1. Business Data Communications
Chapter One
Introduction to Data Communications

2. Changing our World

3. Primary Learning Objectives
Identify five data communications phases
Understand the importance of protocols and standards
Be familiar with the OSI and TCP/IP networking models
Describe the benefits of a layered architecture
Recognize the general categories of networks

4. What is data communication?
Not to be confused with telecommunication—
Any process that permits the passage from a sender to one or more receivers of information of any nature, delivered in any easy to use form by any electromagnetic system.
Data communication-
Defined as a subset of telecommunication involving the transmission of data to and from computers and components of computer systems.
More specifically data communication is transmitted via mediums such as wires, coaxial cables, fiber optics, or radiated electromagnetic waves such as broadcast radio, infrared light, microwaves, and satellites.

5. Five Data Communications Phases
1960s - Digitization of Data
1970s - Growth of Data Communications
1980s - An Era of Deregulation
1990s - The Internet as a Common Tool
2000s - Pervasive Computing

6. History of Telecommunications
Invention of telegraph Samuel Morse – 1837
Invention of telephone- Alexander Graham Bell – 1876
Development of wireless By ??? – 1896
Concept of universal access and growth of AT&T
Divestiture of AT&T—what year??

7. History of Telecommunications Continued….
Telecommunications Act of 1996
Three main developments that led to the growth of data communications systems:
Large-scale integration of circuits reduced the cost and size of terminals and comm equipment
Developments of software systems made establishment of communication networks easy
Competition among providers of transmission facilities reduced the cost of data circuits

8. History of Data Communication
Transistor developed by Bell Labs (which is now ???) 1947
Hush-a-Phone Case
Carterphone case
MCI and Long Distance
Creation of networks (LAN’s and WAN’s)
Data Link Protocols
Microcomputers

9. History of the Internet
See web page link–

10. 1960s – Digitization of Data
Digitization transcribes data into binary form
First large-scale, mainframe computer systems are proprietary and they use a closed architecture technology
The trend today is for open architecture technologies

11. 1960s – Digitization of Data

12. 1970s – Growth of Data Communications
With greater frequency, businesses automate their previously manual processes, using computer technology
As a result, computers become more prevalent
Increasingly, computers need to communicate with each other so that their data and resources can be shared
Data communication infrastructures evolve in response to this need, particularly packet-switching networks

13. 1970s – Growth of Data Communications

14. 1980s – An Era of Deregulation
Initially, the telecommunications industry in the United States runs as a monopoly under Bell Telephone/AT&T
In 1984, the United States deregulates long distance telecommunication resulting in the breakup of Bell Telephone/AT&T
Deregulation’s intent is to provide greater competition in a given market

15. 1990 – Internet as Common Tool
In 1969, ARPA evolves into ARPANET, which eventually evolves into today’s Internet
IPv4, the original protocol version for the Internet
Not designed with multimedia data in mind
Today, hundreds of millions of people worldwide connect to the IPv4 Internet
IPv6, the latest version of the Internet, will gradually replace IPv4

16. 1990 – Internet as Common Tool

17. 2000s – Pervasive Computing
A technology so commonly used it can be taken for granted
Essential to future pervasive computing will be wireless technologies
For example, telemetry allows the wireless transmission and reception of data for monitoring equipment and environmental conditions

18. 2000s – Pervasive Computing

19. Acme’s use of Telemetry

20. Data Communications
Currently a subset of telecommunications, although the differences are beginning to blur
Telecommunications includes television, telegraphy, and telephony
Data communications focuses primarily on the transmission of data between computing devices

21. Encoding Schemes Data is transmitted using binary encoding schemes
Binary encoding schemes, of which there are several, use the binary digits 0 and 1
A new binary encoding scheme called Unicode will allow for the encoding of more than 64,000 unique characters
Traditional encoding schemes, such as EBCDIC and Extended ASCII, allow for only 256 unique characters

22. Features of Communication
Four things required
Sender, receiver, medium, and message
Types of messages
File
Request
Response
Status
Control
Correspondence
Understandability
Error Detection

24. Online System Requirements
Response Time
Throughput
Consistency
Flexibility

25. Online Systems Requirements Continued
Availability
Reliability
Mean time between failure (MTBF)
Mean time to repair (MTTR)
Fault Tolerance
Recovery
Security

26. Protocols Data communications also depend on protocols
Protocols determine the rules for how something is performed or accomplished
Protocols become established or defined through a standards process

27. Standards Standards may be formal or informal
Informal standards are also called “de facto” standards
Standards can be proprietary or open
The trend is toward open standards
There are numerous standard-setting bodies
ISO, ANSI, IEEE, IETF, to name a few

28. Network Topology, Architecture, and Complexity
Network topology refers to the physical layout of a network, the way that nodes attach to the communication medium
Network architecture refers to the way in which media, hardware, and software are integrated to form a network
Network complexity is concerned with extent to which network architectures are simple or diverse in their make
Figures 1-5, 1-6, and 1-7 illustrate various levels of complexity

29. Figure 1-5

30. Figure 1-6

31. Figure 1-7

32. Networking Models Models are logical and based on theory
In data communications, two important models are:
OSI – Open Systems Interconnection
TCP/IP – Transmission Control Protocol/Internet Protocol
The OSI and TCP/IP models are both open system models that use a layered architecture
The OSI has seven Layers
The TCP/IP has four or five layers, depending on the source

33. The Layering Approach
In a layered model, each layer is responsible for specific functions
A layer must be able to communicate with the layer immediately above or below it
However, a layer does not have to “understand” how a layer above or below works
Designers of networking technologies can create products that function within a specific layer

34. Data Communication Frameworks
Two major data communication frameworks have been developed to help ensure that networks meet business and communication requirements:
Open Systems Interconnection (OSI) reference model developed by the International Standards Organization (ISO)
Transmission Control Protocol/Internet Protocol (TCP/IP) suite

35. History of the OSI Model
Open Systems Interconnected Model
was created in the 70’s by the ISO (although the CCITT came up with their own model)
10 different people got together and considered all functions of communications
was created because people realized that our computers needed to talk to each other(and there was no one dominant computer system)
ISDN was a big factor
7 layers = 4 upper and 3 lower

36. OSI Reference Model in Practice
The OSI reference model is used in many ways:
To provide assistance when troubleshooting network problems
To provide a common terminology and framework for networking technology developers
To facilitate the development of connectivity standards needed for flexible open architectures
To enable the development of protocol stacks that allow network nodes to communicate with one another

37. The OSI Model LAYER 7– APPLICATION
The visual interface level between the user and the network, or computer. (Ex Word, Excel, Access, )
LAYER 6-- PRESENTATION
This layer is responsible for converting the visual interface into a code that is then sent through the computer or network. For example, this layer may convert ASCII code (what many applications like Word use) to an 8-bit code.
LAYER 5 – SESSION
This layer keeps track of whose turn it is to receive traffic, basically it is a dialog control. This is the level that acknowledges receipt of a transmission as well as sends the message to the network.
LAYER 4 – TRANSPORT
All streams of data are received and combined into one single stream so that data may be sent through the network. Multiplexing and demultiplexing occurs on this layer.

38. The OSI Model BOTTOM/LOWER LAYERS LAYER 3– NETWORK
On this level the router exists to determine if the message is meant for the system or if it needs to be redirected to its final destination. This is done by a header system, which is programmed to accept or reject depending if the header is the one used by the network.
LAYER 2– DATA LINK
There is where a check of the message occurs. That is the message is checked for the proper frame, formation, synchronization, power level, voltage, and wavelength. If the test is a successful, the message is sent to the network layer to determine if the message is truly meant for the system.
LAYER 1– PHYSICAL
Where the actual physical makeup of the message is identified. That is the duration of bits, the right number of bits, and the right wavelength is checked. As with the other two layers, if this test is successful, the message is sent up the chain.

39. OSI LAYER INTERACTIONS

40. TCP/IP Protocol Suite
The TCP/IP suite provides insights into the inner workings of the Internet
Like the OSI model, the TCP/IP suite is layered
Because the protocols found at each layer are independent of those at the other layers, a given protocol can be modified without affecting those found at other layers
TCP/IP layers and layer-specific protocols are illustrated in Figure 1-9

41. Figure 1-9

42. Moving Bits through the Network

43. Putting It all Together
Data Communications Supports Applications
The Operating System manages the resources of the computer.
There must however, be a system that provides a bridge between applications and the devices so they can communicate—this is called a Transaction Control Process (TCP)

44. The TCP/IP Layers Application Transport Network Data Link Physical
The application layer of the TCP/IP model includes the application, presentation, and session layers of the OSI model.

45. OSI and TCP/IP These models have several similarities
Both offer layered architectures
Both are open models
They have similar data link layer functions
They have similar physical layer functions
Of the two, TCP/IP is the older and the more popular

46. Business Data Communications Issues
Major data communications issues include:
Cost-effectiveness
The Internet
Bandwidth
Evolving technologies
Convergence
Standards
Privacy and security

47. Important Standard-Setting Organizations Table 1-5

48. Business Data Communication Careers
There are numerous job opportunities and career paths for individuals interested in data communications and networking
Table 1-6 includes examples of data communication job titles
Table 1-7 summarizes some of the major professional certifications for networking and data communications specialists

49. Table 1-6

50. Table 1-7

51. Networks
Standards and protocols are critical in data communications when creating a network
Networks have four general classifications
Local Area Network – LAN
Backbone Network – BN
Metropolitan Area Network – MAN
Wide Area Network – WAN
Networks are based on models

52. Key Data Communication Concepts
Session: communication dialog between network users or applications
Network: interconnected group of computers and communication devices
Node: a network-attached computer
Link: connects adjacent nodes (see Figure 1-4)
Path: end-to-end route within a network
Circuit: the conduit over which data travels
Packetizing: dividing messages into fixed-length packets prior to transmission over a network’s communication media
Routing: determining a message’s path from sending to receiving nodes.

53. A Local Area Network

54. A Possible Backbone Network

55. A Metropolitan Area Network

56. A Wide Area Network

57. In Summary Data communications is a multifaceted field
Many technologists end up specializing in specific areas
Many standard-setting bodies affect its direction
Pervasive computing will transform how the average person uses and experiences data communications technology