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 Logan World

4. Central Office Trunks Subscribers Cross point Switch Switch Control Console (Fiber and Copper) (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) Inductor (Henrys) Resistor (Ohms) Voltage Source 6Volts DC

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 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) TakeoffLanding RoutingRouting Routing

22. Communication Subsystems Physical Link Data Link Network Transport Physical Link Data Link Network Transport Program 2 (Session) System 1System 2 Typical layers in a communication subsystem The layers communicate via protocols Program 1 (Session) Presentation Application

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

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