EWSD Overview

ALT CBSNLALT CENTRE

T

EWSD Overview

H.S.Jakhar D.G.M. (SW-II) ALTTC Ghaziabad1/3/2012 SW-II/EWSD_Overview/HSJ 1

BSNL

System Features

ALT CALT CENTRE

T

EWSD Digital switching system has been designed and manufactured by M/s Siemens, Germany. The name is the abbreviated form of German equivalent of Electronic Switching System Digital (Electronische Wheler Systeme Digitale). EWSD switch can support maximum 2,50,000 subscribers or 60,000 incoming, outgoing or both way trunks, when working as a pure tandem exchange.

1/3/2012

SW-II/EWSD_Overview/HSJ

2

BSNL

System Features It can carry 25,200 Erlang traffic and can withstand 1.4 million BHCA. It can work as local cum transit exchange Can support CCS No.7 ISDN IN V5.X features.

ALT CALT CENTRE

T

1/3/2012


3

System ArchitectureBSNL

ALT CALT CENTRE

T

The main HW units of an EWSD switch are as under: (1) Digital line unit (DLU) - functional unit on which subscriber lines are terminated. (2) Line/Trunk Group (LTG) - Digital Trunks and DLUs are connected to LTGs. (3) Switching Network (SN) All the LTGs are connected to the SN which inter connects the line and trunks connected to the exchange in accordance with the call requirement of the subscribers. CCNC and CP are also connected to SN.

1/3/2012


4

BSNL

System Architecture

ALT CALT CENTRE

T

(4) Coordination Processor (CP) - It is used for system-wide coordination functions, such as, routing, zoning, etc. However each subsystem in EWSD carryout practically all the tasks arising in their area independently. (5) Common Channel Signaling Network Control (CCNC) Unit - This unit functions as the Message Transfer Part (MTP) of CCS#7. The User Part (UP) is incorporated in the respective LTGs.

1/3/2012


5

ALT CBSNL ACCESS DLUDLUC

T

LTGGP

SWITCHING NETWORK

ALT CENTRE

LTGGP

COMMON CHANNEL SIGNALING CCNCCCNP

COORDINATIONSYPC

SYP MB CCG SGC

EM OMT

CPMBC

DISTRIBUTED CONTROLS IN EWSD1/3/2012 SW-II/EWSD_Overview/HSJ 6

Digital Line Unit (DLU)BSNL

ALT CALT CENTRE

T

Analog or Digital (ISDN) subscribers, PBX lines or V5.1 interface are terminated on DLU DLUs can be used locally within the exchange or remotely as remote switch unit , in the vicinity of the groups of subscribers. DLUs are connected to EWSD sub-systems via a uniform interface standardized by CCITT, i.e., Primary Digital Carrier (PDC) to facilitate Local or Remote installation. A subset of CCS# 7 is used for CCS on the PDCs. One DLU is connected to two different LTGs for the reasons of security.1/3/2012 SW-II/EWSD_Overview/HSJ 7

BSNL

SUBSCRIBER LINES AND PBX LINES

LOCAL APPLICATION

ALT CALT CENTRE

T

DLU 4 Mbps 4Mbps

LTG

SN

SUBSCRIBER LINES AND PBX LINES

REMOTE APPLICATION DLUPDC0 WITH CCS PDC1 W/O CCS PDC2 WITH CCS PDC3 W/o CCS

LTG

CP

APPLICATIONS AND CONNECTION OF DIGITAL LINE UNIT1/3/2012 SW-II/EWSD_Overview/HSJ 8

BSNL

Digital Line Unit (DLU)

ALT CALT CENTRE

T

A local DLU is connected to two LTGs via two 4 Mbps (64 TSs) links, each towards a different LTG. In case of remote DLUs, maximum 4 PDCs of 2 Mbps (32 TSs) are used per DLU, two towards each LTG. 120 channels are used for user information (speech or data) and signaling information is carried in TS16 of PDC0 and PDC2. In case of a local DLU interface, TS32 carries CCS.

1/3/2012


9

ALT CBSNL

T

Digital Line Unit (DLU)

ALT CENTRE

Within the DLU, the analog subscribers are terminated on SLMA (Sub-scriber Line Module Analog) cards (module). Digital (ISDN) subscribers are terminated on the SLMD modules. Each module can support 16 subscribers. One DLU can carry traffic of 100 Erlangs. A standard rack of DLU (local ) can accommodate two DLUs of 992 subscribers each. In case the link between a remote DLU and the main exchange is broken, the subscribers connected to the remote DLU can still dial each other.1/3/2012 SW-II/EWSD_Overview/HSJ 10

Digital Line Unit (DLU)BSNL

ALT CALT CENTRE

T

For emergency service DLU-controller (DLUC) always contain up-to-date subscribers data. Stand Alone Service Cr. card (SASCE) is provided in each R-DLU for switching calls in such cases. This card is also used for interconnecting a number of remotely situated DLUs (maximum 6), in a cluster, called a Remote Control Unit (RCU) All DLUs are provided with a Test Unit (TU) for performing tests and measurements on SLCAs, subscribers lines and telephones. An ALEX (ALarm Externals) module is used for forwarding external alarms. Numbers of SLMAs are accordingly reduced to accommodate these modules.1/3/2012 SW-II/EWSD_Overview/HSJ 11

ALT CBSNL DLU SLMA Test line DLUC0 TO TWO LTGS PDC2 SLMD DIUD1 PDC3 DIUD0 PDC0 PDC1ALT CENTRE

T

ANALOG AND ISDN SUBSCRIBER LINES, PBX LINES

DLUC1 TU 4096 KBPS NETWORK 0 4096 KBPS NETWORK 1 CONTROL NETWORK 0 CONTROL NETWORK 1

MAIN COMPONENTS OF A DLU1/3/2012 SW-II/EWSD_Overview/HSJ 12

Line/Trunk Groups(LTG)BSNL

ALT CALT CENTRE

T

LTG forms the interface between the digital environment of an EWSD exchange and the SN. They are connected in any of the following ways :-(i) Via 2/4 Mb/s PDCs with remote/local DLUs to which analogue or ISDN subscribers are connected. -(ii) Via 2 Mbps digital access lines to other digital exchanges in the network ( MF R2 Trunks, CCS#7 Trunks). CCS#7 Trunks). -(iii) Via Primary rate Access lines to ISDN PBXs (ISDN sub-scribers with PA). PA). -(iv) V5.2 Trunks, Announcements Trunks, OCANEQ, IP (SSP). (SSP).

1/3/2012


13


ALT CALT CENTRE

T

Functions Call processing functions, i.e., receiving andanalyzing line and register signals, injecting audible tones, switching user channels from and to the switching network, etc.

Safeguarding functions, i.e., detecting errors in theLTG and on transmission paths within the LTG, analyzing the extent of errors and initiating countermeasures such as disabling channels or lines, etc.

Operation

i.e., acquiring traffic data, carrying out quality-of-service measurements, etc.SW-II/EWSD_Overview/HSJ 14

and

maintenance

functions,

1/3/2012

BSNL

DIFFERENT Functional TYPES IN LTGFUNCTIONAL TYPEB FUNCTION (FOR DLUS[L&R], PRI,V5.2,OCANEQ, COU) C FUNCTION (FOR TRUNKS ON CAS & CCS AND CCS#7 SIGN.CHLS)

ALT CALT CENTRE

T

FRAME TYPE of LTGNF:LTGN(A) (FOR DLUS[L&R], PRI, TRUNKS)

LTG

LTG

F: LTGN(B) (FOR SPL. FUNCTIONS LIKE COUC, PHMA ( V5.2), ATE:N, OCE:N)

ONE LTG SUPPORTS 128 TS (I/P & O/P) MAX. ERLANG CAPACITY PER LTG IS 100 ERL.1/3/2012 SW-II/EWSD_Overview/HSJ 15


ALT CALT CENTRE

T

Although the subscriber lines and trunks employ different signaling systems, the LTGs present signaling independent inter-face to the switching network. The bit rate on all highways linking the line/trunk groups and the switching network is 8192 kbps ( 8 Mbps ). Each 8 Mbps highway contains 128 channels at 64 kbps each. Each LTG is connected to both planes of the duplicated switching network.

1/3/2012


16


ALT CALT CENTRE

T

The functional units of the line/trunk group are: Line / Trunk Unit (LTU) is a logical unit that comprises a number of different functional units, i.e. - Digital Interface unit ( DIU30 ) for connection of 2 Mbps digital trunks and either DLU or PA. One LTG can comprise four DIU30. - Code Receivers (CR) are Multi-frequency code receivers for trunks or DTMF subscribers. - Conference Unit, module B or module C (COUB or COUC) for conference calls. - Automatic Test Equipment for Trunks (ATE:N) checks trunks and Tone Generators (TOG) during routine tests.

1/3/2012


17

BSNL

Line/Trunk Groups(LTG)

ALT CALT CENTRE

T

tones, Code Receivers (CR) for MFC signaling and push-button dialing and Receiver Module for Continuity Check (RM:CTC) y Group Switch (GS) which functions as non-blocking time stage switch ( 512 TS) controlled by the GP. y Link Interface Unit (LIU) connects LTG to SN via two parallel 8 Mbps SDCs. y Group Processor (GP) controls the functional units of the LTG. The received signals from LTU, SU, GS & LIU are processed with help of GP SW.

y Signaling Unit (SU) comprises Tone Generator (TOG) for audible

1/3/2012


18

LTU BSNL DIU:LDIB DIU30 or LTU COUC COUB or LTU CR or LTU OCANEQPHMA ATE:T

SU CR TOG CTC

GS

LIU

ALT CALT CENTRE

T

SPHI SPHO SIHI SIHO Addr. signals

8Mb/s

SN0 to/from SN(8Mbps) SN1

GP (PU, MU, SMX and GCG)

SILC

INTERNAL STRUCTURE OF LTG1/3/2012 SW-II/EWSD_Overview/HSJ 19

ALT CBSNL

T

Line/Trunk Groups(LTG)

ALT CENTRE

In LTGG, GS and LIU have been combined into GSL module. One LTG rack can accommodate 40 PCMs in five LTGG frames, each containing two LTGGs. LTGM was the next standard type of LTG. Only three modules are necessary for a complete LTGM namely DIU120A or DIU:LDIM, GPL and GSM. Upto 30 LTGM can be installed in one rack with each frame containing 5 LTGM. LTGN is the latest release of LTG. Only one module makes up a complete LTGN for the basic tasks. Upto 16 LTGN can be installed in one frame and a rack can contain 64 LTGN.

1/3/2012


20

Switching NetworkBSNL

ALT CALT CENTRE

T

Different peripheral units of EWSD, i.e., LTGs, CCNC, MB are connected to the Switching Network (SN) via 8192 kbps highways called SDCs (Secondary Digital Carriers), which have 128 channels each. The SN consists of several duplicated Time Stage Groups (TSG) and Space Stage Groups (SSG) housed in separate racks. Connection paths through the TSGs and SSGs are switched by the Switch Group Controls (SGC) provided in each TSG and SSG, in accordance with the switching information from the coordination processor (CP). The SGCs also independently generate the setting data and set the message channels for exchange of data between the distributed controls.1/3/2012 SW-II/EWSD_Overview/HSJ 21

ALT CBSNL LTG 1 SDC:LTG TIME STAGE GROUP SNALT CENTRE

T

SDC:SSG

LTG n

SDC:LTG SDC:SSG

SPACE STAGE GROUP

CCNC

SDC:CCNC

CP

MB

SDC:TSG

SDC:SGC SGC SDC:SGC SGC

Switching Network1/3/2012 SW-II/EWSD_Overview/HSJ 22


ALT CALT CENTRE

T

The switching network is always duplicated (planes 0 &1). Each connection is switched simultaneously through both planes, so that a standby connection is always immediately available in the event of a failure. Each TSG can accommodate 63 SDCs from LTGs and one SDC to MB. One SDC is extended from SGC of each TSG and SSG towards MB. The switching network can be expanded in small stages by adding plug-in modules and cables and if necessary by assigning extra racks.

1/3/2012


23


ALT CALT CENTRE

T

The smallest duplicated SN:63 LTG configuration which can handle 30,000 subscriber lines or 7,500 trunks when fully equipped is installed in a single rack and can handle 3150 erlangs traffic. In its maximum configuration, the EWSD switching network has 8 TSGs and 4 SSGs ks) to connect 504 LTGs and has a traffic handling capacity of 25,200 erlangs. SNs for 126 LTGs and 252 LTGs are also available which can handle 6300 and 12600 erlangs traffic respectively. SN has 7 type of modules.

1/3/2012


24

BSNL

Switching Network

ALT CALT CENTRE

T

SN(B) has only 5 types of modules.Each TSG & SSG is accommodated in only two shelves of the respective racks. Remaining shelves accommodate LTGs. Main Functions:- Speech Path Switching - Message Path Switching - CCS#7 signalling channels connection (NUC)

1/3/2012


25

BSNL

Coordination Area

ALT CALT CENTRE

T

Coordination Processor (CP) handles the data base as well asconfiguration and coordination functions, e.g.: Storage and administration of all programs, exchange and subscriber data, Processing of received information for routing, path selection, zoning, charges. Supervision of all subsystems, receipt of error messages, alarm treatment, error detection, error location and error neutralization and configuration functions. Handling of the man-machine interface.

1/3/2012


26

BSNL

Coordination Processor (CP)

ALT CALT CENTRE

T

The CP113C is multiprocessor and can be expanded in stages. It has a maximum call handling capacity of over 1,400,000 BHCA. The rated load of n processors is distributed among n+1 processors. This means that if one processor fails, operation can continue without restriction (redundancy mode with n+1 processors).

1/3/2012


27

BSNL

BASIC CONFIG. 11 . OF CP 113C .0B:IOC

IOP

IOP

11 . . 0B:IOC

IOP

IOP

ALT CALT CENTRE

T

IOP

IOP

IOP

IOP

CAP0 . . .

CAP5

BAPM

BAPS

IOC0 IOC1

IOC2

IOC3

BCMY0 BCMY1

CMY1 CMY0

HARDWARE STRUCTURE OF THE CP113C 1/3/2012 SW-II/EWSD_Overview/HSJ 28

Coordination Processor (CP)BSNL

ALT CALT CENTRE

T

The Basic functional units of CP 113C are as follows:

Base Processor (BAP) for operation & maintenance and call processing. Common Memory (CMY)- 256 to 1024 MB in 4 memory banks consisting of 4 Mb DRAM chips. Input / Output Controller (IOC) - 2 to 4 IOCs coordinate and supervise accessing of CMY by IOPs. Input/output processors (IOP) -Various types of IOPs to connect the CP113C to other subsystems & to the external mass storage devices (EM i.e., MDD, MTD, MOD), the two O&M terminals (OMT/ BCT). Maximum 12 IOPs can be connected to one IOC. The other functional units of CP 113C are call processors (CAPs) which are similar to BAPs

1/3/2012


29

BIOC0CCNP

IOP:MB IOP:MB

IOP:UN1

BIOC1 Number depends on SN size.

BSNLMBGCCG

IOP:MB IOP:MB IOP:MB IOP:MB

MDD MOD C MTD ALT CENTRE OMT/ BCT Data line,

ALT

T

IOP:UN1

Alarm function : monitors fans of CP racks

IOP:TA IOP:TA IOP:MB

SYPCIOP:MB

IOP: SCDP LCUB LCUB (IOP:LAU) IOC0 IOC1 LAUB LCUB (LAU)

MDD MOD MTD OMT/ BCT Data line, V.24/V.28 X.21/V35 X.25 links to e.g. OMC, CT or billing centre

BCMY0 BCMY1

Structure of the CP113C input/output system with 2 IOCs1/3/2012 SW-II/EWSD_Overview/HSJ 30

ALT CBSNL

T

Coordination Area

ALT CENTRE

Other units assigned to CP are: Message Buffer (MB) for coordinating internal message traffic between the CP, the SN & the LTGs. Central Clock Generator (CCG) for the synchronization of the exchange and, where necessary, the network. The CCG is extremely accurate (10-9). It can, however, be synchronized even more accurately by an external master clock (10-11). System Panel Display (SYPD) to display system internal alarms and the CP load. The SYP also displays external alarms such as fire and air-conditioning system failure . It is installed in the Equipment Room or in the Exploitation Room.

1/3/2012


31

BSNL

Coordination Area

ALT CALT CENTRE

T

Some more units assigned to CP are: Operation and Maintenance Terminals/ Basic Craft Terminal for Input/output. Two OMTs/ BCTs are provided for O&M functions. External memory (EM), for - Programs & data that dont always have to be resident in CP - An image of all resident programs and data for automatic recovery, - Call charge and traffic measurement data. To ensure that these programs and data are safeguarded under all circumstances, the EM is duplicated (two MDDs). The EM also has a magneto optical disk ( MOD) and/or magnetic tape device (MTD), for input and output.

1/3/2012


32

ALT CBSNLALT CENTRE

T

Common Channel Signaling Network Control (CCNC) The CCITT- CCS#7 is one of the systems that is used for inter-exchange signalling in EWSD. For flexibility, a distinction is made between a message transfer part (MTP) and the user parts (UP). The user parts vary according to the specific application (e.g. TUP: telephone user part, ISUP: ISDN user part. The common MTP functions in an EWSD exchange are handled by the common channel signalling network control (CCNC). The UP is incorporated in the software of the relevant LTG.

1/3/2012


33

ALT CBSNL

T

Common Channel Signaling Network Control:

ALT CENTRE

A maximum of 254 common signaling channels can be connected to the CCNC . The digital links are extended from the LTGs over both planes of the duplicated SN and multiplexers to the CCNC. The CCNC is connected to SN via two 8 Mbps highways. Analog signaling links are linked to the CCNC via modems. CCNC consists of upto 32 signaling link terminal (SILT) groups, each with 8 signaling links & one duplicated CCNP. The CCNC, equipped in one rack can handle upto 48 signaling links. Equipments handling upto 96 signaling links can be equipped in additional racks.

1/3/2012


34

BSNLCCS via analog data links

Modem

Multiplexer

CCS via digital data links

ALT CALT CENTRE

T

0

7

0

7

SILT group 0

SILT group 31

0

31

0

31

CCNP 0

CCNP 1

CP bus system

COMMON CHANNEL SIGNALLING NETWORK CONTROL1/3/2012 SW-II/EWSD_Overview/HSJ 35

System DataBSNL

ALT CALT CENTRE

T

Call-handling capacityNo. of Subscriber linesmax. 250 000 No. of Trunks max. 60 000 Switchable traffic max. 25 200 E. Supply voltage: -48 V nominal D.C. Clock accuracy: Maximum relative frequency deviation : Plesiochronous 10-9; Synchronous 10-11 Signaling systems All conventional signaling systems:MF R2, No.7 etc.1/3/2012 SW-II/EWSD_Overview/HSJ 36

BSNL

System Data

ALT CALT CENTRE

T

Traffic routing

Per destination one primary route & max. 15 alternate routes. Sequential or random selection of idle trunks of a trunk group Max. 1000 incoming and Max. 1000 outgoing and Max. 1000 bothway

Number of trunk groups per exchange:

Call charge reg.

Periodic pulse metering, AMA Billing (CAMA, LAMA) IACHASTA

1/3/2012


37

System DataBSNL Call

ALT CALT CENTRE

T

Charge reg.

Max. 511 zones Max. 6 tariffs per zone Tariff switchover possible in 15m intervals

Space requirements: Example: Exchange for 24000 lines 2 units approx. 100m Environmental conditions Ambient temperature: 5C to 40C Relative humidity: 10% to 80%

1/3/2012


38

ALT CBSNL

T

EWSD Overview

ALT CENTRE

THANK YOU

1/3/2012


39

Documents

EWSD Overview