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Understanding Computer Networks Course Overview

This course provides an in-depth look at computer networks, covering topics such as the physical and data link layers, local area networks, and protocol analysis. It includes homework assignments and tests to assess understanding. Gain a solid foundation in networking concepts with a focus on elementary protocol specification and performance analysis. Explore various network models and classifications, communication protocols, and basic terms related to data communication and processing. Learn about different network examples like LANs, WANs, cable TV, and cellular networks. Study network topologies, switching techniques, and the OSI model. Understand the purposes of networks, network industries, and the evolution of network services. Discover the convergence of the computer and communication industries and how they have merged over time.

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Understanding Computer Networks Course Overview

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  1. CS3502:Data and Computer NetworksINTRODUCTION

  2. introduction: CS3502 • overview of computer networks Track • course objectives • homeworks, tests, grading • approximate schedule

  3. objectives: CS3502 • gain good overview of networking • detailed knowledge of • physical layer • data link layer • local area networks • elementary protocol specification and analysis • elementary performance analysis

  4. homeworks, etc: CS3502 • homeworks passed out in class OR in electronic form. NOT GRADED. • solutions for majority of homeworks provided. • 3 tests spaced roughly 1/3 of quarter • tests based - in order of priority- on • homeworks • class notes, lectures • text

  5. introduction: CS3502 • network definitions • classifications • models (high level) • ISO model • DOD model • IEEE model • purposes of networks • network industries • communication protocols

  6. Basic Terms - 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 • Communication • Information • Data • Node • Data Communication • Data Processing

  7. Examples of Networks • local, long distance telephone networks • computer LANs: ethernet, token ring • ARPANet/MILNET WANs • Cable TV networks • Cellular phone networks • The INTERNET

  8. network definitions • Networks • computer network • distributed network • LAN, MAN, WAN • integrated network • internetwork/Internet

  9. network classification • geographical coverage (LAN ... WAN) • topology • switching technique • speed (data rates) • data/information content

  10. geographical coverage • LANs • simpler, less software layers • higher data transfer rates (generally) • simple routing • IEEE standards • easily connected together via bridges • examples: ethernet, token ring, FDDI

  11. geographical coverage • MANs • traditional category • cable TV, local phone • DQDB, FDDI (?) • less used, as most networks can be classified into LAN/WAN

  12. geographical coverage • WANs • data speeds slower, in general (this distinction fading) • national, international boundaries • includes internetworking • ARPANet first example • much more complex software • OSI model

  13. network topologies • star • ring • bus • fully connected • tree • mesh

  14. switching techniques • broadcast • no switching or routing; 1 station transmits, all others can receive • collisions occur if more than 1 attempts to transmit at once • examples: ethernet LAN and radio networks, satellites (to some degree)

  15. switching techniques • circuit switching • 3 distinct phases • traditional voice network • nice for user, but inefficient use of transmission facilities • served traditional voice networks well, but gradually becoming outdated by new technology

  16. switching techniques • message switching • sends entire message as single transmission • efficiency problems from unbound msg. size • packet switching • fixed packet size • much more efficient use of facilities • several refinements; fast packet switching (ATM) is culmination

  17. network model: ISO 7-layers • designed ~1970; still heavily referenced • 7 layer model for networks -- 1. physical - moves a bit from a to b using a physical(electrical, optical, etc.) signal 2. data link - groups bits into frames, or messages, for error control and information 3. network - routing function

  18. network model: ISO 7-layers 4. transport - end to end; interface between user apps and the network/internet 5. session, presentation - ?? 7. application - user interface to network, and user services: email, file transfer, world wide web, etc.

  19. network model: IEEE LAN model • complements ISO model for LAN specific networks; • more specific in data link, physical layers; other layers unchanged • layers: • physical • MAC: media access control • LLC: logical link control

  20. network model: DoD model • Alternative view; viewed networks as basic building blocks, thus not included in model • Fewer layers • Applications • host-host (transport; now TCP ) • internet layer (now IP) • network interface layer

  21. purposes of networks • resource sharing • increased reliability (redundancy, etc.) • efficiency • communications • future applications: voice, video, data, images, appliances, .... ?

  22. basic network services • e-mail • file transfers (ftp, etc) • remote login (rlogin, telnet) • WWW (web)

  23. network ing industry • historically two separate and very different industries -- computers and communications • computer industry: IBM, DEC, Sun, Apple, Cray, SGI, Compaq, Dell, Gateway, Microsoft, etc • communications: AT&T, Sprint, MCI-WorldCom, RBOCs, GTE, other phone companies, etc.

  24. network ing industry • these 2 industries have been merging • signs of the merging • initial purpose of each • signals • importance of each to the other • research labs • Sun’s logo “the network is the computer”

  25. industry sectors • Computer Industry • mainframes, “big” computers - IBM, Cray • mid-size, workstations - Sun, SGI, (DEC, Tandem) • personal computers (manufacurers) -Compaq, Dell, Gateway • PCs - software - Microsoft • semiconductors for PCs - Intel, AMD, NSM

  26. industry sectors • Communications • long distance telephone (ATT, Sprint) • local telephone (Pacific Bell, etc.) • telecom. equipment (Lucent, Nor. Telecom) • telco eqmt (Lucent, etc.) • data; internet (Cisco, 3Com) • internet service providers (AOL, etc) • radio, wireless data, satelite, etc

  27. standards for networks • reasons for standards • advantages • disadvantages • standards organizations

  28. communication protocols • protocol: the algorithm or procedure used for communication between processes at the same layer • examples: telephone call; e-mail • protocol processes make use of lower layers as a service. • heart of communications process

  29. communication protocols • some things protocols do • bit interpretation to signals • group bits into messages • error detection and correction • synchronization • make more efficient use of networks facilities

  30. communication protocols • three basic phases of data communications 1. connection establishment 2. data transfer 3. connection termination • connection-oriented/connectionless

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