Digital Line Unit (DLU)

Information

Access

Digital Line Unit (DLU)

A30828-X1150-K100-1-7618

2 A30828-X1150-K100-1-7618

Digital Line Unit (DLU) InformationAccess

Trademarks:

All designations used in this document can be trademarks, the use of which by third parties for theirown purposes could violate the rights of their owners.

Copyright (C) Siemens AG 2000

Issued by the Information and Communication Networks GroupHofmannstraße 51D-81359 München

Technical modifications possible.Technical specifications and features are binding only insofar asthey are specifically and expressly agreed upon in a written contract.

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This document consists of a total of 57 pages. All pages are issue 1.

Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2 DLU Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.1 Central Functional Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.2 Peripheral Functional Units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132.3 Functional Units for Remote Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

3 DLU Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213.1 Central Functional Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213.1.1 Control for DLU (DLUC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223.1.2 Digital Interface Unit for DLU (DIUD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233.1.3 Digital Interface Unit for Local DLU Interface, Type D (DIU:LDID) . . . . . . . 253.1.4 Bus Distributor Basic Module for DLU (BDB) . . . . . . . . . . . . . . . . . . . . . . . 263.1.5 Bus Distributor Extension Module for DLU (BDE). . . . . . . . . . . . . . . . . . . . 283.1.6 Bus Distributor Module with Clock Generator for DLU (BDCG) . . . . . . . . . 283.2 Peripheral Functional Units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313.2.1 Subscriber Line Module, Analog (SLMA) . . . . . . . . . . . . . . . . . . . . . . . . . . 313.2.2 Subscriber Line Module, Digital (SLMD). . . . . . . . . . . . . . . . . . . . . . . . . . . 323.2.3 Subscriber Line Module, Extended (SLMX) . . . . . . . . . . . . . . . . . . . . . . . . 353.2.4 Subscriber Line Module Internet,

Feature programmable Modem, Type A (SLMI:FMA). . . . . . . . . . . . . . . . . 363.2.5 Subscriber Line Module Internet,

Symmetrical Digital Subscriber Line, Type A (SLMI:SDA) . . . . . . . . . . . . . 383.2.6 Subscriber Line Module Internet, Packet Hub, Type A (SLMI:PHA). . . . . . 403.2.7 Function Test Module for the Test Unit (FMTU) . . . . . . . . . . . . . . . . . . . . . 423.2.8 Line and Circuit Measuring Module (LCMM) . . . . . . . . . . . . . . . . . . . . . . . 443.2.9 Metallic Test Access A (MTAA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463.2.10 Metallic Test Access B (MTAB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473.2.11 Ringing and Metering Voltage Generator (RGMG). . . . . . . . . . . . . . . . . . . 473.3 Functional Units for Remote Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 493.3.1 Stand-Alone Service Control (SASC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 493.3.2 External Alarm Set (ALEX) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 503.4 Power Supply in the DLU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

4 Safeguarding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

5 Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

4 A30828-X1150-K100-1-7618


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1 IntroductionThe Digital Line Unit (DLU) is used in the Digital Electronic Switching System (EWSD)to connect the subscribers and to concentrate the subscribers’ traffic in the direction ofthe EWSD network node.

DLUs can be installed as part of the network node in an exchange (local) or as remoteconnection units in the vicinity of a subscriber group. Remote DLUs can be installed inpermanent buildings, in containers or in shelters (for small groups of subscribers). Theshort subscriber lines obtained in this manner and the concentration of subscriber trafficto the network node on digital and fiber-optic transmission links result in an economicalsubscriber network with optimum transmission quality.

The types of line that can be connected to a DLU are:– analog subscriber lines (plain old telephone service, POTS)– ISDN basic access (ISDN-BA)– high-bit-rate lines (aymmetrical digital subscriber line, ADSL.Lite, symmetrical digital

subscriber line, SDSL)– V5.1 interface

Analog subscriber lines and ISDN basic access give subscribers reliable, error-free ac-cess to the classical telephony services and access to the Internet via a point of pres-ence (PoP).

The Asymmetrical Digital Subscriber Line (ADSL.Lite) and the Symmetric Digital Sub-scriber Line (SDSL) represent a standardized, high-bit-rate and low-cost method of ac-cess to the Internet. As well as high-speed data access the ADSL.Lite and the SDSLalso offer the subscriber an analog telephone line. Optionally, SDSL also offers the al-ternative of an ISDN basic access.

The ADSL.Lite line and the SDSL line in the EWSD network node separate Internet traf-fic from voice traffic. The Internet traffic will be concentrated into the Packet Hub (PHUB)and routed past the switching network (SN) directly to the Internet Service Provider(ISP). Internet traffic thus does not impose a load on the EWSD network nodes.

A DLU also provides V5.1 interfaces to different subscriber access networks (AN). V5.1is the name of a standardized interface between non-system hardware such as an ANand the network node.

Integration in the system

The Digital Electronic Switching System (EWSD) is divided into a number of functionalareas. Independent subsystems are responsible for carrying out the tasks of each func-tional area.

The DLU is integrated in the functional area ”Access”.

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Features

The principal features of the DLU are:• Connection capacity of a rack

Depending on which modules are equipped and what traffic volume is to be carried– up to 952 analog subscriber lines or– up to 928 digital subscriber lines (ISDN basic access)– up to 384 ADSL.Lite subscriber lines– up to 192 SDSL subscriber lines

• High reliability is ensured by:– connecting each DLU to two Line Trunk Groups (LTG)– duplicating all DLU units performing central functions, with load sharing– continuous self tests

• High transmission capacity to the Internet• Cost-effective operation in local or remote mode• Transfer of Internet traffic without placing any additional load on the network node• Emergency service for remote DLU (RCU) in the event of total failure of the trans-

mission links to the network node.

Access Switchingnetwork

ControlManagement

Signaling

HTI

LTG

LTG

DLU

RSU

CP

CCG

SN

MB

SSNC* alternative

CCNC

NetManager

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Structure

The hardware units of the DLU can be grouped in several functional groups:• Central Functional Units• Peripheral Functional Units• Functional Units for Remote Operation

The central functional units in the DLU are duplicated and together form DLU systems0 and 1.

The peripheral functional units are:• Subscriber Line Modules (SLM)• Test Equipment• Ringing and Metering Voltage Distribution

The high-bit-rate subscriber line modules ADSL.Lite and SDSL and the packet hub areadd-on units to the peripheral functional units.

The functional units for remote operation include:• Stand-Alone Service Control (SASC)• External Alarm Set (ALEX)

Fig. 1.1 shows a view of the DLU functional units.

Fig. 1.1 DLU functional units

DLUs are installed in racks or shelters. The racks or shelters contain the module framesof the DLU for various combinations of subscribers (depending on the equipment vari-

Emergencycontrol

Testing andmeasurement

Ext. testsystem

Internetsubscribers

Digitalsubscribers(ISDN-BA)

Analogsubscribers

V5.1interfaces

DLU system0

Externalalarms

SASC

SLMA

TU

ALEX

RGMG

MTA

SLMD

SLMX

SLMIPHub

ATM25

LTG

Central Functional Units

Peripheral Functional Units

Functional Units for RemoteOperation

Internet

8 A30828-X1150-K100-1-7618


ant). The modules belonging to one DLU are installed in two rows in a module frame.The space for one row of modules is called a shelf.

For details of the mechanical design of the DLU (rack, frames, modules) refer to theMaintenance Manual Construction.

Interfaces

The DLU has the following external interfaces:• Subscriber interfaces

Analog and digital subscriber line modules provide POTS and ISDN functions in theDLU.The high-bit-rate subscriber lines ADSL.Lite and SDSL provide an economicalmeans of accessing the Internet.

• V5.1 interfacesNon-system hardware (subscriber access networks) can be connected to the DLUvia the Subscriber Line Module, Extended (SLMX)(max. 16 x 2 V5.1 interfaces (per frame)

• Interfaces to LTGConnection options for the DLU exist via one, two or four Primary Digital Carriers(PDC) to Line/Trunk Group (LTG) in B function.With the Local DLU interface (LDI) at the LTG, the DLU can be connected to a LTGvia one 4096-kbit/s link instead of two 2048-kbit/s links.

• Interface to the Internet service provider (ISP)

The DLU has the following internal interfaces:• ATM25 interfaces

Data and internet protocolls (Simple-Network-Management-Protocol, SNMP) be-tween ADSL.Lite/SDSL modules and packet hub are transmitted via ATM25 interfac-es.

• Control network interface (CN interface)The CN interface is used to control the modules via MML (man machine language)and for signaling of analog connections.

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2 DLU FunctionsThe Digital Line Unit (DLU) is subdivided into functional units:• Central Functional Units• Peripheral Functional Units• Functional Units for Remote Operation

2.1 Central Functional UnitsThe central functional units in the DLU are duplicated and form together the DLU system0 and 1. A DLU system consists of:• Control for DLU (DLUC)• Digital interface units (DIUD, or alternatively DIU:LDID)• Bus Distributor Module with Clock Generator for DLU (BDCG)• Bus systems

The central functional units are failure units. If a fault occurs in a central functional unitof one DLU system, calls can continue to be processed via the other DLU system (re-stricted load).

Control for DLU (DLUC)

The Control for DLU (DLUC) controls internal DLU functional sequences and distributesor concentrates signaling flows to and from the line circuits. To ensure reliability and toincrease throughput, the DLU contains two DLUCs. They work independently of eachother in task-sharing mode, so that the second DLUC can take control of all tasks if thefirst fails.

The DLUC is the point of departure for the DLU-internal control bus to the shelves. Allfunctional units that incorporate their own microprocessor are accessed via this bus.The units are polled for messages to be sent and accessed directly for the transfer ofcommands and data.

The DLUC also executes test and supervision routines and is thus able to detect errors.

Digital interface units

The digital interface units control the transmission of voice and signaling between DLUCand LTG.

There are the following types of digital interface unit:• Digital Interface Unit for DLU (DIUD)

The DIUD has two 2048-kbit/s interfaces for connecting two PCM30 highways or Pri-mary Digital Carriers (PDC PCM24). The PDCs link the DLU with line/trunk groups(LTG). Balanced-pair or coaxial cables can be connected.

• Digital Interface Unit for Local DLU Interface, Type D (DIU:LDID)The DIU:LDID has one 4096-kbit/s interface for the connection of a locally deployedDLU to LTG. When the DIU:LDID is employed, the contents of 60 speech/data chan-nels and one CCS signaling link are carried over a single 4096-kbit/s highway (in-stead of two PCM30 highways).

In addition, the DIUD and DIU:LDID provide interfaces to the DLU-internal 4096-kbit/sbus for the shelves. This 4096-kbit/s bus is used to distribute speech/data informationto the subscriber line modules (SLM) and to receive information from the SLMs.

The DIUD supplies the system clock (CLK) and FS to the SLMs and other functionalunits (e.g. TU, ALEX or SASC) via the bus distributor BDCG (BD part).

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Starting at the DIUD, a maximum of eight shelves (0...7) containing their own BD unitscan be accessed over separate lines (star topology). Clock signals are supplied to fouroutputs (0...3) of a shelf, each serving one quarter-shelf on one line (max. four SLMs).The SLMs have a clock selection facility.

A signal for synchronizing the clock generator is derived from the PDC’s line clock.

To detect errors, the DIUD and DIU:LDID execute test and supervision routines.

When a remote DLU is operating in stand-alone mode (because all connections to bothLTGs have failed), the DIUD generates call progress tones (dial tone, ringing tone andbusy tone). These tones are injected into the 4096-kbit/s bus via the PDC interface. Instand-alone mode, the transmit and receive channels have a fixed setting (loopback ofthe speech/data channels).

Stand-alone service is not provided for locally deployed DLUs. In such cases, theDIU:LDID does not inject tones or loop back the channels.

Bus Distributor Module with Clock Generator for DLU (BDCG)

The DLU clock can be regenerated from the line clock from the LTG in the DIUD(DIU:LDID). In the same way, the frame signal (FS) can be regenerated from the framealignment signal (FAS) of the PCM link.

The DIUD (DIU:LDID) synchronizes the clock generator (CG) with the 2048-kHz lineclock and the 4-kHz frame signal derived from the PCM line clock (LCLK) and forwardsboth signals to the functional unit BDCG (CG part). The CG uses these signals to gen-erate the 4096-kHz system clock (CLK) and the 8-kHz frame signal (FS), which it returnsto the DIUD.

The clock generator is duplicated (BDCG0 and BDCG1) for reliability.

The two clock generators (CG0 and CG1) operate on the master/slave principle. Undernormal conditions, the clock generator designated as the master is active while the slavegenerator is on standby. The master supplies clock signals to both DLU systems. If themaster should fail, the slave is activated and takes over the supply of clock signals toboth DLU systems. The clock generator can also be switched over by the operator(switch on the front panel of BDCG1).

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Fig. 2.1 Clock generation and distribution in the DLU

Bus systems

Central and peripheral functional units communicate over a duplicated bus system. Bussystem 0 handles the flow of information in DLU system 0 and bus system 1 serves DLUsystem 1.

The DLU bus systems include (Fig. 2.2):• Control buses

The control buses carry control information, i.e. customer line signaling and com-mands from the DLUC to the SLM, customer line signals and messages in the otherdirection. The control buses operate at a bit rate of 187.5 kbit/s in both directions,with an effective data rate of about 136 kbit/s.Control buses 0 and 1 originate at DLUC0 and DLUC1 respectively. A DLUC haseight interfaces (one for each possible shelf) at which the control lines to the BD unitsin the shelves originate. After the BD units, the control bus fans out in groups to themounting locations for those functional units that contain microprocessors. Bothcontrol buses, 0 and 1, extend to every mounting location in the shelves, enablingthe second bus to serve all mounting locations if the first should fail.In the BD units, the signals are regenerated and either fanned out again to other out-puts to the periphery or, in the case of signals originating at the periphery, concen-trated onto fewer lines.

0

1 70 0 2

PCMinter-face

BDCG1CG1

(Slave/Master)

LTG

Clock interface

Master/slave control

Generation of system clock (CLK) andframe signal (FS) and forwarding of

these signals to the partner CG

PCMinter-face

Signaldistribution

Signaldistribution

DIUD1(LDID1)

DLUC

LTG

1 2 7

BDB11-0

BDB00-0

BDE7-0

3

BDCG00-1

BDCG11-1

e.g.SLM 2-0

CLK, FS

BDE2-0

0 3

BDE2-1

BDE7-1

3

0

BDCG0CG0

(Slave/Master)

CLK, FS DLUC

CLK, FS CLK, FS

DIUD0(LDID0)

0 3 0 3 0 3 0 3 0 3 0 3 0 3

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• 4096-kbit/s busesThe 4096-kbit/s buses carry speech/data information to and from the SLMs. Eachbus has 64 channels in each direction and each channel operates at a bit rate of 64kbit/s (64 x 64 kbit/s = 4096 kbit/s). There is a fixed assignment between the chan-nels of the 4096-kbit/s buses and the channels of the PDC, determined through theDIUD or DIU:LDID.The 4096-kbit/s buses 0 and 1 originate at DIUD0 and DIUD1 (DIU:LDID0/1) respec-tively. A DIUD has eight interfaces (one for each possible shelf) at which the lines tothe BD units in the shelves originate.In the shelf, the information flowing on each of the two bus systems 0/1 is deliveredto all mounting locations for SLMs via a bus distributor module (BD). This means thatevery SLM can be reached by either of the two DLU systems.The signals traveling over the buses are synchronized with the clock.

• Collision detection busesThe collision detection bus is used to control the transmission of packetized X.25data on the D channel of an ISDN basic access.Its function is to prevent simultaneous access to the Bd channel. One time slot onthe 4096-kbit/s bus is assigned to the Bd channel.The collision detection bus is duplicated and works parallel to the 4096-kbit/s bus. Itis only relevant to SLMD, SLMX or internet module SLMI:SDA.

• Ringing and metering busThe ringing and metering buses feed ringing and metering voltage (RGMG0/1) to theBDBs and BDEs and perform selection (single feed) of subscriber line modules

Signal distribution is handled by:– Bus Distributor Basic Module for DLU (BDB)– Bus Distributor Module with Clock Generator for DLU (BDCG)– Bus Distributor Extension Module for DLU (BDE)

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Fig. 2.2 4096-kbit/s buses, collision detection buses and control buses

2.2 Peripheral Functional UnitsThe interface to the subscriber line is formed by the subscriber line modules (SLM), thetest equipment modules and the ringing and metering voltage distribution modules.

The peripheral functional units comprise the following modules:

Subscriber line modules (SLM)• Subscriber line module, analog (SLMA)• Subscriber line module, digital (SLMD)• Subscriber line module, extended (SLMX)• Subscriber line module Internet, feature programmable modem, type A (SLMI:FMA)• Subscriber line module Internet, symmetrical digital subscriber line, type A

(SLMI:SDA)• Subscriber line module Internet, packet hub, type A (SLMI:PHA)

4096-kbit/s bus 1 a. collision detection bus 0Shelf 0

TU

Shelf 7 (2...7)

SLMDIU0

DLUC0

BDCG0

BDE1

Control bus 0

BDB0

BDE0

SLM SLM

SLM SLMSLM SLM

Control bus 1

SLM SLMBDCG1

4096-kbit/s bus 1 a. collision detection bus 1

SLM SLM BDB1

DLUC1

DIU1

Shelf 1

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Test equipment• Function Test Module for the Test Unit (FMTU)• Line and Circuit Measuring Module (LCMM)• Metallic Test Access (MTAA or MTAB)

Ringing and Metering Voltage Distribution• Ringing and Metering Voltage Generator (RGMG)

Subscriber line module, analog (SLMA)

The Subscriber Line Module, Analog (SLMA) is used for the connection of analog sub-scribers to the DLU.

An SLMA contains four, six or eight analog subscriber line circuits (SLCA), dependingon the variant.

There are numerous variants for different types of line, including analog subscriber linemodules for DLU:– for ordinary subscribers (SLMA:COS), containing eight subscriber line circuits– with integrated SLIC, programmable, type B (SLMA:FPB) with eight subscriber line

circuits– for emergency telephone (SLMA:FPS) with four subscriber line circuits– with silent reversal for coinbox telephones (SLMA:CSR), containing four circuits– 12-kHz/16-kHz meter pulse injection, line reversal and loop open (SLMA:CMRL),

containing six circuits– for direct inward dialing (SLMA:DID), containing eight circuits (loop signaling)– for direct inward/outward dialing (SLMA:DIOD), containing four circuits

(pulse signaling)– for two-party lines (SLMA:TPL), containing four circuits for the connection of eight

subscribers via front-end equipment (secrecy box)

Subscriber line module, digital (SLMD)

A Subscriber Line Module, Digital (SLMD) contains eight digital subscriber line circuits(SLCDs), a control section with a system adapter, a line card processor (LCP), and aSystem Adapter Processor (SAP). Each subscriber line circuit provides an interface forthe ISDN Basic Access (BA).

Ringing AC voltage is not fed to the SLMD. The SLMD sends a digital ringing commandto the terminal and ringing tone is generated in the terminal itself.

Data are transmitted between the SLMD and the line side over a balanced 2-wire line atan overall data rate of 160 kbit/s. The overall data rate is made up of 144 kbit/sspeech/data information and 16 kbit/s for synchronization, supervision and diagnosis.The availability of 144 kbit/s for speech and data gives each subscriber simultaneousaccess to two B channels of 64 kbit/s each for the bit-transparent transfer of information(speech, text, data and images) and one D channel operating at 16 kbit/s.

The D channel is used to transfer signaling information between the subscriber and thenetwork node and for the transmission of low-bit-rate data (e.g. packetized X.25 data).

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Subscriber line module, extended (SLMX)

The Subscriber Line Module, Extended (SLMX) serves two V5.1 interfaces. Electrically,these interfaces correspond to the PCM interface in the DIU (2048 kbit/s according toETSI).

Any combination of the examples listed above is possible, within the limit of max. 32ports or 30 V5 time slots being assigned.

The following subscriber configurations e.g.can be implemented at one V5.1 interface:• ISDN subscribers/PBX = 1 B channel = max. 30 subscribers• ISDN subscribers/PBX = 2 B channels = max. 15 subscribers• PSTN = 1 B channel = max. 30 subscribers• ISDN packet data = no B channel = max. 32 subscribers

Subscriber line module Internet, feature programmable modem, type A(SLMI:FMA)

The ADSL.Lite function is implemented on the SLMI:FMA (Subscriber Line Module In-ternet: Feature programmable Modem, type A). The SLMI:FMA can be used in conjunc-tion with the Packet Hub only.

Each SLMI:FMA offers data functions and POTS functions simultaneously for eight sub-scriber lines. The voice and data traffic arriving via the subscriber line will be separatedin the SLMI:FMA. The analog telephone signals will be handled using the classical Sub-scriber Line Module Analog (SLMA). Data traffic will be transferred via ATM25 connec-tions to the Packet Hub.

Subscriber line module Internet, symmetrical digital subscriber line, type A(SLMI:SDA)

The SDSL function is implemented on the subscriber line module Internet, symmetricaldigital subscriber line, type A. The SLMI:SDA can be used in conjunction with the PacketHub only.

Each SLMI:SDA simultaneously provides data functions or ISDN functions for four sub-scriber lines.

The SLMI:SDA emulates the functions of the analog subscriber line module (SLMA) forlow bit rates at every analog subscriber line interface or emulates the digital subscriberline module (SLMD) for ISDN basic access arrangements. The incoming stream of voiceand data information from the SDSL network termination (SDSL-NT) is separated in theSLMI:SDA. The data stream is forwarded over ATM25 interfaces to the packet hub.

Subscriber line module Internet, packet hub, type A (SLMI:PHA)

The Module SLMI:PHA (Subscriber Line Module Internet, Packet Hub, type A) can al-ways only be used in conjunction with ADSL.Lite module SLMI:FMA and/or SDSL mod-ule SLMI:SDA.

The main task of the Packet Hub is to transfer to the network interfaces data receivedfrom the SLMI:FMA and SLMI:SDA (e.g. 100BASE-T, E3/T3 or E1/T1).

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For onwards transport of the data to the Internet Service Provider (ISP) there are differ-ent options, over:• ATM Multiplexer (cross connect function)• Broadband Remote Access Server (B-RAS)

Redundancy is another feature of the Packet Hub. In the case of redundant equipmentof a complete shelf, each Internet subscriber line module is connected to both PacketHubs via ATM25 interfaces. The Packet Hubs communicate via the ATM25 Cross Chan-nel.They operate in master/slave mode. If the master fails, the other Packet Hub takesover the entire traffic of all Internet subscriber line modules.

Up to fifteen SLMI:FMAs or SLMI:SDAs can be attached via front panel connectors.

Test unit (TU)

The Test Unit (TU) is used to carry out tests and measurements on subscriber lines(comprising the line termination, the subscriber line and the subscriber line circuit).

The Test Unit TU consists of two modules:– Function Test Module for the Test Unit (FMTU)– Line and Circuit Measuring Module (LCMM)

Modules FMTU and LCMM provide single elementary test steps. These are started bycommends from the TLF (translation function for subscriber line measuring) to the mod-ule. Modules FMTU and LCMM do not themselves contain any control programs whichare able to have whole sequences of such elementary test steps executed.

For electrical tests modules FMTU and LCMM need a metallic access option to the sub-scriber line and the SLC. The test buses are routed to the Metallic Test Access (MTA)for each shelf. For tests with the TU the test bus of the shelf involved is connected to theTU in the MTA.

The FMTU and LCMM contain identical functional parts. These include the processorpart, the signaling interface and the PCM interface.

Tests must be initiated by the operator using NetManager. The following can be tested:– analog line circuits– analog lines and terminals– feed to digital subscribers– digital lines– extended-range subscribers

The TU can measure voltage, current, resistance and capacitance; timing can also beevaluated in the case of voltage and current measurement.

Metallic Test Access (MTA)

The Metallic Test Access (MTA) allows external line testing systems to access the ana-log subscriber lines connected to a DLU.

There are two MTA variants:– Metallic Test Access A (MTAA)– Metallic Test Access B (MTAB)

The following functional units are used for the Metallic Test Access A (MTAA)(Fig. 2.3):– Metallic Test Access Module (MTAM)– Line Test Bus Access controller Module for DLU (LTBAM)

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The MTAM module contains two ports with identical functions for connecting up to twoexternal testing systems.

The MTAM is required for the DLU to which the external testing system is connected.

The LTBAM modules form the link between the NTT/OGT interfaces and the test bus.Two LTBAM modules, one with a Test Bus Access function (TBA) and one with a LineTest Access function (LTA), are used for each DLU.

The DLUs belonging to a Remote Control Unit (RCU) are connected together by meansof an inter-DLU test bus. All subscriber lines in the area covered by this bus are acces-sible via the MTA interfaces.

Up to four tests can be performed simultaneously on each DLU using external testingequipment.

Fig. 2.3 Metallic Test Access A (MTAA)

For the Metallic Test Access B (MTAB) (Fig. 2.4), one LTBAM module is installed foreach DLU. The external test equipment is connected to the LTBAM module in the DLUand, via the SLMA test coupling module, to the analog subscriber line to be tested. EachDLU is equipped with two measuring interfaces. Consequently, up to two tests can becarried out with external testing equipment simultaneously on one DLU.

All tests and measurements are carried out by means of the measuring interfaces locat-ed on the DLUs. They represent the metallic access for the local external testing/mea-

commoninterface

Digit asDIGIT BLOCK

Metallic test accessand Signalling

DLU

DLU-internaltest bus

LTBAM:LTA*

LTBAM:TBA

DLU

MTAM

Externaltest unit

CP

Identifica-tion of the

testsubscriberfrom thenumberdialed

setupcommand

* access to SLM (a/b wire) via LTA function

DLU

LTBAM:LTA*

LTBAM:TBA

DLU

LTBAM:LTA*

LTBAM:TBA

LTBAM:LTA*

LTBAM:TBA

18 A30828-X1150-K100-1-7618


suring equipment at the network node. The measuring interfaces of a DLU are used totest subscriber lines connected to that DLU.

The control interface is used to connect and disconnect the measurement interfaces. Itis implemented by means of a Mediation Function Personal Computer (MF-PC) at thenode, which is connected via control lines to an external testing system and to the Co-ordination Processor (CP). The MF-PC converts the message format which must beused to the system-specific message format.

Fig. 2.4 Metallic Test Access B (MTAB)

Ringing and Metering Voltage Distribution

Each Ringing and Metering Voltage Generator (RGMG) has access to a distribution sys-tem for ringing and metering voltage (ringing and metering bus). RGMG0 supplies allmounting locations for analog subscriber line modules SLMA in the left half-shelves(SLM0...7) via ringing/metering bus 0 and the BD units. RGMG1 supplies all mountinglocations for SLMA in the right half-shelves (SLM8...15) via ringing/metering bus 1 andthe BD units.

The connection from the RGMGs to the BD units is implemented as a ring.

If one RGMG is faulty, all BD units (BDB and BDE) can switch autonomously to the oth-er, intact RGMG, which then supplies ringing and metering voltage to the entire DLU.

Ringing voltage is applied through a short-circuit protection switch in the BD units andforwarded unamplified to the mounting locations in the associated half-shelf.

Conversion ofconnection com-mand into MMLcommand

Connectioncommands

CPDLU

LTBAM*

Connection command(Signalling)

* access to SLM (a/b wire) via LTA function)

Metallic testaccess

DLU

LTBAM*

DLU

LTBAM*

DLU

LTBAM*

Externaltest unit

MF-PC

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2.3 Functional Units for Remote OperationThe following modules are needed for remote operation:• Stand-alone service control (SASC)• External alarm set (ALEX)

Stand-alone Mode for Remote DLUs and RCUs

A DLU operates in stand-alone mode if it cannot communicate with at least one LTG viaa PDC with common channel signaling (CCS), e.g. in the event of total failure of the linksto the LTGs.

During stand-alone service for a remote DLU , the Stand-Alone Service Control (SASC)allows connected subscribers to set up connections to and from each other (internalDLU traffic) even when the connection to the controlling network node has been inter-rupted. In stand-alone service for push-button subscribers in the DLU, the SASC acti-vates the tone receivers to facilitate DTMF dialing.

The SASC handles signaling and speech paths between one DLU and another (up tosix DLUs in one Remote Control Unit, RCU) or between subscribers served by the sameremote DLU (e.g. shelter DLU).

In internal DLU traffic up to 30 connections (corresponding to 60 channels) can be han-dled simultaneously. The 31st connection attempt does not receive a dial tone, becausethere are no more free channels.

The SASC performs some important tasks during normal operation:– Supervisory functions such as

Storing DLU data (SLM information, subscriber data, e.g. directory numbers)Monitoring the integrity of stored code and dataPerforming diagnosis at the request of the DLUCMonitoring information received from the DLUC, e.g. state transitions

– Receiving and storing data from the LTG via the DLUC concerning changes to orexpansion of subscriber line circuits and subscriber lines

– Switching to stand-alone service when requests are received simultaneously fromboth DLUCs. The SASC starts to operate in stand-alone mode after a guard time of<60 s (after receiving the stand-alone service request from both DLUCs).

The main tasks performed by the SASC in stand-alone mode are:– Controlling the setup and release of calls between subscribers served by the same

DLU– Controlling the setup and release of calls to subscribers served by other DLUs in the

same RCU– Switching from stand-alone mode back to normal operation when the link between

one DLUC and the network node has been restored– Checking the database and updating it where necessary (after switching back to

normal operation)– Performing internal hardware routine tests and some supervisory functions (the

same supervisory functions as in normal operation)– Controlling the tone receivers

Alarm Handling

The External Alarm Set (ALEX) is used to forward up to 16 different external alarms (e.g.power failure, unauthorized access) to the NetManager and/or to the network node.

20 A30828-X1150-K100-1-7618


The functions of the ALEX are to:– identify, store and evaluate the state of up to 16 alarm contacts– exchange data with DLUC0 and DLUC1– test its own firmware and end communication with the DLUS if a firmware error is

detected– test its own hardware and report the detection of hardware faults

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3 DLU HardwareThe DLU hardware is made up of several major functional groups:• Central functional units• Peripheral functional units• Functional units for remote operation

The tasks performed by the functional units are implemented in modules. The followingblock diagrams only show the principal functional units of the DLU modules. Similarly,the interfaces are shown in extremely simplified form.

Fig. 3.1 Functional units of DLU

3.1 Central Functional UnitsThe Central Functional Units include as follows:• Control for DLU (DLUC)• Digital Interface for DLU (DIUD) or alternatively• Digital Interface for Local DLU Interface, Type D (DIU:LDID)• Bus Distributor Basic Module for DLU (BDB)• Bus Distributor Extension Module for DLU (BDE)• Bus Distributor Module with Clock Generator for DLU (BDCG)

RGMG0

Packet Hub(SLMI:PHA)

Shelf 0

Shelf 7

8

1 PDC0

SASC

TU

MTA (opt.)

SLMX (V5.1)

ALEX

BD..SLMA

..CG0

DIUD0

DLUCPDC1

DLU system 0

SLMD

SLMI:FMA

SLMI:SDA

to the Internet over:

E3,T3

E1,T1

25Mbit/sATM

Shelf 0

Shelf 7

PDC2

PDC3

100BaseT

8

1

12

8

1

4

1

1

0

22 A30828-X1150-K100-1-7618


3.1.1 Control for DLU (DLUC)The control for DLU (DLUC) controls the internal functional sequences in normal DLUoperation and in standalone operation, and distributes or concentrates the signalingmessages sent between the subscriber line modules. It then sends these messages tothe DIUD (or alternatively to the DIU:LDID) via a 64-kbit/s interface.

The main tasks of the DLUC module are:– receiving the data of the CCS signaling link, which is separate from the digital inter-

face units (DIUD or DIU:LDID), by means of the HDLC chip– reading the signals sent to the DIUD from the RAM by means of the DMA control

and inserting them in the CCS link to the DIUD with the aid of the HDLC chip– converting the formats similar to signaling system No. 7 to the control bus format for

the subscriber line circuits (SLC)– initializing the DMA with the buffer addresses, in order to transfer the data of the in-

put/output processor (IOP) to the RAM– performing supervisory and testing tasks– generating HDLC or SS7 signals– interrogating the SLMs cyclically– selecting the SLCs directly, in order to transfer commands and data– converting and forwarding emergency data between SLMCP and SASC– selecting the status display on the front panel of the module

Fig. 3.2 Block diagram of the DLUC module

The main components of module DLUC are (Fig. 3.2):

BD

A/D bus

I/O bus

DLU processor (DLUP)

RAM

Bank address register

ROM

Input/Output processor(IOP)

Direct Memory Access(DMA)

HDLC-chip

Status display on frontpanel

I/O decoding

DIUD

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DLU processor (DLUP)

The DLU Processor (DLUP) is implemented with a microprocessor and apart from per-forming safeguarding tasks (e.g. initiating the speech/data bus test) is mainly concernedwith format conversion tasks for formats related to SS7.

I/O decoder

The I/O decoder is used to select the ROM banks to be switched (via the bank addressregister), the HDLC chip, the IOP, as well as the status displays on the front panel.

Program memory (ROM, RAM, bank address register)

The address range of the DLUP is restricted to 64 kBytes as a result of the 16-bit-wideaddress bus; the top 40 kBytes are reserved for the RAM. The ROM is extended by sub-dividing the low address range into banks. These banks are selected by means of sep-arate write operations in a bank address register.

Input/output processor (IOP)

The IOP controls data communication with the peripheral functional units (e.g. SLMA)via the control bus and makes sure that the DLUP is executable (watchdog function).

DMA control

The DMA control facilitates data communication between the HDLC chip and the RAMand between the IOP and the RAM.

HDLC chip

The HDLC chip operates transparently. DMA control is used for the exchange of databetween the HDLC chip and the RAM. The HDLC chip only communicates with theDLUP directly by issuing transmit and receive interrupt requests and by exchanging con-trol register data.

Front panel of the DLUC module

The light emitting diodes (LEDs) on the front panel of the DLUC module provide infor-mation about the mode of operation of the DLU and the CCS.

3.1.2 Digital Interface Unit for DLU (DIUD)The DIUD has two interfaces for connecting two digital PCM30 carriers (PDC, or alter-natively for PCM24), which themselves connect the DLU to the LTG.

Important functions of the DIUD module:– transferring messages to and from the LTG in time slot 16 (CCS)– multiplexing and demultiplexing the 2048-kbit/s information from the primary digital

carriers (PDC0 and PDC1) on the 4096-kbit/s bus (speech/data bus)– synchronizing the clock generator with the 2048-kHz route clock and a frame align-

ment signal– echoing the time slot of the 4096-kbit/s bus during emergency operation– supplying dial tones, ringing tones and busy tones during emergency operation– in-service monitoring for the PDC transmission systems– indicating alarms on the front panel of the module by means of LEDs– PDC loopback for diagnosis

24 A30828-X1150-K100-1-7618


Fig. 3.3 Block diagram of modules DIUD and DIU:LDID

The main components of the module are (Fig. 3.3):

HDB3 interface

The HDB3 interface converts the DC-free line code to transistor-transistor-logic (TTL)signals.

PDC synchronization

The PDC synchronization circuit aligns the clock and frame signals to the PCM30 inter-faces and to the PCM24 interfaces. It obtains the synchronization information from theregenerated route clock and the frame alignment signal.

Time slot control

The tasks of the time slot control are as follows:– converting 2 x 2 Mbit/s signals to 4 Mbit/s signals– supplying audible tones in emergency operation– supplying the loop test tone (SLM)– connecting test loops

Speech/data bus interface

The speech/data bus interface makes 4-Mbit/s data and clock/frame alignment signalsavailable.

from/toshelves(via BD)

SLMD, SLMX

(via BD)DLUC

DLUC

HDB3inter-face

(LTG)

Time slotcontrol

CCSinterface

PDCsynchroni-

zation

(LTGinterface

forDIU:LDID)

2 Mbit/s

Collisiondet. bus

Emergencytone

generator

(loop testinterface forDIU:LDID)

Processor

CGClockcondi-tioner

Speech/data businterface

2 Mbit/s

4 Mbit/s

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CCS interface

Control information is exchanged between the LTG and the DLU on a common channelsignaling (CCS) link.

The CCS information which is received in time slot 16 of PDC0 is extracted from thisslot, converted to a continuous 64-kbit/s stream in shift registers and passed on directlyto the DLUC.

Processor

The processor– is used to control the bit-serial signaling interface to the input/output processors

(DIU:IOP) of the DLUC via the control bus– handles central control functions on the DIUD– analyzes alarms– monitors error thresholds– performs tests on the DIUD

Emergency tone generator

The emergency tone generator generates the audible tones (dial, ringing and busytones) during emergency operation, as well as a loop test tone for the speech bus, andevaluates the tones which are echoed back by the SLMA according to the instructionsit receives from the DLUP.

The audible tones which are generated by the emergency tone generator are suppliedto the 4096-kbit/s bus via the PDC interface.

Collision detection bus

The collision detection bus is used to control transfer of packetized X.25 data via the Dchannel of the ISDN basic access. It prevents simultaneous accesses to the Bd channel.A time slot is reserved for the Bd channel on the 4096-kbit/s bus.

Clock conditioner

In the DIUD, the line clock (LCLK) of 2.048 MHz is derived from the PCM30 link carryingthe CCS channel and forwarded to module BDCG for synchronization together with theline frame signal (LFS) of 4 kHz.

3.1.3 Digital Interface Unit for Local DLU Interface, Type D (DIU:LDID)The DIU:LDID module has a 4-Mbit/s interface for connecting a local DLU to a line trunkgroup with a B function.

This module performs the following functions:– Transferring data, timing signals and synchronization information from the 4096-

kbit/s transmission interface to the LTG– Inserting test loops– Generating and evaluating the checksums calculated for the 4096-kbit/s data stream

When the DLU is employed in local mode, DIU:LDID replaces DIUD. The constructionof the DIU:LDID is based on that of module DIUD. In terms of functions, the main differ-ences between this module (Fig. 3.3) and the DIUD are:

26 A30828-X1150-K100-1-7618


LTG interface

The following signals are transmitted between the LTG and the DLU:– 4096-kbit/s data– 4096-kHz clock– 8-kHz synchronizing pulse

Time slot control

If the DIU:LDID is used, there is no conversion from 2 Mbit/s to 4 Mbit/s. There is more-over no form of emergency operation when the DLU is used locally. No emergencytones are supplied.

Loop test interface

A test tone is transmitted to the SLM within the framework of the DLU-internal, routinePCM test; it is echoed there and evaluated on the DIU:LDID.

A transmitter generates checksums for the 4096-kbit/s data and inserts them in a vacanttime slot of the signal which is to be transmitted.

A receiver matches the received signals to the DLU system clock and monitors thechecksums.

3.1.4 Bus Distributor Basic Module for DLU (BDB)The bus distributor basic module for DLU (BDB) supplies the 4096-kbit/s bus information(64 time slots) from the DIUD to the various SLMs. The BDB selects one SLM for theDLU-internal control information with the aid of the 4-bit address information from theDLUC, whereby the serial interface of the SLM is connected to the IOP of the DLUC viathe BDB.

The connection between the RGMG0, RGMG1 and the two BDBs is fully transposed.During normal operation, RGMG0 supplies the left-hand half of the shelf and RGMG1the right-hand half.

If one RGMG fails, module-internal supervisory circuits detect the fault. The BDB deter-mines the failure by means of a signal and disconnects the ringing voltage for the halfshelf concerned. The BDB then switches over to the other RGMG. The BDB connectsthe ringing voltage line to the SLMA with the RGMG after a glare time has elapsed. Thevoltage limiting function for its own half shelf and for the RGMG is also the responsibilityof the BDB.

The BDB performs the following functions:– Distributing the information from the 4096-kbit/s bus to the subscriber line modules– Collecting voice information and forwarding it to the DLUC– Distributing ringing and metering voltage

Figures 3.4 and 3.5 show the bus distributor basic module BDB with the digital and an-alog functional units.

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Fig. 3.4 Bus distribution module BDB, digital part

The main components of the bus distribution module BDB, digital part (Fig. 3.4) are:• Clock and frame alignment signal

The internal DLU 4096-kHz clock (CLK) and the associated matched 8-kHz framealignment signal are each transferred from the DIUD and routed via the line driver.

• Speech/data transfer– Distributing the speech information in the receive direction

From the DIUD the whole speech/data information is sent to the BD. On the sub-scriber side the SLMs are collected into groups of four. One of the data lines leadsto each of these four groups. The speech information is extracted on the appro-priate SLM.

– Collecting the speech information in the send directionOn the subscriber side the 16 SLMs (maximum) are collected into four groups offour. From each of these groups data lines lead to the bus distributor.

• Signaling– Select and polling circuit

The select and polling circuit can be used to initiate blocking via the DLUC (or can-cellation of blocking) of the SLMs collected into groups of four. It can also deter-mine whether the ringing and metering voltage generators (RGMG) are error-freeand whether the supply voltage has failed in the half shelf.

– DecoderData from the DLUC are transferred to the bus distributor. After regeneration ofthe signal by the bus distributor the information must be distributed to the 16 mod-ules of the shelf.

– SelectorThe 16 SLMs transfer their information to the BD.

Clock and framealignment signal

DIUD

Speech/data transfer

SLM

Signaling

Selection andinterrogation

circuit

Selector

DLUC

SLM, DIUD

Decoder

28 A30828-X1150-K100-1-7618


Fig. 3.5 Bus distribution module BDB, analog part

The main components of the bus distribution module BDB, analog part (Fig. 3.5) are:• Ringing and metering voltage

The BDB distributes ringing and metering voltage to the half shelves.• Switchover unit

If a fault occurs in module RGMG0, the switchover unit transfers control to the re-dundant RGMG1.

• Voltage monitorAll DC voltages used in the half shelf are monitored.

3.1.5 Bus Distributor Extension Module for DLU (BDE)The bus distributor extension module is used exclusively in the DLU expansion shelves.

The functions and structure of the bus distributor extension module (BDE) are similar tothose of the BDB module. In addition to the 4096 kbit/s, collision detection bus and con-trol bus functions, the BDE also switches over the ringing current. A current limiting cir-cuit for the RGMG in the allocated half shelf is provided on the BDE module.

3.1.6 Bus Distributor Module with Clock Generator for DLU (BDCG)The bus distributor module with clock generator (BDCG) is redundant and contains twoseparate functional units.• Bus Distributor (BD)• Clock Generator (CG)

Bus Distributor Part (BD)

The bus distributor (BD) on the module takes care of the distribution tasks for DLU sys-tem 0 or 1 on shelf 0 or shelf 1. It distributes the speech/data information which is re-ceived from the DIUD, the frame alignment signal and the clock of the subscriber linemodules (SLM) on the shelf. In the opposite direction, the BD picks up the speech/datainformation from the various subscriber line modules and transfers it to the DIUD.

Interrogationcircuit

Ringing voltage

Metering voltage

RGMGSLM

DCC0, DCC1SLM,BDCG

Metering voltagedistribution

Ringing line

Voltage monitor

Switchover unit

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The functions of the BD part are:– Distributing the internal DLU clock (CLK) of 4096 kHz and the associated frame

alignment signal (FS) of 8 kHz– Transmitting voice information to and from the subscriber line modules– Transferring signaling information to and from the subscriber line modules

For the structure of the bus distributor BD part, see the bus distributor basic module forDLU (BDB).

Clock Generator Part (CG)

The clock generator (CG) generates the 4096-kHz system clock required by the DLU aswell as the associated frame alignment signal from the regenerated 2048-kHz line clockof PDC0 or PDC2 and the associated frame alignment signal (FAS).

The two clock generators operate on the master/slave principle. Under normal circum-stances the clock generator defined as the master is active whereas the slave clock gen-erator is in the standby state. The master determines the clock signals for both DLUsystems. Failure of the master clock generator causes a switchover to the slave clockgenerator which then also determines the clock signals for the two DLU systems.

The CGs perform phase synchronization through exchange and synchronization infor-mation, in which case the generator that is in the standby state synchronizes to a masterclock supplied by the active clock generator. If there is a fault the master and slave stateis swapped before a phase difference could have a detrimental effect in the periphery.

The functions of the CG part are as follows:– Generating and synchronizing the system clock of 4096 kHz and the associated

frame alignment signal (FS) of 8 kHz

Fig. 3.6 Clock generator CG part

from DIUD

Watchdog

IOP

Input section

Master/Slavepreselect

Phase regulation

Output section

LFSLCLK

CLKFS

to DIUD

partnerCG

30 A30828-X1150-K100-1-7618


The main components of the clock generator CG part are (Fig. 3.6):• Input/Output processor (IOP)

The IOP monitors the generation of the internal DLU clock and the correspondingframe alignment signal on module CG. The monitoring is performed using clock su-per-vision circuits for which the status is evaluated by the IOP.

• Master/slave preselectThe backplane wiring generally sets CG0 as the master. This master function isshown by a LED on the module faceplate. If however the signal connected to system1 should prove to be more stable, the configuration can be changed to master usingthe rocker switch on the faceplate of CG1 (on CG0 this switch has no function).

• Input sectionModules CG0 and CG1 obtain their 2048-kHz-line clock (LCLK) and the 4-kHz lineframe signal (LFS) from the appropriate DIUD or DIU:LDID. An input counter dividesthe 2048 kHz to 8 kHz and is synchronized by LFS.On each CG module the 8-kHz clock of the own input counter in the clock super-vi-sion circuit and the 8-kHz clock of the partner input counter are monitored. The clockof the partner module, subdivided to 8 kHz, is routed to the clock supervision circuitand the corresponding own 8-kHz clock is transferred to the supervision circuit of thepartner module.Both CG modules feed the 8 kHz clock subdivided by the master module into theirphase regulation circuit.

• Phase regulationPhase regulation consists of the Phase Locked Loop (PLL) and the phase lockedloop supervision. The phase discriminator obtains the clock subdivided to 8 kHz andcompares the 8-kHz clock derived from the oscillator frequency with the referenceclock.If the 8-kHz reference clock of the master module fails, switchover takes place to theclock of the partner.The phase locked loop supervision checks whether the 8-kHz clock output by theoutput divider is synchronized with the 8-kHz reference clock. Phase differencesgreater than 2ms lead to an alarm.If there is a phase alarm in the clock generator operating as the master then theclock generator which was previously operating as the slave assumes the masterfunction.

• Output sectionComing from the phase regulation circuit, the frame alignment signal and the 4096-kHz clock of both modules are routed to the output section. The frame alignment sig-nal and the clock are passed to the partner module. Since the two modules CG ob-tain the frame signal (FS) and the clock from the output counter of one of the twomodules, the requirement for synchronous operation of the two PCM bus systemsin the DLU is fulfilled.The frame alignment signals are checked by the clock supervision. The clock super-vision is responsible for its own 8-kHz FS select gate drive signal and for the corre-sponding signal from the partner module.Since the supervision circuits derive their input signal from the 8-kHz outputs of theoutput counters they also check the 4096-kHz clocks taken from the phase regula-tion circuit.If there is no error message for the master for its own frame signal FS then its ownclock and own frame alignment signal are switched through in the clock select to theDIUD or DIU:LDID.

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3.2 Peripheral Functional UnitsThe peripheral functional units comprise:

Subscriber line modules (SLM)• Subscriber line module, analog (SLMA)• Subscriber line module, digital (SLMD)• Subscriber line module, extended (SLMX)• Subscriber line module Internet, feature programmable modem, type A (SLMI:FMA)• Subscriber line module Internet, symmetrical digital Subscriber Line, Type A

(SLMI:SDA)• Subscriber line module Internet, packet hub, type A (SLMI:PHA)

Test equipment• Function Test Module for the Test Unit (FMTU)• Line and Circuit Measuring Module (LCMM)• Metallic Test Access (MTAA or MTAB)

Ringing and Metering Voltage Distribution• Ringing and Metering Voltage Generator (RGMG)

3.2.1 Subscriber Line Module, Analog (SLMA)The SLMA contains up to eight analog Subscriber Line Circuits (SLCA), depending onthe variant, and a shared control section with the processor (SLMCP).

The subscriber line module analog for ordinary subscribers (SLMA:COS) is used as thestandard module in the DLU.

The most important functions performed by the SLMA:COS module are as follows:– high-impedance line supervision for identifying events which occur in the idle state– high and low-impedance supply with loop short and ground fault supervision

(SLMA:COS only for normal subscribers with loop start)– receiving dial pulsing– transferring push-button dialing (DTMF)– unbalanced application of ring on the tip, ring tripping when the subscriber goes off-

hook– connecting the line and circuit sides to a test multiple– providing protection against overvoltage conditions and external voltages– DC decoupling for the speech signals– adjustable relative transmit and receive levels– adjustable 2-wire impedance– 2/4-wire conversion with programmable line balancing– encoding/decoding speech signals– fulfilling ITU-T transmission requirements– redundant PCM speech interface with 2x64 programmable time slots– signal preprocessing in the SLMCP– redundant signaling interface

32 A30828-X1150-K100-1-7618


Fig. 3.7 Block diagram of subscriber line module SLMA:COS


Subscriber line circuits analog (SLCA)

The subscriber line circuits analog (SLCA) on the SLMA:... modules are controlled by aprocessor (SLMCP). The SLCAs contain the necessary indication and feeding circuitsas well as the analog-digital and digital-analog converters for voice information.

Subscriber line module processor (SLMCP)

Every subscriber line module processor is linked to the two DLUCs over a duplicatedcontrol bus, and is hence able to control all call-processing functions on the module.

Voice/signal transmission

Exchange of data with the DLUC and the LTGs takes place through the voice/signaltransmission unit. It transfers call-processing, safeguarding and O&M information.

Test access

The test access unit allows a subscriber line circuit to be connected to the test bus onthe circuit side and on the line side. Consequently, the test unit (TU), under the controlof the LTG, is able to test the circuit side and the line side separately.

3.2.2 Subscriber Line Module, Digital (SLMD)The digital Subscriber Line Module (SLMD) accommodates eight digital subscriber linecircuits (SLCD) and the common control section. Each subscriber line circuit providesan interface for the ISDN Basic Access (BA).

Control bus 0

SLMCP

0

AnalogSub-scriberlines

4096-kbit/sbus 0

Sub-scriber

interface

Testconnector

Testmatrix

Speechconverter

Speechtrans-

mission

4096-kbit/sbus 1

Control bus 1

Signaltrans-

mission

7

Testmatrix

Speechconverter

Signaling

SLCA7

Signaling

SLCA0

Testingequip-ment

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The SLMD feeds a direct current converter in the Network Termination (NT), which inturn supplies the operating voltage to the interface circuits. The NT has a separate pow-er supply, to allow the terminal equipment to be fed via the S0 bus. During emergencyoperation, i.e. in the event of an AC line voltage failure at the NT, the telephones aresupplied with power by the SLMD via the S0 bus.

The functions of the SLMD are as follows:– transmitting the subscriber data on two-wire subscriber lines at a rate of 144 kbit/s

(two 64-kbit/s channels, one 16-kbit/s channel)– 2/4-wire conversion– transmission using the adaptive echo method– automatic matching if the wires of the subscriber line are interchanged– fulfilling transmission requirements (e.g. ETSI)– controlling the activation/deactivation procedure– remote-feeding of the Network Termination (NT) via the subscriber line– short-circuit and ground supervision for the subscriber line– providing protection against overvoltage conditions and external voltages– switching over the subscriber line and the subscriber line circuit for test purposes– controlling the data flow on the B and D channels with the aid of the Line Card Pro-

cessor (LCP)– redundant 4096-kbit/s bus with 2 x 64 programmable time slots for speech/data

transmission (B channels)– assembling and disassembling the D channel information, comprising signaling and

packet data– redundant collision detection bus for controlling packet data transfers in one time slot

(Bd channel) of each 4096-kbit/s bus– exchanging signaling data with the DLUC via the redundant control bus by means of

a single-chip microcomputer (SAP)– providing support for DLU system maintenance, e.g. diagnosis, on-line supervision

34 A30828-X1150-K100-1-7618


Fig. 3.8 Block diagram of subscriber line module digital SLMD


Extended PCM interface controller (EPIC)

The extended PCM interface controller (EPIC) routes the data on the B channels of theeight subscriber lines to the interface, and provides them with the system clock and theassociated frame alignment signal.

ISDN D-channel exchange controller (IDEC)

The ISDN D-channel exchange controller (IDEC) is a serial HDLC chip that supportspacket data transfer on the D channel of all eight subscriber lines.

High-level serial communication controller extended (HSCX)

The high-level serial communication controller extended (HSCX) controls the transmis-sion of packet data.

System adapter processor (SAP)

The system adapter processor (SAP) controls the exchange of data with the DLUC. Itreceives messages for the DLUC via the LCP.

Line card processor (LCP)

The line card processor (LCP) controls the flow of data on the module.

Bus and memory controller (BMC)

The bus and memory controller (BMC) is responsible for the access control of all com-ponents accessed by the SAP and LCP.

Control bus 1

4096-kbit/sbus 0

4096-kbit/sbus 1

Control bus 0

Testing equipment

Collision detectionbus 1

Collision detectionbus 0

NTSLCD0

LCP PROM

SLCD7

Control section

HSCX

EPIC

RAM

BMC SAP

IDEC

NT

Inter-face

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3.2.3 Subscriber Line Module, Extended (SLMX)To connect the V5.1 interface to the DLUs the Subscriber Line Module SLMX is used.This module services two V5.1 interfaces (Port 0 and Port 1), with a maximum of twotimes 32 channels. These interfaces correspond electrical to the PCM interface of theDIU (2048 kbit/s as per ETSI).

No ringing or metering voltage is supplied to the SLMX and it requires no voltage supplyby the voltage converter (DCC).

The main functions of module SLMX are:– Providing up to three communication channels (C channels) per V5.1 interface and

flexibly assigning the ISDN subscribers to the C channels– Optional analog subscriber line access (PSTN access)– Nailed-up connection (NUC) at 64 kbit/s for 1 or 2 B channels of an ISDN-BA– Layer-2 termination of the V5.1 protocol

Fig. 3.9 Block diagram of the SLMX module


V5.1 interface

The V5.1 interface consists of the line interface chip (ISDN Primary Rate Access Trans-ceiver, IPAT) and the frame aligner chip (Advanced CMOS Frame Aligner, ACFA). EachV5.1 interface has one of each of these two chips.

2048kbit/s

V5.1Port 0

Collision detec-tion bus 0Micro-

Con-troller

(QUICC)

EPROM(Flash)

V5.1-Interface

HDLCCon-troller

RAM

Voltage converter –48V / –60V

DLU-PCM-Bus-Inter-face(PCI)

4096-kbit/sbus 0

Control bus 1

Control bus 0

Collision detec-tion bus 1

4096-kbit/sbus 1V5.1-

Interface

Switchingmatrixchip

DLU-PCM-Bus-Inter-face(PCI)

2048kbit/s

V5.1Port 0

36 A30828-X1150-K100-1-7618


DLU-PCM interface (PCI)

The DLU-PCM bus interface (PCI) represents the interface to the DLU-PCM system.From the system side (DLU) the SLMX obtains the normal DLU interfaces to the twoPCM systems (4096-kbit/s buses and collision detection buses) of DLU side 0 and 1.

Switching matrix chip

A switching matrix chip on the SLMX is used to transfer the time slots between the V5.1interface and the DLU.

HDLC controller

The HDLC controller controls the three communications channels, the interface to theIOP:DLUC (control bus) and the interface to the frame handler (collision bus).

Microcontroller (QUICC)

The SLMX contains a microcontroller (QUICC) with integrated interfaces for:– HDLC with collision detection for the two Bd-DLU channels– UART (Universal Asynchronous Receiver/ Transmitter = interface module) for the

two asynchronous control bus interfaces to the two DLUs– UART as V.24 test interface

Memory

The EWSD contains the module’s firmware. The RAM (random access memory) is themodule’s working memory.

Power supply for SLMX

The SLMX requires no voltage supply by the voltage converter (DCC). The SLMX con-tains an on-board-DCC (+5 V).

3.2.4 Subscriber Line Module Internet,Feature programmable Modem, Type A (SLMI:FMA)On the module SLMI:FMA POTS functions and data functions are implemented in ac-cordance with the ITU-T G.Lite Standard.

The main characteristics of module SLMI:FMA are:– high-bit-rate access over the subscriber line– permanent alternation between voice and data– transmission rate (send) of 512 k/bit/s (upstream)– transmission rate (receive) of up to 1.5 Mbit/s (downstream)– ADSL-compatible– plug-and-play solution– permits greater range of loop to subscriber

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Fig. 3.10 Block diagram of the SLMI:FMA module


Broadband Multi channel Subscriber Line Interface Concept (B-MuSLIC)

The block for the POTS functions comprises the Broadband Multi channel SubscriberLine Interface Concept (B-MuSLIC). The B-MuSLIC supports the full range of integratedline testing functions (ILTF).

The B-MuSLIC supports all functions for analog modules (BORSCHT) with programma-ble transmission technology, charge pulse generation, feeding and integrated ringinggeneration. It consists of the following chips– Advanced High Voltage B-SLIC,– Broadband Quad Analog Front End for POTS (B-QAP),– Broadband Multichannel Processor for POTS (B-MuPP)– Subscriber Line Module Coordination Processor (SLMCP)

The Subscriber Line Module Coordination Processor (SLMCP) controls the POTSfunction. The SLMCP also provides the control interface to the classical EWSD (LTGand CP) for data communications.The SLMCP software is derived from the tried and tested POTS software of the SL-MA. In addition to controlling the analog connections, it includes the test functions ofthe SLMA including those of ILTF.

– Siemens programmable Interface Circuit for telecommunication Application (SICA)The SICA implements the interface to the control and 4096-kbit/s buses.

ADSL.Lite-DSP-Block

B-SLIC4...7

B-QAP

1

PLDfor FS

B-SLIC0...3

B-QAP

0

B-MuPP

Flash

SDRAM

DataPro-

cessor

SAR

ATM

ATM

DPRAM

SLMCP

SICAPCMRing/Tip

0

Ring/Tip7

CN

ATM25

ATM25

B-MuSLIC

PowerSupply +3,3V

+1,8V

-48V/-60V

38 A30828-X1150-K100-1-7618


ADSL.Lite-DSP-Block

The ADSL.Lite data stream at the interface to the subscriber is transferred in four soft-ware-programmable Digital Signal Processors (DSP).

Data Processor

Central control of data transfer for eight ADSL.Lite channels and the ATM25 interface isundertaken via data processor with integrated SAR function (Segmentation And Reas-sembly) for ATM interfaces.

Memory

Communication between SLMCP and data processor uses a dual-port RAM (DPRAM).

The synchronous dynamic random access memory (SDRAM) is used as the data andprogram memory in the SLMI:FMA.

The flash EPROM (flash erasable programmable read-only memory) contains the mod-ule’s firmware in compressed form.

Power supply

Two on-board DC converters generate the required logic voltages of +3.3 V and +1.8 V.

3.2.5 Subscriber Line Module Internet,Symmetrical Digital Subscriber Line, Type A (SLMI:SDA)The SLMI:SDA makes 12 more B channels available in addition to the standard ISDN-BA access arrangement (2 B + D). Furthermore, it is possible to use any of these addi-tional B channels for packet switching or circuit switching, as required. If transmissionquality is of great importance for a particular application, a suitable connection can beprovided by circuit-switching the 12 B channels; in other cases, the data stream is feddirectly into the packet-switching network.

The main characteristics of module SLMI:SDA are:– simultaneous ISDN and data services– compatible with the ISDN standard– plug-and-play solution– high bidirectional transmission capacity of up to 1048 kbit/s

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Fig. 3.11 Block diagram of module SLMI:SDA


SDSL transceiver MuBIC (multi-bitrate integrated circuit)

The SDSL transceiver MuBIC with a configured transmission rate of 928 kbit/s is usedfor the transmission of data to the NT of the subscriber line. It contains an analog frontend (AFE) and a digital signal processor (DSP) in a single package. The timing sourcefor the MuBIC chips is a 20.48-MHz clock. The MuBIC chips on module SDSL:SDA areoperated in slave mode, and so the TDM/IOM (time division multiplex/ISDN-orientedmodular) interface receives timing signals from an external clock, which is synchronizedwith the incoming (upstream) and outgoing (downstream) clocks.

Time division multiplex/ISDN-oriented modular interface (TDM/IOM)

In the TDM/IOM, the ISDN channels are decoupled from the TDM interface and fed tothe corresponding time slots of the IOM2 interface, and vice versa. The high-bit-rateuser data are transmitted unchanged to the core controller.

Core controller

The core controller consists of three main functional units:– CPU (PowerPC core)

The CPU is the main processor for the firmware in the SLMI:SDA.– Communications processor module (CPM)

The CPM contains the serial communication channels.

b3

a3

b1

a1

b0

a0

MuBIC

MuBIC

TDM/IOM

MuBIC

MuBIC

CoreController

SDRAM

FEPROMEPLD

ASICSCA2

DRAM

Powersupply

-48V/-60V

ATMinter-face

ATM25

Buffer

FSRAM

CN, CD, PCM, CLK(DLU interface)

3,3 V

5,0 V

2,0 V

ATM25

CPU CPM

SIU

b2

a2

40 A30828-X1150-K100-1-7618


– System interface unit (SIU)The SIU provides a variety of functions, e.g. control functions for system start, theclock and the processor bus.

SCA2 (SLM control ASIC)

The SCA2 is an application-specific integrated circuit (ASIC). It provides the duplicatedDLU interfaces.

The SCA2 in the SLMI:SDA has the following functions:– collision detection bus interface (CD)– PCM highway interface– CN interface– clock interface with timing supervision and PLL synchronization of timing signals– HDLC protocol termination for the Bd channels– switching matrix function for 32 B channels

SCA2-DRAM

The SCA2-DRAM is needed to store data buffers (Bd and CN channels) and initializa-tion data for the IC control functions.

ATM interface

The high-bit-rate data traffic passes through the duplicated ATM interfaces and onwardto the packet hub, after which it bypasses the switching network and is forwarded direct-ly to the Internet service provider (ISP).

Memory

The Synchronous Dynamic Random Access Memory (SDRAM) is used as the data andprogram storage for the SLMI:SDA.

The flash Erasable Programmable Read-Only Memory (flash EPROM) contains themodule’s firmware in compressed form. The boot section is stored uncompressed.When the processor is initialized, the boot program unpacks the code and copies it tothe SDRAM.

The Fast Static Random Access Memory (FSRAM) is used primarily as storage for buff-er data.

Power supply

Three on-board DC converters generate the required logic voltages of +5 V, +3.3 V and+2.0 V.

3.2.6 Subscriber Line Module Internet, Packet Hub, Type A (SLMI:PHA)The packet hub provides the Internet access via IP over PPP (Internet Protocol overPoint-to-Point-Protocol). The Internet traffic is passed into the ATM backbone directly.

The main characteristics of the module are:– forwarding of IP traffic without placing any additional load on the network node– traffic concentration– a high degree of flexibility in adapting to the requirements of different network con-

ditions

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Fig. 3.12 Block diagram of the SLMI:PHA module

ATM25 interface

The high-bit-rate subscriber line modules are connected via the ATM25 interface.

ATM MUX

The ATM MUX consists mainly of 3 high integrated devices.• ATM Layer Processor

– polices the incoming (upstream) traffic on the basis of configured policing param-eters

– collects the traffic statistical data for each connection– transforms the Local Address Identifier (LCI) into the external address scheme for

cells transferred in downstream direction• ATM Operation, Administration and Maintenance (OAM)-Processor

– handles the Loopback cells– monitors up to 128 connections

• ATM Buffer Manager– assigns connections up to 1024 queues

Inverse Multiplexing ATM (IMA)

The IMA (Inverse Multiplexing ATM) is method to combine several physical links to onelogical ATM link. On the packet hub the IMA is used to support ATM traffic via the E1/T1interfaces.

PHUBCore Controller

PCM30Framer

100BASE-T-Inter-

face

FramerE3/T3

FEPROM SRAM

SDRAM EEPROM

AT

M25

-Int

erfa

ce

AT

M M

UX

DLU0 DLU1DLU-Interface

PowerSupply

E3/T3

100BASE-T

E1/T1

10

23

Network-Interface

012

14

SLM-InterfaceATM25

DLU-InterfaceClock, Speechbus, CD-Bus and

Control Net- 48V/- 60V

CPU CPM SIU

IMA

42 A30828-X1150-K100-1-7618


Phub Core Controller

The Core Controller basically consists of three functional units:– CPU (PowerPC core)

The CPU is the central processor for the Packet Hub firmware– Communications Processor Module (CPM)

The CPM contains the serial communications interface– System Interface Unit (SIU)

The SIU connects the above functional units to the external bus

Memory

An SDRAM is used for the CPU data memory and an SRAM for the CPM data memory.The packet-hub firmware is stored in a flash EPROM. The EEPROM contains module-specific configuration data, for instance MAC addresses.

100Base-T interface

The 100Base-T interface carries IP traffic via Ethernet to the data network.

E3/T3 interface

The E3/T3 interface routes IP traffic via ATM to the data network.

Power supply

Two on-board voltage converters generate the necessary +5 V and +3.3 V logic voltag-es.

3.2.7 Function Test Module for the Test Unit (FMTU)Module FMTU is used for testing and monitoring the functions of the Subscriber Line Cir-cuit (SLC) and the subscriber station.

Module FMTU passes the connected line or circuit side on to module LCMM. Each testcircuit or each signal is connected via this module to the item under test (subscriber linemodule).

Modules FMTU and LCMM do not exchange any commands or messages with eachother.

The main functions of module FMTU are:– connecting the TU to a subscriber line circuit– feeding the subscriber line and loop indicator– setting loops between a/b and loop current indicator– sending and receiving ringing voltage– sending and receiving meter pulses– supervisory functions– pulse measurement– frequency measurement

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Fig. 3.13 Block diagram of the FMTU module


Connecting relays

The connecting relays allow the FMTU module to be connected to the test bus (eitherthe internal or external part of the test object).

Line current indicator

The line current indicator determines whether the disconnected subscriber wishes tomake a telephone call during the circuit test.

SLIC, SICOFI and 12-/16-kHz generator

The circuit comprising the SLIC, the SICOFI and the 12-/16 kHz generator is responsiblefor any necessary feeding during the subscriber line test, and it identifies loop closures.

Frequency measuring circuit

The frequency measuring circuit weights the amplitude and measures the frequency ofthe signals sent by the SLMA, meter pulses and ringing voltage.

4096-kbit/sbus 0

4096-kbit/sbus 1

module-in-ternal bus

FMTU

FMTU pro-cessor

a

PeripheralBoard

Controller(PBC)

Connectingrelay

SLIC SICOFI

12/16 kHz

Freq. measuringcircuit

Voltagemeasurement

Line terminations

Line currentindicator

Control bus 1

Control bus 0

SLM

b

Test relayson SLM

Subscriber LineCircuit (SLC)

SLMCP

LCMM

44 A30828-X1150-K100-1-7618


Voltage measurement

The voltage measuring circuit measures the tip and ring voltages to ground and calcu-lates the difference between the two. The FMTU processor determines the indicator in-formation concerning the operating status of the subscriber line from this difference.

Line termination

With the line terminations the a-wire and b-wire can be bridged with different impedanc-es (e.g. for loop resistance measurement).

Peripheral Board Controller (PBC)

The peripheral board controller (PBC) serves as an interface chip between the PCMbus, the SICOFI and the microprocessor.

FMTU processor

The FMTU processor controls the internal processes in the module.

3.2.8 Line and Circuit Measuring Module (LCMM)The LCMM module is used to measure levels, voltages, capacitances and resistances.It is required for the subscriber line test (integrated test position) and for the circuit test.The line and transmission parameters are measured with the LCMM module.

The main characteristics of module LCMM are:– voltage and capacitance measurement– measurement of loop, isolation and ground resistance– level measurement on the analog/digital side with filter evaluation– level sending to the analog/digital side– variable line termination– 2x300-ohm balanced line termination for measurement of rejection factor

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Fig. 3.14 Block diagram of the LCMM module

The main components of module LCMM are (Fig. 3.14):

Line and Circuit Processor (LCMP)

The LCMP is connected to control buses 0 and 1 via a serial channel and the signalinginterface. It controls the line and circuit signal processor (LCSP), the interface chip andthe Peripheral Board Controller (PBC).

Line and Circuit Signal Processor (LCSP)

The Line and Circuit Signal processor (LCSP) handles the tasks of level transmission,level reception and line parameter measurement. To do this it has access via the PBCto the 4096-kbit/s bus and is connected to the analog side via an A/D converter and aD/A converter.

b

4096-kbit/sbus 0

4096-kbit/sbus 1

Control bus 1

module-internalbus

FMTU

LCMP

LCMM

A

a

PBC

D

Connectingrelay

Control bus 0

A

D

Test relayson SLM

Subscriber LineCircuit (SLC)

SLMCP

SLM

LCSP

Measuringequipment

VoltageCurrent

46 A30828-X1150-K100-1-7618


3.2.9 Metallic Test Access A (MTAA)The metallic test access A (MTAA) allows test connections to be set up both from exter-nal test equipment and from the subscriber terminal being tested.

The main characteristics of the metallic test access A are:– low-impedance feeding when idle (NTT mode)– OGT mode with loop current monitoring– forwarding of dual-tone multifrequency (DTMF) signals– detection of error conditions– high-impedance feeding under error conditions– encoding/decoding of voice frequencies

The metallic test access A is implemented by:– the subscriber line module analog for metallic test access (MTAM)– the loop test and bus access module for DLU (LTBAM)

The main components of the subscriber line module for metallic test access MTAM are(Fig. 3.15):

Fig. 3.15 Subscriber line module analog for metallic test access MTAM

COSLAC

The main function of the COSLAC (customer-optimized subscriber line audio process-ing circuit) is to convert analog subscriber signals into digital form (A/D). In the oppositedirection, the COSLAC receives digitalized signals from the PCM30 links and convertsthem to the equivalent analog signals (D/A).

Voice transmission interface

The voice transmission interface supplies the digitalized voice signals from and to theCOSLAC for forwarding to the PCM bus system.

Processor for subscriber line module for DLU (SLMCP)

The processor for subscriber line module for DLU (SLMCP) controls and monitors theinternal processes in the module; for instance it communicates with the COSLAC andselects the clock for control of the module and for PCM communication.

Voicetransmission

interface

SLMCP

COSLAC0

COSLAC1 EPROM

RAM

Powersupply

a1

a2

b1

b2

CLK

-50 V

A30828-X1150-K100-1-7618 47

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Memory

The EPROM (erasable programmable read-only memory) contains the module’s firm-ware in compressed form.

The RAM (random access memory) is used as temporary working memory.

Power supply

The module is supplied with the required logic voltages of +12 V, -12 V, +5 V and -5 V.

3.2.10 Metallic Test Access B (MTAB)One LTBAM module is used for each DLU in the MTAB variant. The external testingequipment is connected to the LTBAM module and, via the test matrix SLMA, to the an-alog subscriber line that is to be tested. Each DLU has two measurement interfaces.Two tests can thus be performed simultaneously on a DLU using external testing equip-ment.

The subscriber line circuit which is to be tested is connected to the measurement inter-face by means of the test matrices provided for each circuit (four-wire connection to theshelf-internal test bus). The LTBAM module in turn connects this test bus to the mea-surement interface.

In order to connect the subscriber line circuit, the control of the external testing systemsends a command in a standard format to a special mediation PC via one of several se-rial data interfaces. This PC converts the connection command to an MML commandand forwards it to the CP. The CP determines which of the two LTGs is to be used fromthe parameters specified in the command and passes on the connection request. TheLTG then forms a setting command for the test matrixes of the subscriber line circuit andthe LTBAM.

3.2.11 Ringing and Metering Voltage Generator (RGMG)The Ringing and Metering voltage Generator (RGMG) generates the sinusoidal ringingand metering voltages required in the DLU for analog subscribers, as well as a synchro-nizing signal for connecting the ringing tone if necessary.

Various frequencies (16 2/3 Hz, 20 Hz or 25 Hz) must be set with the switches on theRGMG module for the ringing voltage and the ringing voltage magnitude (70 Volt or90 Volt).

The ringing and metering voltages are monitored for undervoltage conditions. If themonitoring circuit responds, the failure is indicated by the fact that the LED on the frontpanel of the module goes out and a relay with a relay contact drops out.

The functions of the RGMG in conjunction with the other modules of the DLU are:– generation of ringing voltage– monitoring of ringing voltage– generation of a synchronizing signal derived from the ringing voltage– generation of metering voltage– monitoring of metering voltage

48 A30828-X1150-K100-1-7618


Fig. 3.16 Block diagram of the RGMG module

The main components of module RGMG are (Fig. 3.16):

Forward converter

From the input voltage which is supplied, the forward converter generates the DC volt-ages required to generate the ringing and metering voltages.

Metering voltage generator

The metering voltage generator generates a sinusoidal metering AC voltage, the fre-quency of which must be set to different values (12 kHz or 16 kHz).

Voltage monitor

The voltage monitor monitors the ringing AC voltage and the metering voltage for und-ervoltage conditions and overload conditions.

Ringing voltage generator

The ringing voltage generator supplies a sinusoidal ringing AC voltage, the frequency ofwhich must be set to different values.

Synchronizing signal generator

The synchronizing signal is generated prior to every zero crossing of the ringing AC volt-age.

Alarm

Ringing voltage

Metering voltage

Synchronizing signal

Auxiliary voltageSynchroniz-ing signalgenerator

Voltage monitor

Voltage monitor

Ringing voltagegenerator

Forward converter

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3.3 Functional Units for Remote OperationThe functional units for remote operation include:• Stand-alone service control (SASC)• External alarm set (ALEX)

3.3.1 Stand-Alone Service Control (SASC)The stand-alone service control module (SASC) handles signaling and speech pathsfrom DLU to DLU (maximum of six DLUs in a Remote Control Unit, RCU) or users withina remote DLU. In addition, the SASC handles emergency operation for pushbutton us-ers in the DLU. The SASC is assigned the code receiver function to enable DTMF dialingfor pushbutton subscribers in DLU emergency service.

Fig. 3.17 Block diagram of the SASC module

The main components of module SASC are (Fig. 3.17):

Inter-DLU interface

In the SASC the line interface for each 4096 kbit/s bus is implemented with the ASICchip ASIC:LDIMX (Local DLU interface multiplexer). This generates and monitors theline clock and the frame synchronization signal and contains the interface to the internalsystem buses. The ASIC:EMU (equalization memory unit) is required to synchronize thevarious clock systems.

Time Switch Unit (TSU)

The Time Switch Unit is implemented by means of a chip (TSU). During inter-DLU trafficthe TSU assigns appropriate time slots on one of the two internal DLU 4096-kbit/s buses

4096-kbit/sbus 1

DLU businterface

(CPI)

HDLC

0

TimeSwitch

Unit(TSU)

Control range

4096-kbit/sbus 0

Control bus 1

Control bus 0

Inter-DLUinterface

EMU LDIMX

4 EMU LDIMXEMU

50 A30828-X1150-K100-1-7618


to the speech channels on the inter-DLU lines. Moreover, the TSU is needed to forwardthe assigned time slots on one of the internal DLU 4096-kbit/s buses to the Code Re-ceiver Processor (CRP).

DLU bus interface (CPI)

The DLU bus interface is implemented by the Control and PCM Interface circuit (CPI).The CPI handles the following:– Communication with the DLUC via the control buses– Interfaces to the DIUD via the 4096-kbit/s buses (speech/data bus)– Interfaces to the SASC Processor (SASCP)– Supervision of clock and frame signals from the 4096-kbit/s– SASC reset after start-up (initial start)

Control range

The control range of the SASC includes:– Control Net Processor (CNP)

The CNP communicates with the second processor (SASCP) via a dual port inter-face - i.e., a memory that is connected to two bus systems.

– SASC Processor (SASCP)The SASC Processor (SASCP) performs the central emergency functions. The ini-tialization and load programs are contained in an EPROM while the database is lo-cated in a RAM.

– Code Receiver Processor (CRP)8 code receiver functions are implemented on the SASC module for emergency op-eration for pushbutton subscribers. Messages are transferred between the CRP andSASCP by means of interrupts.

HDLC controller

The HDLC controllers extract and insert incoming and outgoing control information fromthe SASCP for the inter-DLU/DLU interface. They also perform the layer-2 functions(transport saving via HDLC). Two interface functions are implemented on each HDLCcontroller chip.

3.3.2 External Alarm Set (ALEX)The ALEX module is employed in the remote DLU. The ALEX responds to alarms exter-nal to the switching system (e.g.: fire, unauthorized entry, temperature exceeding a giv-en threshold, ...) and forwards the alarm information via the NetManager to the CP.

The main functions of the module are:– evaluating the status of external alarm equipment– reporting changes of status to the DLUC– testing the selection circuits by means of alarm simulation– testing the alarm simulation circuit

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Fig. 3.18 Block diagram of the ALEX module

The main components of the ALEX module are (Fig. 3.18):

Constant current source

The constant current source generates a constant test current of about 20 mA for thealarm indicators. The constant current source is activated and deactivated by the con-troller via an optocoupler.

Interrogation circuit

The interrogation circuit detects whether test current is flowing over the alarm contactsor through the hardware test circuit and passes this information on to the controller.

Hardware test circuit

The hardware test circuit is activated by the controller and switches all inputs of thealarm indicators to GNDR (ground for constant current source). This unique state of allalarm indicators allows the hardware to be checked.

Alarm indicators

The controller addresses the alarm indicators in turn and connects the test current toeach alarm contact in turn via the optocoupler. For protection against overvoltages atthe alarm inputs, the alarm indicators are connected via diodes.

Controlbus 1

Controlbus 0

Alarm 15

Supplyvoltage

Back-plane

Alarm-indicator 15

Alarm-indicator 0

Alarm 0

ALEX-CP

Watch-dog

Hardware testcircuit

Signaltrans-

mission

Voltagesuper-vision

PeripheralresetsignalPRS

Re-coverycircuit

Control section

Portexpan-

sion

Failuretest

Interroga-tion circuit

Constantcurrentsource

52 A30828-X1150-K100-1-7618


Controller

The main function of the controller is exchanging data with the two DLUCs. To guaran-tee this exchange of data the controller has further functions:– executing an independent start-up after the ALEX is plugged in, after power is re-

stored, after the watchdog expires or if polling from the two DLUCs does not occur– cyclic interrogation of the switching status of the alarm contacts by scanning– storage of the current switching status of all alarm contacts and comparison with

previous switching states– identifying hardware faults within the alarm handling circuits

A microcomputer (ALEXCP) coordinates the functions of the external alarm set ALEX.It has the following tasks:– determination, storage and evaluation of up to 16 alarm contacts– data exchange with the two DLUCs (DLUC0 and DLUC1)– testing its own firmware and aborting the data exchange with the DLUCs if a firm-

ware error is identified– testing its own hardware and reporting the results if a hardware fault is identified

3.4 Power Supply in the DLUThe power supply in the DLU is decentralized. Direct Current Converters (DCC) areused to feed power to the subscriber line modules (SLM) and other functional units inthe DLU module frames.Tab. 3.1

The direct current converters generate the DC voltages required by the SLMs from theexchange voltage –48 Volt/–60 Volt.

The system supply voltage is converted into electronics, ringing and feed voltage bymeans of DC converter systems. All output voltages are generated with metallic isola-

SLM typePower supply

DCCCR DCCDC DCCDD

SLMA:... x x

SLMA:FPB x

SLMA:FPS x

SLMD x*) x

SLMI:FMA x

SLMI:PHA**)

SLMI:SDA x

SLMX **)

Voltage values +12 V, -12 V,+5 V, -5 V

+12 V, -12 V, +5 V,-5 V, +51 V/+53 V,-67 V

+12 V, -12 V, +5 V, -5 V, -97 V

*) if, for example, the SLMD is fed by the exchange battery**) require no DCC (supplied by an on-board DCC)

Tab. 3.1 Direct current converters DCC

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tion. Only the feed voltage for SLMA is fed back with a diode inserted on the secondaryside at the negative pole of the system voltage.

With one DCC per half shelf, eight SLMs each with 8 subscribers can be supplied. Thispermits the failure width to be restricted to 64 subscribers. Because of the feedback di-ode, a short-circuit type load of the feed voltage for SLMA is only prevented via the inputfuse, in which case 12.5 A can flow via the SLMA for 0.5 sec. with synchronous short-to-ground of all subscribers.

Each half shelf in the module frame has its own power supply module for SLMA orSLMD. The direct current converter supplies the electronic voltages +5 V, –5 V and +12V, –12 V. Additional voltages of –68 V and +53 V are provided for the SLMA with SLIC(SLMA:FPB), as well as a remote supply voltage of –97 V for the SLMD or SLMI:SDA.

When the DLU is equipped with SLMAs, SLMDs or SLMIs a DCCCR, DCCDC or DC-CDD is plugged in, depending on the application, and this supplies the entire half shelf.

In principle the SLMI:FMA and the SLMI:SDA can be equipped at all module places ofan SLMA resp. SLMD. In the case a half shelf is equipped with SLMA resp. SLMD whichuses the DCCCR and a SLMI will be installed in this half shelf, the DCCCR has to bereplaced with the DCCDC or the DCCDD.

The subscriber line module, extended (SLMX) as well as SLMI:PHA (on-board-DCC) donot require a direct current converter since -48 V/-60 V is supplied directly to its ownmodule.

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4 SafeguardingOnly small parts of the safeguarding software are implemented in the DLU itself. Themost important parts of this software are implemented in LTG and CP.

The main safeguarding functions of the LTG are error detection, fault treatment and re-covery, i.e. initializing and reloading the DLU.

The CP coordinates all the safeguarding tasks which the LTG is unable to handle (e.g.combined fault reports).

The essential safeguarding functions are outlined below.

Fig. 4.1 shows the DLU-specific safeguarding system and how it is distributed over thefunctional units.

Fig. 4.1 Units with DLU safeguarding functions

Error detection

Errors are detected by various means:• Plausibility checks

Plausibility checks are performed throughout the system. Safeguarding processesprovide their own protection with the aid of consistency checks (audits) and super-visory timers.When a process detects an error, it activates fault analysis for software errors and indoing so updates the error records

• AuditsThe task of audits is to monitor certain software areas of the LTG and DLU.

• Routine test and diagnosisDLU routine test (automatic) and diagnosis (operator input) tests hardware units andlocates hardware faults. The purpose of diagnosis is to verify errors that were de-tected by the routine test. DLU diagnosis provides support in the following activities:– testing the operability of a DLU before it is taken into service– identifying faulty modules– checking the operability of a DLU after module replacementThe routine test and diagnosis detects hardware faults that cannot be detected dur-ing normal program execution.

HierarchyProcessors

DLUCx

LTGy with B function

CP

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Fault treatment

Fault treatment in LTG deals with fault reports from the LTG and DLU error detectionprograms. Fault treatment covers the entire system (CP, LTG, DLU, SLM). Its functionsare to:– evaluate error events– select appropriate fault treatment action– collect error symptoms– keep error statistics

Fault treatment evaluates errors by assigning them an error number. This number de-scribes the error event and assigns it to a specific class of errors for which the sametreatment applies. Errors are defined in relation to a configurable unit in DLU or LTG(DLU equipment, DLU module, DLU port, DIU in LTG). Fault treatment action includes:– configuring the faulty unit– releasing, blocking or allowing call processing activity for the unit concerned– informing the CP of error-related action and the operating state of the unit before and

after the fault– executing recovery for the failed unit after repair or end of the fault condition– measuring the duration of recovery– ignoring the fault– producing fault statistics

Depending on the type of fault or the type of unit affected, fault treatment branches to:– DLU fault analysis– fault treatment for DLU units (e.g. SLM)– CCS fault analysis– software error treatment– statistical error treatment– line fault treatment

Recovery

Recovery actions have the aim of restoring units to an operable condition.

Recovery for the DLU itself is started either in response to software errors or in connec-tion with configuration. There are several degrees of recovery which differ in the extentto which they affect the system as a whole:• Restart

Resetting and initializing a specific process to defined starting conditions. This neveraffects more than one established call.

• New startResetting all processes and restarting operation, without loss of any establishedcalls.

• Initial startResetting all processes and initializing the periphery. This involves releasing all es-tablished calls and, if necessary, reloading code and/or semipermanent data.

For the SLMX only the recovery level initial start is provided.

Recovery is not able to deal with hardware faults. Its only role in this connection is to re-initialize and load the database after a power failure.

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5 Technical DataConnection capacitySubscriber lines (per rack) up to 952 analog subscriber lines

up to 928 digital subscriber lines (ISDN-BA)max. 384 ADSL.Lite subscriber linesmax. 192 SDSL subscriber lines

V5.1 interfaces max. 16 x 2 V5.1 interfaces (SLMX) in the extensionframes

Multiplex highwaysBetween local DLU and LTGB,LTGFB, LTGGB

2048-kbit/s or 1544-kbit/s primary digital carriers(PDC)*

Between local DLU and LTGMB,LTGNB

2048-kbit/s PDC

Between local DLU and LTGFB,LTGGB, LTGMB, LTGNB

4096-kbit/s multiplex highways

Between remote DLU and LTGB,LTGFB, LTGGB, LTGMB, LT-GNB

2048-kbit/s or 1544-kbit/s PDC*

* 1544-kbit/s-PDC only with PCM24

Transmission methodsTransmission method on PDC in accordance with CCITT Recommendations

G.703, G. 704 (HDB3 protocol)

Transmission method on the4096-kbit/s multiplex highways

Proprietary method

Traffic-handling capacity (voice/data channels)With four 2048-kbit/s PDCs(120 voice/data channels)

up to 100 erlang

With two 2048-kbit/s PDCs(60 voice/data channels)

up to 50 erlang

Similar performance is achieved with four1544-kbit/s PDCs (94 voice/data channels) and withtwo 1544-kbit/s PDC (46 voice/data channels)

Voice/data buses (4096-kbit/s buses) between SLC and DIUD or DIU:LDIDNumber per DLU 2 x 4096-kbit/s buses

Bit rate 4096 kbit/s per system 0, 1

Number of channel pairs per4096-kbit/s bus

64, <60 available for calls in normal mode

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Number of channel pairs per DLU 128 (2x64), <120 available

Bit rate per channel 64 kbit/s

Control buses between SLM and DLUCNumber per DLU 2 control buses, in star topology

Effective bit rate/physical bit rate

136 kbit/s/187,5 kbit/s

Clock signals 4096 kHz and 8 kHz (frame mark bit)

Internet Interfaces to the Data Transport Network4 x E1/T1 2 Mbit/s (PCM30) or 1,5 Mbit/s (PCM24) for FR-traf-

fic or ATM IMAE3/T3 34 Mbit/s or 45 Mbit/s for ATM-trafficEthernet 100Base T 100 Mbit/s for IP-traffic

Operating voltages +5 V/ –5 V, +12 V/ –12 V, +51 V/+53 V,–68 V...–67 V, –97 V

Battery voltage –48 V or –60 V

Documents

Digital Line Unit (DLU)