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Similar to chapter one 1 DATA COMMUNICATION AND NETWORKING.ppt
chapter one 1 DATA COMMUNICATION AND NETWORKING.ppt
- 1. 1-1 Data Communications Data Communicationsand Networking by Behrouz A. Forouzan, 5th Edition
- 2. 1-2 Chapter 1. Introduction 1.Data communications 2. Networks 3. The Internet 4. Protocols and standards
- 3. 1-3 Data Communications • Data –Information presented in whatever form is agreed upon by the parties creating and using the data • Data communication – Exchange of data between two devices – Via some form of transmission medium • Fundamental characteristics of data communication – Delivery – Accuracy – Timeliness – Jitter : Variation in the packet arrival time • Telecommunication: communication at a distance (‘tele’ in Greek=‘far”)
- 4. 1-4 Five Components ofData Communication • Message: Information(data) to be communicated • Sender • Receiver • Transmission medium: Physical path by which a message travels • Protocol: A set of rules that govern data communication
- 5. 1-5 Modes of Communication/DataFlow • Simplex – Unidirectional – As on a one-way street • Half-duplex – Both transmit and receive possible, but not at the same time – Like a one-lane road with two-directional traffic – Walkie-talkie, CB radio • Full-duplex – Transmit and receive simultaneously – Like a two-way street, telephone network – Channel capacity must be divided between two directions
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- 7. 1-7 Network • Network: Aset of devices (nodes) connected by communication links • Node: Computer, printer, or any device capable of sending and/or receiving data • To be considered effective and efficient, a network must meet a number of criteria
- 8. 1-8 Type of Connection •Point-to-point – Dedicated link between two devices – The entire capacity of the channel is reserved – Ex) Microwave link, TV remote control • Multipoint – More than two devices share a single link – Capacity of the channel is either • Spatially shared: Devices can use the link simultaneously • Timeshare: Users take turns
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- 10. 1-10 Physical Topology (A wayin which a network is layout physically)
- 11. 1-11 Mesh Topology • Dedicatedpoint-to-point link to every other nodes • A mesh network with n nodes has n(n-1)/2 links. A node has n-1 I/O ports (links) • Advantages: No traffic problems, robust, security, easy fault identification & isolation • Disadvantages: Difficult installation/reconfiguration, space, cost
- 12. 1-12 Star Topology • Dedicatedpoint-to-point link only to a central controller, called a hub • Hub acts as an exchange: No direct traffic between devices • Advantages: Less expensive, robust • Disadvantages: dependency of the whole on one single point, the hub
- 13. 1-13 Bus Topology • Onelong cable that links all nodes • tap, drop line, cable end • limit on the # of devices, distance between nodes • Advantages: Easy installation, cheap • Disadvantages: Difficult reconfiguration, no fault isolation, a fault or break in the bus stops all transmission
- 14. 1-14 Ring Topology • Dedicatedpoint-to-point link only with the two nodes on each sides • One direction, repeater • Advantages: Easy reconfiguration, fault isolation • Disadvantage: Unidirectional traffic, a break in the ring cab disable the entire network
- 15. 1-15 Hybrid Topology • Example:Main star topology with each branch connecting several stations in a bus topology • To share the advantages from various topologies
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- 17. 1-17 LAN • Usually privatelyowned • A network for a single office, building, or campus a few Km • Common LAN topologies: bus, ring, star • An isolated LAN connecting 12 computers to a hub in a closet
- 18. 1-18 MAN • Designed toextend to an entire city • Cable TV network, a company’s connected LANs • Owned by a private or a public company
- 19. 1-19 WAN • Long distancetransmission, e.g., a country, a continent, the world • Enterprise network: A WAN that is owned and used by one company
- 20. 1-20 Internetwork • Internetwork (internet): two or more networks are connected by internetworking devices • Internetworking devices: router, gateway, etc. • The Internet: a specific worldwide network
- 21. 1-21 Internetwork Example • Aheterogeneous network : four WANs and two LANs
- 22. 1-22 The Internet • TheInternet has revolutionized many aspects of our daily lives. It has affected the way we do business as well as the way we spend our leisure time. The Internet is a communication system that has brought a wealth of information to our fingertips and organized it for our use. • 1967: ARPANET proposed by DoD’s ARPA(Advanced Research Project Agency) • 1969: ARPANET in a reality: UCLA, UCSB, SRI, U. of Utah • 1973: Vint Cerf and Bob Kahn propose TCP, • To split TCP into two protocols TCP and IP
- 23. 1-23 Internet Today • ISP(Internet service providers) • NISP (national ISP) • NAP (network access point)
- 24. 1-24 Protocols • Protocol :rule – A set of rules that govern data communication – For communication to occur, entities must agree upon a protocol • Key elements of a protocol – Syntax: structure or format of data – Semantics: meaning of each section in the structure – Timing: when and how fast data should be sent
- 25. 1-25 Standards: agreed-upon rules •Standards is essential in – Creating/maintaining open and competitive markets – Guaranteeing national/international interoperability • Two categories – De jure (“by law” or “by regulation’) standards – De facto (“by fact” or ‘by convention’) standards
- 26. 1-26 Standards Organizations • Standardsare developed by – Standards creation committees – Forums – Regulatory agencies • Standards committees & forums – Standards committees are slow moving – Forums are made up of interested corporation
- 27. 1-27 Standards Committees • ISO –Voluntary international organization • ITU-T – Formerly, CCITT formed by UN • ANSI – Private non-profit corporation in the US • IEEE – The largest engineering society in the world • EIA – Non-profit organization in the US
- 28. 1-28 Internet Standards • IETF(Internet Engineering Task Force) • Internet Draft – working document with no official status – with a 6-month lifetime • RFC (Request for Comment) – Edited, assigned a number, and made available to all interested parties
Editor's Notes
- #5 Citizen band