1 / 35

4123702 Data Communications System

4123702 Data Communications System. By Ajarn Preecha Pangsuban. Part 1 Overview of Data Communications and Networking. Chapter 1 Brief description of data communication, networking, and protocol standards Chapter 2 Network models. Chapter 1 - Introduction. Data Communication.

akeem-graves
Download Presentation

4123702 Data Communications System

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 4123702Data Communications System By Ajarn Preecha Pangsuban

  2. Part 1Overview of Data Communications and Networking • Chapter 1 • Brief description of data communication, networking, and protocol standards • Chapter 2 • Network models 4123702 Data Communications System @YRU

  3. Chapter 1 - Introduction

  4. Data Communication • Why study data communications? • Data communication is the exchange of data between two devices via a transmission medium • Effectiveness depends on: • Delivery • Accuracy • Timeliness 4123702 Data Communications System @YRU

  5. Communication System Components 4123702 Data Communications System @YRU

  6. Data Representation • Text – represented as a bit pattern, a sequence of bit (0s or 1s); codes often used: • ASCII; Extended ASCII; Unicode; ISO • Numbers – represented by binary equivalent • Images – bit patterns representing pixels • Audio • Video 4123702 Data Communications System @YRU

  7. A Communications Model DTE: Data Terminal Equipment DCE: Data communication Equipment 4123702 Data Communications System @YRU

  8. Simplified Communications Model 4123702 Data Communications System @YRU

  9. Simplified Data Communications Model 4123702 Data Communications System @YRU

  10. Simplified Network Model 4123702 Data Communications System @YRU

  11. Direction of Data Flow • Simplex – unidirectional; one transmits, other receives 4123702 Data Communications System @YRU

  12. Direction of Data Flow (cont) • Half-duplex – each can transmit/receive; communication must alternate 4123702 Data Communications System @YRU

  13. Direction of Data Flow (cont) • Full-duplex – both can transmit/receive simultaneously 4123702 Data Communications System @YRU

  14. Networks • A network isset of devices (nodes) connected by communication links (media) • A node can be a computer,printer,or other device capable of sending and/or receiving data • Link connecting the devices are often called communication channels • Most network use distributed processing • Advantages? 4123702 Data Communications System @YRU

  15. Network Criteria (Standard) • Performance – depends on number of users, type of medium, HW/SW • Reliability – measured by freq of failure, recovery time, catastrophe vulnerability • Security – protection from unauthorized access, viruses/worms 4123702 Data Communications System @YRU

  16. Types of Connections • Point-to-point – dedicated link 4123702 Data Communications System @YRU

  17. Types of Connections (cont) • Multipoint (Multidrop) – shared a single link 4123702 Data Communications System @YRU

  18. Physical Topology • The way in which a network is laid out physically • 4 basic types: mesh, star, bus, ring • May often see hybrid 4123702 Data Communications System @YRU

  19. Mesh Topology • Dedicated point-to-point links to every other device • Has n(n-1)/2 physical channel to link n devices • Devices have n-1 I/O • Advantages? • Disadvantages? 4123702 Data Communications System @YRU

  20. Star Topology • Dedicated point-to-point links to central controller (hub) • Controller acts as exchange • Advantages ? • Disadvantages ? 4123702 Data Communications System @YRU

  21. Bus Topology • Multipoint configuration • One cable acts as a backbone to link all devices • Advantages ? • Disadvantages ? 4123702 Data Communications System @YRU

  22. 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? 4123702 Data Communications System @YRU

  23. Categories of Networks • LAN – smaller geographical area • WAN – large geographical area 4123702 Data Communications System @YRU

  24. Local Area Network • Usually privately owned and links the devices in a single office, building, or campus • LAN size is limited to a few kilometers. • LANs are designed to allow resources to be shared (hardware , software and data ) • Today LANs to have data rates of 100 Mbps to 10Gbps • Backbone Networks (BN), have a scale of a few hundred meters to a few kilometers. Include a high speed backbone linking the LANs at various locations. 4123702 Data Communications System @YRU

  25. Figure 1-2 Local Area Network (cont) 4123702 Data Communications System @YRU

  26. Figure 1-2 Local Area Network (cont) 4123702 Data Communications System @YRU

  27. Wide Area Network • WAN provides long distance transmission of data, voice, image, and video information over large geographical areas • Comprise a country, a continent, or even the whole world (Interlink age of many LANs and MANs) • Low data transmission rate (below 1 Mbps) • Unlimited number of miles example: Internet Network 4123702 Data Communications System @YRU

  28. Figure 1-4 Wide Area Network (cont) 4123702 Data Communications System @YRU

  29. Internetworks • Connection of two or more networks by the use of internetworking devices which include routers and gateways • Internet is a generic term used to mean an interconnection of networks • The Internet is the name of a specific worldwide network. 4123702 Data Communications System @YRU

  30. Figure 1-5 Internetworks (cont) 4123702 Data Communications System @YRU

  31. 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 4123702 Data Communications System @YRU

  32. The Internet today 4123702 Data Communications System @YRU

  33. Protocols and Standards • Why do we need them? • A protocol is a set of rules that governs data communication; the key elements of a protocol are • Syntax – data formats and Signal levels • Semantics – control information and error handling • Timing – speed matching and sequencing • Standards are necessary to ensure that products from different manufacturers can work together as expected. 4123702 Data Communications System @YRU

  34. Standards • Types – • De jure (Formal) – legislated by an officially recognized body • De facto – by convention or widespread use • Standards Organizations • Committees – ISO, ITU-T, ANSI, IEEE, and EIA • Forums – special-interest groups that quickly evaluate and standardize new technologies • regulatory agencies – FCC • Internet Standards • Drafts (6 month lifetime) • RFC is an idea or concept that is a precursor to an Internet standard. 4123702 Data Communications System @YRU

  35. Credits • All figures obtained from publisher-provided instructor downloads Data Communications and Networking, 3rd edition by Behrouz A. Forouzan. McGraw Hill Publishing, 2004 4123702 Data Communications System @YRU

More Related