COE 341: Data

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COE 341 Data Computer Communications
(T062)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 of sequence
• Small chunks (packets) of data at a time
• 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