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Computer Networks and the Internet

Computer Networks and the Internet. Internet Service Providers (ISP) Networks WAN Wide Area Network LAN Local Area Network Computers Sneakernet Sharing ARPA Internet. Phone vs. Data. Point to Point Single Address per line All calls to a Central Office Party (Shared) Lines.

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Computer Networks and the Internet

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  1. Computer Networks and the Internet • Internet Service Providers (ISP) • Networks • WAN Wide Area Network • LAN Local Area Network • Computers • Sneakernet • Sharing • ARPA • Internet

  2. Phone vs. Data • Point to Point • Single Address per line • All calls to a Central Office • Party (Shared) Lines

  3. Telephone Communications Central Office USU World Logan

  4. Central Office Trunks (Fiber and Copper) Switch Control Console Cross point Switch Subscribers (Mostly Copper Wire)

  5. Electrical Parameters • Voltage (Electromotive Force) • Current (Amperes, # of electrons flowing) • Resistance (conversion of energy) • ohms • Impedance (Alternating Current Resistance) • Henrys (inductors), farads (capacitors)

  6. Electrical Circuit Capacitor (Farads) • DC 6Volts Voltage Source Inductor (Henrys) Resistor (Ohms)

  7. Components • Resistor • Turns electrical energy into heat linearly • Capacitor • Holds electrical charge, discharges logarithmically • Inductor • Holds electrical energy as magnetism, discharges logarithmically

  8. Square Wave

  9. Fast Square Wave

  10. Logarithmic Curve

  11. Exponential Curve

  12. Sine Wave

  13. Transmission Line Equivalent

  14. Transmission Speeds • Cycles per second (Hertz) • Bits per second • Baud • 1GB/sec (Ethernet) • 100MB/sec (Ethernet) • 10MB/sec (Ethernet) • 1.544MB/sec (DS1)

  15. Twisted Pair Transmission Line • Category 3 • Category 5 (More twists per inch)

  16. Transmission Line details • Characteristic Impedance • Termination • Length Limitations • Loss due to • Resistance • Crosstalk • Mutual Inductance • Radiation

  17. Transmission Line Losses • Measured in DECIBELS • Ratio of input voltage/current to output voltage/current • DB = 20log(voltage1/voltage2) • 20 DB is 100 volts in and 10 volts out

  18. Fiber Optics • Single Mode • Multimode Light Detector Light Source Light Detector

  19. Network Topologies • Bus • Simple but can be failure prone • Star • Simple, uses more wire than Bus, less failure prone • Ring • Like Bus system • Mesh • Redundant but complicated

  20. Conversations

  21. Airplane Trip • Ticket (purchased) Ticket (complain) • Baggage (check) Baggage (claim) • Gates (load) Gates (unload) • Takeoff Landing • Routing Routing • Routing

  22. Communication Subsystems Typical layers in a communication subsystem System 1 System 2 Application Application Presentation Presentation Program1 (Session) Program2 (Session) Transport Transport Network Network DataLink DataLink PhysicalLink PhysicalLink The layers communicate via protocols

  23. Communication Subsystems Typical layers in a communication subsystem System 1 System 2 Application Application WSFTP,Netscape Presentation Presentation FTP, HTTP Session Session Sockets Transport Transport TCP,SPX Network Network IP,IPX DataLink DataLink Ethernet PhysicalLink PhysicalLink Wire The layers communicate via protocols

  24. Physical Layer • Operates on the wire using the following standards: • Fiber Optic (long distances) • Ethernet (twisted pair, fiber, coax) • PPP (twisted pair phone lines)

  25. Link Layer • Operates using the following standards: • Ethernet protocol • Most LANS • PPP (Point to Point Protocol) • Phones Lines • DSL

  26. Network Layer • Operates using the following standards: • TCP/IP (Tranmission Control Protocol/Internet Protocol • IPX (Internet Packet Exchange) • AppleTalk

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