Introduction and Netrwork Hardware


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Introduction and Netrwork Hardware

  1. 1. CS 313 Introduction to Computer Networking & Telecommunication Introduction Chi-Cheng Lin, Winona State University
  2. 2. Topics <ul><li>Introduction </li></ul><ul><li>Metric Units </li></ul><ul><li>Network Hardware </li></ul><ul><li>Network Software </li></ul><ul><li>Reference Models </li></ul><ul><li>Example Networks </li></ul><ul><li>Standards and Standards Organizations </li></ul>
  3. 3. Introduction <ul><li>First two decades of computing </li></ul><ul><ul><li>Highly centralized computer systems </li></ul></ul><ul><li>Now </li></ul><ul><ul><li>A large number of SEPARATE but INTERCONNECTED computers </li></ul></ul><ul><ul><li> Computer networks </li></ul></ul>
  4. 4. What is Computer Network? <ul><li>An INTERCONNECTED collection of AUTONOMOUS computers </li></ul><ul><ul><li>Interconnected: Able to EXCHANGE INFORMATION via transmission media </li></ul></ul><ul><ul><ul><li>Media: copper wire, fiber optics, microwaves, communication satellites </li></ul></ul></ul><ul><ul><li>Autonomous: no master/slave relation </li></ul></ul><ul><ul><ul><li>NOT autonomous: </li></ul></ul></ul><ul><ul><ul><ul><li>One computer can control another one </li></ul></ul></ul></ul><ul><ul><ul><ul><li>e.g., a large computer with remote printers and terminals </li></ul></ul></ul></ul>
  5. 5. What is Telecommunication? <ul><li>What is data communication ? </li></ul><ul><ul><li>Exchange of data between two devices via some form of transmission media </li></ul></ul><ul><ul><li>Data are represented by bits – 0s and 1s </li></ul></ul><ul><li>What is telecommunication ? </li></ul><ul><ul><li>Exchange of information over distance using electronic equipment </li></ul></ul>
  6. 6. What is Telecommunication? <ul><li>Components of data communication </li></ul><ul><ul><li>Sender, receiver, medium, message, and </li></ul></ul><ul><ul><li>Protocol : set of rules governing data communication </li></ul></ul><ul><li>Key elements of a protocol </li></ul><ul><ul><li>Syntax </li></ul></ul><ul><ul><ul><li>Structure/format </li></ul></ul></ul><ul><ul><li>Semantics </li></ul></ul><ul><ul><ul><li>Meaning </li></ul></ul></ul><ul><ul><li>Timing </li></ul></ul><ul><ul><ul><li>When and how fast </li></ul></ul></ul>
  7. 7. Data Communication <ul><li>Components of data communication </li></ul>Sender Receiver Medium Message Step 1: … Step 2: … : Protocol Step 1: … Step 2: … : Protocol
  8. 8. Distributed System vs. Computer Network <ul><li>Distributed system </li></ul><ul><ul><li>TRANSPARENCY </li></ul></ul><ul><ul><ul><li>A collection of independent computers appear as a single coherent system </li></ul></ul></ul><ul><ul><li>Single model/paradigm to users </li></ul></ul><ul><ul><li>Middleware on top of OS </li></ul></ul><ul><ul><li>Example? </li></ul></ul><ul><li>Computer network </li></ul><ul><ul><li>No such coherence, model, middleware </li></ul></ul><ul><ul><li>Machines visible to users </li></ul></ul><ul><ul><ul><li>Users log onto remote machines </li></ul></ul></ul>
  9. 9. Distributed System vs. Computer Network <ul><li>A distributed system is a SOFTWARE system built on top of a network </li></ul><ul><li>Distinction between network and distributed system </li></ul><ul><ul><li>Software (especially OS) rather than hardware </li></ul></ul><ul><li>However, considerable overlap between the two subjects </li></ul>
  10. 10. Uses of Computer Networks <ul><li>Business applications </li></ul><ul><ul><li>Resource sharing </li></ul></ul><ul><ul><li>Communication medium </li></ul></ul><ul><ul><li>E-commerce </li></ul></ul><ul><li>Client-server model </li></ul><ul><ul><li>Client requests, server performs & then replies </li></ul></ul><ul><ul><li>E.g., one or more file servers, many clients </li></ul></ul>
  11. 11. Business Applications of Networks <ul><li>A network with two clients and one server. </li></ul>
  12. 12. Client-Server Model 1 2 3
  13. 13. Uses of Computer Networks <ul><li>Home applications </li></ul><ul><ul><li>Access to remote information </li></ul></ul><ul><ul><ul><li>On-line publishing, digital library, WWW </li></ul></ul></ul><ul><ul><li>Person-to-person communication </li></ul></ul><ul><ul><ul><li>Email, instant messaging, peer-to-peer communication, videoconferencing, Internet phone, E-learning </li></ul></ul></ul><ul><ul><li>Interactive entertainment </li></ul></ul><ul><ul><ul><li>Video on demand (VOD), games </li></ul></ul></ul><ul><ul><li>E-commerce </li></ul></ul><ul><ul><ul><li>Home shopping, electronic banking and investment, on-line auction </li></ul></ul></ul>
  14. 14. Home Network Applications (2) <ul><li>In peer-to-peer system there are no fixed clients and servers. </li></ul>
  15. 15. Mobile Users <ul><li>Notebook, PDA, cellular phone </li></ul><ul><li>M-commerce </li></ul><ul><li>Wireless networking and mobile computing </li></ul>
  16. 16. Metric Units <ul><li>The principal metric prefixes. </li></ul>
  17. 17. Network Hardware <ul><li>By transmission technology </li></ul><ul><ul><li>Broadcast links </li></ul></ul><ul><ul><ul><li>smaller, geographically localized networks </li></ul></ul></ul><ul><ul><li>Point-to-point links </li></ul></ul><ul><ul><ul><li>larger networks </li></ul></ul></ul><ul><li>By scale </li></ul><ul><ul><li>PAN </li></ul></ul><ul><ul><li>LAN </li></ul></ul><ul><ul><li>MAN </li></ul></ul><ul><ul><li>WAN </li></ul></ul>
  18. 18. Classification by Scale
  19. 19. Broadcast Network <ul><li>A single communication channel shared by all machines on the network </li></ul><ul><li>Packets (short messages) sent by any machine are “received” by all the others </li></ul><ul><ul><li>Address field of packet: whom it is intended </li></ul></ul><ul><li>Message transmission </li></ul><ul><ul><li>Unicast: one sends, one receives </li></ul></ul><ul><ul><li>Broadcasting: one sends, all receive </li></ul></ul><ul><ul><li>Multicasting: one sends, a group receives </li></ul></ul>
  20. 20. Point-to-Point Networks <ul><li>Many connections between pairs of machines </li></ul><ul><li>Intermediate machines (called routers ) might have to be visited by a packet from source to destination – more than one path is possible </li></ul><ul><li>Routing algorithms are important </li></ul><ul><ul><li>Routing : process of finding a path from a source to the destination(s) in the network </li></ul></ul>
  21. 21. Local Area Network (LAN) <ul><li>Private-owned Networks </li></ul><ul><li>Within a single building/campus </li></ul><ul><li>Size: up to a few kilometers </li></ul><ul><li>Characteristics </li></ul><ul><ul><li>Size </li></ul></ul><ul><ul><ul><li>Restricted by size </li></ul></ul></ul><ul><ul><ul><li> worst-case transmission time bounded and known in advance </li></ul></ul></ul><ul><ul><ul><li> network management simplified </li></ul></ul></ul>
  22. 22. LAN <ul><li>Characteristics </li></ul><ul><ul><li>Transmission technology </li></ul></ul><ul><ul><ul><li>Machines attached to a single cable </li></ul></ul></ul><ul><ul><ul><li>Speed/capacity (High): 10 - 100 Mbps, Gbps </li></ul></ul></ul><ul><ul><ul><ul><li>Mbps/Gbps: Megabit/Gigabit per second </li></ul></ul></ul></ul><ul><ul><ul><ul><li>1 megabit=1,000,000 (not 2 20 =1,048,576) bits </li></ul></ul></ul></ul><ul><ul><ul><li>Delay (low): microseconds, nanoseconds </li></ul></ul></ul><ul><ul><ul><li>Errors: very few </li></ul></ul></ul>
  23. 23. LAN <ul><li>Characteristics </li></ul><ul><ul><li>Topology – the way in which a network is laid out </li></ul></ul><ul><ul><ul><li>Examples: bus, ring, tree, star, fully-connected </li></ul></ul></ul>Bus Ring
  24. 24. LAN - Topology <ul><li>Bus (linear cable) </li></ul><ul><ul><li>Only one machine can transmit at a time </li></ul></ul><ul><ul><li>Arbitration mechanism needed to resolve conflicts when two or more computers want to transmit simultaneously </li></ul></ul><ul><ul><ul><li>Centralized or Distributed </li></ul></ul></ul><ul><ul><li>Example: IEEE 802.3 (Ethernet): </li></ul></ul><ul><ul><ul><li>Bus-based broadcast network with decentralized control operating at 10 Mbps to 10Gbps. </li></ul></ul></ul><ul><ul><ul><li>If two or more packets collide, each computer just waits a random time and tries again later. </li></ul></ul></ul>
  25. 25. LAN - Topology <ul><li>Tree </li></ul><ul><ul><li>Centralized device </li></ul></ul><ul><ul><li>Example: Ethernet w/ hubs/swtches </li></ul></ul><ul><li>Ring </li></ul><ul><ul><li>Bits propagate around the ring </li></ul></ul><ul><ul><li>Arbitration mechanism is needed, too </li></ul></ul><ul><ul><li>Example: IEEE 802.5 (IBM Token Ring) </li></ul></ul><ul><ul><ul><li>Ring-based LAN operating at 4 and 16 Mbps </li></ul></ul></ul><ul><ul><ul><li>Arbitration is based on “token” </li></ul></ul></ul><ul><ul><ul><ul><li>Only token holder can transmit </li></ul></ul></ul></ul>
  26. 26. LAN - Channel Allocation <ul><li>Needed as all computers share one communication pathway </li></ul><ul><li>Static channel allocation </li></ul><ul><ul><li>Divide up time into discrete intervals </li></ul></ul><ul><ul><li>Run a round robin algorithm </li></ul></ul><ul><ul><li>Allow each machine to broadcast only when its time slot comes up </li></ul></ul><ul><ul><li>Problem: Wasting channel capacity </li></ul></ul>
  27. 27. LAN - Channel Allocation <ul><li>Dynamic channel allocation </li></ul><ul><ul><li>Centralized </li></ul></ul><ul><ul><ul><li>A central entity determines who goes next </li></ul></ul></ul><ul><ul><li>Decentralize </li></ul></ul><ul><ul><ul><li>No central entity </li></ul></ul></ul><ul><ul><ul><li>Each machine decides for itself to transmit or not </li></ul></ul></ul><ul><ul><ul><li>Algorithms needed to resolve potential chaos </li></ul></ul></ul>
  28. 28. Metropolitan Area Network (MAN) <ul><li>Covers city </li></ul><ul><li>Examples </li></ul><ul><ul><li>Cable TV network </li></ul></ul><ul><ul><li>IEEE 802.16 high-speed wireless Internet access </li></ul></ul>
  29. 29. Metropolitan Area Networks <ul><li>A metropolitan area network based on cable TV. </li></ul>
  30. 30. Wide Area Network (WAN) <ul><li>Country or continent </li></ul><ul><li>Components </li></ul><ul><ul><li>Host (end system) </li></ul></ul><ul><ul><ul><li>Machine running user (application) programs </li></ul></ul></ul><ul><ul><li>Communication subnet (subnet) </li></ul></ul><ul><ul><ul><li>Connecting hosts </li></ul></ul></ul><ul><ul><ul><li>Carrying messages from host to host </li></ul></ul></ul>
  31. 31. WAN - Subnet Components <ul><li>Transmission lines </li></ul><ul><ul><li>Move bits between machines </li></ul></ul><ul><li>Switching elements </li></ul><ul><ul><li>Specialized computers that connect two or more transmission lines </li></ul></ul><ul><ul><li>Determine out going line for incoming data </li></ul></ul><ul><ul><li>ROUTER </li></ul></ul>
  32. 32. WAN - Hosts and Subnet : Host : Router H1 H2 R1 R2 R3 R4 R5 R6
  33. 33. WAN - Architecture <ul><li>Contains numerous cables or telephone lines </li></ul><ul><li>Each cable connects a pair of routers </li></ul><ul><li>Two routers must communicate indirectly if they are not connected by a cable </li></ul><ul><li>There might be more than one route between two hosts and it might change from time to time </li></ul><ul><ul><li>E.g., Route from H1 to H2 </li></ul></ul>
  34. 34. WAN - Architecture <ul><li>An intermediate router in a WAN </li></ul><ul><ul><li>Receives a packet in its entirety </li></ul></ul><ul><ul><li>Queues the packet until required output line is free </li></ul></ul><ul><ul><li>Forwards the packet </li></ul></ul><ul><li>Subnet using the principle above is called </li></ul><ul><ul><li>Store-and-forward or packet-switched subnet </li></ul></ul>
  35. 35. Wide Area Networks <ul><li>A stream of packets from sender to receiver. </li></ul>
  36. 36. Topology – LANs vs WANs <ul><li>Local networks </li></ul><ul><ul><li>Bus, Ring, Star </li></ul></ul><ul><ul><li>Tree </li></ul></ul><ul><li>WANs typically irregular </li></ul>
  37. 37. WAN - Broadcast Systems <ul><li>Satellite system </li></ul><ul><ul><li>Each router has an antenna </li></ul></ul><ul><ul><li>Sometimes routers are connected to a substantial point-to-point subnet, with some of them having a satellite antenna </li></ul></ul><ul><ul><li>Inherently broadcast </li></ul></ul>
  38. 38. Wireless Network <ul><li>System interconnection </li></ul><ul><ul><li>Example: Bluetooth </li></ul></ul><ul><li>Wireless LANs </li></ul><ul><ul><li>Easy to install </li></ul></ul><ul><ul><li>IEEE Standard 802.11 </li></ul></ul><ul><li>Wireless WANs </li></ul><ul><ul><li>IEEE Standard 802.16 </li></ul></ul>
  39. 39. Wireless Networks <ul><li>Bluetooth configuration Wireless LAN </li></ul>
  40. 40. Wireless Network <ul><li>Combinations of wired and wireless networking (e.g., flying LAN) </li></ul>
  41. 41. Home Network Categories <ul><li>Computers </li></ul><ul><ul><li>Desktop PC, PDA, shared peripherals </li></ul></ul><ul><li>Entertainment </li></ul><ul><ul><li>TV, DVD, VCR, camera, stereo, MP3 </li></ul></ul><ul><li>Telecomm </li></ul><ul><ul><li>Telephone, cell phone, intercom, fax </li></ul></ul><ul><li>Appliances </li></ul><ul><ul><li>Microwave, fridge, clock, furnace, aircon </li></ul></ul><ul><li>Telemetry </li></ul><ul><ul><li>Utility meter, burglar alarm, babycam </li></ul></ul>
  42. 42. Internetwork <ul><li>What is internetwork ? </li></ul><ul><ul><li>A collection of interconnected networks </li></ul></ul><ul><li>&quot;Internet&quot; and &quot;internet&quot; </li></ul><ul><ul><li>internet: internetwork </li></ul></ul><ul><ul><li>Internet: the worldwide internetwork using TCP/IP protocol suite </li></ul></ul><ul><ul><ul><li>The “Big Picture” </li></ul></ul></ul><ul><li>Problem: Communication between networks with different SW/HW </li></ul><ul><ul><li>Solution: Gateways </li></ul></ul><ul><ul><ul><li>Machines connect different, incompatible networks </li></ul></ul></ul><ul><ul><ul><li>Connection and translation </li></ul></ul></ul>