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

2. COE 341 – Dr. Marwan Abu-Amara 2 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

3. COE 341 – Dr. Marwan Abu-Amara 3 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)

4. COE 341 – Dr. Marwan Abu-Amara 4 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

5. COE 341 – Dr. Marwan Abu-Amara 5 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

6. COE 341 – Dr. Marwan Abu-Amara 6 Simplified Communications Model - Diagram

7. COE 341 – Dr. Marwan Abu-Amara 7 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

8. COE 341 – Dr. Marwan Abu-Amara 8 Communications Tasks Transmission system utilizationAddressing InterfacingRouting Signal generationRecovery SynchronizationMessage formatting Exchange managementSecurity Error detection and correctionNetwork management Flow control

9. COE 341 – Dr. Marwan Abu-Amara 9 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)

10. COE 341 – Dr. Marwan Abu-Amara 10 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)

11. COE 341 – Dr. Marwan Abu-Amara 11 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)

12. COE 341 – Dr. Marwan Abu-Amara 12 Circuit Switching Dedicated communications path established for the duration of the conversation e.g. telephone network

13. COE 341 – Dr. Marwan Abu-Amara 13 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

14. COE 341 – Dr. Marwan Abu-Amara 14 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)

15. COE 341 – Dr. Marwan Abu-Amara 15 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

16. COE 341 – Dr. Marwan Abu-Amara 16 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

17. COE 341 – Dr. Marwan Abu-Amara 17 LAN Configurations Switched  Switched Ethernet May be single or multiple switches  ATM LAN  Fibre Channel Wireless  Mobility  Ease of installation

18. COE 341 – Dr. Marwan Abu-Amara 18 Metropolitan Area Networks (MAN) Middle ground between LAN and WAN Private or public network High speed Large area

19. COE 341 – Dr. Marwan Abu-Amara 19 Networking Configuration