1. CIS 321 – Fall 2004 Data Communications & Networking Chapter 1 - Introduction

2. University of South Alabama Computer and Information Sciences 2 321 Topics to be Covered  Network Topologies & Categories  Transmission Modes  Network Models  Signaling and Media  Encoding and Modulating  High Speed Digital Access  Multiplexing  Error Detection and Correction  Data Link Control and Protocols  LANs/WANs, VLANs/VPNs  Frame Relay, ATM  Internetworking  Security  Compression  TCP/IP  Application Services

3. University of South Alabama Computer and Information Sciences 3 Part 1 Overview of Data Communications and Networking  Chapter 1 Brief description of data communication, networking, and protocol standards  Chapter 2 Network models

4. University of South Alabama Computer and Information Sciences 4 Data Communication  Why study data communications?  Data communication – exchange of data between two devices via a transmission medium  Effectiveness depends on: Delivery, Accuracy, Timeliness

5. University of South Alabama Computer and Information Sciences 5 Communication System Components

6. University of South Alabama Computer and Information Sciences 6 Data Representation  Text – represented as a bit pattern; codes often used: ASCII; Extended ASCII; Unicode; ISO  Numbers – represented by binary equivalent  Images – bit patterns representing pixels  Audio  Video

7. University of South Alabama Computer and Information Sciences 7 Direction of Data Flow  Simplex – unidirectional; one transmits, other receives  Half-duplex – each can transmit/receive; communication must alternate  Full-duplex – both can transmit/receive simultaneously

8. University of South Alabama Computer and Information Sciences 8 Networks  Set of devices (nodes) connected by media  Distributed processing  Advantages

9. University of South Alabama Computer and Information Sciences 9 Network Criteria  Performance – affected by # users, type of medium, HW/SW  Reliability – measured by freq of failure, recovery time, catastrophe vulnerability  Security – protection from unauthorized access, viruses/worms

10. University of South Alabama Computer and Information Sciences 10 Types of Connections  Point-to-point – dedicated  Multipoint – shared

11. University of South Alabama Computer and Information Sciences 11 Physical Topology  Physical or logical arrangement  4 basic types: mesh, star, bus, ring  May often see hybrid

12. University of South Alabama Computer and Information Sciences 12 Mesh Topology  Dedicated point-to-point links to every other device  Advantages  Disadvantages

13. University of South Alabama Computer and Information Sciences 13 Star Topology  Dedicated point-to-point links to central controller (hub)  Controller acts as exchange  Advantages  Disadvantages

14. University of South Alabama Computer and Information Sciences 14 Bus Topology  Multipoint configuration  One cable acts as a backbone to link all devices  Advantages  Disadvantages

15. University of South Alabama Computer and Information Sciences 15 Ring Topology  Dedicated point-to-point configuration to neighbors  Signal is passed from device to device until it reaches destination  Each device functions as a repeater  Advantages  Disadvantages

16. University of South Alabama Computer and Information Sciences 16 Categories of Networks  Local Area Network (LAN) – smaller geographical area  Metropolitan Area Network (MAN) – network extended over an entire city  Wide Area Network (WAN) – large geographical area

17. University of South Alabama Computer and Information Sciences 17 Internetworks  Connection of two or more networks  Internet vs. internet

18. University of South Alabama Computer and Information Sciences 18 The Internet  Collaboration of more than hundreds of thousands interconnected networks  1969 – started as ARPAnet, a small network of connected computers  1972 - Cerf and Khan – packet delivery and Transmission Control Protocol (TCP)  Shortly thereafter – evolution of TCP/IP  A brief history of the Internet A brief history of the Internet  Internet Timeline Internet Timeline

19. University of South Alabama Computer and Information Sciences 19 Protocols and Standards  Why do we need them?  Protocol – set of rules that govern data communication; defines what, how, and when Key elements – syntax, semantics, timing  Standard – provides a model for development; allows for interoperability

20. University of South Alabama Computer and Information Sciences 20 Standards  Types – De jure/Formal – legislated by an officially recognized body De facto – by convention or widespread use  Standards Organizations – committees, forums, regulatory agencies  Internet Standards Drafts RFC Process

21. University of South Alabama Computer and Information Sciences 21 Summary  Introduction to data communication, networking, and protocol standards  Next chapter… Network models

22. University of South Alabama Computer and Information Sciences 22 Credits  All figures obtained from publisher-provided instructor downloads Data Communications and Networking, 3rd edition by Behrouz A. Forouzan. McGraw Hill Publishing, 2004