7/28/2019 49700940-switching

1/19

SWITCHING

1

7/28/2019 49700940-switching

2/19

What is switching?

How is switching is made?

Switching is setting up a temporary connection b\w

2 or more exchange termination.

Exchange provide a temporary path for simultaneous,bi-directional transmission of speech

2

7/28/2019 49700940-switching

3/19

EXCHANGE

STORED PROGRAM

CONTROLLED EXCHANGE

ELECTROMECHANICAL

EXCHANGE

Relays and switches are used for

providing a closed path b\w two

subscriber for the data, voiceexchangement

Modification impossible

Subscribers cant modify their owndata entries for supplementary

services, such as on-demand call

transfer, dialing, short code etc.

Routine test required to check faults

These exchanges works according to

the data store in the processor

Modification become possible by

changing the data stored in

processor

Can provide modification service to

subscriber

Automatically faults are detected

3

7/28/2019 49700940-switching

4/19

BLOCK SCHEMATIC OF SPC EXCHANGE

TERMINAL EQUIPMENT

SWITCHING NETWORK

SWITCHING PROCESSOR SWITCHING PERIPHERALS

SIGNALING INTERFACES

DATA PROCESSING PERIPHERALS

4

7/28/2019 49700940-switching

5/19

In this equipment, line , trunk, and service

circuit are terminated for the detection,

signaling, speech, transmission, and

supervision of calls.

5

7/28/2019 49700940-switching

6/19

Largest sub-system in terms of size of the

equipment. Its main function :

Switching

Transmission

Types of electronic switching system

o Space divisiono Time division

6

7/28/2019 49700940-switching

7/19

Continuous physical path is set up betweeninput and output terminations.

Path is separate for each connection and is

held for entire duration of the call.

Same path is used by number of call.

The path is sequentially shared by number of

call for a fraction of time {time=125s}7

7/28/2019 49700940-switching

8/19

Network

Special purpose real time computer, designedand optimised for dedicated application ofprocessing telephone calls

Block schematic of a switching processor

Central control processor

Programme Store

Data store

Translation Store

To SwitchingTo Switching

8

7/28/2019 49700940-switching

9/19

There are speed buffer and interface b\w processorand component in telephone switching section asboth operates at different speed.

Scanner

Marker

Distributor

Bus system

Line interface circuits Analogue subscriber line interface

Transmission interface

Signaling interface9

7/28/2019 49700940-switching

10/19

Type of signaling

CAS ( Common associated signaling )

CCS ( Common channel signaling )

10

7/28/2019 49700940-switching

11/19

Electronic exchanges work on the principle of

Stored Program Control. All the call processing

functions are performed on the basis of pre-

designed programme which is stored on the

memory of the central processor.

11

7/28/2019 49700940-switching

12/19

12

7/28/2019 49700940-switching

13/19

C_DOT DSS MAX :Universal digital switch { perform local, transit, or

integrated local and transit switch role }

BASIC GROWTH/BULIDING MODULESBASE MODULE

CENTRAL MODULE

ADMINISTRATION MODULE

INPUT OUTPUT MODULE

7/28/2019 49700940-switching

14/19

14

The Base Module (BM)

The basic growth unit of the system.

It interfaces the external world to the switch.

The interfaces may be subscriber lines,analogue and digital trunks.

Each Base Module can interface upto 2024

terminations.

It carries out majority of call processing

functions

7/28/2019 49700940-switching

15/19

15

The Single Base Module (SBM)

In Single Base Module (SBM) exchange

configuration, the Base Module acts as anindependent switching system and providesconnections to 1500 lines and 128 trunks.

In such a configuration, the Base Module directlyinterfaces with the Input Output Module .

It is a very useful application for small urban andrural environments.

With minimum modifications in hardware a BaseModule(BM) can be remotely located as aRemote Switch Unit (RSU), parented to the mainexchange using PCM links.

7/28/2019 49700940-switching

16/19

16

Central Module (CM)

It consists of a message switch and a spaceswitch to provide inter-modulecommunication

It perform voice and data switching betweenBase Modules.

It communicates with Administrative Module

for operation and maintenance functions. It also provides clock and synchronisation on a

centralised basis.

7/28/2019 49700940-switching

17/19

17

Administrative Module

It support administration and maintenancefunctions

It communicates with the Base Module via the

Central Module. It supports the Input Output Module for

providing man- machine interface.

It also supports the Alarm Display Panel forthe audio-visual indication of faults in thesystem.

7/28/2019 49700940-switching

18/19

18

Input Output Module (IOM)

It is a powerful duplex computer system

It interfaces various secondary storage devices

like disk drives, cartridge tape drive and floppy

drive.

It supports printers and ports for video

display units which are used for man- machine

communication interface.

7/28/2019 49700940-switching

19/19

19

REMOTE SWITCH UNIT The normal BM can be modified for remoting

with the host exchange via 2 Mbps digital links. The number of 2 Mbps links between the Main

Exchange and RSU is primarily determined by the

traffic.

Operation and maintenance functions are

handled by the host exchange.

A maximum 16 RSUs are possible in C-DOT DSSMAX-XL and 8 RSUs in MAX-L.