) and UKN (USE)

Options UKJ (USA) and UKN (USE), provide generation and measurement of Structured or Unstructured PDH at interface rates of 2.048 Mb/s (E1),

8.448 Mb/s (E2), 34.368 Mb/s (E3) and 139.264 Mb/s (E4).

Structured test signal rates of 64 kb/s, 2.048 Mb/s, 8.448 Mb/s and 34.368 Mb/s are provided.

Frequency Offset can be added at the interface rates. Line rate frequency can be measured. Provides 75 Ω unbalanced or 120 Ω balanced input and

output interfaces. Allows selection of PRBS, WORD or USER patterns

Option UKJ (USA)

Allows selection of Line Code AMI, HDB3 or CMI Interface and test signal rates can be Framed or

Unframed MUX connector allows a 2 Mb/s signal from external

equipment to be inserted into the HP 37717C test signal.

DEMUX connector allows a 2 Mb/s signal from the HP 37717C to be Dropped to external equipment.

Option UKN (USE) also provides generation and measurement of PDH signals with ATM payloads.

Information on the ATM capabilities of the UKN (USE) module is given in the “Users Guide” and the “ATM Concept Guide”.

Introduction to PDH Testing

Binary Interfaces. Option UH3 (US7)

Option UH3 (US7) provides binary NRZ interfaces for the structured PDH module option UKJ (USA), and the unstructured PDH module option UKK (USB).

The interfaces can operate at any of the standard rates ± 100 ppm. When used with option UKK (USB), with an external binary clock input,

the interfaces can operate at any rate in the range 700 kb/s to 170 Mb/s.

TTL signal levels, at data and clock ports, and external clock port, are valid from 700 kb/s to 50 Mb/s, 75Ω to ground.

ECL signals, at data and clock ports, and external clock port, are valid from 700 kb/s to 170 Mb/s, 75Ω to -2V.

The external clock input may be used to clockcoded data from the PDH / DSn transmitter at standard rates. In addition if Option UKK (USB), Unstructured PDH, is ﬁtted can clock coded data in the range 700 kb/s to 170 Mb/s.

Option UH3 (US7)

Simultaneous jitter of binary clock and binary data outputs is possible (2, 8, 34 & 140 Mb/s) if Option UHK (USB) or A3K, Jitter Generator, is ﬁtted.

Jitter measurement on the binary clock input is possible (2, 8, 34 & 140 Mb/s ±;100 ppm) if Option UHN, A3L, A3V or A3N , Jitter Measurement, is ﬁtted.

Frequency measurement of the external clock input and binary clock input is provided.

Introduction to PDH Testing

Multiple PDH Outputs. Option UHC (US6)

Option UHC (US6), Multiple PDH Outputs, provides three additional 75Ω PDH outputs.

OUT 1 is delayed by 4 bits relative to the main PDH OUT. OUT 2 is delayed by 8 bits relative to the main PDH OUT. OUT 3 is delayed by 12 bits relative to the main PDH OUT.

Introduction to PDH Testing

DS1, DS3, E1 and E3 Transmit and Receive Interfaces for PDH/DSn Payloads. Option 110

DS1, DS3, E1 and E3 Transmit and Receive Interfaces for PDH/ DSn Payloads. Option 110

Option 110, provides generation and measurement of PDH /DSn signals at interface rates of: 1.544 Mb/s (DS1),

44.736 Mb/s (DS3), 2.048 Mb/s (E1), and 34.368 Mb/s (E3). Frequency Offset can be added at the interface rates. Line rate frequency can be measured. Provides the following RZ input and output interfaces:

DS3 and E3: 75 Ω unbalanced E1: 75 Ω unbalanced, 120 Ω balanced. DS1: 100 Ω balanced.

Allows selection of Line Code as: AMI or B8ZS at DS1 AMI or HDB3 at 2Mb/s. At DS3 the line code is ﬁxed at B3ZS. At 34 Mb/s the line code is ﬁxed at HDB3.

Provides Input sensitivity level selection. Provides output level control for DS1 and DS3.

DS1: DSX-1 or DS1-LO DS3: DS3-HI, DSX-3 or DS3-900’.

Allows errors and alarms to be injected into the test signal. An E1 Drop/Insert port allows an E1(2.048 Mb/s) signal to be

dropped/inserted from a E3 (34 Mb/s) signal. In conjunction with the SONET/SDH test module (option 120), this port allows the insertion of E1 into a TU-12/VT2.

A DS1 Drop/Insert port allows a DS1 signal to be dropped/ inserted from a DS3 or TU-11/VT1.5 when used in conjunction with the SONET/SDH test module.

Introduction to PDH Testing

DS1, DS3, E1 and E3 Transmit and Receive Interfaces for PDH/DSn Payloads. Option 110

Alarm Monitoring page 10 Analysis of N x 64 kb/s page 13 BERT Testing page 17 Cross Multiplexer Testing page 22 FAS Monitoring page 28 Frequency Measurement page 32 Frequency Offset Tolerance page 35 Multiplexer Testing page 39 Round Trip Delay page 44 M.2100, M.2110, M.2120 Analysis page 47

2 PDH / DSn Testing

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

PDH / DSn Testing

Alarm Monitoring

Options Required Structured PDH UKJ (USA), 110 or UKN (USE)

Application

Problems in the network at all levels in the hierarchy can be detected by the occurrence of alarms in each tributary of structured PDH systems.

Using the HP 37717C in a receive only mode, each tributary can be scanned and the state of Frame Loss, Remote (RAI) and AIS alarms viewed 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. Select , , set STORED SETTINGS NUMBER to 0 and ACTION to .

OTHER

STORED SETTINGS

RECALL

RESULTS

Test Setup Procedure (Alarm Monitoring)

This setup procedure is based on Structured PDH 140 Mb/s line trafﬁc interfaced at the line equipment 75 Ω protected Monitor point. If a protected Monitor Point is not available then an HP 15510A Protective Probe may be used at an unprotected Monitor point.

When 120 Ω Balanced alarm monitoring is desired at an unprotected Monitor point use an HP 15511A Protective Monitor Probe. The instrument is used in a receive only mode to monitor Frame Loss, AIS and Remote alarms.

PDH / DSn Testing

Alarm Monitoring

1 Connect the HP 37717C to the line

terminal equipment protected Monitor point and set up the display

MAIN SETTINGS

RECEIVE

as shown opposite.

The GAIN and EQUALIZER settings should be set to optimize the received signal.

2 Set up the display

STRUCTURED SETTINGS

RECEIVE

as shown

opposite.

2M PAYLOAD determines the Framing and selection which should match that of the network equipment.

PDH / DSn Testing

Alarm Monitoring

Start the Test (Alarm Monitoring)

1 Set up the display as shown

opposite and select

RESULTS

PDH ALM SCAN

If any of the three alarms, Frame Loss, RAI or AIS has occurred the appropriate point in the hierarchy will be highlighted.

The test can be halted at any time by selecting on the

PDH ALM SCAN

OFF

RESULTS

display.

2 T o determine which alarm has occurred

set the PDH ALM SCAN and then set the

STRUCTURED

RECEIVE

SETTINGS

OFF

display to the tributary highlighted as shown opposite and press .

RUN/STOP

Example 2Mb number 2 of 8Mb number 1 of 34 Mb number 1 is highlighted.

3 Now view the Alarm Seconds results

on the display to determine

RESULTS

which alarms have occurred.

PDH / DSn Testing

Analysis of N x 64 kb/s

Option Required Structured PDH UKJ (USA) or DS1,DS3,E1, E3 structured PDH 110

Application

Many customer premises receive subrate signals for example 128 Kb/s or 384 kb/s. The timeslots which make up these services may or may not be contiguous. Testing these services requires that the test set to be able to insert a pattern across the required timeslots.

T esting N x 64 kb/s channels structured within a 2 Mb/s signal can be carried out on an End to End basis using two test sets.

Default (Known State) Settings

OTHER

STORED SETTINGS

RECALL

Test Setup Procedure (N x 64 kb/s Analysis)

This setup procedure is interfaced at 2 Mb/s, with a test signal of 6 X 64 kb/s noncontiguous timeslots. A PRBS test pattern is transmitted across the 6 timeslots. A BER measurement is performed on the received test pattern.

PDH / DSn Testing

Analysis of N x 64 kb/s

HP 37717C #1

1. Set up the

CONTROL

OTHER

SETTINGS

display as shown opposite.

Any settings change made on the

or displays will

TRANSMIT

RECEIVE

automatically occur on the other.

2. Connect the HP 37717C to the line equipment and set up the

MAIN SETTINGS

TRANSMIT

display as shown

opposite. The settings of SIGNAL rate and LINE

CODE must match those of the network equipment.

PAYLOAD TYPE selects the Framing which must match that of the network equipment.

3. Set up the display

STRUCTURED SETTINGS

TRANSMIT

as shown

opposite. In this example timeslots 3, 5, 9, 25, 26

and 27 are selected.

PDH / DSn Testing

Analysis of N x 64 kb/s

4. Set up the display as shown

RESULTS

opposite. The RESULTS type may be changed

during the measurement without interrupting the test.

HP 37717C #2

1. Set up the

CONTROL

OTHER

display as shown opposite.

SETTINGS

Any settings change made on the

TRANSMIT

or displays will

RECEIVE

automatically occur on the other.

2. Set up the display

MAIN SETTINGS

RECEIVE

as shown opposite.

The settings of SIGNAL rate and LINE CODE must match those of the network equipment.

PAYLOAD TYPE selects the Framing which must match that of the network equipment.

PDH / DSn Testing

Analysis of N x 64 kb/s

3. Set up the

SETTINGS

RECEIVE

display as shown opposite.

STRUCTURED

In this example timeslots 3, 5, 9, 25, 26 and 27 are selected.

4. Set up the display as shown

RESULTS

opposite. The RESULTS type may be changed

during the measurement without interrupting the test.

Run the Test (N x 64 kb/s Analysis)

1. Press .

• The measurement results and alarms are available on the display

RUN/STOP

RESULTS

during the test period.

• The test can be halted at any time by pressing .

RUN/STOP

PDH / DSn Testing

BERT Testing

Options Required Structured PDH UKJ (USA), DS1,DS3,E1, E3 structured PDH 110 or Unstructured PDH UKK (USB)

Application

A transmission system must be speciﬁed for its overall error performance, measured over a period of time. Conformance to these speciﬁcations ensures that an installed system will meet the requirements of an Integrated Digital Network (IDN).

After troubleshooting, or during installation or commissioning, it is necessary to check that the transmission link meets this error performance.

This can be performed in two ways:

• End T o End - Error performance measurements are made on an end-to-end basis

testing the Go and Return paths separately but simultaneously . The measurements are often performed unattended and the results and other events, alarms for example, logged on a printer or disc and timed by a real time clock facility.

Two HP 37717C's are required for this measurement, one at each end of the link.

End-to End Test

PDH / DSn Testing

BERT Testing

• Loopback - Error performance measurements are made via a loopback at the

remote end of the system testing the combined Go and Return paths. The measurements are often performed unattended and the results and other events, alarms for example, logged on a printer or disc and timed by a real time clock.

Loopback Test

Default (Known State) Settings

OTHER

NUMBER to 0 and ACTION to .

STORED SETTINGS

RECALL

Test Setup Procedure (BERT Testing)

This setup procedure is based on 140 Mb/s, CMI, PRBS test data terminated in 75Ω . A SINGLE test period of 24 HOURS is used and use of the a printer or disc for recording of results and alarms is included. A graphical record of the results can be viewed on the HP 37717C display at the end of the test period.

GRAPH

PDH / DSn Testing

BERT Testing

1. Set up the

CONTROL

OTHER

display as shown opposite

SETTINGS

(on both HP 37717C's if end to end). Any settings change made on the

or displays will

TRANSMIT

RECEIVE

automatically occur on the other.

2. Connect the HP 37717C to the line equipment and set up the

TRANSMIT

display as shown opposite (on both HP 37717C's if end to end).

3. Select the function as

LOGGING

shown opposite (on both HP 37717C's if end to end).

A LOGGING PERIOD selection of [USER PROGRAM] [10 MIN] provides the following:

A complete set of period and a complete set of cumulative results logged on the printer or disc every 10 minutes.

A complete set of cumulative results logged on the printer or to disc at the end of the test period.

PDH / DSn Testing

BERT Testing

4. Set the

TIMING CONTROL

RESULTS

as shown opposite

(on both HP 37717C's if end to end).

5. Select the

ERROR ANALYSIS

RESULTS

PDH RESULTS

display

The RESULTS type displayed can be changed during the test period without interrupting the test.

The RESULTS

TIMING CONTROL

STORAGE selection enables the graphics. To disable graphics select STORAGE [OFF].

Start the Test (BERT Testing)

1. Press (on both HP 37717C's if end to end). The measurement results and alarms are available on the display during

RUN/STOP

RESULTS

the test period. The graphical measurement results and alarms are stored in non volatile memory for

viewing later on the display. The test can be halted at any time by pressing .

GRAPH

RUN/STOP

At the End of the Test (BERT Testing)

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

selected logging device.

• All results are logged on the selected logging device at 10 minute intervals.

• Any alarms which occur during the test period will be logged on a printer or disc.

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

the printer or disc.

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

PDH / DSn Testing

BERT Testing

GRAPH

display. If Remote Control option A3B or A3D is ﬁtted the graph results

can be logged to an external 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. If GRAPH STORAGE RESOLUTION [FULL] is selected on the display

OTHER

MISCELLANEOUS

the capacity reduces to 10,000 events. The resolution, determined by the selection made under STORAGE on the

RESULTS

TIMING CONTROL

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

TIMING CONTROL

PDH / DSn Testing

Cross Multiplexer Testing

Option Required Structured PDH UKJ (USA), DS1, DS3, E1, E3 structured PDH 110

Application

For comprehensive testing of network equipment it is essential that the test equipment can multiplex/demultiplex the test signal.

The insertion of tributary signals into the PDH multiplexer, which are then multiplexed into the 140 Mb/s PDH structure should take place without introducing errors. The insertion and structuring process is tested by adding a test pattern to the tributary inserted at the tributary insert port. At the high rate side of the PDH multiplexer the tributary is destructured and a BER test performed.

By using a protected monitor point at the high rate side of the PDH multiplexer the mux/demux need not be taken out of service.

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. Select , , set STORED SETTINGS NUMBER to 0 and ACTION to .

Cross Multiplexer Testing Test Setup Procedure

In this setup a 2 Mb/s Framed tributary, containing a test pattern, is inserted at the tributary insert port of the PDH multiplexer. The 140 Mb/s structured PDH signal is obtained from a protected monitor point. The 2 Mb/s tributary is destructured by the HP 37717C test set and an Error measurement is performed on the 2 Mb/s tributary test pattern.

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

The HP 37717C PDH/SDH test set GRAPHICS function is enabled. The graphical results can be viewed on the display.

OTHER

STORED SETTINGS

RECALL

GRAPH

PDH / DSn Testing

Cross Multiplexer Testing

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

SETTINGS CONTROL

OTHER

display as shown

opposite.

+ 67 hidden pages

Agilent 37717C PDH Concept Guide

Specifications and Main Features

Frequently Asked Questions

User Manual

1 Introduction to PDH Testing

Introduction to PDH / DSn

Binary Interfaces. Option UH3 (US7)

Multiple PDH Outputs. Option UHC (US6)

2 PDH / DSn Testing

Alarm Monitoring

Application

Default (Known State) Settings

Test Setup Procedure (Alarm Monitoring)

Start the Test (Alarm Monitoring)

Analysis of N x 64 kb/s

Application

Default (Known State) Settings

Test Setup Procedure (N x 64 kb/s Analysis)

Run the Test (N x 64 kb/s Analysis)

BERT Testing

Application

Default (Known State) Settings

Test Setup Procedure (BERT Testing)

Start the Test (BERT Testing)

At the End of the Test (BERT Testing)

Cross Multiplexer Testing

Application

Default (Known State) Settings

Cross Multiplexer Testing Test Setup Procedure