1. Data Communications Making computers talk to each other

4. How computers communicate Let’s do lunch

5. Telecommunications 0 1 0 0 0 0 0 1 LA NY Analog Phone System in U.S.

6. Telecommunications 0 1 0 0 0 0 0 1 LA NY Bandwidth = 300 - 3000 hz

7. Telecommunications 0 1 0 0 0 0 0 1 LA NY Analog Phone System in U.S. Bandwidth = 300 - 3000 hz What are two terms that describe this form of information?

8. Telecommunications 0 1 0 0 0 0 0 1 LA NY Analog Phone System in U.S. Bandwidth = 300 - 3000 hz 1) Binary 2) Digital

9. Telecommunications Ok, so what we want to do is send digital information over a network designed to support analog signals. This presents some compatibility problems ...

10. Telecommunications Lets take a look at what ANALOG information looks like... Time --> + - 0

11. Telecommunications Lets take a look at what DIGITAL information looks like... + - 0 Time -->

12. Telecommunications 0 1 0 0 0 0 0 1 LA NY Analog Phone System in U.S. OK, so what we need is a DIGITAL to ANALOG converter. First thing we need to design is a . . .

13. Telecommunications 0 1 0 0 0 0 0 1 LA NY Analog Phone System in U.S.

14. Telecommunications 0 1 0 0 0 0 0 1 LA NY Analog Phone System in U.S. Black Box

15. Telecommunications 0 1 0 0 0 0 0 1 LA NY The black box is a hardware device, next we need some type of software to control how and when the bits are sent from the computer to the black box...

16. Telecommunications 0 1 0 0 0 0 0 1 LA NY The black box is a hardware device, next we need some type of software to control how and when the bits are sent from the computer to the black box... Bit control software Bit control software

17. Telecommunications 0 1 0 0 0 0 0 1 LA NY The black box is a hardware device, next we need some type of software to control how and when the bits are sent from the computer to the black box... How to handle a zero or a one? Bit control software

18. Telecommunications 0 1 0 0 0 0 0 1 0 LA NY Need to convert the zero to a tone... Lets use 1000 hz Working with bit # 1 Send 1000 hz --> Receive --> 1000 hz Working with bit # 1 Convert tone into a zero ... Convert zero into a tone ...

19. Telecommunications 0 1 0 0 0 0 0 1 0 1 LA NY Need to convert the ONE to a tone... Lets use 2000 hz Working with bit # 2 Send 2000 hz --> Receive --> 2000 hz Working with bit # 2 Convert tone into a ONE ... Convert ONE into a tone ...

20. Telecommunications 0 1 0 0 0 0 0 1 LA NY Need to convert the ONE to a tone... Working with bit # 8 Send 2000 hz --> Receive --> 2000 hz Working with bit # 8 Convert tone into a ONE ... Convert ONE into a tone ... 0 1 0 0 0 0 0 1

21. Telecommunications 0 1 0 0 0 0 0 1 LA NY Need to convert the ONE to a tone... Working with bit # 8 Send 2000 hz --> Receive --> 2000 hz Working with bit # 8 Convert tone into a ONE ... Convert ONE into a tone ... 0 1 0 0 0 0 0 1 What term describes the black box ?

22. Telecommunications Modem (Modulator-Demodulator) Digital to Analog = Modulator Analog to Digital = Demodulator

23. Telecommunications 0 1 0 0 0 0 0 1 LA NY Have some logistical problems... How does NY know that LA is getting ready to send the FIRST bit ? Working with bit # 1

24. Telecommunications 0 1 0 0 0 0 0 1 LA NY Before every byte, a start tone is sent to the receiving computer Ready to transmit first bit Get ready to receive bit # 1 Send a START tone 500 hz --> Receive START tone --> 500 hz

25. Telecommunications 0 1 0 0 0 0 0 1 LA NY After every byte, a stop tone is sent to the receiving computer Done with last bit Sequenced completed Send a STOP tone 800 hz --> Receive STOP tone --> 800 hz 0 1 0 0 0 0 0 1

26. Telecommunications 0 1 0 0 0 0 0 1 LA NY Last major logistical problem ... How fast are we sending the bits down the phone line? 0 1 0 0 0 0 0 1

27. Telecommunications BAUD RATES 300 baud 600 baud 1200 baud 2400 baud 4800 baud 9600 baud 12,000 baud 14,400 baud 19,200 baud 28,800 baud 38,400 baud 57,600 baud Low speed Medium speed High speed An approximate definition of BAUD is “bits per second”

28. Computer Networks Making computers work together

29. What is a Computer Network Two or more computers connected together

33. Wide Area Network (WAN) Computers interconnected in a large area (campus, multiple building, office complex)

34. Municipal Area Network (MAN) Computers interconnected throughout the municipality (city-wide/county-wide)

36. Sneaker Net Hand carry a floppy disk from one computer to another in order to share files.

37. Peer to Peer Sharing Data

38. Client/Server Clients Server Clients use files and programs that are stored on the server

39. Distributed Data is distributed between servers on various networks. When data is requested, the computer checks all connected systems for data. The user probably does not know which computer the data came from. Connected Servers

42. Ethernet (Twisted Pair) HUB

43. Ethernet (Coaxial) Echo Terminator

44. Token Ring

45. How Data Flows A B Computer A wants to send information to computer B.

46. How Data Flows A B Network software in computer A builds a PACKET or PACKETS and puts the information onto the network media.

47. How Data Flows A B Packet(s) Start Length | Destination Address | Source Address | Length Count | Data | Frame Check Sequence What the packet contains:

48. How Data Flows A B Computer B receives the PACKET(S) from the network media. The network software separates the information from the PACKET(S).

49. Next, What’s the internet?