Basics of Computer Networking<br />Prof. Anish Goel<br />
Contents<br />Introduction<br />History of Communication<br />Computer Networks<br />Current Scenario<br />Complexity<br /...
Introduction<br />Where do you see computers ?<br />What is the purpose of connecting them in network ?<br />Transmission ...
Telephone Networks and Circuit Switching<br />Signal for “ae” as in cat<br />Microphone<br />Loudspeaker<br />analog<br />...
The N2 Problem<br />1<br />2<br />N<br />. . .<br />3<br />4<br />For N users to be fully connected directly<br />Requires...
Circuit Switching<br />Patch cord panel switch invented in 1877<br />Operators connect users on demand<br />Establish circ...
Digitization of Telephone Network<br />Pulse Code Modulation digital voice signal<br />Voice gives 8 bits/sample x 8000 sa...
Computer Connection Control<br />Computer<br />Switch connects<br />Inlets to Outlets<br />. . .<br />. . .<br />Voice<br ...
Computer Network Evolution Overview<br />1950s:  Telegraph technology adapted to computers <br />1960s: Dumb terminals acc...
What is a protocol?<br />Communications between computers requires very specific unambiguous rules<br />A protocol is a se...
Computer-to-Computer Networks<br />As cost of computing dropped, terminal-oriented networks viewed as too inflexible and c...
Packet Switching<br />Message Switching<br />Transfer arbitrary message size<br />But in store-and-forward operation, long...
Current Scenario<br />High-speed data transmission.<br />More bandwidth.<br />Multimedia traffic increasing.<br />Wi-Fi an...
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Basics Of Comuter Networking

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Basics of Computer Communication and Network with Emphasis on the history of communication. It also mentions the current scenario of computer networks.

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Basics Of Comuter Networking

  1. 1. Basics of Computer Networking<br />Prof. Anish Goel<br />
  2. 2. Contents<br />Introduction<br />History of Communication<br />Computer Networks<br />Current Scenario<br />Complexity<br />Layered Architecture<br />Computer Networks<br />
  3. 3. Introduction<br />Where do you see computers ?<br />What is the purpose of connecting them in network ?<br />Transmission from Analog to Digital Communication.<br />Impact of computers on the communication methods.<br />Most common form of communication ???<br />Magic number of 64Kbps !!!!<br />Computer Networks<br />
  4. 4. Telephone Networks and Circuit Switching<br />Signal for “ae” as in cat<br />Microphone<br />Loudspeaker<br />analog<br />electrical<br />signal<br />sound<br />sound<br />Alexander Graham Bell (1875) working on harmonic telegraph to multiplex telegraph signals<br />Discovered voice signals can be transmitted directly<br />Microphone converts voice pressure variation (sound) into analogous electrical signal<br />Loudspeaker converts electrical signal back into sound <br />Telephone patent granted in 1876<br />Bell Telephone Company founded in 1877<br />Computer Networks<br />
  5. 5. The N2 Problem<br />1<br />2<br />N<br />. . .<br />3<br />4<br />For N users to be fully connected directly<br />Requires N(N – 1)/2 connections <br />Requires too much space for cables<br />Inefficient & costly since connections not always on<br />N = 1000<br />N(N – 1)/2 = 499500<br />Computer Networks<br />
  6. 6. Circuit Switching<br />Patch cord panel switch invented in 1877<br />Operators connect users on demand<br />Establish circuit to allow electrical current to flow from inlet to outlet<br />Only N connections required to a central office<br />Computer Networks<br />
  7. 7. Digitization of Telephone Network<br />Pulse Code Modulation digital voice signal<br />Voice gives 8 bits/sample x 8000 samples/sec = 64x103 bps<br />Time Division Multiplexing for digital voice<br />T-1 multiplexing (1961): 24 voice signals = 1.544x106 bps<br />Digital Switching (1980s)<br />Switch TDM signals without conversion to analog form<br />Digital Cellular Telephony (1990s)<br />Optical Digital Transmission (1990s)<br />One OC-192 optical signal = 10x109 bps<br />One optical fiber carries 160 OC-192 signals = 1.6x1012 bps!<br />All digital transmission, switching, and control<br />Computer Networks<br />
  8. 8. Computer Connection Control<br />Computer<br />Switch connects<br />Inlets to Outlets<br />. . .<br />. . .<br />Voice<br />A computer controls connection in telephone switch<br />Computers exchange signaling messages to:<br />Coordinate set up of telephone connections<br />To implement new services such as caller ID, voice mail, . . .<br />To enable mobility and roaming in cellular networks<br />“Intelligence” inside the network<br />A separate signaling network is required<br />Computer Networks<br />
  9. 9. Computer Network Evolution Overview<br />1950s: Telegraph technology adapted to computers <br />1960s: Dumb terminals access shared host computer<br />1970s: Computers connect directly to each other<br />ARPANET packet switching network<br />TCP/IP internet protocols<br />Ethernet local area network<br />1980s & 1990s: New applications and Internet growth<br />Commercialization of Internet<br />E-mail, file transfer, web, P2P, . . .<br />Internet traffic surpasses voice traffic<br />Computer Networks<br />
  10. 10. What is a protocol?<br />Communications between computers requires very specific unambiguous rules<br />A protocol is a set of rules that governs how two or more communicating parties should interact<br />Internet Protocol (IP)<br />Transmission Control Protocol (TCP)<br />HyperText Transfer Protocol (HTTP)<br />Simple Mail Transfer Protocol (SMTP)<br />Computer Networks<br />
  11. 11. Computer-to-Computer Networks<br />As cost of computing dropped, terminal-oriented networks viewed as too inflexible and costly<br />Need to develop flexible computer networks<br />Interconnect computers as required<br />Support many applications<br />Application Examples<br />File transfer between arbitrary computers<br />Execution of a program on another computer<br />Multiprocess operation over multiple computers<br />Computer Networks<br />
  12. 12. Packet Switching<br />Message Switching<br />Transfer arbitrary message size<br />But in store-and-forward operation, long messages induce high delay on interactive traffic that consists of short messages<br />Packet switching introduced<br />Network transfers packets using store-and-forward<br />Packets have maximum length<br />Break long messages into multiple packets<br />Low delays for interactive traffic<br />ARPANET testbed led to many innovations<br />Computer Networks<br />
  13. 13. Current Scenario<br />High-speed data transmission.<br />More bandwidth.<br />Multimedia traffic increasing.<br />Wi-Fi and Wi-Max.<br />ATM Networks.<br />Optical Bandwidth Exploration.<br />Speed limitation on electronic switching.<br />Computer Networks<br />

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