tt&s lec1
TRANSCRIPT
To familiarize with different types of switching systems
To have a understanding of various types signaling systems
To have a knowledge of traffic engineering and concepts
To have a concept about Various Transmission Systems
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COURSE OBJECTIVECOURSE OBJECTIVE
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Telecommunications Switching, Traffic & Networks J.E. Flood
Data Communication and Networking, 4th Edition Behrouz A. Forouzan
Data and computer Communication , 7th Edition William Stalling
Signaling in Telecommunication Network John G.van Bose
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Books
Class Notes/Discussions
READINGSREADINGS
Introduction (Chapter1 J.E Flood)
Evolution of Switching systems (Chapter 8 B.A Foruzan)
Signaling in PSTN (John G.van Bose)
ISDN (William Stalling)
Next Generation Network
SIGTRAN
ATM and Signaling in ATM
Optical Fiber network-SDH (Siemens CBTs+Notes)
DWDM networks (Misc)
GPON (Misc) & Miscellaneous Topics
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COURSE OUTLINECOURSE OUTLINE
Grading Policy is tentative
Assignments 5%
Quizzes 15%
First Sessional 15%
Second Sessional 15%
Final Exam 50%
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GRADING POLICYGRADING POLICY
You are expected to take active part during lectures
You are strongly discouraged to enter the lecture room after the class has already begun
You are strongly advised to attend lectures
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RULES & REGULATIONSRULES & REGULATIONS
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Overview
Introduction to telecommunication
Early Telephone network
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Switching
Transmission MediaSignaling
Standards
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A telecommunications network can be considered as a system of the following interacting subsystems
Switching Systems
Transmission Systems
Signaling Systems
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INTRODUCTION TO TELECOMINTRODUCTION TO TELECOM
A better idea was to connect all the telephones to a central switching office. There an operator could connect one telephone to another via a switch board
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Stringing a wire between every pairsof telephones that might want to communicate was not good Long Term Policy
EARLY TELEPHONE NETWORKEARLY TELEPHONE NETWORK
In this telephone system, each telephone user could connect to any other telephone in the town by a cranking handle
This would ring a bell in the switching office to attract the attention of the operator
The operator talked to the telephone user to enquire to whom they wished to be connected to. She then manually connected the caller to the calle using a jumper cable on a plug board to physically connect the telephone wires
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SWITCHING OFFICESWITCHING OFFICE
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SWITCHING EXCHANGESWITCHING EXCHANGE
It was soon apparent that the callers did not just want to talk to the people in the same town but also to the peoples in the neighboring town
To connect every telephone in a number of towns to a single switching office was impractical .The wires were toolong and the operator would have been overloaded
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EVOLUTION OF TRUNK EXCHANGESEVOLUTION OF TRUNK EXCHANGES
The answer was to have switching offices
Using this two-tier hierarchy It was possible to connect a caller to the switching office that could connect them in turn to the switching office in the destination town
Automatic switching offices enables switching in a fractionof a second
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TRUNKSTRUNKS
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Soon Customer wanted to talk to different regions , states and other countries. To cope with this, even more tiers were added to the hierarchy.
To make a call we now dial a number. This number is examined by the local exchange, which decides if it can connect with local telephone exchange or if it needs to connect you via a higher level of hierarchy
PUBLIC SWITCHED TELEPHONE NETWORKPUBLIC SWITCHED TELEPHONE NETWORK
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PSTN EXCHANGES HIERARCHYPSTN EXCHANGES HIERARCHY
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Provides POTs, PRIs, BRIs
Serves the subscribers
Features for subscribers
Either subscribers on both the ends or subscribers on one end and switch on other end
Gets the clock from Tandem
LOCAL EXCHANGELOCAL EXCHANGE
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Provide POTS, PRIs, BRIs
A center point for local exchanges
More PRIs links
Subscribers Features
Gets the clock from transit
Can be connected to : Local Tandem Transit
TANDEM EXCHANGETANDEM EXCHANGE
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No provision of POTs
Connection to Transit on one end and Tandem on other end
Lots of PRI links
TRANSIT EXCHANGETRANSIT EXCHANGE
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Serves same as local tandem
No provision of POTS
Connected both ends to Transit
Gets the clock from international gateway
TANDEM-TRANSIT EXCHANGETANDEM-TRANSIT EXCHANGE
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No provision of POTS
Connected to Transit on one end and International Gateway on other end
Source of Clock
INTERNATIONAL GATEWAY EXCHANGEINTERNATIONAL GATEWAY EXCHANGE
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Class 1Class 1 exchanges are international gateways - handing off and exchanges are international gateways - handing off and receiving traffic from outside country or national networks. receiving traffic from outside country or national networks.
Class 2Class 2 exchanges are tandem exchanges which interconnected exchanges are tandem exchanges which interconnected whole regions of the national network. whole regions of the national network.
Class 3Class 3 exchanges are tandem exchanges connecting major exchanges are tandem exchanges connecting major population centers within particular region of the national population centers within particular region of the national network. network.
Class 4Class 4 exchanges are tandem exchanges connecting the various exchanges are tandem exchanges connecting the various areas of a city or towns in a region. areas of a city or towns in a region.
Class 5Class 5 exchanges are the exchanges to which end-users exchanges are the exchanges to which end-users telephone lines would connect. telephone lines would connect.
CLASSIFICATION OF SWITCHESCLASSIFICATION OF SWITCHES
In traditional analogue telephone systems the telephone is connected to the local exchange via Cat 3 UTP cables This connection is called local loop. It is typically between 1Km and 10 Km in length.
Higher up in the hierarchy, higher bandwidth cables are used to carry multiple telephone calls. Specifically digital lines on fiber is used
Analogue systems used a technique called Frequency Division multiplexing (FDM) is used to do so
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TRANSMISSION MEDIATRANSMISSION MEDIA
In telephony context ,signaling means the passing of infoand instructions from one point to another relevant to setting up and supervision of a telephone call
By Tradition signaling has been divided into two typesSubscriber SignalingTrunk signaling
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SIGNALINGSIGNALING
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The trunk Signaling has further been divided into
Channel Associated signaling Common Channel Signaling
Channel Associated Signaling (CAS) i.e. Signaling in the speech channel (in-band )
Common Channel Signaling (CCS) i.e signaling in a channel that is totally separated from the speech channels and where the signaling channel is common for a large number of speech channels
SIGNALINGSIGNALING
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British System Local/Access Network Exchange Local Exchange Junction Trunk Trunk Exchange Trunk network
North American System Customer’s loop Central office end office Inter-office trunk Junctor Toll office Trunk network
TERMINOLOGIESTERMINOLOGIES
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ITU-T ( former Consultative committee of telephone and telegraph) : It studies technical questions, operating methods, tariffs and data communications.ITU-R ( former Consultative committee of international radio communication) : p2p communications, mobile services and broadcasting
STANDARDSSTANDARDS
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Physical layer : defines interface of connections, voltage Physical layer : defines interface of connections, voltage level and data rate (connectors, signal form, modulation)level and data rate (connectors, signal form, modulation)Link layer : error detection and correction (point to point Link layer : error detection and correction (point to point communication)communication)Network layer : establish connection b/w nodes (End to Network layer : establish connection b/w nodes (End to end connectivity)end connectivity)Transport layer : establish connection b/w hops (End to Transport layer : establish connection b/w hops (End to end reliable transfer and flow control)end reliable transfer and flow control)Session layer : setting up and maintaining a session Session layer : setting up and maintaining a session (begin, end, suspend sessions, integrate connections)(begin, end, suspend sessions, integrate connections)Presentation layer : concerned with the format of the data Presentation layer : concerned with the format of the data (Represent information, compression, encryption) (Represent information, compression, encryption) Application layer : defines nature of the task to be Application layer : defines nature of the task to be performed. For example e-mail, word processing. (service performed. For example e-mail, word processing. (service to the end usersto the end users
OSI REFERENCE MODELOSI REFERENCE MODEL
Local loop connects subscriber to the localexchange
Trunk connects different exchanges
In PSTN Local loop is analogue and trunk is digital employing digital multiplexing techniques e.g. TDM and WDM
SS7 is a common channel signaling protocol
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SUMMARYSUMMARY
Chapter 1 : Introduction Telecommunications Switching, Traffic and networks by J.E Flood
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RECOMMENDED READINGRECOMMENDED READING