1. Business Data Communications and Networking, 6th ed.
FitzGerald and Dennis

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3. Introduction to Data Communications
Chapter 1
Introduction to Data Communications

4. Objectives Become familiar with…
the history of communications and information systems,
the applications of data communication networks,
the major components of networks,
the importance of standards,
three key trends in communications and networking,
Understand the role of network layers.

5. INTRODUCTION

6. Why Study Data Communications?
We have moved into an information society dominated by computers, data communications, and highly skilled individuals...
At no other time in our history, has success (whether individual, corporate, or national) depended so heavily on intelligence and information.

7. Why Study Data Communications?
The key technology of the information age is communications.
Data communications and networking is a truly global area of study, both because the technology enables global communication, and because new technologies and applications often emerge from a variety of countries and spread rapidly around the world.

8. A Brief History of Communications in the U.S.
Samuel Morse exhibited a working telegraph system.
Alexander Bain patented a printing telegraph.
Alexander Graham Bell, invented the first telephone capable of practical use.
first private manual telephone switchboard
first pay telephone

9. A Brief History of Communications in the U.S.
Canadian government began regulating telephone rates.
ICC regulated interstate telephone business.
first transcontinental telephone serve and first transatlantic voice connections.
Communications Act transferred regulation of interstate telephone traffic from ICC to FCC.

10. A Brief History of Communications in the U.S.
transistor invented in Bell Labs
first direct long distance dialing
first international satellite telephone call
Carterfone court decision allowed non-Bell equipment to connect to Bell System Network
Picturefone service began

11. A Brief History of Communications in the U.S.
permitted MCI to provide limited long distance service in competition to AT&T.
deregulation of AT&T
1980s - public service of digital networks
1990s - cellular telephones commonplace
U.S. Congress enacted the Telecommunications Act of 1996
International agreement signed by 68 countries to reduce regulation in TC markets

12. A Brief History of Communications in the U.S.
Telecommunications Competition and Deregulation Act of 1996
Practically overnight, the local telephone industry in the U.S. went from a highly regulated and legally restricted monopoly to open competition.
Local service in the U.S. is now open for competition.
RBOCs are now permitted to provide long distance services.

13. A Brief History of Communications in the U.S.
The Internet has been a different story. Virtually all RBOCs, LECs, and IXCs, have aggressively entered the Internet market.
Today, there are more than 5000 Internet Service Providers (ISPs) who provide dial-in access to the Internet to millions of small business and home users.

14. A Brief History of Information Systems in the U.S.
1950s - computer systems used batch processing with discrete files.
1960s - data communication across telephone lines became more commonplace.
1960s-1970s - online real-time systems were developed.

15. A Brief History of Information Systems in the U.S.
1980s - widespread adoption of personal computer.
1990s - more than 60 percent of all PCs in the U.S. were networked.
As we move into the new century, the most important aspect of computing is networking.
Networks already have had a dramatic impact on the way business is conducted.

16. DATA COMMUNICATIONS NETWORKS

17. Data Communications Data Communications Telecommunications
The movement of computer information from one point to another by means of electrical or optical transmission systems.
Such systems are often called data communications networks.
Telecommunications
Includes the transmission of voice and video as well as data.

18. Components of a Network
Server (or Host computer)
Central computer in the network, storing data or software that can be accessed by the clients.
Client
The input/output hardware device at the other end of a communications circuit.
Circuit
The pathway through which the messages travel.

19. Components of a Network

20. Components of a Network
Peer-to-peer networks
Do not need a server or host, but are designed to connect similar computers which share their data and software with each other.
Microcomputer networks are connected by a hub and cables (circuit).
A router is used to connect two or more networks, enabling computers on one network to communicate with computers on other networks (e.g. the Internet).

21. Types of Networks
Networks can be classified in many different ways. One of the most common is by geographic scope:
Local Area Networks (LAN)
Backbone Networks (BNs)
Metropolitan Area Networks (MANs)
Wide Area Networks (WANs)

22. Types of Networks

23. Types of Networks Local Area Networks (LAN)
A group of microcomputers of terminals located in the same general area and connected by a common circuit.
Covers a clearly defined small area, such as within or between a few buildings,
Support data rates of 10 to 100 million bits per second (Mbps).

24. Types of Networks Backbone Network (BN)
A larger, central network connecting several LANs, other BNs, metropolitan area networks, and wide area networks.
Typically span up to several miles.
Support data rates from 64 Kbps to 45 Mbps.

25. Types of Networks Metropolitan Area Network (MAN)
Connects LANs and BNs located in different areas to each other and to wide area networks.
Typically span from miles.
Supports data rates of 100 to 1000 Mbps.

26. Types of Networks Wide Area Network (WAN)
Connects BNs and MANs and are usually leased from inter-exchange carriers.
Typically span hundreds or thousands of miles.
Supports data rates of 28.8 Kbps to 2 Gbps.

27. NETWORK MODEL

28. Network Model
A method of describing and analyzing data communications networks, by breaking the entire set of communications functions into a series of layers, each of which can be defined separately.
This allows vendors to develop software and hardware to provide the functions separately.

29. Networking Model
Open System Interconnection (OSI) Model, developed in 1984, helped change the face of network computing.
Other models like TCP/IP have become more prominent in the design of networks and network technology.

30. Networking Model

31. Simplified Network Model
Application layer (Layer 4)
The application software used by the network user, allows the user to define what message are sent over the network.

32. Simplified Network Model
Network layer (Layer 3)
Takes the message generated by the application layer and performs three functions before passing them to the data link layer.
1. Translates the destination of the message into an address understood by the network.
2. If multiple routes possible, it decides which routes to take.
3. Collects message accounting information that can be used to identify how many messages each user has sent and to track errors.

33. Simplified Network Model
Data link layer (Layer 2)
Takes the message generated by the network layer and performs three functions before passing the message on the physical layer.
1. It controls the physical layer by deciding when to transmit messages over the media.
2. It formats the message by indicating where messages start and end, and which part is the address. (It may break it into smaller packets).
3. It detects and corrects any errors that have occurred in the transmission of the message.

34. Simplified Network Model
Physical layer (Layer 1)
The physical connection between the sender and receiver.
It transfers a series of electrical, radio, or light signals through the circuit from sender to receiver.
It specifies the type of connection, and the signals that pass through it.

35. Network Models
For Communications to be successful, each layer in one computer must be able to communicate with its matching layer in the other computer.
This is accomplished by standards.

36. NETWORK STANDARDS

37. The Importance of Standards
Standards are necessary in almost every business and public service entity.
The primary reason for standards is to ensure that hardware and software produced by different vendors can work together.
The use of standards makes it much easier to develop software and hardware that link different networks because software and hardware can be developed one layer at a time.

38. The Standards Making Process
Two types of standards:
Formal standards are developed by an official industry or government body.
Defacto standards emerge in the marketplace and supported by several vendors, but have no official standing.

39. The Standards Making Process
Formal standardization process has three stages
1. Specification stage: developing a nomenclature and identifying the problems to be addressed.
2. Identification of choices stage: those working on the standard identify the various solutions and choose the optimum solution from among the alternatives.
3. Acceptance, the most difficult stage: defining the solution and getting recognized industry leaders to agree on a single, uniform solution

40. Telecommunications Standards Organizations
International Organization for Standards (ISO)
Member of the ITU, makes technical recommendations about data communications interfaces.

41. Telecommunications Standards Organizations
International Telecommunications Union - Telecommunication Standardization Sector (ITU-TSS)
Technical standard setting organization of the UN ITU. Formerly called the Consultative Committee on International Telegraph and Telephone (CCITT)
Comprised of representatives of over 150 Postal Telephone and Telegraphs (PTTs), like AT&T, RBOCs, or common carriers.

42. TC Standards Organizations
American National Standards Institute (ANSI)
Institute of Electrical and Electronics Engineers (IEEE)
Electronic Industries Association (EIA)
National Institute of Standards and Technology (NIST)
National Exchange Carriers Association (NECA)
Corporation for Open Systems (COS)
Electronic Data Interchange -(EDI) of Electronic Data Interchange for Administration Commerce and Transport (EDIFACT).

43. FUTURE TRENDS IN COMMUNICATIONS AND NETWORKING

44. Future Trends
Between now and the year 2010, data communications will grow faster and become more important than computer processing itself.
There are three major trends driving the future of communications and networking:
Pervasive Networking
The Integration of Voice, Video and Data
New Information Services

45. Pervasive Networking
In the future, communications networks will be everywhere.
This pervasive networking means that virtually any computer will be able to communicate with any other computer in the world.
This will increase telecommuting in which employees perform some or all of their work at home instead of going to the office each day.

46. Pervasive Networking
Cellular telephone networks will begin to compete directly with the current wired telephone network.
Pervasive networking will also increase the use of electronic data interchange (EDI), the paperless transmission of business documents between companies.
The Internet has experienced such rapid growth that it now connects millions of computers in virtually every country in the world.

47. The Integration of Voice, Video and Data
The integration of voice and data is largely complete in wide area networks.
The integration of video into computer networks has been much slower, partly due to past legal restrictions, and partly due to the immense communications needs of video.

48. New Information Services
The World Wide Web has changed the nature of computing so now that almost anyone with a computer can be their own publisher.
Never before in the history of the human race has so much knowledge and information been available to ordinary citizens.

51. End of Chapter 1