Mayur Report

8/3/2019 Mayur Report

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INTRODUCTION

Today, BSNL is the No. 1 telecommunication company and the largest public sector undertaking of

India and its responsibilities includes improvement of the already impeccable quality of telecom

services, expansion of telecom services in all villages and instilling confidence among its customers.

Apart from vast network expansions, especial emphasis has given for introducing latest technologies

and new services like I-NET, INTERNET, ISDN (INTEGRATED SERVICES DIGITAL NETWORK), IN

(INTELLIGENT NETWORK), CDMA, GSM and WLL (WIRELESS IN LOCAL LOOP), BROADBAND, 3G services

etc. Now BSNL has also entered in mobile communication. BSNL has all the new services send

technological advantages, which are available with any well, developed Telecom network anywhere

else in the country. Full credit for all above achievement goes to the officers and staff of the BSNL. The

administration is fully aware of the challenges lying ahead and quite committed to provide the latest

and best telecom services by their continued support and active co-operation.


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Company Profile

Bharat Sanchar Nigam Limited (BSNL) is India's leading

telecommunications provider and the country's largest public-sector firm.

BSNL provides local-exchange access and domestic long-distance services

through a network of more than 45million access lines covering most of India. It

also offers wireless communications, data and Internet services, as wellas business voice and data services. The company is still

controlled by the government, as is one of India's other large

phone companies, Mahanagar Telephone Nigam Limited (MTNL). Plans to

merge the two companies have been discussed but seem to be on

hold.

HIGHLIGHTS

Bharat Sanchar Nigam Limited has a vast reservoir of highly skilled and Experienced work force of about 3, 57,000personnel.

We believe that our staff, which is one of the best trained manpower in the telecom sector, is our biggest

asset.

To meet the technological challenges, employees are trained for technology up-gradation,

modernization, computerization etc in BSNL's training Centers spread across Country.

To apex training centers of BSNL i.e. Arera Telephone Exchange Center (ATX) at Bhopal is

comparable to any world class Telecom Training Center. Moreover, 43 zonal training centers and a

National Academy of Telecom Finance and Management have been running for several years now.

Different curriculums run in these centers to impart technology based training, Training for

Attitudinal change, basic educational and skill development Program etc.


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CONTENTS

Acknowledgement

Preface

Certificate Company Profile Introduction Structure and about the exchanges

1. Computer unit

2. Power plant

3. AC Plant (CENTRAL AIR CONDITIONER)

4. MDF (MAIN DISTRIBUTION FRAME)

C o n n e c t i n g S y s t e m

E W S D E x c h a n g eGeneral overview

Introduction of EWSDFunctional block diagram of EWSD

General features

Positional structures

Capacity stages

Functional unit of SN

Switching network

Rack assignment

Module frame layout

Interconnections of switching module

FunctionsO&M aspects

Exercises

Switching techniques

Internet Call record data(CRD) Leased circuit Conclusion Glossary of terms and abbreviations


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STRUCTURE AND ABOUT THE EXCHANGES

All telephone subscribers are served by automatic exchanges, which perform the functions the human

operator. The number being dialed is stored and then passed to the exchanges central computer,

which in turns operates the switching to complete the call or routes it a higher level switch for further

processing. Todays automatic exchanges uses a pair of computers, one running the program that

provides services and the second monitoring the operation of the first, ready to takeover in a few

seconds in the event of equipment failure.

Various exchanges present in BSNL are:

C-DOT

E-10B

OCB283 (Exchange & TAX)

EWSD (Exchange & TAX)

All exchange has some purposes and some basic structural units, which are:

1.Subscribers connection unit

2. Switching network (CX)

3. Control unit

4. OMC (Operational & maintenance Control)

Structure of the exchange

For smooth working of an exchange following unit are very important: -

1. Computer Unit: - it deals with additional services of the exchange to the customers with the help of

computers.

2. Power Plant:- to feed proper power supply to exchange

3. AC Plant: - to maintain the continuous temperature + or 2 degree Celsius to the digital switch

(exchange).4. MDF: - to connect switch (exchange) with the external environment (subscriber) i.e. it is the

interface between subscribers and exchange.

CONNECTING SYSTEM

Exchange Side Line Side

EXCHANGE MDF CABINETS PILLARS

DISTRIBUTIONSUBSCRIBERS


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Computer unit: -

As the name specified it is the main part of the exchange that deals with the all services provided by

the exchange to the customers with the help of computer. It also provides the updated data to all

other part of the exchange. The customers are using the services of the exchange by using the internet

also gets connected to the main server present this room via an internet room. It mainly consists of the

servers that are providing the different services. The main servers of this room are:-IVRS is used for the change

number services provided by the exchange.CERS are provided by the exchange to avoid the problems that the users are

facing the repairing of telephone. In this system when the user enters its complained it gets directly

entered to the server and user is allotted with an id number. LOCAL DIRECTORY ENQUIRY is another services

provided by the exchange, by using this; subscribers calls the particular number and gets the directory enquiry. The server

present in the main computer room provides this service. INTERNET DIRECTORY ENQUIRY is the latest service by the

exchange. In this type of service makes it enquiry using the internet, which gets connected to the main

server at the internet room in the exchange and further to the main server in the computer room.2.

POWERPLANT: -

As we know that, the power is the main source or any organization. It isthe case of E-10B exchange.

That is the first requirement of any organization isthe input. The main source of this exchange is ACsupply. However, as soon as the powersupply is gone off, then what is source? No one think on this

that the telephone is always plays its role in the human life. Even if the power supply gone off. Thus

there must be adjustment source of power. The main parts of the power room are:

i.Batt eries: - these are t he instant sources of th e power as soon as power is gone off.

ii.Cha rging - Di schargi ng Un it: - t he b atter ies we are using in t hepower room need timely

charging. As soon as the AC power supplyis on, we make use of the charging unit present in the power

room. The slowly charging of the batteries is known as the tricklecharging. But sometimes we need the

BOOSTER charging. In thistype of charging awe take of the batteries from the load and chargeseparately,

until it gets fully charged. The main work of the discharging unit is to control the dischargingof the

batteries.iii.Inverter and Converter Unit: - the main use of this system is tochange AC mains to DC and vice versa

as required by the parts of exchange.

iv.Engine Room:-we know that the batteries are the instant source of supply but we cannot use it for

much larger time, thus for this, we have an engine to generate the power supply. They are of 885

KVA. Thus, this room controls the supply of the engine.

UPS OPERATING MODES:

UPS system has three operating mode which can be designated as

1. Normal mode

2. Emergency mode

3. Recovery mode

I . N O R M A L M O D E :

The rectifier charger draws power from the ac mains & converts it into DC. This DC power is supplied to

the inverter which converts it back into AC power to feed the critical load connected to the output of

the inverter.

Inverter and Converter Unit: - the main use of this system is to change AC mains to DC and vice versa

as required by the parts of exchange.

Engine Room:-we know that the batteries are the instant source of supply but we cannot use it for

much larger time, thus for this, we have an engine to generate the power supply. They are of 885 KVA.

Thus, this room controls the supply of the engine.


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CENTRAL AIR CONDITIONER

For the function of electrical equipment, cooling system is basic requirement. The basic advantages of

cooling systems are following-

It provides the thermal stability so that the temperature does not reach the tolerance limit of

electronic equipment

It saves equipment from dust so to avoid malfunction ofequipments.

It protects equipment from excess humidity which can caused rusting of equipment.

The basic unit of measurement used in the industry is known as ton of refrigeration (TR) which is

equivalent to the heat extracted in 24 hours for converting thousands kg of liquid to ice at zero degree.

The compressor is the heart of the AC system and the costliest. It increases the pressure and

temperature of the refrigerant gas coming from the evaporator coils by compressing it.

Compressor comes in various types. The most widely used is simple reciprocal type a cylinder and

piston arrangement. For capacity more than 120 TR, centrifugal compressors are used. The condenser

liquefies the refrigerant gas by a heat exchange process. The capillary tube or the expansion valve

pressurizes liquid refrigerant and meters it flows to the evaporator.

The refrigerant then passes through the evaporator coils, which extract heat out of the ambience.

MAIN DISTRIBUTION FRAME

The primary function of MDF is:

The fault of telephone number is removed in the MDF; it is called as Fault Remove Section.

For removing the fault of telephone number, we use the testing

These testing are T.T.Y. testing, Group testing, etc.

For any type of testing firstly we need the vertical no. or the live tester, printer and computer test N.E.

number of that particular telephone number.

The telephone numbers are also disconnected in the MDF because of some specific reason.

ORGANISATION OF THE MDF

PARTS OF THE MDF

Horizontal side

Vertical side

HORIZONTAL SIDE:

It is again subdivided in to two parts

Exchange side

Line side

Description of the horizontal side:-

RACK: - On the rack, the tags are situated. One rack is having eight tags. The courting is done from up

(0) to down (7).

TAG: - Each rack consists of eight tags.

1 tag = 4 core

1 core = 4 bunch


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1 bunch = 2 line

N.E.:- The word NE stands for the NUMBER OF EQUIPMENT.

It is a 128 pair cable. The EWSD and MDF connected by NE.

WEDGE:-If we want to disconnect any two numbers then we insert a wedge between subscriber side

and exchange side. Here wedge works as insulator made of plastic.

VERTICAL SIDE:

The vertical aside connected to the underground cable. This cable is having 100 pairs.

These pair is distributed when we allot the telephone number to the subscriber.

Vertical side is again subdivided in two parts:

One part is connected with the horizontal side and another with the subscriber line by using 100 pair

underground cable.

This is how the present day telephone system works. Different exchanges have different architectures

of switching call routing and other features.

Now let us see how BSNL has kept up with the changing world and provided the subscribers with thelatest facilities technologies, which include the V-SAT network, Internet, the WLL (wireless in local

loop) and the GSM mobile.

EWSD

EWSD and Office Switch

1. General OverviewEWSD (Elektronisches Whlsystem Digital in German, Electronic Digital Switching System/Electronic

World Switch Digital in English) is one of the most widely installed telephone exchange systems in the

world. EWSD can work as a local or tandem switch or combined local/tandem, and for landline or
http://en.wikipedia.org/wiki/File:EWSD.jpg


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mobile phones. It is manufactured by Siemens AG, who claims that EWSD switches perform switching

for over 160 million subscriber lines in more than 100 countries.

DeTeWe bought its first EWSD under license in 1985 for remote switching. Bosch built its first EWSD as

a local exchange in 1986. Deutsche Telekom, formerly Deutsche Bundespost, the largest German

telephone company, uses EWSD and System 12 (Alcatel), the former more than the latter.

In 2007, Nokia Corporation and Siemens AG formed the new company Nokia Siemens Networks, and

responsibility of further development and shipments of the EWSD system is dependent on this new

company.

Contents

1 Hardware

2 Software

3 Technical data

Hardware

Main subsystems are:

CP (Central Processor)

MB (Message Buffer)

CCNC (Common Channel Network Control)

LINE (Analog Line Group) LTG (Line Trunk Group)

DLU (Digital Line Unit)

SN (Switching Network)

All system units are redundant so the inactive side can take over immediately in case of an error.

DLU handles analog and ISDN lines and includes codecs for analog lines, one of the BORSCHT functions

for subscriber lines. Digital signals are assigned a time slot. DLU concentrates traffic onto a Line B unit,

as well as Primary ISDN and V5.2 connections. Supervision and address signaling (dial pulse, DTMF) are

also integrated in the DLU. For PCM-30 (E-1) connections to other exchanges, Line C Units are used,

which also handle signaling including SS7, MFC R2 signaling, IKZ (dial pulse), and E&M.

he Switching Network consists of 4 space division stages of 16x16 switches, and a time division sectionwith 16 stages of 4x4 switches. Control is provided by the CP Co-ordination Processor.

There are the following kinds of Co-ordination Processors:

CP103 with max 22,000 call attempts in the busy hour

CP112 with max 60,000 call attempts in the busy hour

CP113D with max one million call attempts in the busy hour

CP113C with max six million call attempts in the busy hour

CP113E with max ten million call attempts in the busy hour

Software

The software of EWSD is called APS (Automatic Program System). The APS is on a hard drive and

includes the operating system, developed by Siemens in cooperation with Bosch. It is predominantly

written in the CHILL language. Application software is switch specific and serves among other things

traffic management, path search, and call charging. Support software serves translating programs,

binding modules as well as administration of libraries for generating data. Operating and data

communication software serve for co-operation of maintenance centers and switching centers.

Technical data

Number of access lines: to 250,000

Number of feeder lines: 240,000

Traffic connection: 25,200

Call attempts in busy hour: 10 million


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Operating voltages: -48V -60V -90V

Rate zones: 127, for each zone of 6 tariffs

Tariff change-over at 15 minute intervals

Space requirement with 10,000 access lines: 35 square meters

15-25 *C Temperature

2. INTROCDUCTION OF EWSDSwitching network (SN) performs the switching function for speech as well as for messages in an EWSD

exchange. For this purpose it is connected to LTGs and CCNC for speech/data and to CP (through MB)

for exchange of control information. Switching network with ultimate capacity up to 63 LTGs is called

SN DE4. For larger exchanges SN DE5.1 is used which can connect up to 126 LTGs. Similarly SN DE5.2

can connect up to 252 and SN DE5.4 up to 504 LTGs.

DLU LTG(B)

LTG(C)

CCNC

MB

CCGSYP

OMT PRINTER

CP

MTUMDD

SN

Figure 1. Position of Switching Network in EWSD


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3. BLOCK DIAGRAM OF EWSDEWSD switching system structure chart

DLUDigital line unit

SLM(A,D,X,I) -

subscriber line modules

DLUC - Digital line unit

controller

LTGLine trunk group

SNSwitching network

SSNC Signaling system network

control

CCNC Common channel network

control

MBMessage buffer

CPCoordinating processor

BAP - base processor

CAP - call processor

CMY - common

memory

IOC- I/O controller

AMP - ATM bridge

processor

B:CMY0(1) - commonmemory access bus

CCGCentral clock generator

Net

Manager

Network management system


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4. GENERAL FEATURESSwitching network is provided in capacity stages SN: 63LTG to SN: 504LTG, i.e. up to 63 LTGs can be

connected or, via other intermediate capacity stages, up to 504 LTGs can be connected. The modularly

expandable SN has negligibly small internal blocking and can be used in EWSD exchanges of all types

and sizes.

The self monitoring switching network uses a uniform through connection format. Octets (8 bit speech

samples) from the incoming time slots are switched to the outgoing time slots leading to the desired

destination fully transparently. This means that each bit of all octets is transmitted to the output of the

switching network in the way that it appears at the input (bit integrity). For each connection made via

the switching network, the octets have the same sequence at the output as at the input (digit

sequence integrity). The switching networks full availability makes it possible for each incoming octet

to be switched at any time to any outgoing highway at the output of the switching network. The time

slots used in switching network for making through-connections make up a 64 Kbit/s connection path.

All of the switching networks internal highways have a bit rate of 8192 bits/s (Secondary Digital

Carriers, SDCs). 128 time slots with a transmission capacity of 64 Kbits/s each (128x64 = 8192 Kbits/s)

are available on each 8192 Kbits/s highway. Separate cables each containing several (eight or sixteen)such internal highways, are used for each transmission direction. All externally connected highways

also have the same uniform bit rate.

The switching network combines the numerous switching network functions in a few module types.

These modules work at very high through-connection bit rates; 8192 Kbits/s and some even at 32768

Kbit/s. For example 1024 connections can be switched simultaneously through a space stage with 16

inputs and 16 outputs. Although these highly integrated switching network modules switch a large

number of connections with a high degree of reliability, the EWSD switching networks are always

duplicated. The amount of space needed for the switching network in the EWSD exchange is still very

low despite this duplication.

Two different switching network versions have been supplied in India:

* Switching network [SN] supplied with first 110K order.

* Switching network B [SN (B)] supplied with subsequent orders.

5. Position and Functional StructureSwitching network is connected to LTGs and CCNC for speech/data and to CP (through MB) for

exchange of control information. Figure 1 shows the position of switching network in EWSD exchangewith reference to other equipments.

For security reasons, entire SN is duplicated. The two sides of SN (SN0 and SN1) are called planes. The

external highways for both transmission directions i.e. between the switching network and one LTG or

between the switching network and one Message Buffer Unit (MBU) are identified as follows as shown

in figure 2.

* SDC: LTG interface between SN and LTG: time slot 0 for message exchange between the

LTG and coordination processor (CP) as well as between two LTGs, time slot 1 to 127 for

subscriber connections.


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* SDC: CCNC interface between the SN and the common channel signaling network (CCNC):

for common channel signaling.

* SDC: TSG interface between SN and a message buffer unit assigned to CP (MBU: LTG) for

message exchange between the CP and the LTGs as well as between the LTGs.

* SDC: SGC between the SN and an MBU: SGC of the CP for setting up and clearing

connections.

Switching network in EWSD exchanges uses time and space switching and therefore it is functionally

divided into Time Stage Group (TSG) and Space Stage Group (SSG). SN DE4 with capacity stage SN:

63LTG has a TST structure and TSG/SSG division is not applicable in this case.

TSGs and SSGs are interconnected through internal 8 Mb/s interfaces called SDC:SSG. TSGs of both

planes are connected to SSGs of both planes, and thus these provide further security.

Each TSG and SSG have its own Switch Group Control(SGC) that is connected to CP via MB through

interfaces SDC:SGC.

LTG 1

LTG n

CCNC

CP

MBU

MBU

MBU

SPACE

STAGE

GROUP

OF

SN:DE5

TIME

STAGE

GROUP

OF

SN:DE 5

OR

SN:DE4

SGC

SGC

Figure 2: SN Internal and External Interfaces

SDC:LTG

SDC:LTG

SDC:CCNC

SDC:TS

SDC:SG

SDC:SG

SN

MB

SDC:SSG

SDC:SSG


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TABLE 1: SN Capacity Stages

Capacity stages of

switching network

SN:63LTG

(DE 4)

SN:126LTG

(DE 5.1)

SN:252LTG

(DE 5.2)

SN:504LTG

(DE 5.4)

Switchable

traffic(E)

3150 6300 12600 25200

Local Exchanges

No. of lines 30000 60000 125000 250000

Transit Exchanges

No. of trunks

7500 15000 30000 60000

Structure TST TSSST TSSST TSSST

Connectable no. of

LTGs or

LTG+CCNC

63

or

62+1

126

or

125+1

252

or

251+1

504

or

503+1

6. Capacity StagesThe present version of SN is available in capacity stages SN:63LTG, SN:126LTG, SN:252LTG and

SN:504LTG. Modular structure permits partially equipped SN. Up gradation from DE5.1 to DE5.2 and

from DE5.2 to DE5.4 is possible with the help of supplier. SN DE4 is not upgradable to DE5.1 as TSG and

SSG are not separately identified in SN DE4. The traffic handling capacity, connect ability for various

capacity stages of SN are shown in Table 1.

7. Functional Units of SN7.1 Switching path

The switching network is subdivided into time stage groups (TSG) and space stage groups (SSG). Due to

its modular structure, the EWSD switching network can be partially equipped as needed and expanded

step by step. The switching network uses the following switching stages:

one time stage incoming (TSI)

three space stages (SS) and

One time stage outgoing (TSO).


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These time and space stages (functional units), shown in figure 3, are located in the following module

types:

Link interface module between TSM and LTG (LIL)

time stage module (TSM)

link interface module between TSG and SSG (LIS)

space stage module 8|15 (SSM8|15)

space stage module 16|16 (SSM16|16)The switching network capacity stage SN:63LTG, however has a TST structure with only one space

stage as shown in figure 4. Module types LIS and SSM 8|15 are not there in SN:63 LTG. Further, the

modules and the TSGs/SSGs are interconnected

A list of the various modules used in SN is given in Table 2.

LTG

MBU:SGC

SN1

SN0

LIL TSM SSM 16|16

TSO

SSG1.0

LTG

MBU: SGC

TSG1.0

TSG0.0

LIL TSM

LIS

TS0

MBU: SGC

SSG0.0

LIS SSM 8|15

SSM16|16

SSM

15|8

Figure 3: The seven module types in SN: DE5


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7.1.1 LIL & LIS:

The receiver components of the LIL and LIS compensate for differences in propagation

times via connected highways. Thus, they produce phase synchronization between the incoming

information on the highways. These differences in propagation times occur because an exchanges

racks are set up at varying distances to each other. Module LIL is connected on the interface to LTGs

and has 4 inputs and 4 outputs while module LIS is connected on the interface to SSG and has 8 inputs

and 8 outputs.

7.1.2. TSM:The number of TSMs in a switching network is always equal to the number of LILs. Each TSM contains

one time stage incoming (TSI) and one time stage outgoing (TSO) (Figure 5). The TSI and the TSO

handle the incoming or outgoing information in the switching network. Between input and output,

octets can change their time slot and highway via time

Stages. Octets on four incoming highways are cyclically

written into the speech memory of a TSI or TSO

(4x128 = 512 locations corresponding to 512 different

time slots). The speech memory areas 0 and 1 are

used alternately in consecutive 125- microseconds

periods for writing the octets. The connections to be

made determine the octet sequence during read-out.

The stored octets are read-out to any one of 512 time

slots and then transferred via four outgoing

highways.

7.1.3. SSM8|15 and SSM 16|16:The SSM 8|15 contains two space stages as shown in figure 6. One space stage is used for

transmission direction LIS SSM 8|15 SSM 16|16 and has 8 inlets and 15 outlets while a second

space stage is used for transmission direction SSM 16|16 SSM 8|15 LIS and has 15 inlets and 8

outlets. Via space stages, octets can change their highways between input and output, but they retain

the same time slot. Space stages 8|15, 16|16 and 15|8 switch the received octets synchronously with

the time slots and the 125-microsecond periods. The connections to be switched change in

consecutive time slots. In this process, the octets arriving on incoming highways are spatially

distributed to outgoing highways . In capacity stages with a TST structure, the SSM 16|16 Switches the

octets received from the TSIs directly to the TSOs.

LIL

0

SSM16|16 or LIS

0

TSM

Figure 5 : Time stage

module TSM

LIL

0

TSO

0

SSM16|16 or LIS

3


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SDC: LTG

0

1

2

3

4

5

6

7

56

57

58

59

60

61

62

63

01

2

3

0

1

2

3

0

1

2

3

0

1

2

3

01

2

3

TSMB-00

1

2

3

0

1

2

3

TSMB-70

1

2

3

0

12

3

0

1

2

3

0

1

14

15

0

1

14

15

0

10

2

3

14

15

0

1

2

3

0

1

14

15

TSGx-x

Fig. Time Stage group internal

connections


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INTERNET

Introduction:

The Internet is not a program, not software, not hardware or a big system. It is a group of various co-

operating computers worldwide interconnected by computer based on TCP\IP communication

protocols. People use it to get information over a standard communication link. The hundreds or

thousands or millions of computer network are connected to each other for exchanging the

information which is based on the unique identity and set of procedures. Internet is a series of

interconnected networks providing global link to information.

GIAS: BSNL launched the Gateway Internet Access Service (GAIS) through dial up/leased/ISDN network.

Users can access GAIS from 99 cities in India by this means.

INTERNET TECHNOLOGY

The basic function of Internet can be summarized as under-

Interconnecting of computers to form a network.

Interconnecting of computers to form a network of networks.

To establish a communication link between two computers within as network.

To provide alternate communication link among the networks, even if one network is not working.

These are based on TCP/IP communications protocol.

Transfer of a file through Internet:-Suppose a file is to be transmitted on Internet from one computer to other ones

Break the file in to small packets

Attached destination and source address in o packets

Multiplexed and transmit these packets

At destination de-multiplex the packets

Remove address bits from the packets and assemble the data in to the original file

Make source bits as destination address and send the acknowledgement in to the source

Therefore, it is clear that network hardware sends the packets to specified destination and network

software reassembles of communications, the computer network performs the following functions-

Addressing and routing

Fragmentation and error correction

Data error checking

Connectivity control

Multiplexing and de-multiplexing


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Data flow control

End users interface etc.

The data handling

A single module cannot handle the entire process. One that adopted as a standard is an open system

interconnection (OSI) model.

COMMON TERMINOLOGY USED IN INTERNET:

WWW:

World Wide Web (WWW) is a wide area hypermedia information retrieval aiming to give universal

access to a large universe of documents.

HTTP:

Hyper text transmission Protocol (HTTP) is the communication protocol used to transfer documents

from the server to client over the WWW (http:// www).

HTML:

Hyper Text Markup Language (HTML) is a system of marking or tagging the various parts of web

documents to tell the browser software how to display the document text, link graphics and link

media.

ISDN:

Integrated Service Digital Network (ISDN) is a digital phone connection technology that provides both

voice and data services over the same connection.

ISP:

Internet Service Provider (ISP) is an agency that provides Internet access and other net related services.

NATIONAL INTERNET BACKBONE (NIB)

Networking is a key component of any Internet Services Provider (ISP) operations. The networkingequipments like access servers, routers and modems are critical to the successful functioning of ISP.

An ISP node where subscribers enter internet, consists of a set of equipments as given below.

Access server

Router

Modem bank

LAN (Local Area Network) components

Security server


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Rack, console & power supply

Network management agent.

Help desk

Call Detail Record (CRD)

A call detail record (CDR), also known as call data record, is a data record produced by a telephone

exchange or other telecommunications equipment documenting the details of a phone call that passed

through the facility or device. It is the automated equivalent of the paper toll tickets that were written

and timed by operators for long-distance calls in a manual telephone exchange.

Contents

A CDR is composed of fields that describe the exchange. Examples of fields include:

* the number making the call (calling party)

* the number receiving the call (called party)

* when the call started (date and time)

* how long the call was (duration)

* the phone number charged for the call

* the identifier of the telephone exchange writing the record

* a sequence number identifying the record

* additional digits on the called number used to route or charge the call

* the result of the call (whether it was answered, busy etc)

* the route by which the call entered the exchange* the route by which the call left the exchange

* call type (voice, SMS, etc)

* any fault condition encountered

Each exchange manufacturer decides which information is emitted on the tickets and how it is

formatted. Examples:

* Send the timestamp of the end of call instead of duration

* Voice-only machines may not send call type

* Some small PBX does not send the calling party

* to make all the records correct

Production

CDRs are produced by the charging system of the telephone exchanges. In Nortel exchanges and in

other North American exchanges, the charging system is called Automatic Message Accounting. In an

Alcatel OCB switch, the charging system is software known as TX.


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TransportComputer networks are used for transporting CDRs to a central point for processing, with X.25 links

being widely used worldwide for transporting CDRs. The CDRs of calls still in progress are held by the

sending exchange until the call is completed.

ProcessingCall accounting or call logging software is generally used for retrieving and process CDRs. This system

can be called a business support system (BSS). In the billing system the price of the call will becalculated.

Besides for billing, CDRs can be used for supporting the operations of the telephone company by

providing information on faulty calls, and measures of the amount of traffic taken along particular

routes.

Station messaging detail record

A station messaging detail record (SMDR) is similar to a CDR, but the most important difference is in

the usage. CDRs are for telephone company use, and may carry information about the processing of a

call. To create actual billable call records, it may be necessary to correlate several CDRs. CDRs may also

have a role in internal financial transfers among phone companies

Major Account Billing Exchange Logistical record or MABEL, is a vehicle for the exchange of majoraccount billing data between carriers. The records cover all of the billing elements of a major account,

including summary billing information and call detail-level information.

A wireless service provider or a company that acts as a liaison to a wireless service provider uses

MABEL. Also defined in MABEL is a Major Account Consolidator, which can be the wireless service

provider or third party that acts as a liaison to the corporate entity. MABEL

SMDR, in contrast, is intended for end-user organization, and as a way to understand their telephone

usage and billing.

Leased Line

To transmit data between computer and electronic information devices, BSNL provides data

communication services to its subscribers. It offers a choice of high, medium and low speed leaseddata circuits as well as dial-up lines. Bandwidth is available on demand in most of the cities. Managed

leased Line Network (MLLN) offers flexibility of providing circuits with speeds of n x 64 Kbps up to 2

Mbps. Useful for internet leased lines and international principle Leased Lines (IPLCs).

For dedicated point to point speech, private wire, tele-printer and data circuits are given on lease basis.

Leased circuits are provided to subscribers for internal communication between their offices/factories

at various sites within a city/town or different cities/town on point to point basis, or on a network basis

interconnecting the various sites.

Managed Leased Line Service(MLLN): The MLLN is a Managed Leased Line Network system which is

proposed to provide Leased line connectivity. The State-of-the-art technology equipment MLLN isdesigned mainly for having effective control, monitor on the leased line so that the down time is very

much minimized services .

Speech Circuits (Hot Line or Private Wire) - Local or Long distance circuits within two locations in a city

or between two different cities provided for the same applicant. The Terminating equipment at both

ends is telephone without dialing facility. Both way signaling and speech is possible.

Data Circuits - Local or Long distance data circuits at different speeds viz. nx64 kbps and 2 mbps. Data

Circuits are of different types:

Point to Point Data Circuits - Local and Long Distance


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Private Data Network - More than one Local or Long Distance leased circuits converging on a location

such that data from one leased circuit can be transferred automatically to another leased circuit for the

same subscriber.

Closed User Group - Leased circuits can be used by more than one legal entity if they form closed user

group. The following categories of user groups constitute closed user groups for the purpose of

licensing Private Telecom Networks.

1. Producer of goods and his whole -sale traders /agents.

2. Provider of service (not being a telecommunication service) and his whole-sale traders/agents.

3. Producers of same categories of goods.

4. Providers of the same category of service.

5. Holding company and its subsidiaries.

6. Interconnected undertakings.

7. Companies under the same management

8. Travel agents issuing tickets on the member airlines, whose network they use including the

network of a group of member airlines.

9. Computerized Reservations System (CRS) service providers owned by airlines.

10. Shared networks of banks for use of Automatic Teller Machines (ATMs), Electronic Points of

Sale(EPOS)/credit authorization terminals.

11. Financial institutions registered primarily to deal in securities and their agents/dealers.12. Financial institutions registered as Mutual funds and their agents.

13. Financial institutions which are registered as depositories and their agents/dealers.

14. Other non-banking financial institutions.


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CONCLUSION

Hence in the last I can say that taking training in such an organization proved to be very beneficial for

me. I learnt quite a lot about electronic exchange, Internet, Land line, WLL, Mobile GSM & 3G, and the

basis of processing Exchange. I also got firsthand knowledge of how a Telephone Exchange works.

The first phase of training has proved to be quite fruitful. It provides an opportunity to encounter with

such huge machines.

The architecture of company has various units. They are linked and working of whole plant is

controlled make the student realized that engineering is not just learning the structure description and

working of various machines. But the greater part is planning proper management.


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GLOSSARY OF TERMS AND ABBREVIATIONS

ADM Add/Drop Multiplexers

ANALOGUE An electrical signal which is analogous

to changing physical quantity measured

BSC Base Station Controller

BTS Base Tran receiver Station

C-DOT Centre for Development of Telemetric

CD Cabinet Cable Distribution Cabinet

CDMA Code Division Multiple Access

CKM Cable conductor kilometer cable

sheath kilometers multiplied by the

number of conductor pairs in each cable

CLIP Calling Line Identification Processing

COAXIAL CABLE A cable with a single wire in the centre

of cylindrical conductor forming a pair

of carrying electrical signals

CT BOXES Cable Termination Boxes

DECT Digital Enhanced Cordless

Telecommunications

DEL Direct exchange lines, one each for

every telephone connection

DIGITAL EXCHANGE The exchange having signals coded into

binary pulses and having little or nomoving parts

DIU DECT interface unit

DLC Digital Loop Carrier

DWDM Dense Wavelength Multiplexing

Terminal

EDX Electronic Data Exchange

EPABX Electronic Private Automatic Branch

Exchange

ETRP Electronic Trunk Relay PlatesEWSD TAX Electronic Wheeler System of Digital

Trunk Automatic Exchange

GHz Giga Hertz

GSM Global System for Mobile

Communications

HDPE High density polyethylene

HDSL High bit rate Digital Subscriber Line

Hertz or Hz Frequency (cycles per second), named

after Heinrich Hertz - usually in ranges


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of kilo 1000 - KHz, mega 1,000,000 -

MHz or giga 1,000,000,000 - GHz

IDR Intermediate Data Rate

ISDN Integrated Services Digital Network

LDST Long Distance Satellite Telephone

LOI Letter of Intent

MARR Multi Access Rural RadioMBM Multi Base Module

Mbps Mega bits per second denoting digital

frequency

MCPC Multi Channel Per Carrier

MDF Main Distribution Frame

MUX Multiplex

NIT Notice Inviting Tender

NE Lines Non Exchange Lines

OFC Optical Fiber Cable

Optical Fiber (OF) Glass fibers using light waves for

transmission of signals

OLA Optical Line Amplifiers

OYT Own your telephone

PABX Private Automatic Branch exchange

PBX Private branch exchange

PCM Pulse Code Modulation

PCO Public Call Offices

PDH Plesiochronous Digital Hierarchy

PERT Chart Programmed Evaluation Review

Technique Chart

PIJF Cable Polyethylene Insulated Jelly Filled Cable

PSPDN Packet Switch Public Data Network

PST Progressive Stock Taking

PSTN Public Switched Telephone Network

PVC Polyvinyl chloride

PW Private Wires

RLU Remote Line Unit

RSU Remote Switching Unit

SACFA Standing Advisory Committee on Radio

Frequency Allocation

SDH Synchronous Digital Hierarchy

SMPS Switch Mode Power Supply

SRCs Subscriber Record Cards

SSAs Secondary Switching Areas


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STD Subscriber trunk dialing

STM Synchronous Transport Module

TAX Trunk automatic exchange

TDMA Time Division Multiple Access A

transmission technique used in digital

radio transmission in which the use of a

frequency is divided into time slots that

are shared amongst several users.

TELEX TelePrompTer exchange

TTH Triangular Tubular Hybrid

UHF Ultra high frequency (300 to 3000 MHz)

VHF Very high frequency

VPT Village Public Telephones

VSAT Very small aperture terminal

WLL Wireless-in-Local Loop

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Mayur Report

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