COE 341: Data & Computer Communications (T081) Dr. Marwan Abu-Amara Chapter 1: Data Communications & Networking Overview.

COE 341: Data & Computer Communications (T081)Dr. Marwan Abu-Amara

Chapter 1: Data Communications & Networking Overview

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Acknowledgements

Many figures, slides, and course notes were made

available by: Pearson Prentice-Hall

Data & Computer Communications, W. Stallings McGraw-Hill

Data Communications & Networking, B. Forouzan Previous Course Offerings at KFUPM COE by:

Dr. Radwan E. Abdel-Aal Dr. Ashraf Mahmoud Dr. Taha Landolsi

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Course Outline Data Communications & Networking Overview (Ch. 1) Protocol Architecture (Ch. 2) Data Transmission (Ch. 3) Guided and Wireless Transmission (Ch. 4) Signal Encoding Techniques (Ch. 5) Digital Data Communication Techniques (Ch. 6) Data Link Control (Ch. 7) Multiplexing (Ch. 8)

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Agenda Introduction Communications Model

Main blocks and functionality Communication Tasks

Data Communications Data Communication Networking

Wide Area Networks Circuit switching Packet switching Frame Relay ATM

Local Area Networks

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Introduction Fundamental purpose of communications

system is exchange of data between 2 parties 3 general areas:

Data Communications (main concern of COE341) Transmission of signals in reliable & efficient manner Covers signal transmission, transmission media, signal

encoding, interfacing, data link control, multiplexing Networking

Covers technology & architecture of communication networks

Divided into LANs & WANs Protocols

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Simplified Communications Model - Diagram

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A Communications Model Source

Generates data to be transmitted Transmitter

Converts data into transmittable signals (modulation, encoding, …)

Transmission System Carries data

Receiver Converts received signal into data (opposite to “Transmitter”

role) Destination

Takes incoming data

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Communications Tasks

Transmission system utilization Addressing

Interfacing Routing

Signal generation Recovery

Synchronization Message formatting

Exchange management Security

Error detection and correction Network management

Flow control

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Simplified Data Communications Model

May involve buffering and/or encoding of digital data (Ch. 5) Modulated signal, s(t), matched to media (Ch. 3 & 4) Transmission Impairments: noise, distortion, etc. (Section 3.3) Ideally received info, m’, should be identical to original input info, m

(Ch. 7) If not, error correction may help restore m (Ch. 7) Else, retransmission is required (Ch. 7)

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Networking

Point to point communication not usually practical Devices are too far apart Large set of devices would need impractical

number of connections (full connectivity of N nodes is N (N – 1) / 2)

Solution is a communications network Wide Area Network (WAN) Local Area Network (LAN)

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Wide Area Networks

Large geographical area Rely in part on common carrier circuits Alternative technologies

Circuit switching Packet switching Frame relay Asynchronous Transfer Mode (ATM)

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Circuit Switching

Dedicated communications path established for the duration of the conversation

e.g. telephone network

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Packet Switching

Data sent out in sequence of small chunks (packets) of data

Packets passed from node to node between source and destination

Used for terminal to computer and computer to computer communications

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Frame Relay

Packet switching systems have large overheads to compensate for errors

Modern systems are more reliable Errors can be caught in end system Most overhead for error control is stripped out Variable-length packets (called frames)

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Asynchronous Transfer Mode (ATM) Evolution of frame relay Combines circuit switching & packet switching Little overhead for error control Fixed-length packets (called cells) Anything from 10Mbps to Gbps Constant data rate while using packet

switching technique

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Local Area Networks

Smaller scope Building or small campus

Usually owned by same organization as attached devices

Data rates much higher Usually broadcast systems Now some switched systems and ATM are

being introduced

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LAN Configurations

Switched Switched Ethernet

May be single or multiple switches ATM LAN Fibre Channel

Wireless Mobility Ease of installation

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Metropolitan Area Networks (MAN) Middle ground between LAN and WAN Private or public network High speed Large area

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NetworkingConfiguration