Digital Line Unit G (DLUG)

Information

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Digital Line Unit G (DLUG)

A30828-X1150-K109-2-7618

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Digital Line Unit G (DLUG) InformationAccess

f Important Notice on Product SafetyElevated voltages are inevitably present at specific points in this electrical equipment. Some of theparts may also have elevated operating temperatures.

Non-observance of these conditions and the safety instructions can result in personal injury or in prop-erty damage.

Therefore, only trained and qualified personnel may install and maintain the system.

The system complies with the standard EN 60950 / IEC 60950. All equipment connected has to complywith the applicable safety standards.

The same text in German:

Wichtiger Hinweis zur Produktsicherheit

In elektrischen Anlagen stehen zwangsläufig bestimmte Teile der Geräte unter Spannung. Einige Teilekönnen auch eine hohe Betriebstemperatur aufweisen.

Eine Nichtbeachtung dieser Situation und der Warnungshinweise kann zu Körperverletzungen undSachschäden führen.

Deshalb wird vorausgesetzt, dass nur geschultes und qualifiziertes Personal die Anlagen installiert undwartet.

Das System entspricht den Anforderungen der EN 60950 / IEC 60950. Angeschlossene Gerätemüssen die zutreffenden Sicherheitsbestimmungen erfüllen.

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 2000-2001.

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 34 pages. All pages are issue 2.

Contents

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

2 DLUG Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.1 Central Functional Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.2 Peripheral Functional Units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.3 Functional Units for Remote Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 162.4 DLU for V5.1 Interfaces (DLUV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182.5 Transmission Systems in the DLUG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

3 DLUG Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193.1 Central Functional Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193.1.1 Control for Digital Line Unit (DLUC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193.1.2 Bus Distributor Module (BDG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.2 Peripheral Functional Units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213.2.1 Subscriber Line Module, Analog (SLMA) . . . . . . . . . . . . . . . . . . . . . . . . . . 213.2.2 Subscriber Line Module, Digital (SLMD). . . . . . . . . . . . . . . . . . . . . . . . . . . 223.2.3 Subscriber Line Module with Internet Access,

Feature-Programmable Modem (SLMI:FMx) . . . . . . . . . . . . . . . . . . . . . . . 243.2.4 Subscriber Line Module with Internet Access,

Asymmetrical Digital Subscriber Line (SLMI:AMx) . . . . . . . . . . . . . . . . . . . 243.2.5 Subscriber Line Module with Internet Access,

Symmetrical Digital Subscriber Line (SLMI:SDx) . . . . . . . . . . . . . . . . . . . . 253.2.6 Subscriber Line Module with Internet Access, Packet Hub

(SLMI:PHUB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263.2.7 Subscriber Line Module with Internet Access, Modem

Pool Card (SLMI:MPx) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263.2.8 Metallic Test Access Type B (MTAB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273.3 Functional Units for Remote Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 283.3.1 Standalone Service Control (SASC-G) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283.3.2 External Alarm Set (ALEX) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

4 Safeguarding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

5 Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

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1 IntroductionThe digital line unit G (DLUG) is used to connect subscriber lines to the switch and toconcentrate the traffic on those lines in the direction of the network node.

DLUGs can be installed as an integral part of the network node or located outside thenode, in the vicinity of a group of subscribers. Remote DLUGs can be installed, for in-stance, in permanent buildings, containers or shelters (for a very small group of subscri-bers). Reducing the length of the subscriber lines in this way, and concentrating the linetraffic to the network node onto digital and optical transmission links, results in an eco-nomical line network with optimum transmission quality.

The following types of line can be connected to a DLUG:– analog subscriber lines (plain old telephone service, POTS)– ISDN basic access arrangements (ISDN-BA)– high bit-rate xDSL lines operating at up to 8 Mbit/s, such as: G.Lite (asymmetrical

digital subscriber line (ADSL) with reduced bandwidth), asymmetrical digital subs-criber line (ADSL), symmetrical digital subscriber line (SDSL)

– V5.1 interfaces (DLUV)– line/network termination modules LTCD

Analog subscriber lines and ISDN basic access lines provide subscribers with reliableaccess to conventional telephone services and access to the Internet via a point ofpresence (PoP).

Internet traffic using xDSL services is separated from voice traffic in the DLU, before re-aching the rest of the switch. It is concentrated in the packet hub (PHub) and routed di-rectly to the Internet service provider (ISP), without placing any load on the networknode.

The DLUG provides a V5.1 interface for the connection of other vendors’ access net-works (AN). V5.1 is the name of an interface standard that allows different vendors’hardware to inter-operate, for instance an AN and a network node.

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Features

The DLUG offers the following main features:• High traffic capacity (up to 390 erlangs)• High level of reliability, assured by

– connection of the DLUG to up to four line/trunk groups (LTG)– duplication of DLU units, with centralized functions and load sharing– continuous self-tests

• High transmission capacity to the Internet (data rate up to 8 Mbit/s)• Cost-effective deployment, with a choice of local or remote operation• Separation of Internet traffic, sparing the load on the network node• Emergency mode in remote DLUs in the event of total failure of the transmission

links to the network node• Reduced footprint (50% less)• 30% reduction in the power dissipation of analog ports• Small failure units of 32 analog ports• Complete freedom to mix SLMA and SLMD• Up to 8 packet data channels between DLUG and frame/packet handler

For more detailed performance data, see Technical Data.

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 DLUG are grouped in three major sets of functional units:• central functional units• peripheral functional units• functional units for remote operation

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

The peripheral functional units comprise:• subscriber line modules (SLM)• test equipment

The high bit-rate subscriber line modules for ADSL, G.Lite and SDSL, and the packethub, are add-on units to the peripheral functional units.

The functional units for remote operation comprise:• standalone service control (SASC)• external alarm set (ALEX)

For information on the mechanical design of the DLUG see Maintenance Manual Me-chanical Design.

Bild 1.1 gives an overview of the structure of the DLUG functional units.

Bild 1.1 DLUG functional units

Standalone ser-vice control

Digital lines(ISDN-BA)

Analog lines

V5.1 interfaces

External alarmset

Line/net-work termi-

nation LTCD

SASC

DLUV

SLMA

SLMD

ALEX

Internetusers

SLMI PHub

HBRS (high bit-ratestar interface)

Central functional units

Peripheral functional units

Functional units forremote operation

Internet

LTGDLU side 1

(DLUC)

DLU side 0(DLUC)

Test bus LTBAM

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Interfaces

The DLUG has the following external interfaces:• Subscriber line interfaces

POTS and ISDN functions are provided via the analog and digital subscriber linemodules in the DLUG.The high bit-rate xDSL subscriber lines offer cost-efficient access to the Internet.

• Interfaces to LTGThe DLUG can be connected to line/trunk group N (LTGN) via up to 16 primary di-gital carriers (PDC).The local DLU interface (LDI) in the LTG allows the DLUG to be connected to anLTGN via four 4096-kbit/s links instead of eight 2048-kbit/s links.

• ISP (Internet service provider) interface

The DLUG has the following internal interfaces:• ATM interfaces

Data traffic and Internet protocols (simple network management protocol, SNMP)are transmitted between the xDSL modules and the packet hub via the ATM inter-faces.

• Control network (CN) interfaceThe CN interface is used for module control by means of MML and for line signalingfor analog calls.

Transmission systems in the DLUG

The transmission systems implemented in the DLUG support connections to the net-work node and to other remote DLUs (e.g. remote shelter), and if required to other 2-Mbit/s interfaces such as to V5.1 networks.

For these functions, the DLUG can be equipped with HDSL (high-rate digital subscriberline) transmission systems for copper cable.

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2 DLUG FunctionsThe sequence of functions required to handle a call request and their path through thenetwork node are illustrated in Fig. 2.1

Fig. 2.1 Schematic of the functional sequence of a call request

Call request by a calling subscriber

The subscriber line modules (SLM) detect the calling subscriber’s call attempt throughtheir cyclic polling of the subscriber lines, and report detection to the control for DLU(DLUC).

The DLUC forwards the call request to the group processor (GP) in the LTG.

The GP then identifies the subscriber’s line category by interrogating its database, se-lects a free timeslot for the call on the channels leading to the switching network (SN),and sends a message to the coordination processor (CP) with information on the callrequest and the selected timeslot. The GP makes a corresponding selection for the con-nection to the DLU and sends a message identifying the selected timeslot to the DLUC.The outgoing and incoming timeslots are then connected together in the subscriber linemodules in order to test the circuit on the side of the calling party.

The CP analyzes the dialing information, determines the destination of the call requestand identifies the tariff zone. The CP checks its database to see whether the called partyis free. If the called party is busy, the call request is rejected. The CP selects a paththrough the switching network.

The following sections describe the method of working of the various functional units ofthe DLUG and their components in detail.

DLU

LTG SN

CP

LTG

DLU

SLM DLUC

SLM DLUC

Calling party

GP

GP

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2.1 Central Functional UnitsThe central functional units of the DLUG are duplicated and together form DLU sides 0and 1. The central functional units are:• control for DLU (DLUC)• bus distributor module (BDG)• bus systems (voice bus and data bus, CD bus)

The central functional units of the DLUG are failure units. If a fault occurs in a centralfunctional unit on one DLU side, call processing is still able to continue via the other DLUside (load restriction).

Control for DLU (DLUC)

The control for DLU (DLUC) controls the execution of functions inside the DLU and per-forms safeguarding tasks for all of the functional units in the DLUG. In addition, theDLUC controls communication with the LTGs in both directions.

The DLU’s internal control bus leads from the DLUC to the shelves. All functional unitsthat are equipped with their own input/output processor for DLUC (IOP:DLUC) are ad-dressed via this bus. The units are polled cyclically for messages waiting to be sent, andare accessed for the transfer of commands and data.

Another task of the DLUC is to execute test and monitoring routines with the aim of de-tecting errors. It also interrogates external alarm information.

The control for DLU (DLUC) performs a variety of functions:• Digital interface unit (DIU)/local DLU interface (LDI) function

The DIU/LDI function provides the following interfaces:– PCM30 interfaces (or PCM24 interfaces)

The DIU function has eight 2048-kbit/s interfaces for the connection of eightPCM30 primary digital carriers (PDC). The PDCs provide the links between theDLU and the line/trunk groups N (LTGN). Balanced or coaxial cables can be usedfor these links.

– LDI interfaceThe LDI function has four 4096-kbit/s interfaces for the connection of one local(co-located) DLU to the LTGNs. Balanced copper cables are used for this link. Onthe LDI connection, the content of 240 voice or data circuits and four signalinglinks (common channel signaling, CCS) are transmitted over four 4096-kbit/s mul-tiplex lines (instead of eight PCM30 multiplex lines).

• Group clock generator (GCG) functionThe GCG function generates the 4096-kHz system clock (CLK) required for theDLUG and the associated frame synchronization (FS) signal from the regenerated2048-kHz line clock from the PDCs and the line frame signal. To ensure dependabil-ity, the GCG is duplicated.GCG0 and GCG1 operate on the master/slave principle. Under normal operatingconditions, the clock generator designated as the master is active and selects theclock signals for both DLU sides. If the master clock generator fails, there is achangeover to the slave generator, which then takes control of the selection of clocksignals for both DLU sides.

• External alarm set (ALEX) functionThere are two groups of ALEX functions: one group implemented on the DLUC mod-ule and another group implemented as an independent ALEX (external alarm set)

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module. The external alarm set forwards alarm signals (e.g. power failure, overheat-ing, unauthorized entry,...) to the network node.The choice between the ALEX function implemented in the DLUC and that providedby the external alarm set (ALEX) module depends on the operator’s alarm require-ments.The principle difference lies in the interfaces. The external alarm set module (ALEX)has 16 outputs, all at 60 V. The ALEX function in the DLUC only has 15 outputs, 11at TTL level (e.g. for shelter applications) and 4 at 60 V.The DLUC supports the ALEX function for alarm lines of up to 2 m in length. If thelength of the alarm lines exceeds 2 m, the ALEX module must be used.

Bus distributor module (BDG)

The bus distributor module (BDG) forms the link between the subscriber line modules(SLM) and the central functional unit DLUC on one DLU side. A DLUG can accommo-date up to four BDG modules per DLU side.

Each BDG is assigned to a specific DLU side in terms of control bus, voice and data busand collision detection (CD) bus. The BDGs in shelves 0, 2, 4 and 6 are assigned to DLUside 0, while the BDGs in shelves 1, 3, 5 and 7 are assigned to DLU side 1. One BDGserves one system side containing 32 SLMs.

Bus systems

Communication between the central functional units and the peripheral functional unitstakes place over a duplicated bus system. The components of the DLUG duplicated bussystem are:• Voice and data bus

The voice and data buses transfer user information (voice and data) to and from theSLMs at a rate of 4096 kHz or 8196 kHz. There is a fixed allocation between thechannels of the voice and data buses and the channels of the PDCs, determined bythe DIU/LDI function in the DLUC.Each voice and data bus has its point of departure in one of the functional unitsDLUC0 or DLUC1 (star network from the DIU component to the BDGs, star bus fromthe BDGs to the SLMs).Within a shelf, the flow of information on each bus system is routed via the BDGs toall mounting locations for SLM. This means that every SLM can be reached fromboth sides of the DLU.The bus signals are synchronized with the system clock.

• Collision detection (CD) busThe collision detection bus is duplicated and is used exclusively by the digital sub-scriber line modules (SLMD) or the Internet subscriber line modules (SLMI:SDx). Itruns parallel to the voice and data bus. The collision detection bus regulates bus ac-cess. If two different SLMs try to send data over the Bd channel (a B channel usedfor a packet data connection) to the LTG at the same time, the collision detection busprevents them from accessing the Bd channel simultaneously. One timeslot is re-served for the Bd channel on the voice and data bus.

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• Control bus 0/1 (CN bus)The two control buses carry control information, i.e. line signaling and commandsfrom the DLUC to the SLMs and line signaling and messages in the opposite direc-tion. They have a bit rate of 187.5 kbit/s or 375 kbit/s in both directions.Each control bus has its point of departure in one of the functional units DLUC0 andDLUC1. The DLUC addresses each SLM separately over a star network.At the output of the BDG units, the control bus is distributed onward in groups to themounting locations for functional units equipped with microprocessors. The controlbuses are routed to every mounting location in the shelves, enabling the second busto serve all mounting locations in the event of failure on one control bus.In the BDG units, the signals are regenerated and fanned out to further outputs lead-ing to the periphery, and signals arriving from the periphery are concentrated ontofewer lines.

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

The peripheral functional units comprise the following modules:

Subscriber line modules (SLM)• Subscriber line module, analog (SLMA)• Subscriber line module, digital (SLMD)• Asymmetrical digital subscriber line, G.Lite standard (G.Lite)• Subscriber line module with Internet access, asymmetrical digital subscriber line

(SLMI:AMx)• Subscriber line module with Internet access, symmetrical digital line (SLMI:SDx)• Subscriber line module with Internet access, packet hub (SLMI:PHUB)• Subscriber line module with Internet access, modem pool card (SLMI:MPx)

Test equipment• Metallic test access, type B (MTAB)

Subscriber line module, analog (SLMA)

Analog subscribers are connected to the DLU by means of the Subscriber line module,analog (SLMA). The SLMA provides self-healing protection against short circuits on thesubscriber line.

An SLMA module contains 32 analog subscriber line circuits (SLCA) and a commoncontrol unit containing the processor (DOLCE). Subscriber lines with normal and specialfunctions (e.g. coinbox lines) can be connected to the SLMA.

The full range of ILTF functions is implemented in the available SLMA modules bymeans of test functions integrated in the line circuits:– Periodic access test (PAT)

All of the connected subscriber lines are tested at 5-minute intervals. If the line pa-rameters, such as capacitance or resistance, lie outside defined, programmable lim-its, an error message is sent to the NetManager.

– Open test interface (OTI)The OTI replaces the use of test probes for external test systems with integrated linetest functions, providing access to test data recorded in the LTG or CP through theOTI. In systems where the OTI is used, there is no need for module LTBAM to pro-

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vide test access between the individual shelves and the test interfaces and the testswitching relays on the SLMAs.

Several versions of the SLMA are available:• SLMA:ITFG

Subscriber line module, analog, with integrated test and measurement functions (in-tegrated line test function, ILTF), without classical MTA, for 32 subscriber lines

• SLMA:ITMGSubscriber line module, analog, with ILTF, for classical MTAB, for 32 subscribers

• SLMA:ITHGSubscriber line module, analog, with ILTF, for classical MTAB, for 32 subscribers,with higher loop current at ports 0, 1 and 2Module SLMA:ITHG provides the option of connecting special-purpose terminalsthat require a higher amperage, up to 45mA (e.g. certain coinbox phones) to the first3 ports.

Subscriber line module, digital (SLMD)

A Subscriber line module, digital (SLMD) contains 16 digital subscriber line circuits(SLCD). Each subscriber line circuit provides an interface for ISDN basic access (BA).

Tab. 2.1 lists the SLMD variants that can be deployed.

The SLMD (with ILTF) provides a periodic access test (PAT) function. This test involvesactivating layer 1 at the SLMD ports at regular intervals of 5 minutes; if it is possible toactivate the layer at least as far as the ISDN network termination (NT), the line is con-sidered to be accessible.

The PAT does not test the ability of the line circuit to receive power feed nor the analogline parameters of the SLMD; if an error is detected when layer 1 is activated for testing,the SLMD performs further fault analysis on the line circuit and reports the cause of theerror to the system.

If needed, the system is capable of starting other analysis routines. The ability of theSLCD to receive power feed and the analog parameters of the ISDN line can be tested.To do this, a selected SLMA with ILTF function is used in pure ILTF mode. The first 8SLCAs (0...7) on this ILTF test SLMA are reserved for special test functions. The specialtest functions are: test of the ability of the ILTF-SLMD to receive power feed, measure-ment of the analog parameters of the ISDN line for fault location, monitoring functions.Subscriber lines can be connected to the other 24 SLCAs (8...32) on the ILTF test SL-MA.

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.

SLMD type Number ofline circuits

Line code*(depending on ISDN BA)

ILTF

SLMD:TFB 16 4B3T x

SLMD:QFB 16 2B1Q x

* 2B1Q = 2 binary signals to 1 quaternary signal 4B3T = 4 binary signals to 3 ternary signals

Tab. 2.1 SLMD types

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Asymmetrical digital subscriber line, G.Lite standard (G.Lite)

The G.Lite function is implemented on the subscriber line module with Internet access,feature-programmable modem (SLMI:FMx). It has data functions in accordance withITU-T standard G.992, and always has to be deployed in conjunction with the packethub.

Each SLMI:FMx module offers combined data and POTS functions for up to 16 sub-scriber lines. Incoming voice and data traffic arriving over the subscriber line is separat-ed in the SLMI:FMx. Analog telephone signals are treated in the same way as by theclassical analog subscriber line module (SLMA). Data traffic is forwarded to the packethub over HBRS connections.

Subscriber line module with Internet access, asymmetrical digital subscriber line(SLMI:AMx)

The ADSL function is implemented on the subscriber line module with Internet access,asymmetrical digital subscriber line (SLMI:AMx). It always has to be deployed in con-junction with the packet hub.

Each SLMI:AMx module offers combined data and POTS or ISDN functions for up to 8subscriber lines. Incoming voice and data traffic arriving over the subscriber line is sep-arated in the SLMI:AMx. Analog telephone signals are treated in the same way as bythe classical analog subscriber line module (SLMA). Digital telephone signals are treat-ed in the same way as by the classical digital subscriber line module (SLMD). Data trafficis forwarded to the packet hub over HBRS connections.

Subscriber line module with Internet access, symmetrical digital line (SLMI:SDx)

The SDSL function is implemented on the subscriber line module with Internet access,symmetrical digital subscriber line (SLMI:SDx). It always has to be deployed in conjunc-tion with the packet hub.

Each SLMI:SDx module offers combined data and ISDN functions for eight subscriberlines.

The SLMI:SDx module emulates the functions of the analog subscriber line module (SL-MA) for low transmission-rate services at any analog subscriber interface, or the func-tions of the digital subscriber line module (SLMD) at ISDN basic access interfaces. Thevoice and data streams arriving from the SDSL network termination (SDSL-NT) are sep-arated in the SLMI:SDx. From there, the data stream is routed via HBRS interfaces tothe packet hub (PHub), a concentrator for ATM. The DLUG is also designed for internalATM between SLMI and PHub.

Subscriber line module with Internet access, packet hub (SLMI:PHUB)

The subscriber line module with Internet access, packet hub (SLMI:PHUB) is used inconjunction with the G.Lite module SLMI:FMx, the ADSL module SLMI:AMx and/or theSDSL module SLMI:SDx.

The main function of the packet hub is to transfer the data received from SLMI:FMx andSLMI:SDx to the network interfaces (e.g. 100BASE-T, E3/T3 or E1/T1, STM1).

Various options are available for transporting the data onward to the Internet serviceprovider (ISP) via:– ATM multiplexer (cross-connect function)– remote access server (RAS)

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Up to eight SLMI:FMxs, up to six SLMI:AMxs and up to eight SLMI:SDxs can be con-nected to the packet hub.

Redundancy is a further feature of the packet hub. When a complete shelf is equippedwith redundant modules, every Internet subscriber line module is linked to both packethubs via HBRS interfaces. The packet hubs communicate via the ATM cross channeland operate in master/slave mode. In the event of failure of the master unit, the otherpacket hub takes over the traffic handling for all Internet subscriber line modules.

Subscriber line module with Internet access, modem pool card(SLMI:MPx)

The subscriber line module with Internet access, modem pool card (SLMI:MPx) is usedin conjunction with the SLMI:PHUB.

The main function of the modem pool card to assist in signal processing tasks and toprovide an interface between the subscriber lines (analog or ISDN) and the packet hub.

A maximum of two packet hubs can be connected to the modem pool card.

Metallic test access (MTA)

Metallic test access (MTA) allows external subscriber-line test systems to access thesubscriber lines connected to the DLUs. The DLU utilizes metallic test access type B(MTAB) , which is implemented by module LTBAM.

To provide the type-B metallic test access function (MTAB), as shown in Fig. 2.2, oneLTBAM module is installed in each DLU. This gives the DLU two test interfaces. Externaltest equipment is connected to the analog subscriber lines to be tested by means ofmodule LTBAM in the DLU and the test matrix units in the SLMAs. Two tests can be per-formed simultaneously on a DLU using external test equipment.

All tests and measurements are performed via the test interfaces, which are located inthe DLU. They provide metallic test access for the external test equipment and measur-ing instruments installed locally in the network node. The test interface of a specific DLUis used to test the subscriber lines connected to that DLU.

The test interfaces are activated and deactivated via the control interface, which is im-plemented by an MF-PC (PC with switching functions) located in the network node. It isconnected to an external test system and to the coordination processor (CP) by meansof control lines. The MF-PC converts the test system’s message format into the standardmessage format used by the switching system.

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Fig. 2.2 Metallic test access type B (MTAB)

2.3 Functional Units for Remote OperationThe following additional modules are required for remote operation:• standalone service control (SASC-G)• external alarm set (ALEX)

Standalone service control for remote DLUG

A DLU switches to standalone service in situations where it is unable to communicatewith at least one LTG over a PCM system (PDC) with common channel signaling (CCS),e.g. in the event of a total failure of all connections to the LTGs.

When a remote DLUG is operating in standalone mode, the Standalone Service Control(SASC-G) allows the connected subscribers to set up calls to other subscribers servedby the same DLU (DLU internal traffic). For subscribers with DTMF dialing served by thatDLU, the SASC-G reconfigures the tone receivers to allow them to continue to useDTMF dialing.

The SASC-G handles signaling and speech-path control within the DLU and for sub-scribers served by a remote DLUG (e.g. remote shelter DLU).

DLU internal traffic allows a maximum of 30 calls (or 60 channels) to be processed si-multaneously. The 31st call request does not receive dial tone because no more chan-nels are available.

Conversion ofactivation com-mands into MMLcommands

Activationcommand

CPDLU

LTBAM*

Activation command(signaling)

* The SLMs are accessed via the LTBAM (tip/ring)

Metallic testaccess

DLU

LTBAM*

DLU

LTBAM*

DLU

LTBAM*

Externaltest

equip-ment

MF-PC

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The main functions of the SASC-G under normal operating conditions are:– Supervisory functions, e.g.

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

– Receiving and storing data sent by the LTG via the DLUC relating to changes to oradditional properties of subscriber lines and ports

– Starting standalone service, on receipt of simultaneous requests from both DLUCs.The SASC-Gs switch to standalone service after a guard time of <60 s (after the re-quest for standalone service from the two DLUCs).

The main functions of the SASC-G in standalone service are:– controlling the setup and release of calls made by subscribers served by that DLUG– verifying the database and updating it when necessary (after restoral of normal op-

erating conditions)– carrying out internal hardware routine tests and some supervisory functions (equiv-

alent to those carried out under normal operating conditions)– controlling the tone receivers– terminating standalone service when the connection between at least one DLUC

and the network node has been restored

Alarm treatment

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 the network node.

Operators can choose to use the DLUC ALEX function or install external alarm set mod-ules (ALEX), according to their requirements.

The ALEX performs the following functions:– reading, identifying and evaluating the states of up to 16 alarm contacts– handling data communication with DLUC0 and DLUC1– monitoring its own firmware and terminating the exchange of data with the DLUCs

on detection of firmware errors– monitoring its own hardware and sending analysis reports on detection of hardware

faults

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2.4 DLU for V5.1 Interfaces (DLUV)The DLUV is used for the connection of up to 10 V5.1 interfaces. The DLUV is an au-tonomous DLU without any logical connection to the DLUG.

Further information can be found in the description entitled Digital Line Unit V (DLUV)

2.5 Transmission Systems in the DLUGThe transmission systems in the DLUG provide support for connections to the networknode or to other remote DLUs (e.g. remote shelter) and, if required, to other 2-Mbit/s in-terfaces such as V5.1 networks.

For such purposes, the DLUG can be equipped with transmission systems supportingthe HDSL (high bit-rate digital subscriber line) standard for copper cable.

Transmission systems for the DLUG:– Line termination equipment consisting of:

line/network termination for 2 lines operating at 2 Mbit/s each, copper cable usingHDSL standard (LTCD)

The network components for transmission functions can be configured according to cus-tomer requirements and allow remote DLUs to be deployed in a star configuration in thenetwork. The required number of transmission units depends on the necessary trans-mission capacity, the network structure and the number of subscribers to be served bythe DLUs.

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3 DLUG HardwareThe DLUG hardware is composed of a number of functional groups:• Central Functional Units• Peripheral Functional Units• Functional Units for Remote Operation

The functions of the functional units are implemented in hardware modules.

Fig. 3.1 Hardware structure of the DLUG

3.1 Central Functional UnitsThe central functional units comprise the following modules:• control for digital line unit (DLUC)• bus distributor (BDG)

3.1.1 Control for Digital Line Unit (DLUC)The control for DLU (DLUC) controls the internal sequence of functions under normaloperating conditions and during DLU standalone service. It distributes and concentratesthe signaling between the subscriber line modules.

PDC15

PDC7

PDC8

32

1

SASC-G

LTBAM (opt.)

DLUV (V5.1)

ALEX

LTCD

PDC0DLU side 0

to Internet via:

E3,T3

STM1HBRS

100BaseT

BDG

SLMA32

1

16

SLMI:SDA

1

161

4SLMI:SDx

SLMI:FMx

DLUC

Packet hub

1

10

SLMD16

GCG

DIU/LDI

ALEXfunction

E1,T1

LTG

1

nSLMI:AMx

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Fig. 3.2 Module DLUC

The main functions of the DLUC are:– transfer of messages to and from the LTGs– clock synchronization– cyclic polling of the SLMs– direct addressing of the subscriber line circuits (SLC) for the transfer of commands

and data– execution of monitoring and test functions

3.1.2 Bus Distributor Module (BDG)The bus distributor module (BDG) is responsible for distributing all signals from the bussystem to the various mounting locations of the shelves.

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Fig. 3.3 Bus distributor module (BDG)

The functions of the BDG module are:– distribution of the internal DLU 4096-kHz clock CLK and the associated 8-kHz frame

synchronization signal– transferring voice information to and from the subscriber line modules– transferring signaling information to and from the subscriber line modules

3.2 Peripheral Functional UnitsThe peripheral functional units comprise the following modules:

Subscriber line modules (SLM)• Subscriber Line Module, Analog (SLMA)• Subscriber Line Module, Digital (SLMD)• Subscriber Line Module with Internet Access, Feature-Programmable Modem

(SLMI:FMx)• Subscriber Line Module with Internet Access, Asymmetrical Digital Subscriber Line

(SLMI:AMx)• Subscriber Line Module with Internet Access, Symmetrical Digital Subscriber Line

(SLMI:SDx)• Subscriber Line Module with Internet Access, Packet Hub (SLMI:PHUB)• Subscriber Line Module with Internet Access, Modem Pool Card (SLMI:MPx)

Test equipment (optional)• Metallic Test Access Type B (MTAB)

3.2.1 Subscriber Line Module, Analog (SLMA)The analog subscriber line module with integrated test function (ILTF) for the subscriber-line access network is the standard SLMA for use in the DLUG and handles subscriberlines with normal and special functions.

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Fig. 3.4 Subscriber line module, analog (SLMA:ITFG)

The following main functions are implemented on the SLMA:ITFG module:– high-impedance loop supervision for the detection of events when the line is idle– constant power feed at selectable current values during talk state, transferring to re-

sistance feed at high loop resistance values– extended range (boost battery)– reception of pulse dialing signals (rotary dialing)– forwarding of DTMF dialing signals– transmission of meter pulses at 12 or 16 kHz– duplicated PCM interface with 2 x 64 programmable timeslots– integrated circuit test (self-test)– periodic access test (PAT)– integrated line test (on demand, by test command)– integrated terminal test (on demand, by test command)– short-circuit protection (self healing)– foreign voltage protection up to 300 Vac (self healing)

3.2.2 Subscriber Line Module, Digital (SLMD)A digital subscriber line module (SLMD) can contain 16 digital subscriber line circuits(SLCD). Each subscriber line circuit provides one interface for ISDN basic access (BA).

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Fig. 3.5 Block diagram of subscriber line module SLMD:QFB

Main functions of SLMD:– transmitting user data at 144 kbit/s in each direction (two channels at 64 kbit/s each,

one channel at 16 kbit/s) over two-wire subscriber lines– transmission using adaptive echo cancellation– conformance with required transmission standards (e.g. ETSI)– remote feeding of the network termination (NT) over the subscriber line– supervision of the subscriber line for short circuits and shorts to ground– protection against overvoltage and foreign voltage– test switching between subscriber line and SLCD– controlling the flow of data on the B and D channels by the line card processor (LCP)– duplicated 4096-kbit/s bus with 64 selectable timeslots for voice/data transmission

(B channels)– separation and merging of D-channel information comprising signaling and packet

data– duplicated collision detection bus for the regulation of packet data transfer in one

timeslot (Bd channel) on each of the 4096-kbit/s buses– exchange of signaling data with the DLUC by the system adapter processor (SAP)

over the duplicated control bus– support for DLU system maintenance, e.g. diagnosis, online supervision– periodic access test (PAT)

Ports 12...15

Ports 8...11

Control bus 1Control bus 0

a/b

D channels

D channels

Ports 4...7

D channels

Reset

IOM2 bus 1

Ports 0...3

ELIC

D channels

LCP

FlashEPROM

D-RAM

SCA

SAP

EPIC

IOM2 bus 2

IDEC

IDEC

a/b SLCD0NT

ILTF testSLMA

IDEC

IDECSLCD15NT

4096-kbit/s bus 0/collision bus 0

4096-kbit/s bus 1/collision bus 1

SACCO

SACCO

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– support for the ILTF test procedure

3.2.3 Subscriber Line Module with Internet Access,Feature-Programmable Modem (SLMI:FMx)Module SLMI:FMx implements POTS and data functions in accordance with the ITU-TG.Lite standard.

Fig. 3.6 Block diagram of module SLMI:FMx

The main features of module SLMI:FMx are as follows:– high bit-rate access over the subscriber line– possibility to transmit voice and data simultaneously– upstream transmission rate of 512 kbit/s– downstream reception rate of up to 1.5 Mbit/s– compatible with G.Lite– plug-and-play solution

3.2.4 Subscriber Line Module with Internet Access,Asymmetrical Digital Subscriber Line (SLMI:AMx)The main features of module SLMI:AMx are as follows:– high bit-rate access over the subscriber line– possibility to transmit voice and data simultaneously

G.Lite DSPblock

B-SLIC4...7

B-QAP

1

PLDfor FS

B-SLIC0...3

B-QAP

0

B-MuPP 0

Flash

SDRAM

MPC860

ATM

ATM

DPRAM

DolcePCMRing/Tip

0

Ring/Tip7

CN

B-MuSLIC

B-MuPP 1

B-SLIC

12...15

B-QAP

3

B-SLIC8...11

B-QAP

2

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– upstream transmission rate of 800 k/bit/s– downstream reception rate of up to 8.1 Mbit/s– plug-and-play solution

3.2.5 Subscriber Line Module with Internet Access,Symmetrical Digital Subscriber Line (SLMI:SDx)The SLMI:SDx provides an additional 12 B channels over and above the standard ISDN-BA channels (2B+D). It also offers the option of using each of the additional B channelsfor packet-switched or circuit-switched services, as required. If a service requires supe-rior transmission quality, this can be achieved by circuit-switching the 12 B channels;otherwise the data stream is fed directly into the packet-switched network.

Fig. 3.7 Block diagram of module SLMI:SDx

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

b3

a3

b1

a1

b0

a0

MuBIC

MuBIC

TDM/IOM

MuBIC

MuBIC

Corecontroller

SDRAM

FEPROMEPLD

ASICSCA2

DRAM

ATM inter-face

ATM

Buffer

FSRAM

CN, CD, PCM, CLK (DLUinterface)

ATM

CPU CPM

SIU

b2

a2

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3.2.6 Subscriber Line Module with Internet Access, Packet Hub(SLMI:PHUB)The packet hub provides access to the Internet by means of IP over PPP (Internet pro-tocol over point-to-point protocol). Internet traffic is routed directly onto the ATM back-bone.

Fig. 3.8 Module SLMI:PHUB

The main features of this module are:– through-forwarding of IP traffic without placing load on the network node– traffic concentration– a high degree of flexibility offering adaptation to the requirements of differing network

environments

3.2.7 Subscriber Line Module with Internet Access, ModemPool Card (SLMI:MPx)The modem pool card (MoPC) performs signal processing tasks and provides an inter-face between the subscriber lines (analog or ISDN) and the packet hub (PHub).

The MoPC converts voice/data signals received from users of analog data modems intodigital signals and packetizes them, concentrates the traffic and forwards the data to thePHub. Data arriving from the PHub are de-packetized, allocated to a user port and sentto the user as analog signals. The module supports all standard modem protocols.

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Fig. 3.9 Module SLMI:MPx

3.2.8 Metallic Test Access Type B (MTAB)The metallic test access type B (MTAB) allows test connections to be set up from exter-nal test equipment to a subscriber line to be tested.

The metallic test access type B (MTAB) is implemented by module LTBAM.

One LTBAM module is installed per DLU. This gives the DLU two test interfaces. Theexternal test equipment is connected to the LTBAM module and via the test matrix in theSLMA to the analog subscriber line under test. This arrangement allows two tests to beperformed simultaneously on a DLU using external test equipment.

The subscriber line under test is connected to the test interface via the test matrix inte-grated in each subscriber line circuit using four-wire lines leading to the DLU test bus ineach half-shelf of the DLU. The LTBAM module, in turn, connects this test bus to the testinterface 0 or 1.

In order to establish a test connection, the control unit of the external test equipmentsends a command in a standardized format over one of several serial data interfaces toa special-purpose converter PC. The latter converts the activation command into anMML command and forwards it to the coordination processor (CP). From the parame-ters in the command, the CP identifies one of the two possible LTGs and forwards theactivation request. The LTG converts this request into two setting commands, one forthe test matrix in the subscriber line circuit and one for the LTBAM module.

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3.3 Functional Units for Remote OperationThe functional units for remote operation comprise the following modules:• standalone service control (SASC-G)• external alarm set (ALEX)

3.3.1 Standalone Service Control (SASC-G)The standalone service control (SASC-G) handles signaling and speech paths in theDLU or subscriber lines within a remote DLUG. The SASC-G also handles standaloneservice for DTMF subscribers served by the DLU. It contains the code receiver functionsneeded to enable pushbutton subscribers to use DTMF dialing during DLU standaloneservice.

Fig. 3.10 Block diagram of module SASC-G

3.3.2 External Alarm Set (ALEX)The ALEX module is employed in remote DLUs. The ALEX responds to system-externalalarms (e.g.: fire, unauthorized access, excessive temperature level, ...) and routes thealarm information via the CP to the NetManager.

4096-kbit/sBus 1

DLU bus in-terface (CPI)

HDLC

0

Channelalloca-

tion unit(TSU)

Control section

4096-kbit/sbus0

Control bus 1

Control bus 0

Inter-DLU inter-face

EMU LDIMX

4 EMU LDIMXEMU

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Fig. 3.11 Block diagram of module ALEX

The main functions of the module are:– evaluating the status of external alarm signaling units– reporting changes of state to the DLUC– testing the selector circuits by means of alarm simulation– testing the alarm simulation circuits

Control bus 1

Control bus 0

Alarm 15

Supplyvoltage

Back-plane

Alarmindicator 15

Alarmindicator 0

Alarm 0

ALEX-CP

Watch-dog

Hardware testcircuit

Signaltrans-

mission

Volt-age su-pervisi

on

PeripheralresetsignalPRS fromDCCReset

circuit

Control section

Portexpan-

sion

Failuretest

Pollingcircuit

UPS

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4 SafeguardingOnly small proportion of the safeguarding software is implemented in the DLU itself. Allof the more important parts of the DLU safeguarding software are implemented in theLTG and in the CP. The main safeguarding functions in the LTG are error detection, faultanalysis and recovery, i.e. initializing and reloading the DLU.

The CP coordinates those safeguarding tasks which the LTG is unable to handle alone(e.g. combined error messages).

The main safeguarding functions are described below.

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

Fig. 4.1 Units containing 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 and watchdog 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 diagnosisThe DLU routine test (automatic) and diagnosis (started by the system operator)functions test hardware units and locate hardware faults. The purpose of diagnosisis to verify errors that were detected by the routine test. DLU diagnosis provides sup-port 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 functions detect hardware faults that cannot be de-tected during normal program execution.

HierarchyProcessors

DLUCx

LTGN

CP

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Fault analysis

The fault analysis function in the LTG processes error messages issued by the error de-tection programs in the LTG and DLU. Fault analysis functions are spread throughoutthe whole system (CP, LTG, DLU, SLM). The tasks performed by fault analysis are:• analyzing error events• choosing the method of fault treatment• collecting error symptoms• compiling and maintaining error statistics

In order to analyze error events, they are assigned error numbers by fault analysis.These numbers identify the error events and classify them according to error types thatcall for the same type of fault treatment. The location of the fault is specified relative toa configurable unit of the DLU and LTG (DLU equipment, DLU module, DLU port, DIUin LTG). Types of fault treatment comprise:• re-configuring the affected unit to isolate the fault• releasing, blocking or allowing call-processing activities for the affected unit• informing the CP of the occurrence of the fault and reporting the operating state of

the faulty or no longer faulty unit• executing recovery in the failed unit after it has been repaired or when an end-of-

fault message is issued• measuring the recovery duration (downtime)• ignoring the error• compiling error statistics

Depending on the type of unit affected by the fault or the type of fault, fault analysis pass-es control to:• fault analysis for DLU• fault analysis for DLU unit (e.g. SLM)• fault analysis for common channel signaling (CCS)• software error treatment• statistical fault analysis• subscriber line fault analysis

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Recovery

The recovery function performs actions designed to restore the faulty units to an opera-ble condition.

Recovery in the DLU itself is triggered by software errors or in connection with the exe-cution of configuration commands. The recovery actions are graduated according to theseverity of their effect on the system as a whole:• Restart

Resetting and initializing a specific process to a defined initial state. This recoveryaffects no more than one call.

• New startResetting of all processes and restarting operation, whereby all calls are maintained

• Initial startResetting of all processes and initializing the periphery, combined with the releaseof all established calls and, if necessary, the reloading of code and/or semiperma-nent data

Hardware faults cannot be cleared by means of recovery. All that can be done is to re-initialize and reload the database after a power outage.

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5 Technical DataConnection optionsSubscriber lines(per rack)

max. 1984 analog subscriber linesmax. 720 digital subscriber lines (ISDN)max. 304 SDSL subscriber linesmax. 864 ADSL.Lite subscriber lines

V5.1 interfaces(in F:DLU(G))

max. 4 x 10 V5.1 interfaces (DLUV)

Transmission systemsTransmission system used onPDCs

conformant with CCITT Recommendations G.703,G.704(HDB3 transmission format) or ISDN-PRA

Transmission system used on4096-kbit/s multiplex highways

proprietary method

Transmission system used onHDSL

transmission system

Traffic capacity (voice/data circuits)Up to sixteen 2048-kbit/s PDCs up to 400 erlangs

Up to eight 2048-kbit/s PDCs up to 200 erlangsEquivalent values apply to systems equipped withfour 1544-kbit/s PDCs (94 voice/data channels) andtwo 1544-kbit/s PDCs (46 voice/data channels).

Transmission system in the DLU (optional)Line/network termination,copper cable (LTCD)

2 ports each operating at 2.048 Mbit/s, bidirectional,copper cable via HDSL (electrical)

Interface to DLU (DIU) conformant with CCITT Recommendation G.703

Control buses between SLM and DLUC (DLUS)Number per DLUG 2 control buses, star topology

Physical bit rate 187.5 kbit/s or 375 kbit/s

Clock pulses 4096 kHz and 8 kHz (frame alignment bit)

Internet interfaces to the data networks4 x E1/T1 2 Mbit/s (PCM30) or 1.5 Mbit/s (PCM24)E3/T3 34Mbit/s or 45 Mbit/sSTM1 622 Mbit/sEthernet 100Base T 100 Mbit/s

34 A30828-X1150-K109-2-7618


Operating voltages +5 V, +52 V, –68 V, –97 V

Battery voltage –48 V or –60 V

Digital Line Unit G (DLUG)

Documents

subscriber line module

digital line unit dluc193

subscriber lines

internet access

central functional units

peripheral functional

digital slmd

bus distributor module