Testing 1 - AXE Access 910 Configuration and Verification

1AXE System Testing 1 AXE Access 910 Configuration & Verification

Access: PSTN, ISDN, ADSL, and HDSLSubscriber Switching Subsystem

AXE Access 910

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3Table of Contents

1. Introduction 7

1.1Chapter Introduction 71.2AXE Access 910 71.3Ericsson Access 910 71.4This is a training document 71.5Introduction to Access Nodes 8

2.System Overview 15

2.1Chapter Introduction 152.2AXE and Ericsson Access 910 15

2.3EMG Concept 162.4Main Hardware Structure 162.5Survey of Access Units 182.6Connection of ISDN-PRA 192.7AUS, Access Unit Switch 19

2.8AUS Network 212.9Software Introduction 232.10Set of Parts, CRT level 232.11Multiple Access Unit Switch, MAUS 242.12Test Unit (TAU) 262.13Equipment in the Local Exchange 27

3.Hardware Structure 29

3.1Chapter Introduction 293.2BYB 501 in Access 910 293.3Subracks in AXE Access 910 323.4Cabinets 353.5Cabling Inside Access 910 38

4.The V5 Interfaces 43

4.1Chapter Introduction 434.2Survey 434.3The V5 Interface in AXE Access 910 444.4C-channel Concentration, CCC 454.5Signalling within V5.1 45

AXE Access 910

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5.Definition of MACCG 49

5.1Chapter Introduction 495.2Concepts 495.3Definition of Equipment in the Local Exchange 505.4Definition of a MACCG 53

6. PSTN Access 59

6.1Chapter Introduction 596.2Description 596.3Hardware 616.4Software 636.5Operation 656.6Maintenance 67

7.ISDN Basic Rate Access 69

7.1Chapter Introduction 697.2Description 69

7.3ISDN BA Access 717.4BA IMPLEMENTATION 737.5Hardware 767.6Software 777.7Operation 787.8Maintenance 80

8.ISDN PRA Access 81

8.1Chapter Introduction 818.2Introduction to ISDN-PRA 818.3Connection to AXE Access 910 828.4Group Switch connected PRA (GS-PRA): 858.5PRA Maintenance 90

9. External V5 91

9.1Chapter Introduction 919.2V5-GS 919.3V5 on Access 910 969.4Hardware 989.5Maintenance 989.6V5 Commands 98

510.ADSL Access 101


11.HDSL Access 103


12. TAU 105


13.Subscriber Line Maintenance 111

13.1Chapter Introduction 11113.2Subscriber Line Maintenance 11113.3Tests on Subscriber Lines 11213.4ISDN Accesses Supervision and Statistics 11313.5Stand Alone Function, SAF 124

AXE Access 910

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71. Introduction

1.1 Chapter IntroductionThis chapter will give you an a description of the scope of this document as well as some general information about access nodes in a modern network.

1.2 AXE Access 910AXE Access 910 is the name of the new access system from Ericsson for connection to the AXE local exchange. As the name reflects, it has to be connected to an AXE exchange.

1.3 Ericsson Access 910Ericsson Access 910 is the name of the access system that may be connected to any type of local exchange. The only requirement is that the local exchange can handle the ETSI interface V5.2.

1.4 This is a training documentPlease note that this is a training document and not a formal description of the system. Therefore, it may include simplifications of the system. Implementation details may also change while this book is being written. For accurate information about the system, please consult the official system descriptions.

After completing this chapter, you will be able to: describe the differences between Ericsson and AXE Access 910 describe the general functions of an access node account for the different interfaces available in AXE Access 910.

Chapter Objectives

AXE Access 910

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1.5 Introduction to Access Nodes

1.5.1 The Subsystem SSSThe AXE system contains, among other things, functions for different accesses and services related to these accesses.

The Subscriber Switching Subsystem, SSS, provides the interface between the subscribers in a fixed network and the rest of the functions in an exchange. The SSS contains hardware and software to handle normal telephony, ISDN subscriber access as well as broadband access such as HDSL and ADSL. Only exchanges with subscribers have an SSS; an international or a transit exchange would not normally have an SSS.

The access for the subscribers are implemented in AXE by two different subsystems:

Subscriber Switching Subsystem (SSS) - providing the interface between the subscriber and the rest of the exchange

Subscriber Control Subsystem (SCS) - coordinating traffic functions between SSS and the Traffic Control Subsystem (TCS) as well as providing access to supplementary services.

This description will in primary describe the subsystem SSS.

1.5.2 Functions in SSSThe Subscriber Switching Subsystem contains the following main func-tions:

Access - connection of the 2-wire copper cables originating from the subscribers

AD / DA conversion - Analogue to Digital conversion of the PSTN subscriber

Switching - establish connections to other subscribers or to lines to the local exchange/group switch

Subscriber line signalling - tone sending and reception of digits Power feed of the subscriber line Concentration of traffic Maintenance of both access equipment as well as subscriber lines

Introduction

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Figure 1.1Switching in SSS

The subscribers speech or data can be either switched internally within the subscriber switch or directed towards the group switch. The switching functions in SSS is handled by the time switch unit.

One effect of the switching function is that the number of subscriber lines can be larger than the number of speech connections to the group switch. This is the normal circumstance in a live exchange as all subscribers connected to the SSS do not generate traffic at the same time.

The E1 (European multiplexing level of the first order) links between the subscriber switch and the group switch is a 2048 kbit/s flow, built up by a frame of 32 time slots. The E1 links are some times called System Lines or PCM lines. The European standard is used in the major part of the word, but in North America and Japan, a 24 time slot frame and one frame align-ment bit forms a 1544 kbit/s flow, then called a T1.

SSS GSS

GSSSSS

Group Switching SubsystemSubscriber Switching Subsystem

TimeSwitch

InternalPCMSystem

ExternalPCMSystem

Pulse Code ModulationPCM

AXE Access 910

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Figure 1.2Multiplexing level of the first order

Figure 1.3Concentration in SSS

SSS concentrates the number of lines, and also the traffic, in the access node. The concentration ratio is dependent of the traffic generated by the subscribers and the Erlang loss formula has to be used to do a proper dimensioning. Figure 1.3 shows an access node and the concentration done from a large number of subscriber lines to a limited number of digital channels towards the local exchange and the group switch.

32 time slots x 8 bits x 8000 = 2048 kbit/s

American PCM frame

(24 time slots x 8 bits + 1 bit) x 8000 = 1544 kbit/s

125 us

European PCM frame

SSS

GSS,Max 3000PSTNSubscribers

Min. 2, and upto max 36E1 Links (2.048 Mbit/s)

1

3000

GroupSwitch

AccessNode

Introduction

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1.5.3 Remote Access NodesAccess nodes are in most cases located remote. This means that they are broken loose from the local exchange and located far away. The reasons for doing this are many:

One access node may replace a small rural exchange with some thousand subscribers.

The access nodes may be located closer to subscribers to shorten subscriber lines and making the access network less costly from a maintenance point of view.

The access nodes may be located in an area with analogue exchanges to provide modern services to some subscriber groups (e.g. business subscribers).

In most networks, the majority of all access nodes will be located remotely. Some networks will have up to 80% of all access nodes remote. Figure 1.4 shows how the access nodes can be remotely or centrally located.

Figure 1.4Centrally and remotely located access nodes

If the access node is located remotely, the distance between the local exchange and the access node can be quite long. As ordinary transmission systems are used, the distance is in practice unlimited.

1.5.4 Access TypesA modern access node must be capable of connecting all types of access types. This is important as the operator of the network does not know in advance the mixture of access types in a given area. It must be possible to change access types from ordinary access (PSTN) to, for example, ISDN without changing access node.

Figure 1.5 shows a survey of all the different variants of accesses supported by AXE Access 910 and the AXE switch. Please note that this book also covers access connected directly to the Group Switch in AXE.

Suburb

VillageLocal

Exchange

Gro

up

Sw

itch

CP

AXE Access 910

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These accesses are not physically connected to AXE Access 910 but handle by the subsystem SSS.

Figure 1.5Access overview

PSTN, Public Switched Telephone NetworkThe traditional interface to a telephone exchange based upon the 2-wire copper cable (in most cases).

ISDN-BA, Integrated Services Digital Network - Basic AccessA digital interface giving the subscriber 2 x 64 kbit/s as well as a 16 kbit/s channel. Mainly used for private persons and small business subscribers.

ISDN-PRA, Integrated Services Digital Network - Primary Rate AccessA digital interface for Private Automatic Branch Exchanges based upon a digital 2.048 Mbit/s interface.

HDSL, High-speed Digital Subscriber LineA standard making it possible to have digital communication up to 2.048 Mbit/s over a twisted pair cable (2-wire copper cable). For example, HDSL can be used to connect the Mini version of AXE Access 910 for outdoor usage.

ADSL, Asymmetrical Digital Subscriber LineA standard making it possible to have digital communication up to 8 Mbit/s over a twisted pair cable (2-wire copper cable).

PSTN

GSS,GroupSwitch

ISDN-BA

ISDN-PRA (V3)

HDSL

PABX

NT

A910

ADSL

V5.1

V5.2

Mini

NT

?

?

ETC

ETC

ETC

ISDN-PRA (V3)

V5.1

V5.2

ETC

ETC

AXE Core part

AXEAccess

910

Introduction

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V5.1, ETSI interface for multiplexersAn ETSI standard for connecting multiplexers over a standard 2.048 Mbit/s digital line. The equipment connected via V5.1 does not concentrate the traffic but acts as a multiplexer. Any type of access equipment supporting ETSI V5.1 can be connected (that is why there is a ? in the figure).

V5.2, ETSI interface for concentratorsAn ETSI standard for connecting concentrators concentrating from several thousand of subscribers to maximum 16 digital 2.048 Mbit/s links. Any type of access equipment supporting ETSI V5.2 can be connected (that is why there is a ? in the figure).

AXE Access 910

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2. System Overview

2.1 Chapter IntroductionThis chapter will give you an overview of AXE Access 910. Basic concepts and the main structure of the system will be explained as well as some points about access nodes in general. By reading this chapter, you will get a general picture of the different parts of AXE Access 910 and its functions.

2.2 AXE and Ericsson Access 910Ericsson develops two variants of the access system Access 910. One variant, referred to as AXE Access 910, can only be connected to AXE exchanges. One can say that AXE Access 910 replaces the existing SSS/RSS as some proprietary interfaces are kept. The other variant, the Ericsson Access 910, can be connected to any suppliers local exchange as long as it supports the standard interface V5.2. More about the V5 interface later on in the book.

At the same time, both indoor and outdoor versions of these two variants are developed in different sizes. Figure 2.1 shows the variants developed and how they relate to each other.

The main difference between Ericsson Access 910 and AXE Access 910 is software and operation & maintenance. The basic hardware structure described in this document applies for both variants except for some few printed circuit boards in one of the subracks.

After completing this chapter, you will be able to: Describe the general system structure of AXE Access 910 Describe how the different parts of the system co-operate State the units used in the system and understand their basic

functions.

Chapter Objectives

AXE Access 910

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Figure 2.1Relationship between AXE and Ericsson Access 910

From a hardware point-of-view, the difference between AXE and Ericsson Access 910 is one single board. The differences between the in-door and out-door version is the mechanics surrounding the subracks.

2.3 EMG ConceptOne of the requirements of SSS is that the size of the subscriber switch must be variable. Therefore the whole subscriber switch has been divided into modules. These modules are called Extension Module Groups (EMGs). The number of EMGs connected to the exchange depends on the number of subscribers and type of accesses. When the exchange is installed, or extended by more EMGs, the EMGs are given names that reflect their location.The EMGs are connected to the group switch by means of E1 links. The EMG is a concept for the control part in AXE, APZ. The EMG also has to be defined as an access group for the switching part APT, and is therefore, regarded as a MACCG (Multiple ACCess Group).

2.4 Main Hardware Structure

2.4.1 Access Unit and Access Unit SwitchThe hardware structure of AXE Access 910 is very simple compared with previous version of access systems. There are less board types, and more functions are put on each printed board assembly (PBA). The mechanics, which will be explained in chapter 3, is based upon the state-of-the-art building practice BYB 501.

Figure 2.2 shows a slightly simplified hardware structure of AXE Access 910.

AXE Access 910 Ericsson Access 910

In-door

Out-door

AXE management Separate managementsystem (UNIX based)

xDSL

MiniMidiMaxi

MiniMidiMaxi

This document

xDSL management

System Overview

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Figure 2.2The main hardware structure of AXE Access 910

The Access Units (AU) are line boards, Line Interface Boards in the context of SSS5. The AUs differ in size and capacity. Different access units are used to deliver different types of services (e.g. POTS, ISDN-BA, HDSL or ADSL). For test of both the AUs and the subscriber lines, there is a test unit referred to as TAU. TAU stands for Test, Maintenance and Administration Unit. The number of subscribers per TAU is determined by the intensity of subscriber line test.

The Access Unit Switch (AUS) is the common parts assembled in one single board. The AUS contains a time switch, keyset code receivers, tone senders, and a processor. Several AUs are connected to one AUS by means of standard 2 Mbit/s lines. The AUS concentrates the traffic to a few 2 Mbit/s lines towards the local exchange.

In the local exchange, the 2 Mbit/s lines are connected via ETCs, Exchange Terminal Circuits, to the group switch. For communicating with the AXE Access 910, a number of RPGs are needed. RPG stands for regional processor with group switch interface.

2.4.2 The AUS NetworkAll the AUSs in one access node are connected to each other. Please study Figure 2.3.

AU

AU

TAURPG

AU

AU

TAU

ETC

CP-A CP-B

ETC

ETC

ETC

RPG

RPRP

AU

2 Mbit/s

AUS

AU

TAURPG

AU

AUS

AU

TAU

ETC

CP-A CP-B

ETC

ETC

ETC

RPG

GS

RPRPRPB

ISDN-PRA

AU

SDH (155 Mbit/s)

ET

AXE Access 910 AXE core part

ISDN-BA

ADSL

PSTN

AXE Access 910

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Figure 2.3AUS in one access node, and the AUS network

Figure 2.3 shows a number of AUSs in one access node. From each AUS, there are 1-6 lines of 2 Mbit/s going to the local exchange. The AUS network, which is further explained in section 2.8 on page 21, is used for EMRP communication and for the internal and overflow traffic within the access node. The AUS network is also based on standard 2 Mbit/s links.

2.5 Survey of Access UnitsThe general term access unit is used to denote all types of accesses that can be used in AXE Access 910. Different access units will be developed for different types of narrowband and broadband applications. Today, there are two main variants for narrowband:

Two different access unit for PSTN access- LIC30 based upon standard SLIC circuits with or without 12/

16 kHz private meter pulse sending- ALB30 with high functionality requested on some markets

only

An access unit for ISDN-BA access (2B+D).

As broadband is included in AXE Access 910, there will be special line boards for this type of access as well:

An access unit for HDSL, high-speed digital subscriber line An access unit for ADSL, asymmetrical digital subscriber line

ISDN PRA, primary rate access, can also be connected to the AXE Access 910 system. However, it is connected directly to the AUS without using any specific access unit.

AUAUS

AU

AUAUS

AU

AUAUS

AU

To Local Exchange

AUS Network

System Overview

19

All existing narrowband access units have some common parts. Figure 2.4 shows a block diagram valid for all types of narrowband access units.

Figure 2.4Block diagram for an Access Unit, AU (narrowband)

2.6 Connection of ISDN-PRAEach AUS, Access Unit Switch, contains a large number of ET circuits for connection of 2 Mbit/s E1 links. Instead of connecting an AU board, the ET circuit can connect an ISDN PRA connection. The PRA connection is made via a standard E1 link of 2 Mbit/s. The functionality will be in accordance with the ETSI standard. Please study Figure 2.5.

Figure 2.5Connection of ISDN Primary Rate Access

2.7 AUS, Access Unit SwitchThe AUS is, as already mentioned, the central unit in the access node. The unit performs the switching functions and concentrates the traffic to the local exchange. Common telephony functions like digit reception of

-48V

LineInterface

NetworkTerminal

AU Control(processor)

Power

Speech

Data

V5.1

AUS2 Mbit/s

PABX

ET ET

ET

ET

ET

AU AUS

ISDN-PRA

DDF

ET ET

ET

ET

ET

MDF

2.048 Mbit/s

AXE Access 910

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DTMF signals and tone sending are also performed by the AUS. The unit performs the following functions:

Synchronisation of the local time switch (slave to the group switch in the local exchange)

Switching of speech samples in a 1K time switch Attenuation of speech samples Transmission of tones to subscribers (e.g. dial tone) Reception of DTMF signals (digits from push-button telephones) Connection of the 2 Mbit/s digital links (E1 links).

The unit also contains a new EMRP-T (Extension Module Regional Processor connected to the Time switch) and, in two of the AUSs in every access node, functions for an STR, Signalling Terminal Remote. Figure 2.6 shows the main parts of the AUS.

Figure 2.6The main parts of the AUS, Access Unit Switch

Here follows a short description of each unit shown in the figure:

SwitchThe switch handles 1024 channels of 64 kbit/s each. The switch can also attenuate the speech samples.

ClockOne AUS in the access node is master and all other clocks in the node follow the clock of the master. Another AUS has a clock which acts as stand-by master in case of failure. The timing information is distributed

ET

Clock

Switch andattenuation

DTMF,tones

HDLC

ET

ET

ET

ET

ET

ET

ET

pool

EMRP STR

ETKR TSW V24 STCON

EMRPB

DEVCB

To LocalExchange

AUS

To AU

To TAU

Network

Access Unit Switch

V.24

Sync. ring

EMRP-T

orPRA

System Overview

21

via a separate bus. The hardware is a VCXO, Voltage Controlled Crystal Oscillator, delivering 16,384 Mhz.

ET, Exchange TerminalsThe ET circuits terminate the E1 links operating at 2 Mbit/s (2.048 Mbit/s). Channel 0 is used for synchronisation and the remaining 31 channels can be used for calls or signalling (e.g. V5.1 signalling). The links conform to ITU standard G.703, G.704, and G.706. The interface is a 120 ohms balanced interface. The standard AUS board has 28 ET circuits.

HDLC poolThe HDLC circuit is a data communication circuit (high-level data link control) and it is integrated in the microprocessor. The hardware can handle 32 HDLC channels and they will be used for STC-STR communication, AUS interwork via the AUS network, and V5.1 concentration. In the case of standalone traffic, the V5.1 signalling links are terminated in the HDLC circuits.

DTMF tonesThis hardware, that is used to receive DTMF tones, is based upon a DSP, digital signal processor. This hardware has the capacity to handle 32 devices (KRC devices). As well as receiving tones, it also generates them. New tones can be generated without changing the hardware.

AUS control systemThe new powerful EMRP-T will replace the old EMRP, the device processors as well as the STR (in two AUSs per node). In the figure, dashed lines indicate that these latter functions are now handled by the same hardware. The software executed by the new EMRP has to be written in C or C++. Old PLEX-M programs are converted to C before being compiled.

Serial interfaceThe AUS has two V.24/V.28 ports for connecting the local debugger and a portable terminal (PC).

2.8 AUS NetworkThe AUS network is a common name for two separate functions. One function, which replaces the EMRP bus in the old SSS5 structure, is for EMRP-T communication. The other function, which replaces the Time Switch Bus, TSB, in the old SSS5 structure, is for local connections and overflow traffic.

2.8.1 EMRP RingThe EMRP ring is the name for the function replacing the EMRP bus. It is used for EMRP-EMRP communication and uses standard 2 Mbit/s links. It is built as a ring because security and information can be sent in both directions on the ring. If one part of the ring becomes faulty, the ring can still handle signalling between all connected EMRPs. Figure 2.7 illustrates the principle, with 6 AUSs in the subrack.

AXE Access 910

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Figure 2.7The redundant EMRP ring

The 31 channels on the EMRP ring are not fully used for EMRP communications. The EMRP ring will probably need 4 time slots to have the same capacity as the EMRP bus in the old SSS5. Remaining channels can be used by the Mesh network (see next chapter).

2.8.2 Mesh NetworkThe Mesh network will replace the Time Switch Bus in the SSS5 structure and will consequently be used for calls. The Mesh network will also be implemented by standard 2 Mbit/s links and all AUSs will be connected to each other. That is why it is referred to as a Mesh network. Figure 2.8 shows some examples of configurations with 3 to 6 AUS in one node.

Figure 2.8The Mesh network with different numbers of AUSs

AUS

AUS

AUS

AUS

AUS

AUS

AUS

AUS

AUS

AUS

AUS

AUS

Faulty link

Example with fault:

AUS

AUSAUS

AUS AUS

AUS AUS

AUS

AUSAUS

AUS AUS AUS AUS

AUS

AUSAUS

AUS

3 AUS 4 AUS

5 AUS 6 AUS

AUS

AUSAUS

AUS AUS

AUS AUS

AUS

AUSAUS

AUS AUS AUS AUS

AUS

AUSAUS

AUS

System Overview

23

The Mesh network is pre-cabled according to the customers wish of maximum number of AUSs. This means that the subrack is prepared for a maximum number of AUSs and that extensions are made easy and quickly without the need for additional cable work.

Please note that the spare AUS is not shown in the figure.

2.9 Software IntroductionThis sektion will give you an overview of AXE Access 910 software structure. The basic structure is explained as well as the set of parts (CRT). Important function blocks involved in traffic handling which provide insight into the functions inside the system will also be explained.

2.10 Set of Parts, CRT levelSSS, Subscriber Switching Subsystem, is divided into a number of sets of parts. The ABC class for a set of parts is CRT. Each set of part is further divided into function blocks (CNT) and hardware function units (COA and BFD). Under each function block, there is one or several software modules (CAA). Figure 4.1 shows the general structure.

Figure 4.1System structure

AXE

APT

Equipped ANT (SSS)

AUV5 MAUSSWITCH SLM

MAOAM

CNT

NBAMAU

MUS

Cabinets

Access Functions Switching Functions Maintenance Functions

CRT CRT CRT

COA/BFD CNT COA/BFD CNT COA/BFD

MACCG

SIS

AXE Access 910

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The following set of parts are unique for AXE Access 910:

AUV5, Access Unit V5 Application MAUS, Multiple Access Unit Switch MAOAM, Multiple Access, Operation, Administration and

Maintenance.

The set of parts SWITCH and SLM (subscriber line maintenance) are also used for the existing SSS5 product. For example, subscribe line maintenance functions are basically the same in both product variants.

2.11 Multiple Access Unit Switch, MAUSThis set of parts implements the functions needed for the AUS, Access Unit Switch. Functions implemented are:

Administration of the AUS hardware and fault supervision Switching functions between connected ET interfaces and the internal

DSP device (digital signalling processor implementing KRC and tone sending)

Keyset receiver and tone sending from the DSP Concentration of V5.1 signalling channels, so called C-channels Administration of different applications which can be connected to the

platform.

The blocks included in MAUS can be seen in Figure 4.2.

Figure 4.2Blocks in MAUS

TSMT

TS

ANH

KRT

AUS

ET

AUSTS KRT ET ET

ET

Central

Hardware

Regional

Local Exchange

TSMT

TS

ANH

KRT

AUS

ET

AUSTS KRT ET

ETC

ET

ET

Software

Software

DIPSTDIPST

ETDIF

in EMRP-T

Regional Softwarein RP

DIPHID

RST155

RST

AUS Board

System Overview

25

The blocks have the following functions:

ANH, Access Network HandlerThis block owns and handles the AUS Network interconnecting all AUSs in the same access node. The block seizes time slots and performs traffic measurements.

AUS, Access Unit SwitchThis block is the hardware owner of the AUS board and it co-ordinates administration, configuration, and maintenance for other blocks. Functions such as network node, DIP and device administration, and clock handling are also performed by the block.

DIPHID, Digital Path Historical DataThis block stores quality supervision data (logging of data received from DIPST).

DIPST, Digital Path Supervision and TestThe block handles the DIPs between the access node and the local exchange.

ET, Exchange TerminalThere are two variants of ET blocks in the set of parts:

- ET for the access node side taking care of hardware supervision and test of the ET circuits on the AUS board.

- ET for the local exchange side taking care of the same things but for the ETs located in the local exchange.

ETDIF, Exchange Terminal InterfaceThis is an interface block adapting the RST block to the standardized ET interface used in AXE.

KRT, Keyset code Receiver and Tone sendingThis block is the merged KR2 and SSTONE and takes care of keyset code reception and tone sending.

RST, Remote Stage TrafficThis block owns the traffic channels in the 2 Mbit/s lines between the access node and the local exchange. The block also interworks with the GAM, Generic Access Manager, platform when selecting time slots for signalling (e.g. V5).

RST155, Remote Stage Traffic, 155 Mbit/sSame as for RST but handles the 155Mbit/s interface between the local exchange and the Access 910.

TS, Time SwitchThe block connects and releases paths in the time switch in the AUS.

TSMT, Time Switch MaintenanceThe block administrates some operation and maintenance functions related to the time switch.

AXE Access 910

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2.12 Test Unit (TAU)TAU, Test, Maintenance and Administration Unit, is the unit in AXE Access 910 that is responsible for line and circuit tests. The TAU is shared by a large number of subscribers - the exact number depends on how often it is necessary to perform line measurements. TAU has two connections to the Access Units:

one analog test bus which galvanically connects the measurement equipment inside the TAU to the subscriber line and analogue side of the line circuit.

one connection to the AUS which, via the time switch, connects the TAU to the digital side of the line circuit.

The TAU can measure the subscriber line as well as test the line circuit by means of simulated subscriber actions such as on and off hook.

The number of TAU needed for each access node depends on the total number of subscribers as well as the intensity of line tests. The test interval is set by the network operator and varies between different operators. Figure 4.3 shows where the TAU is located in the system.

Figure 4.3The TAU in the AXE Access 910

External test instruments may also be connected to the TAU if needed.

ET

ET

ET

ET

LICTest access

AU

TAU

Test Head

AUSSwitch

ET

ET

ET

LIC

ET

System Overview

27

2.13 Equipment in the Local ExchangeThe local exchange contains all the main software functions for operation, maintenance and traffic control. Central software, stored and executed by the central processor, must communicate with the regional software in the access node. For this reason, reliable communication between the local exchange and the access node is vital.

All AXE Access 910 access nodes will be connected in the same way, regardless of location (via ETC in the local exchange). The reason for this is that it is estimated that 80% of all access nodes will be installed remotely. The hardware required to connect and signal to/from the AXE Access 910 can be divided into the following:

Physical connection of the E1 digital linksThe connection is made by ordinary 2 Mbit/s ETCs in the local exchange. The hardware is the same as any standard ETC.

Signalling with V5.1The V5.1 interface requires regional processors connected to the group switch. These regional processors are referred to as RPG, regional processor with group switch interface, developed for the AXE hardware BYB 501.

Signalling to ISDN-PRA accessOne set of RPG is required for the signalling towards PRA access.

Signalling to TAUA general signalling mechanism has been developed for AXE Access 910. This transport function is referred to as ICS, Internal Communication Service. The RPG is used for this type of signalling too.

Signalling to EMRP software in AUS, CSLM7This type of signalling is used to send orders to the functions implemented in the hardware in the AUS (for example, time switch, digit reception, tones, and I/O). This siganlling comunication between STR (Signalling Terminal Remote) and STC (Signalling Terminal Central) is the Control signaLling Path, CLP. The RPG is used for this type of signalling as well , STC-G (Signalling Terminal Central with Group switch interface)

Figure 4.4 shows the hardware required in the local exchange for handling the V5.1 protocol, PRA access, the TAU communication, and the STC-STR signalling.

AXE Access 910

28

Figure 4.4Equipment needed in the local exchange to connect an AXE Access 910

The number of RPG in the local exchange is reduced due to the fact that each RPG has a large capacity and can in that way control several signalling links. As an example, one RPG can serve several access nodes regarding the TAU signalling. The RPGs are working in n+1 redundancy. This means that one spare is used for a large number of RPG having the same functionality (e.g. one spare RPG for PRA signalling).

ETC

ETC

ETC

ETC GroupSwitch

RPG AU V5

TAU

To/from AU

To/from TAU

To/from STR

ETC

ETC

ETC

ETC

CP-A CP-B

RPB

in AUS

V5

ICSRPG

STC-STR

ETC RPGTo/from PRA ETCV3 PRA

RPG

29

3. Hardware Structure

3.1 Chapter IntroductionThis chapter will give you an overview of the building practice used in AXE Access 910. The building practice has many advantages for the customer and it gives future-proof and flexible mechanics adapted to future broadband services.

3.2 BYB 501 in Access 910

3.2.1 CabinetsBYB 501 can be built in many different sizes and the size used in Access 910 can be seen in Figure 4.1. Other sizes in BYB 501 are 2200 mm height and depth of 300 mm.

Figure 4.1Cabinet size in Access 910

After completing this chapter, you will be able to:

Describe the adaptation of the BYB 501 building practice

Describe the subracks used in Access 910 as well as the configuration alternatives within each subrack

Describe how the cabling is done between subracks

Describe some of the different configuration alternatives for in-door and out-door applications

Chapter Objectives

1800

400600

AXE Access 910

30

Cabinets can be placed in different ways depending on the requirements from the customer. Figure 4.2 shows three different alternatives for arrangements of cabinets.

Figure 4.2Possible arrangements of cabinets

3.2.2 SubracksSubrack is the term used in BYB 501 instead of magazine which was used in BYB 202. The subrack in BYB 501 is much more flexible than the magazine in BYB 202. Plug-in units of various sizes may be used in one and the same subrack.

The standard subrack in BYB 501 is 450 mm wide and it can house up to 21 plug-in units with 20 mm spacing. There is also a half-width subrack available if needed (e.g. APZ 212 25). Figure 4.3 shows the basic dimensions of the subrack used in Access 910.

Figure 4.3Basic dimensions of a subrack in Access 910

The subrack is of product type BFD 518 and the backplane is of product type ROJ 605.

400

600

Back-to-wall

Free-standingsingle row

Back-to-back andthe possibility tohave double-depthcabinet (not used in Access 910)

485 250

300

Hardware Structure

31

3.2.3 CoolingCooling for access products is important as much heat is generated by the line circuits. The main reason for the generated heat is the current feed of the subscriber lines. In case of short subscriber lines, most of the energy is heating the line circuit itself.

The cooling principle used in Access 910 is based upon forced cooling using fans and a combination of serial and parallel cooling. Figure 4.4 shows the main principle.

Figure 4.4Cooling principles of BYB 501 when used in Access 910

It can be seen from the figure that the subracks are cooled by means of a fan that cools two subracks. The other two are cooled by another fan. Two subracks are cooled in series.

3.2.4 Cabling in BYB 501 in GeneralCabling is done by means of cable shafts at the side of the subracks inside the cabinet. From the cable shafts, the cables are put on cable shelves and then up to the connectors on the front of the board. All cabling is done from the front. Figure 4.5 shows the cabling area when looking at the cabinet from above.

Cable shelfFan

Air intake

Air flow

Chimney

FrontAir guiding plate

Fan

Air intake

Sub-rack

Back

AXE Access 910

32

Figure 4.5Cabling area when looking at the cabinet from above (cross section)

From the cable area at the sides of the cabinet, the cables are guided to the correct PCB via the cable shelf. There is one cable shelf for each subrack located just below the subrack. Figure 4.6 shows the main principle of the cable shelf.

Figure 4.6The cable shelf and one connector, side view

3.3 Subracks in AXE Access 910

3.3.1 MUS, Multiple Access Unit SwitchThis subrack contains the switching part of the Access 910 and all the AUS boards are located in this magazine. The AUS boards contains all common equipment as well as the switch. The 2 Mbit/s lines from the connected AUs are connected via the AUS-C board. There are different configuration alternatives available and only one can be explained in this chapter. Figure 4.7 shows one variant of the MUS subrack.

Subrack

Cabling areaFront

Back

Connectors

Cable shelf

Connector

Hardware Structure

33

Figure 4.7One variant of the MUS subrack

Up to 6 AUS can be housed in the subrack. If AUS protection switching is implemented, a spare AUS is needed in position 13. The subrack is prepared for having narrowband AU (access units) in position 1-15. This means that AUS and AU can be mixed within the subrack.

3.3.2 NBA, Narrowband Access SubrackThe narrowband access subrack is used to connect subscribers with POTS and ISDN service. Different AU boards will be used for POTS and ISDN-BA access. Figure 4.8 shows one configuration alternative for the subrack.

Figure 4.8Narrowband access subrack, NBA

Almost the whole subrack is filled with Access Units of type POTS or ISDN. Position 15 has a TAU or a 15:th AU. If no TAU is located in the subrack, a TAU in another subrack measures the AUs via a test access bus going between the TAU-C boards. AUs for POTS or ISDN-BA can be mixed in the subrack. Here are some examples of capacities:

AU

S C

DU

-2A

US

-5

AU

S-0

AU

S C

[AU

S s

pare

]T

AU

-1T

AU

-0TA

U-C

DU

-2#

1#

2

# 11

# 12

# 13

# 14

# 15

# 16

AU

-1

DU

-2A

U-0

AU

-10

AU

-11

AU

-12

AU

-13

TAU

or A

U-1

4T

AU

-C

DU

-2#

1#

2

# 11

# 12

# 13

# 14

# 15

# 16

AXE Access 910

34

The TAU-C boards are interconnected by means of a cable. The cable contains the following:

A serial RS 485 bus for connection to AU processors (control test access bus, ACOM)

Test access bus for measurements of line and LIC Protection switching bus (LCOM) PULSI extension bus, PEBUS

3.3.3 MUA, Multiple Access SubrackThe multiple access subrack has been developed to meet the demands of mixed access types in one and the same subrack. From an operators perspective, it is important that the hardware allows to slowly add more and more broadband accesses. It is difficult for operators to predict where and when subscribers wish to change from narrowband to broadband access. Figure 4.9 show the possible combinations of boards.

Figure 4.9Configuration of MUA subrack

It can be seen from the figure that it is possible to mix narrowband AUs, for POTS and ISDN-BA, and the broadband AUs in the same subrack. For ADSL lines, a filter board is required. This means that there are minimum two boards required for ADSL access. The cell-bus, which runs in the backplane of the subrack, is used to interconnect the ADSL boards with

AU for POTS AU for ISDN No. of subscribers

15 0 450

14 0 420

13 1 390 + 15

12 2 360 + 30

11 3 330 + 45

AU

/ E

T (s

) / F

ilter

DU

-2A

U/E

T

AU

/ ET

(s) /

AD

SL

AU

/ E

T (s

) / F

ilter

AU

... o

r TA

UTA

U-C

DU

-2#

1#

2

# 13

# 14

# 15

# 16

AU

/ ET

(s) /

AD

SL

# 3

Cell-bus(pos 1-15)

Hardware Structure

35

the ET. The first versions will have 4 subscribers per board pair for ADSL access. In the future, there will be 8 subscribers per board pair. This means that the following configuration alternatives are possible (it is assumed that there is a TAU in position 15):

3.3.4 SIS, Single Switch SubrackThe single switch subrack is, as the name indicates, one complete access node in one and the same subrack. This means that AUS, TAU and AUs have to be located in the same subrack. The subrack is also optimized for the so called Outdoor-Midi cabinet which is explained in section 3.4.3 on page 36. Figure 4.10 shows how one SIS subrack could look like.

Figure 4.10The layout of the SIS subrack

The AUs, or filter/ADSL boards can be mixed in the positions 1-11. In position 12, there has to be an ordinary narrowband AU. Position 12 and 13 is used for the AUS and AUS-C boards. TAU is located in position 15. This means that a full access node is housed in one subrack. Up to 360 PSTN subscribers can be served by the subrack.

3.4 Cabinets

3.4.1 In-Door Cabinets for 2520 PSTNThis example shows the maximum number of subscribers that can be connected in case of high traffic loads. The configuration shown here can

AU for POTS AU for ISDN AU for ADSL No. of subscribers

14 0 0 420

10 1 1 300 + 15 + 4 (8 in 2:nd rel) =319

8 1 2 240 + 15 + 8 (16) = 263

6 1 3 180 + 15 + 12 (24) = 207

4 1 4 120 + 15 + 16 (32) = 151

AU

/ET/

Filte

r

DU

-2A

U/E

T

AU

AU

SA

US

-CT

AU

TA

U-C

DU

-2#

1#

2

# 12

# 13

# 14

# 15

# 16

AU

/ET

(s) /

AD

SL

# 3

Cell bus(pos. 1-11)

AXE Access 910

36

handle up to 0.42 Erlang per subscriber (or per B-channel in case of ISDN-BA). There is one MUS subrack and then 6 NBA subracks connected to the MUS. Figure 4.11 shows the two cabinets and how the subracks are located.

Figure 4.11Two cabinets for 2520 PSTN subscribers (max 0.42 Erlang/subscriber)

3.4.2 In-Door Cabinets for 3000 PSTNIf the customers uses the access node in an area with rather low traffic, an additional subrack can be included in the node. This is possible as the number of E1 links to the local exchange is reduced from 6 to 4. The idle ET circuits in all 6 AUS:s then share the connection of the 7:th NBA subrack. Figure 4.12 shows the layout of the two cabinets.

Figure 4.12Two cabinets for 3000 PSTN subscribers (max 0.23 Erlang/subscriber)

3.4.3 Out-Door Cabinet MidiThe out-door cabinets defined for AXE Access 910 are all plug-and-play cabinets with all hardware pre-installed. This means that the factory

14 AU

6 AUS

14 AU

14 AU

14 AU

14 AU

14 AU1 TAU1 TAU

14 x 6 = 84 AU84 x 30 = 2520

15 AU

6 AUS

15 AU

15 AU

15 AU

15 AU

14 AU1 TAU1 TAU

100 x 30 = 3000

11 AU

15 x 5 = 75AU14 + 11 = 25AUIn total 100 AU

Hardware Structure

37

prepares the cabinets and sends them to the customer ready to be connected. The operator then connects transmission, power and the telephone lines to the cabinets and it is ready for service. The Midi variant is built round the SIS subrack (Single Switch subrack) which is one full access node on one cabinet. Up to 360 PSTN subscribers can be connected to the subrack/cabinet. Figure 4.13 shows the contents of the cabinet.

Figure 4.13Two Midi cabinet for out-door usage

3.4.4 Out-Door Cabinet MaxiThe Maxi cabinet is built around one MUS subrack with 2 AUS and two access subracks (NBA or MUA). This makes it possible to connect 900 PSTN subscribers to the cabinet. Figure 4.14 shows the general layout of the cabinet.

Figure 4.14Two Maxi cabinet for out-door usage

SIS subrack

Power

Bat

terie

s

Hea

t Exc

hang

e

Mai

n D

istri

butio

n F

ram

e

Cable shelfFan

STM Transmission

Climate controland switches

MUS subrack

Hea

t Exc

hang

e

Mai

n D

istr

ibut

ion

Fra

me

Cable shelf

Fan and cable shelfSTM Transmission

Climate controland switches

Bat

terie

sB

atte

ries

Power unit 1

Power unit 2

Fan and cable shelf

NBA or MUAsubrack

NBA or MUAsubrack

AXE Access 910

38

3.5 Cabling Inside Access 910

3.5.1 Cabling Between SubracksAccess nodes contains many cables as subscribers are connected to these nodes. There are two wires required for each subscriber and there are additional cables needed to interconnect subracks with test buses and 2 Mbit/s lines. It is not possible to describe all cables and how all subracks are interconnected so some important example are described. Figure 4.15 shows how subscriber lines are connected to the AU and how the AUs are connected to the AUS-C. From the AUS-C, the E1 links to the local exchange are connected to the DDF, digital distribution frame, via a connection field, CCF.

Figure 4.15Cabling inside Access 910, example with one AU and one AUS and only one cable of each type shown

3.5.2 Cabling of TAUThe TAU-C board, always located to the very right in the subrack (in position 16), has cables inter-connecting TAU-C boards with each other. The interconnection makes it possible for one TAU to control and perform measurements in other subracks. The inter-connection contains:

ACOMThe main communication link between the TAU and the AUs. The bus continues in the backplane of the subrack to all AUs within the subrack. The bus is a serial bus (RS 485).

LCOMThis is the bus that makes it possible for the TAU to control the

AU

S-C

AU

MUS

NBACCF

To MDF

To DDF

AU

S2 Mbit/s from AUto AUS

2 Mbit/s from AUSto CCF, DDF andLocal Exchange

30 subscriber lines

Hardware Structure

39

optional function equipment protection switching. The bus interconnects the TAU with the AUS-EP and AU-EP. Also this bus continues in the backplane of the subrack.

Test AccessThe test access connection. This bus inter-connects the measurement equipment on the TAU with the AU. Also this bus continues in the backplane of the subrack.

The inter-connection between the TAU-C boards can be seen in Figure 4.16.

Figure 4.16Connection of TAU-C boards within one cabinet

3.5.3 Cabling within MUS SubrackInside the MUS subrack, with all AUS:s, there are cables according to Figure 4.17. Please note that the total size of the node determines which positions that are actually used. The figure shows the maximum configuration with 6 AUS and up to 17 AU per AUS.

TAU-

C

MUS

NBA/MUA

NBA/MUA

NBA/MUA

TA

UT

AU

TA

UT

AU

Bus termination

Bus termination

AXE Access 910

40

Figure 4.17Cables connected to the AUS-C (front of AUS-C shown)

3.5.4 Cabling PositionsWhen defining a building practice like BYB 501, there is a need for identification of cabinets, subracks, board positions as well as connector positions. The numbering used for BYB 501 is shown by taking an example from the AUS-C board with the empty positions shown dashed. Figure 4.18 shows the numbering of connectors.

RST-0

RST-1RST-2RST-3RST-4RST-5

AU-0AU-1

AU-2AU-3AU-4AU-5AU-6AU-7AU-8AU-9

AU-10

AU-11AU-12AU-13AU-14

alt. AU-15alt. AU-16

alt. TAU

Mesh

not usednot used

MeshMeshMeshMesh

Maximum 6 E1 links to/fromlocal exchange (minimum 1).Less in case of low traffic.

Maximum 15 AUs connectedto one AUS. If low traffic (less than0.23E) up to 17 AUs per AUS.

Mesh network inter-connectingall AUSs

2 E1 links for EMRP Ring

DebugDebug

Sync

Sync

RS232RS232RS232Debug

AUS-n AUS C-n (or AUS EP)

ISIOSI

AUSRAUSR

Synchronisation Ring

Hardware Structure

41

Figure 4.18Cable position identification used in BYB 501 for access products

RST-0

RST-1RST-2RST-3RST-4RST-5

AU-0AU-1

AU-2AU-3AU-4AU-5AU-6AU-7AU-8AU-9

AU-10

AU-11AU-12AU-13AU-14

1, 2

Mesh

not usednot used

MeshMeshMeshMesh

ISIOSI

AUSRAUSR

3, 4 X1025, 6

1, 23, 4 X1035, 6

1, 23, 4 X1045, 6

1, 23, 4 X1055, 6

1, 23, 4 X1065, 61, 23, 4 X1075, 61, 23, 4 X1085, 6

1, 23, 4 X1095, 6

1, 23, 4 X1105, 61, 23, 4 X1115, 61, 23, 4 X1125, 6

1, 23, 4 X1135, 6

1, 23, 4 X1145, 61, 23, 4 X1155, 61, 23, 4 X1165, 6

1, 23, 4 X1175, 6

1, 23, 4 X1185, 6

1, 23, 4 X1195, 6

1, 23, 4 X1205, 6

1, 23, 4 X1215, 6

1, 23, 4 X1015, 6

AXE Access 910

42

43

4. The V5 Interfaces

4.1 Chapter IntroductionThis chapter will give you an overview of the V5 interface specified by ETSI. The interface is quite comprehensive and contains many different things. In this chapter, just a quick survey is made.

4.2 SurveyAn important issue for network operators is the use of an open protocol between the local exchange and the access nodes. Many operators wish to have local exchanges and access nodes which come from different suppliers. The operators can buy the best local exchange and connect that to the best access node, regardless of supplier. This is already a possibility in many mobile systems (e.g. GSM) where base stations and exchanges can be supplied by different supplier.

ETSI, European Telecommunications Standardisation Institute, has developed a number of standard interfaces which can be used between the local exchange and the access node: the V5 interface family. There are two different variants of this interface:

V5.1 is used for multiplexers connected by a standard 32-channel 2 Mbit/s line to the local exchange. A multiplexer does not concentrate the traffic but simply connects one subscriber to a digital time slot.

V5.2 is used for concentrators having the ability to concentrate the traffic towards the local exchange.

Figure 5.1 illustrates the main principle.

After completing this chapter, you will be able to: give a brief description of the V5 standard understand how V5.1 is used in AXE Access 910.

Chapter Objectives

AXE Access 910

44

Figure 5.1The two types of V5 interfaces

In most applications, the concentrator connects between 500 and 2-3000 subscribers, and concentrates the traffic to a few 2 Mbit/s lines. The multiplexer cannot concentrate the traffic, so each subscriber is permanently connected to the same time slot in the 2 Mbit/s link.

4.3 The V5 Interface in AXE Access 910The V5 variant for multiplexers, the V5.1 interface, is used in AXE Access 910. How, then, is that possible since the whole AXE Access 910 is a concentrator and not a multiplexer? The answer is that each AU, Access Unit, is regarded as a multiplexer (and it is...) and is controlled via the V5.1 protocol. The AU has a powerful processor which runs the V5.1 software. The other end of the protocol is in the local exchange where an RPG is used for the V5.1 software. Note that the V5.1 interface is only used for AU of type PSTN and ISDN-BA (not for broadband access). Please study Figure 5.2.

Figure 5.2The V5.1 protocol used in AXE Access 910

Multiplexer

Concentrator

Local Exchange2 Mbit/s

V5.1

V5.21

~ 1000

1

30

2 Mbit/s

AU

AU

AU

AUAUS

ETC

GroupSwitch

RPG

CP-A CP-B

T. 16

T. 16

V5.1

AXE core partAXE Access 910

The V5 Interfaces

45

4.4 C-channel Concentration, CCCThe C-channel is the V5.1 signalling channel between the AU and the AUS. According to the V5.1 protocol, time slot/channel 16 should be used for this signalling. However, in the AUS, several C-channels can be concentrated to one C-channel (statistically multiplexed). The amount of signalling traffic on one channel, for only 30 subscribers, is not that great (particularly not for PSTN). Depending on the traffic, a large number of C-channels may be concentrated in the AUS. Inside the AUS, the HDLC-pool, High Level Data Link Control, pool terminates the V5.1 protocol and multiplexes the signalling traffic to one time slot/channel towards the local exchange. Figure 5.3 illustrates the main principle.

Figure 5.3C-channel concentration

The concentration of C-channels is always done per AUS. In most cases, the number of AUs connected to one AUS is in the range of 14-15. The number of concentrated C-channels per RPG that can be handled depends on the processor used and the traffic. Each configuration has to be dimensioned individually.

4.5 Signalling within V5.1

4.5.1 Functions for V5.1 protocolThe V5.1 interface is divided in a number of different functional units according to Figure 5.4.

AU

AU

AUS

ETC

GroupSwitch

RPG

CP-A CP-B

T. 16

T. 16

HDLC

AXE core partAXE Access 910

AXE Access 910

46

Figure 5.4V5.1 Interface

Each of the functional units, in the figure above, comprises a subset of messages on layer 3.

The following functional requirements are defined for the V5 protocols:

Bearer channels: to provide the bidirectional transmission capability for allocated B-channels from basic access user ports or PCM-encoded 64 kbit/s channels from PSTN user ports.

ISDN D-channel information: to provide the bidirectional transmission capability for D-channel information from basic access user ports (including Ds-, p- and f-type data).

PSTN signalling information: to provide the bidirectional transmission capability, to carry the status and control of each individual user port.

Control Information:- Control of user ports: to provide the bidirectional transmission

capability for signalling information of PSTN user ports.- Control of the 2 048 kbit/s link: frame alignment, multiframe

alignment, alarm indication and CRC information.- Control of layer 2 links: to provide bidirectional

communication capability to carry control and PSTN signalling information.

- Control for the support of common functions: to provide synchronized application of provisioning data and restart capability.

Timing: to provide the necessary timing information for bit transmission, octet identification and frame synchronization. This information may also be used for the synchronization of LE and AN for synchronous operation.

4.5.2 V5 Basic termsThe following terms are important for an understanding of the V5 interface description.

Bearer Channels

ISDN-D Channel Information

PSTN Signalling Information

Control Information

Timing Information

AXE Core partAccess Unit in AXE Access 910

The V5 Interfaces

47

User PortFor non-V5 connected subscribers, the physical subscriber line is the device identity (e.g. LI3-55). For V5, the subscribers are connected to the Access Unit and the position inside the Access Unit is referred to as User Port. The user ports can be of type:

- PSTN (single user or PABX)- ISDN Basic Access- Permanent leased lines- Semi-permanent leased lines.

Bearer ChannelBearer channels are used to provide the bidirectional transmission capability for allocated B-channels from Basic Access user ports, Primary Rate Access user ports, or A-law PCM-encoded 64 kbit/s channels from PSTN user ports. These bearer channels may be used in multiples of 64 kbit/s channels in order to facilitate certain ISDN services.

Data typesThe following data types have been defined:

- p-type data: This is ISDN D-channel data with SAPI 16.- f-type data: This is ISDN D-channel data with SAPI = 32 to

62.- Ds-type: This is ISDN D-channel signalling type data with

SAPI not equal to any of those above.- PSTN: This is PSTN signalling information.- Control: This is control information data.

Bearer Channel Connection (BCC) protocol A protocol which allows the LE to instruct the AN to allocate bearer channels on demand.

Communication Channel (C Channel) A 64 kbit/s time slot on a V5 interface used to carry one or more communication paths, all of different types.

AXE Access 910

48

49

5. Definition of MACCG

5.1 Chapter IntroductionThis chapter will give you some information about how AXE Access 910 is defined by means of commands. The information is based upon a standard definition of a node without any special functions. Most of the new commands and printouts will be found in the chapter related to definition.

5.2 ConceptsThe OPIs used to operate the AXE Access 910 introduce some new concepts. This chapter describes some of the most important concepts used in OPIs and commands. The concepts are listed in alphabetical order, not in the order of importance.

AG, Access GroupAll V5 control channels controlled by the same RPG are grouped in a so called access group. In case of reconfigurations due to hardware faults, all control channels are kept together.

AN, Access NetworkThe term originates from the ETSI standard V5.1 and is defined there as: a system implemented between the Local Exchange (LE) and user, replacing part or the whole of the local line distribution network.

Communication PathSignalling information originating from the V5.1 communication software or from the ISDN subscribers D-channel.

Communication Channel (C-channel)A 64 kbit/s time slot on a V5.1 interface used to carry one or more communication paths.

CSL, Control Signalling LinkThe duplicated 64 kbit/s signalling link between an STR and an STC.

CSP, Control Signalling PathA signalling link terminating in an RPG instead of in an STC. At the remote end, the STR is included in the EMRP-T.

After completing this chapter, you will be able to:

Describe new concepts used in the commands when defining an AXE Access 910

Define a new access node by means of commands.

Chapter Objectives

AXE Access 910

50

EM, Extension ModuleUsed to show how AXE can be extended with new hardware.

EMG, Extension Module GroupThe term used in the old SSS to denote a complete group of subscribers connected to the same TSB/STR pair. In AXE Access 910, the term denotes the APZs view of the access node. The APT part uses the term MACCG. See description of the MACCG.

GAM, Generic Access ManagerAn AXE function developed to control different types of accesses via controlling channels. GAM is used by AXE Access 910 when connecting V5 C-channels to AXE as well as ISDN-PRA accesses.

LAPV5, Link Access Protocol for V5Signalling between the AN (access node) and the local exchange follows the standard LAPV5. An LAPV5 frame is the frame format used for all types of signalling information.

MACCG, Multiple Access GroupThe term used in AXE Access 910 software to denote one complete access node (one EMG). The maximum physical size is two full cabinets with in total 8 subracks.

Network NodeA concept used to denote an AUS, access unit switch.

PIU, Plug-In UnitIs a generic name for all types of PCB, printed circuit board.

V5A set of ETSI standards for connection of access nodes (AN) to the local exchange (LE). The V5.1 supports subscriber multiplexers while the V5.2 standard supports concentrators.

5.3 Definition of Equipment in the Local Exchange

5.3.1 RPG for AU CommunicationThe RPG handling AUs executes the V5.1 protocol software and communicates with the Access Units for both PSTN and ISDN BA. The RPG is defined by the following commands:

EXRPI, defines the RPG with TYPE=RPG1A. EXRUI defines the software to be executed and stored in the RPG. In

AXE Access 910, the software blocks RGEXR, RPFDR belong to the APZ and the blocks STAU, DLAU, CTRLAU, MANAU, MHAU, PSTNAU and PSTNHMA will be defined.

EXEMI defines the EM individuals in the RPG. The block STAU will have 32 devices, one for each V5 channel.

NTCOI and EXDUI are used to connect the RPG to the group switch.

Figure 5.1 shows a printout of the EMs in the RPG used for Access Unit control.

Definition of MACCG

51

Figure 5.1Printout of EM in one RPG used for AU control

There can be several concentrated V5 links connected to one and the same RPG. The present number of channels enables all V5 channels to be connected from one MACCG to one RPG if the traffic is less than 0.2 E per subscriber. For higher traffic loads, two RPGs per MACCG will be needed.

5.3.2 RPG for TAU CommunicationAn RPG is also needed for the communication between the local exchange and the TAUs in the MACCG. The definition is the same as for the RPG used for AU communication. However, the command EXRUI and EXEMI will have other parameter values as other software should be stored and executed by the RPG. Figure 5.2 shows a printout from an RPG communicating with a TAU.

Figure 5.2Printout of EM in one RPG used for TAU communication

One RPG can control up to 30 TAUs. The number of TAUs per MACCG differs from customer to customer. If a standard value is used, then 2 TAUs per MACCG will be used and that means that one RPG can handle some 15 MACCGs (one RPG for up to 45000 PSTN subscribers).

EXEMP:RP=82,EM=ALL;

EM DATA

RP TYPE EM EQM TWIN CNTRL PP STATE 82 RPG1A 0 STAU-0&&-31 PRIM WO 82 RPG1A 1 DLAU-0 PRIM WO 82 RPG1A 4 CTRLAU-0 PRIM WO 82 RPG1A 5 PSTNAU-0 PRIM WO 82 RPG1A 6 MANAU-0 PRIM WO 82 RPG1A 7 MHAU-0 PRIM WO

EXEMP:RP=80,EM=ALL;

EM DATA

RP TYPE EM EQM TWIN CNTRL PP STATE 80 RPG1A 0 STTAU-0&&-31 PRIM WO 80 RPG1A 1 DLTAU-0 PRIM WO 80 RPG1A 2 MXTAU-0 PRIM WO

AXE Access 910

52

5.3.3 RPG for PRA CommunicationISDN PRA, primary rate access, is connected via the Generic Access Manager, GAM, to the RPG in the local exchange. The RPG is defined as shown earlier in this chapter but the software and individuals differ in the two commands EXRUI and EXEMI. Figure 5.3 shows a printout of the RPG used for PRA access.

Figure 5.3Printout of EM in one RPG used for PRA access

The present version of the RPG can control 30 ISDN-PRA accesses.

5.3.4 Definition of RPG for STCAn RPG is also needed for the communication between the STC, signalling terminal central, located in the local exchange, and the STR, signalling terminal remote, located in the MACCG. For reliability reasons, there are two separate control links. Figure 5.4 shows the printout of the two RPGs used as signalling terminals in the local exchange.

Figure 5.4Printout of the two RPGs defined as signalling terminals (STC)

EXEMP:RP=84,EM=ALL;

EM DATA

RP TYPE EM EQM TWIN CNTRL PP STATE 84 RPG1A 0 STPRAE-0&&-31 PRIM WO 84 RPG1A 1 DLPRAE-0 PRIM WO 84 RPG1A 2 MANPRAE-0 PRIM WO

EXEMP:RP=70&71,EM=ALL;

EM DATA

RP TYPE EM EQM TWIN CNTRL PP STATE 70 RPG2A 0 CSLSNT-0 PRIM WO 70 RPG2A 1 CSLM7-0&&-15 PRIM WO

71 RPG2A 0 CSLSNT-1 PRIM WO 71 RPG2A 1 CSLM7-16&&-31 PRIM WO

Definition of MACCG

53

It is also possible to use the command EXCPP to print the signalling link. Figure 5.5 shows the generated printout.

Figure 5.5Printout of the two control signalling links to one MACCG

5.3.5 Definition of ETC in the Local ExchangeThe last type of equipment that has to be defined in the local exchange is the ETCs terminating the E1 links from the MACCG. The commands will not be shown here as there are no differences between ETCs for the access node or ETCs for the trunk network.

5.4 Definition of a MACCG

5.4.1 Definition of MACCG and EMGThe operational instruction Multiple Access Group, Connect should be used when defining a new access node. This OPI will reference other OPIs when AUSs, TAUs and AUs are defined.

The first command to use is:

EXEGI:EMG=MACCG1,RPA=70,RPB=71,STRTYPE=RPG2A;

This command, which defines the EMG, has not been changed since previous version of access system (SSS5). Note again that EMG is an APZ concept and is used to address the access node from APZ functions. The following command defines the MACCG, Multiple ACCess Group:

EXMCI:MACCG=MACCG1,EMG=MACCG1,MACCGVAR=7;

The MACCGVAR parameter specifies the number of AUSs in the MACCG. Figure 5.6 shows the printout of the definitions made by the commands above.

EXCPP:EMG=MACCG1;GS CONNECTED CONTROL SIGNALLING LINK PATH DATA

EMG PATH STATE RDEV CDEV EQMMACCG1 A WORK RST-176 CSLDEV-8 CSLM7-8

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Figure 5.6Printout of EMG data and MACCG data

5.4.2 Definition of Access Unit Switch, AUSThe AUS is a completely new unit but many commands from the old SSS5 have been reused. The new EMRP-T has to be defined in each AUS but the commands are basically the same as in the old SSS5:

EXEPI defines the EMs. The parameter TYPE is set to EMRPT1A. EXEUI is used to define the software that should be loaded into the

EMRP-T. The software identities for this application can be seen in the printout in Figure 5.7 (note that the contents of the printout in the figure is valid for a training exchange).

EXEEI is used to define the equipment in each EM. The printout in Figure 5.7 shows the names used as well as the software identities (software identities from a training exchange are shown).

EXEGP:EMG=ALL;EMG DATA

EMG TYPE SIDE LINK ST MAST EMGNUMMACCG1 REMOTE A CLC-6 WO IDLE 3 REMOTE B CLC-7 WO IDLE 3MACCG0 REMOTE A CLC-4 WO IDLE 2 REMOTE B CLC-5 WO IDLE 2RSS0 REMOTE A CLC-2 WO IDLE 1 REMOTE B CLC-3 WO IDLE 1LSS0 CENTRAL A CLC-0 WO IDLE 0

Definition of MACCG

55

Figure 5.7Printout of EMG software and equipment data

5.4.3 Definition of Routes and DevicesThe next step is to define the routes and devices needed between the access node and the local exchange. A software route in block CJ, Combined Junctor, should also be defined. There are no major differences, in relation to these definitions, between the AXE Access 910 and the old SSS5.

EXROI creates a bothway route with DETY=RST. EXRBC alters route data. EXDRI connects devices (from block RST) to the route. NTCOI defines the SNT (Switching Network Terminal) EXDUI connects the devices to the SNT.

5.4.4 Definition of the Position of AUSWhen the AUS has been defined, its position in the hardware can be defined by command EXPUI. Figure 5.8 shows a printout of the Plug-In Units position.

EXEDP:EMG=MACCG1,EM=0;EMGEM SOFTWARE UNIT AND EQUIPMENT DATA

EMGMACCG1EM 0SUNAME SUID EQM SUPEIEX1R 9000/CAA 203 01 R1B06 H00D6TEETR 9000/CAA 140 054 R1A03 H00B2EMGFDR 9000/CAA 140 007 R1A03 H00ACTSR 9000/CAA 203 04/4 R2A03 TS-96 H00D1KRTR 9000/CAA 203 05/5 R2A03 KRT-4 H0016AUSR 9000/CAA 203 03/3 R2A05 AUS-3 H0095ETR 9000/CAA 203 06/6 R2A03 ETAUS-4 H00DDSTCONR 9000/CAA 140 178/F9 R1B01 STCON-4 H00A3

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Figure 5.8Printout of the position of a PIU

5.4.5 Definition of Network NodeNetwork node is a term used to denote the AUS and all the E1 links connected to it. The network node is defined with a new group of commands starting with the letters NNxxx.

NNCOI:NODE=AUS-0,VAR=1;

This command defines the network node. The parameter VAR indicates the number of ports available in the hardware. A port is the same thing as an ET device handling an E1 link. As stated earlier, the present version of AUS board has 28 ET circuits located on the board. Each ET circuit has a port number in the range from 0 to 27. The following command shows how the E1 link from the local exchange is defined and connected to port 27 on the AUS-C board. Figure 4.17, , on page 40 shows the port numbering.

NNUPI:NODE=AUS-0,PORT=27,DEV=RST-0&&-31;

Figure 5.9 shows a printout of the network node when E1 links to the local exchange have been defined.

EXPUP:PIU=AUS-0;PLUG-IN UNIT DATA

MACCG SR POS PIU STATE BLSTATE STANDBYMACCG0 0 11 AUS-0

Definition of MACCG

57

Figure 5.9Printout of Network Node

NNUPP:NODE=AUS-0;NETWORK NODE USER TO PORT CONNECTION DATA

NODE PORT DEV DIP INTCONNAUS-0 0 YES 1 YES 2 YES 3 YES 4 YES 5 YES 6 YES 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 RST-32&&-63 27 RST-0&&-31END

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6. PSTN Access

6.1 Chapter IntroductionThis chapter will give you a brief description of PSTN access. Although ISDN and ADSL will increase a lot during the coming years, PSTN access will be the dominating access type.

6.2 DescriptionPSTN, Public Switched Telephone Network, is the network delivering the POTS service. POTS stands for Plain Ordinary Telephony Service. During the coming years, this type of access will be dominating even though ISDN and broadband access types will increase dramatically in some markets due to Internet growth.

6.2.1 The AU for PSTNThere are two different versions of access units for PSTN access in AXE Access 910:

LIC30 based upon standard SLIC circuits with or without 12/16 kHz private meter pulse sending

ALB30 with high functionality requested on some markets only

Both version can connect 30 subscribers to one printed circuit board. Note that all connections are wired via the connection field MDF, Main Distribution Frame. The task of the MDF is to terminate the external distribution network, insert over-voltage protection (optional) and change cable to internal cabling. Figure 6.1 shows the main principle.

After completing this chapter, you will be able to: give a brief description of the hardware needed for connecting

PSTN subscribers describe in what subracks the AU for PSTN can be installed give a brief description of the function blocks handling PSTN

access describe how PSTN access is defined in the AXE system when

connected to AXE Access 910.

Chapter Objectives

AXE Access 910

60

Figure 6.1Connection of PSTN subscribers

6.2.2 SubracksThe PSTN access units can be found in many different subracks:

MUS, Multiple Access Unit Switch subrackIf the access node is partly equipped, there will be less than 6 AUS in this subrack. In empty positions, there can be AUs for narrowband access.

NBA, Narrowband Access subrackThis subrack is specially made for narrowband access such as PSTN and ISDN-BA. It is up to the customer to decide the ration between PSTN and ISDN-BA.

MUA, Multiple Access subrackThe subrack is flexible and can have a mix of broadband and narrowband AUs. It is up to the customer to decide the ration between broadband, PSTN and ISDN-BA.

SIS, Single Switch subrackAlso this subrack can handle PSTN access as described in earlier chapters.

The NBA subrack can have up to 15 AUs. Assume that all of these are for PSTN. In that case, 450 subscriber can be served by one single subrack. Also the MUA subrack can have only PSTN access units if the customer wishes. In that case, also 450 subscribers can be served. In case of SIS, up to 12 AUs can be handled by the subrack. That corresponds to 360 PSTN subscribers. Figure 6.2 shows the configuration alternatives.

ET ET

ET

ET

ET

AUAUS

ET ET

ET

ET

MDF1

30

LIC

LICET

PSTN Access

61

Figure 6.2Configuration alternatives for PSTN access

6.3 HardwareThis chapter describes the ALB30 board from a functionality and hardware point of view. The ALB30 is the new board used to connect ordinary PSTN subscribers to the AXE Access 910. Basically, it contains the same functions as the former LIC board in SSS5, holding 4 or 8 Line Interface Circuits. However, due to increased board size and new building practice, it is possible to connect 30 PSTN subscribers to one AU board. The board contains the following functions:

Current feed of the subscriber line can be programmed to be 2 x 400 ohms resistive feed or 30 mA constant current

Ring signal and ring trip (up to 90V and frequencies set to 16, 20, 25 or 50 Hz)

Detection of off-hook (loop closures) Analogue to digital conversion and digital to analogue conversion 2- to 4-wire conversion Software controlled input impedance, balance impedance and levels V5.1 interface Over-voltage protection of the subscriber lines Control of the test access relays.

The board is built up around 4 basic parts:

1. LI, line interfaceA line interface built up with two integrated circuits referred to as SLIC (Subscriber Line Interface Circuit) and QSLAC (Quad Subscriber Line Audio processing Circuit)

2. NT, network terminalA network terminal terminating the 2 Mbit/s link between the AU and the AUS

MUSExample with 3 AUS:

NBA

MUA

SIS

6 positions for AU = 180 PSTN

Maximum 15 AU = 450 PSTN



(no broadband and no ISDN-BA)

(no ISDN-BA)

(no broadband and no ISDN-BA)

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3. AUC, access unit controllerA processor with memory and I/O ports

4. POW, powerA power unit which also generates ring current and, optionally, signals to private meters.

Figure 6.3 shows a simplified block diagram of the board.

Figure 6.3The AU board for PSTN access, AUP3

The processor has two memory types:

Flash memoryThis memory is used as a local backup instead of reloading all software from the CP in case of start-up or reload. This will make restarts faster.

RAM memoryWhen the processor is started or restarted, the contents of the Flash memory is copied to the RAM memory for normal program execution.

The I/O ports connected to the processor have the following functions:

Board positionThe position of the board in the subrack is given to the processor. Fixed for the address within the subrack and via a switch for subrack address.

PBIST, processor based built-in self testThis interface is a standard RS232 (V.24) interface used during manufacturing test. The interface can also be used for local trace and debug.

ACOMThe interface is a serial interface (RS485) which interconnects the AUs

SLIC

SLIC

SLIC

SLIC

SLIC

SLIC

QSLAC NTSpeechSynch.

Data

T.16

1

2

3

4

30

POW

AUC

SLIC

SLIC

SLIC

SLIC

~~

~

~

~

~

QSLAC

Flash

RAM

I/O

Board position

~~

~

RG + PRM-48V

-32V or -48V +5V

To/fromAUS

HDLC

(processor)

LI

PBIST (RS232)ACOM (RS485)

TAU(TestAccess)

PSTN Access

63

to a TAU. The TAU can send orders related to Subscriber Line Maintenance of software upgrades via this interface.

The functions for one subscriber line can be seen, in a simplified way, in Figure 6.4.

Figure 6.4Functions for one subscriber

The SLIC performs the 2- to 4-wire conversion and the QSLAC performs analogue to digital conversion (and vice versa).

6.4 SoftwareSome of the blocks in SSS are dedicated to PSTN access. For access in general, there is a so called set of parts called AUV5, Access Units V5. Some of the blocks in AUV5 are dedicated to PSTN access and they can be seen in Figure 6.5.

Figure 6.5Blocks in AUV5 for PSTN

TAU

Overvoltageprotection

Ringrelay

Ringingsignal

SLIC

Batteryvoltage

Data

Speech QSLACSpeech

(TestAccess)

Hardware

Load

AUPSTN

Local Exchange

Module

AXE Access 910

DLAU CTRLAU PSTN

DLAU CTRLAU PSTN

AUPSTN

LIMALIAU CPRM

V5.1

Central Software

Regional Software

HardwareRPG

in AU processor

GAM SAH

GAM

SAH

Regional Softwarein EMRP-T

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AUPSTN, Access Unit PSTN. The function block AUPSTN is divided into a number of sub software units (CAY). Each CAY is assigned specific functions for configuration, traffic handling, maintenance, measurements, etc. The main functions handled by AUPSTN are:

- Current feeding of the subscriber lines.- Analogue to digital conversion.- Line signalling.- Digit reception.- AU V5.1 System Management and Layer 3 of the Control

protocol.- AU PSTN V5.1 Layer 3 port control protocol.

DLAU, Data Link Layer V5. The function block DLAU is the data link layer handling block for V5.1. It implements the envelope function, the mapping function, the flow control function and the data link handling.

CTRLAU, Control Access Unit. The function block CTRLAU performs message and protocol handling of the control protocol messages that are conveyed over a V5.1 interface. It implements the V5.1 system management functions and performs the data link management for the control and PSTN data links.

PSTN, PSTN protocol handler. The function block PSTN performs message and protocol handling functions for the PSTN layer 3 messages that are conveyed over the internal V5.1 signalling interface.

CPRM, Central Private Metering. The function block CPRM is a command handling block which handles Private Metering connections. The block has commands for connection of Private Metering, disconnection of Private Metering and printing information about Private Metering connections.

GAM, Generic Access ManagerThe block allows the operator to connect, disconnect, and maintain signalling channels. In the case of Access 910, GAM is used for V5 and V3 signalling channels.

SAH, Stand-alone HandlerThe block handles PSTN emergency traffic if the control link to the local exchange is out of order (blocked due to a fault). The block has central software and regional software in the EMRP.

LIMA, Line Interface Multiple AccessThe block is the device owning block for AU connected PSTN user ports. It handles subscriber line functions via the V5.1 interface and the block participates in traffic handling, subscriber data administration, blocking/deblocking of subscriber lines and private metering.

PSTN Access

65

6.5 Operation

6.5.1 Definition of Access UnitWhen defining an AU, the operational instruction Multiple Access Group, Access Unit, Connect should be followed. The Access Units are defined by means of a number of commands. The command NNUPI defines the connection to the AUS and the command DTDII defines the digital path. The digital path is the function used to supervise the 2 Mbit/s link. Finally, the command EXPUI defines the AU as well as its position by stating name of the MACCG, subrack number and position within subrack:

NNUPI:NODE=AUS-0,PORT=7,DEV=LIAU-0;

DTDII:NODE=AUS-0,PORT=7,DIP=0LIAU;

EXPUI:MACCG=MACCG1,SR=1,PIU=AU-0,POS=3;

The digital link then has to be activated by the command DTIDC.

Figure 6.6 shows how the AU has been connected to the AUS (network node).

Figure 6.6Printout of Network Node with one AU connected

6.5.2 Connection of AU to V5The Access Unit is still not connected to the V5.1 interface. The command EXPCI will connect each port on the AU to a specific, fixed, time slot in the V5.1 interface. Interface number 0 will be connected to time slot 1, and the process continued until all the 30 interfaces have been given a time slot.

NNUPP:NODE=AUS-0;NETWORK NODE USER TO PORT CONNECTION DATA

NODE PORT DEV DIP INTCONNAUS-0 0 YES 1 YES 2 YES 3 YES 4 YES 5 YES 6 YES 7 LIAU-0 0LIAU 8 9 .. .. 25 26 RST-32&&-63 27 RST-0&&-31END

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As usual, time slots 0 and 16 are excluded as they are used for synchronization and V5.1 signalling.

EXPCI:PIU=AU-0,DIP=0LIAU,DEV=LIMA-0&&-29;

The command connected a PSTN access unit to the V5 interface.

6.5.3 Connection via Generic Access Manager, GAMGAM is a function for connecting several different types of accesses to the same signalling platform, the RPG-based signalling terminals in AXE. By having one common access manager, operation and maintenance is simplified. Each type of access (i.e. protocol) must have a dedicated RPG. This means that the TAU communication and V5 protocols have to be connected to different RPGs.

In GAM, the different applications are handled as different access groups. One access group comprises all interfaces connected to the same RPG. To connect the AUs to an RPG, the command below has to be used.

GNACI:DIP=0LIAU,AG=5,RPTYPE=RPG;

When the command is executed, GAM defines a path from the DIP stated in the command to an RPG belonging to the access group. The access group is created when the first interface is connected to it. By defining the same access group number, it is possible to connect more interfaces to the same access group. Figure 6.7 illustrates the general principle.

Figure 6.7GAM reserves a path between the DIP and the RPG

Figure 6.8 shows a printout of the access group to the AUs.

AU

AU

AU

AUSETC

GroupSwitch

RPG

CP-A CP-B

AU

T.16AG

DIP

PSTN Access

67

Figure 6.8Printout of Generic Access Manager data

6.5.4 Deblocking The defined AU has to be deblocked before service can start. The deblocking command is:

BLPUE:PIU=AU-0;

The command deblocks a Plug-In Unit (PIU) of type AU. If the DIP is not deblocked, the command DTBLE has to be used. Finally, devices, if any, connected to the AU have to be deblocked. The command EXPCP can be used to list all connected devices.

6.5.5 Connection of PSTN SubscribersThe command SULII command is used to connect an ordinary PSTN subscriber to the device:

SULII:SNB=1234567,DEV=LIMA-0;

6.6 Maintenance

6.6.1 Alarms and related OPIsThere are a number of alarms and related operational instructions connected to AU for PSTN:

Access Unit FaultThis alarm is generated if the AU is found faulty for some reason. This means that the AU itself is faulty and not the subscriber lines (probably).

Seizure Supervision Subscriber LinesIf activated for a subscriber line, it shows that the line has not been used during a specific period and may be faulty. This may be caused by a faulty line interface circuit on the AU.

Subscriber Line Blocking Supervision FaultThis means that too many subscriber lines are blocked. In most cases, it is caused by faults in the access network (e.g. faulty access cables).

Subscriber Line Circuit SupervisionThe alarm is generated when a line interface circuit (LIC) is faulty. It means that one or several LICs are faulty but not the whole board.

GNACP:AG=5;GENERIC ACCESS MANAGER CONNECTION DATA

AG ORDERAG APPTYPE RPTYPE DEV DIP TS CONCG5 5 RPG 0LIAU 16

END

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Subscriber Line Lockout Supervision FaultThe alarm is generated of a line has been on line lockout for too long time. This may be caused by a faulty line interface circuit.

6.6.2 Test InstructionsThe test instruction Subscriber Line Circuit in Multiple Access Group, Test should be used when testing line interface circuits after repair. It may also be used as a guide during general fault finding.

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7. ISDN Basic Rate Access

7.1 Chapter IntroductionThis chapter will give you a description of how ISDN basic rate access subscribers are connected to the AXE Access 910.

7.2 DescriptionISDN, Integrated Services Digital Network, was an idea about the ultimate network for voice, date and video. The first standards where set 1983-84. One part of ISDN is the interface to the network. Two types of interfaces where defined: one for private users or small companies The Basic Access (BA) , and one for larger companies the Primary Rate Access (PRA). The first type, the one for private users, was built up around a digital subscriber line with a bit rate of 160 kbit/s. The bit rate is divided in four main parts:

two so called B-channels of 64 kbit/s (B stands for bearer) one so called D-channel of 16 kbit/s synchronization of the bit stream maintenance (synchronization and maintenance share the remaining 16

kbit/s)

It took ISDN many years to reach higher penetration levels due to lacking of good products and low prices. During the past years, ISDN-BA access is more popular than ever due to the demand from Internet users. It is perfect for Internet access as the subscribers can surf and talk at the same time using the two B-channels: one for Internet access and one for a telephone call.

After completing this chapter, y

Testing 1 - AXE Access 910 Configuration and Verification

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