Introduction

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Introduction

  1. 1. CS3505: The Internet and the Information Highway INTRODUCTION
  2. 2. CS3505 Objectives <ul><li>make better use of the Internet </li></ul><ul><li>make better use of all telecom, data networks </li></ul><ul><li>understand basic Internet architecture </li></ul><ul><li>background, evolution of Internet </li></ul>
  3. 3. CS3505 Admin details <ul><li>lab assignments and homeworks required for passing grade </li></ul><ul><li>class participation required, important part of class </li></ul><ul><li>exam or graded homework, project for letter grade </li></ul>
  4. 4. introduction: CS3505 <ul><li>network examples </li></ul><ul><li>network definitions </li></ul><ul><li>classifications of networks </li></ul><ul><li>layered models (high level) </li></ul><ul><li>purposes of networks </li></ul><ul><li>network industries and standards </li></ul><ul><li>communication protocols </li></ul>
  5. 5. Examples of Networks <ul><li>telephone networks </li></ul><ul><li>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>
  6. 6. network definitions <ul><li>network - 2 or more machines connected, sending data to other, using common media and protocols </li></ul><ul><li>computer network - network of computers </li></ul><ul><li>distributed network - tightly connected, common purpose network. e.g. airline reservation system, real-time battle simulations </li></ul>
  7. 7. network definitions <ul><li>LAN, MAN, WAN (local, metro, wide area networks) </li></ul><ul><li>integrated network - different types of traffic (voice, video, email) </li></ul><ul><li>internetwork/Internet - interconnected networks using TCP/IP protocol </li></ul>
  8. 8. more network definitions <ul><li>intranet - (1) a network internal to an organization, used to connect its clients; (2) a network of nodes separated from the external world by a firewall (ex. NPS Internet) </li></ul><ul><li>extranet - a network using the Internet to connect a set of users, operating over a VPN (virtual private network); uses web-browser technology and the Internet to connect a private community of users (ex. private newsletter using Internet; stock-broker) </li></ul>
  9. 9. network classifications <ul><li>geographical coverage (LAN ... WAN) </li></ul><ul><li>topology (geometry of links) </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>LAN: Local Area Networks </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 via bridges </li></ul></ul><ul><ul><li>examples: ethernet, token ring </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 (4) <ul><li>(1) 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>(2) 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>(3) 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. switching techniques <ul><li>(4) message switching </li></ul><ul><ul><li>sends entire message as single transmission </li></ul></ul><ul><ul><li>efficiency problems from unbound message size </li></ul></ul>
  18. 18. network model: ISO 7-layers <ul><li>designed 1970; still heavily used </li></ul><ul><li>7 layer model </li></ul><ul><ul><li>1 physical layer </li></ul></ul><ul><ul><li>2 data link layer </li></ul></ul><ul><ul><li>3 network layer </li></ul></ul><ul><ul><li>4 transport layer </li></ul></ul><ul><ul><li>5 session layer </li></ul></ul><ul><ul><li>6 presentation layer </li></ul></ul><ul><ul><li>7 application layer </li></ul></ul>
  19. 19. modified ISO model <ul><li>1 physical layer - moves a bit from a to b using a physical(electrical, optical, etc.) signal </li></ul><ul><li>2 data link - groups bits into frames, or messages, for error control and information </li></ul>
  20. 20. modified ISO model <ul><li>3 network layer - moves packets through the network </li></ul><ul><li>3.5 internet layer - routes packets from network to network </li></ul>
  21. 21. modified ISO <ul><li>4 transport - end to end; interface between user apps and the network/internet </li></ul><ul><li>7 application - user interface to network, and user services: email, file transfer, world wide web, etc. </li></ul>
  22. 22. IEEE LAN model <ul><li>specifically for LAN networks </li></ul><ul><li>changes in data link, physical layers; others same </li></ul><ul><li>layers: </li></ul><ul><ul><li>physical - similiar but special for LANs </li></ul></ul><ul><ul><li>MAC: media access control; replaces d.link </li></ul></ul><ul><ul><li>LLC: logical link control </li></ul></ul>
  23. 23. purposes of networks <ul><li>resource sharing </li></ul><ul><li>increased reliability </li></ul><ul><li>efficiency </li></ul><ul><li>communications </li></ul><ul><li>future applications: voice, video, data, images, appliances, .... ? </li></ul>
  24. 24. 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>
  25. 25. basic network services <ul><li>telephone/voice </li></ul><ul><li>instant messages </li></ul><ul><li>intranets </li></ul><ul><li>extranets </li></ul>
  26. 26. network ing industry <ul><li>originally two separate, different industries - computers/communications </li></ul><ul><li>computer: 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>
  27. 27. network ing industry <ul><li>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>
  28. 28. 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 (manufacturers) -Compaq, Dell, Gateway </li></ul></ul><ul><ul><li>PCs - software - Microsoft, Apple </li></ul></ul><ul><ul><li>semiconductors for PCs - Intel, AMD </li></ul></ul>
  29. 29. 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><li>internet service providers (AOL, etc) </li></ul></ul><ul><ul><li>radio, wireless data, satelite, etc </li></ul></ul>
  30. 30. 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>
  31. 31. 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>
  32. 32. 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>
  33. 33. 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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