Data and Computer Networks.ppt

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Data and Computer Networks.ppt

  1. 1. CS3502: Data and Computer Networks INTRODUCTION
  2. 2. introduction: CS3502 <ul><li>overview of computer networks Track </li></ul><ul><li>course objectives </li></ul><ul><li>homeworks, tests, grading </li></ul><ul><li>approximate schedule </li></ul>
  3. 3. objectives: CS3502 <ul><li>gain good overview of networking </li></ul><ul><li>detailed knowledge of </li></ul><ul><ul><li>physical layer </li></ul></ul><ul><ul><li>data link layer </li></ul></ul><ul><ul><li>local area networks </li></ul></ul><ul><li>elementary protocol specification and analysis </li></ul><ul><li>elementary performance analysis </li></ul>
  4. 4. homeworks, etc: CS3502 <ul><li>homeworks passed out in class OR in electronic form. NOT GRADED. </li></ul><ul><li>solutions for majority of homeworks provided. </li></ul><ul><li>3 tests spaced roughly 1/3 of quarter </li></ul><ul><li>tests based - in order of priority- on </li></ul><ul><ul><li>homeworks </li></ul></ul><ul><ul><li>class notes, lectures </li></ul></ul><ul><ul><li>text </li></ul></ul>
  5. 5. introduction: CS3502 <ul><li>network definitions </li></ul><ul><li>classifications </li></ul><ul><li>models (high level) </li></ul><ul><ul><li>ISO model </li></ul></ul><ul><ul><li>DOD model </li></ul></ul><ul><ul><li>IEEE model </li></ul></ul><ul><li>purposes of networks </li></ul><ul><li>network industries </li></ul><ul><li>communication protocols </li></ul>
  6. 6. Basic Terms <ul><li>Communication </li></ul><ul><li>Information </li></ul><ul><li>Data </li></ul><ul><li>Node </li></ul><ul><li>Data Communication </li></ul><ul><li>Data Processing </li></ul>- moving information from one physical node to another - data - a pattern of 0’s and 1’s - a physical system for holding information - moving data from one physical node to another - changing data within a node
  7. 7. Examples of Networks <ul><li>local, long distance telephone networks </li></ul><ul><li>computer LANs: ethernet, token ring </li></ul><ul><li>ARPANet/MILNET WANs </li></ul><ul><li>Cable TV networks </li></ul><ul><li>Cellular phone networks </li></ul><ul><li>The INTERNET </li></ul>
  8. 8. network definitions <ul><li>Networks </li></ul><ul><li>computer network </li></ul><ul><li>distributed network </li></ul><ul><li>LAN, MAN, WAN </li></ul><ul><li>integrated network </li></ul><ul><li>internetwork/Internet </li></ul>
  9. 9. network classification <ul><li>geographical coverage (LAN ... WAN) </li></ul><ul><li>topology </li></ul><ul><li>switching technique </li></ul><ul><li>speed (data rates) </li></ul><ul><li>data/information content </li></ul>
  10. 10. geographical coverage <ul><li>LANs </li></ul><ul><ul><li>simpler, less software layers </li></ul></ul><ul><ul><li>higher data transfer rates (generally) </li></ul></ul><ul><ul><li>simple routing </li></ul></ul><ul><ul><li>IEEE standards </li></ul></ul><ul><ul><li>easily connected together via bridges </li></ul></ul><ul><ul><li>examples: ethernet, token ring, FDDI </li></ul></ul>
  11. 11. geographical coverage <ul><li>MANs </li></ul><ul><ul><li>traditional category </li></ul></ul><ul><ul><li>cable TV, local phone </li></ul></ul><ul><ul><li>DQDB, FDDI (?) </li></ul></ul><ul><ul><li>less used, as most networks can be classified into LAN/WAN </li></ul></ul>
  12. 12. geographical coverage <ul><li>WANs </li></ul><ul><ul><li>data speeds slower, in general (this distinction fading) </li></ul></ul><ul><ul><li>national, international boundaries </li></ul></ul><ul><ul><li>includes internetworking </li></ul></ul><ul><ul><li>ARPANet first example </li></ul></ul><ul><ul><li>much more complex software </li></ul></ul><ul><ul><li>OSI model </li></ul></ul>
  13. 13. network topologies <ul><ul><li>star </li></ul></ul><ul><ul><li>ring </li></ul></ul><ul><ul><li>bus </li></ul></ul><ul><ul><li>fully connected </li></ul></ul><ul><ul><li>tree </li></ul></ul><ul><ul><li>mesh </li></ul></ul>
  14. 14. switching techniques <ul><li>broadcast </li></ul><ul><ul><li>no switching or routing; 1 station transmits, all others can receive </li></ul></ul><ul><ul><li>collisions occur if more than 1 attempts to transmit at once </li></ul></ul><ul><ul><li>examples: ethernet LAN and radio networks, satellites (to some degree) </li></ul></ul>
  15. 15. switching techniques <ul><li>circuit switching </li></ul><ul><ul><li>3 distinct phases </li></ul></ul><ul><ul><li>traditional voice network </li></ul></ul><ul><ul><li>nice for user, but inefficient use of transmission facilities </li></ul></ul><ul><ul><li>served traditional voice networks well, but gradually becoming outdated by new technology </li></ul></ul>
  16. 16. switching techniques <ul><li>message switching </li></ul><ul><ul><li>sends entire message as single transmission </li></ul></ul><ul><ul><li>efficiency problems from unbound msg. size </li></ul></ul><ul><li>packet switching </li></ul><ul><ul><li>fixed packet size </li></ul></ul><ul><ul><li>much more efficient use of facilities </li></ul></ul><ul><ul><li>several refinements; fast packet switching (ATM) is culmination </li></ul></ul>
  17. 17. network model: ISO 7-layers <ul><li>designed ~1970; still heavily referenced </li></ul><ul><li>7 layer model for networks -- </li></ul><ul><ul><li>1. physical - moves a bit from a to b using a physical(electrical, optical, etc.) signal </li></ul></ul><ul><ul><li>2. data link - groups bits into frames, or messages, for error control and information </li></ul></ul><ul><ul><li>3. network - routing function </li></ul></ul>
  18. 18. network model: ISO 7-layers <ul><li>4. transport - end to end; interface between user apps and the network/internet </li></ul><ul><li>5. session, presentation - ?? </li></ul><ul><li>7. application - user interface to network, and user services: email, file transfer, world wide web, etc. </li></ul>
  19. 19. network model: IEEE LAN model <ul><li>complements ISO model for LAN specific networks; </li></ul><ul><li>more specific in data link, physical layers; other layers unchanged </li></ul><ul><li>layers: </li></ul><ul><ul><li>physical </li></ul></ul><ul><ul><li>MAC: media access control </li></ul></ul><ul><ul><li>LLC: logical link control </li></ul></ul>
  20. 20. network model: DoD model <ul><li>Alternative view; viewed networks as basic building blocks, thus not included in model </li></ul><ul><li>Fewer layers </li></ul><ul><ul><li>Applications </li></ul></ul><ul><ul><li>host-host (transport; now TCP ) </li></ul></ul><ul><ul><li>internet layer (now IP ) </li></ul></ul><ul><ul><li>network interface layer </li></ul></ul>
  21. 21. purposes of networks <ul><li>resource sharing </li></ul><ul><li>increased reliability (redundancy, etc.) </li></ul><ul><li>efficiency </li></ul><ul><li>communications </li></ul><ul><li>future applications: voice, video, data, images, appliances, .... ? </li></ul>
  22. 22. basic network services <ul><li>e-mail </li></ul><ul><li>file transfers (ftp, etc) </li></ul><ul><li>remote login (rlogin, telnet) </li></ul><ul><li>WWW (web) </li></ul>
  23. 23. network ing industry <ul><li>historically two separate and very different industries -- computers and communications </li></ul><ul><li>computer industry: IBM, DEC, Sun, Apple, Cray, SGI, Compaq, Dell, Gateway, Microsoft, etc </li></ul><ul><li>communications: AT&T, Sprint, MCI-WorldCom, RBOCs, GTE, other phone companies, etc. </li></ul>
  24. 24. network ing industry <ul><li>these 2 industries have been merging </li></ul><ul><li>signs of the merging </li></ul><ul><ul><li>initial purpose of each </li></ul></ul><ul><ul><li>signals </li></ul></ul><ul><ul><li>importance of each to the other </li></ul></ul><ul><ul><li>research labs </li></ul></ul><ul><ul><li>Sun’s logo “the network is the computer” </li></ul></ul>
  25. 25. industry sectors <ul><li>Computer Industry </li></ul><ul><ul><li>mainframes, “big” computers - IBM, Cray </li></ul></ul><ul><ul><li>mid-size, workstations - Sun, SGI, (DEC, Tandem) </li></ul></ul><ul><ul><li>personal computers (manufacurers) -Compaq, Dell, Gateway </li></ul></ul><ul><ul><li>PCs - software - Microsoft </li></ul></ul><ul><ul><li>semiconductors for PCs - Intel, AMD, NSM </li></ul></ul>
  26. 26. industry sectors <ul><li>Communications </li></ul><ul><ul><li>long distance telephone (ATT, Sprint) </li></ul></ul><ul><ul><li>local telephone (Pacific Bell, etc.) </li></ul></ul><ul><ul><li>telecom. equipment (Lucent, Nor. Telecom) </li></ul></ul><ul><ul><ul><li>telco eqmt (Lucent, etc.) </li></ul></ul></ul><ul><ul><ul><li>data; internet (Cisco, 3Com) </li></ul></ul></ul><ul><ul><li>internet service providers (AOL, etc) </li></ul></ul><ul><ul><li>radio, wireless data, satelite, etc </li></ul></ul>
  27. 27. standards for networks <ul><li>reasons for standards </li></ul><ul><li>advantages </li></ul><ul><li>disadvantages </li></ul><ul><li>standards organizations </li></ul>
  28. 28. communication protocols <ul><li>protocol: the algorithm or procedure used for communication between processes at the same layer </li></ul><ul><li>examples: telephone call; e-mail </li></ul><ul><li>protocol processes make use of lower layers as a service. </li></ul><ul><li>heart of communications process </li></ul>
  29. 29. communication protocols <ul><li>some things protocols do </li></ul><ul><ul><li>bit interpretation to signals </li></ul></ul><ul><ul><li>group bits into messages </li></ul></ul><ul><ul><li>error detection and correction </li></ul></ul><ul><ul><li>synchronization </li></ul></ul><ul><ul><li>make more efficient use of networks facilities </li></ul></ul>
  30. 30. communication protocols <ul><li>three basic phases of data communications </li></ul><ul><li>1. connection establishment </li></ul><ul><li>2. data transfer </li></ul><ul><li>3. connection termination </li></ul><ul><li>connection-oriented/connectionless </li></ul>

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