This document provides an introduction to data communications and computer networking. It discusses the history of data communication and key concepts such as the four components of communication, five components of data communication, and directions of data flow. It also describes network applications, application service providers, and important business data communication issues. Finally, it introduces several data communication frameworks, including the Open Systems Interconnection (OSI) reference model and the Transmission Control Protocol/Internet Protocol (TCP/IP) suite.

2. Introduction to Data
Communications and computer
networking
Presented by: Mahira

3. Data Communications
 The term telecommunication means
communication at a distance. The word
data refers to information presented in
whatever form is agreed upon by the
parties creating and using the data.
Data communications are the exchange
of data between two devices via some
form of transmission medium such as a
wire cable.

4. 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

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

6. Five Components of Data
Communication
1. Message
2. Sender
3. Receiver
4. Medium
5. Protocol

7. Direction of data flow
Simplex
Half Duplex
Full Duplex

8. Network Applications
 The network applications environment
consists of several important
components:
– Application programs
– Operating systems
– Data communication systems
– Database management systems
 The application environment is
illustrated in Figure 1-10

9. Application Service Providers
 Many businesses have turned to third-party
services for some or all of their business and
data communications applications
 Application service providers (ASPs) are
third-party organizations that manage and
distribute software and services to other
companies over the Web
 Many ASPs specialize in integrated e-
commerce and e-business applications

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

11. Introduction to Networks
 Can be defined as a single computer ,
called a host, together with
communication circuits, communication
equipment, and terminals.
 There are many different types of
network configurations (see figures1-4
to 1-8)

12. 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.

14. 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

15. Figure 1-5

16. Figure 1-6

17. Figure 1-7

18. Transmission Speeds
M
ed
iu
m S
p
eed C
o
s
t
T
w
iste
dW
ire 300 bps-10 M
bps Low
M
icrow
a
ve 256 K
bps-100 M
bps
S
a
te
llite 256 K
bps-100 M
bps
C
oa
x
ia
l C
a
ble 56 K
bps-200 M
bps
F
ibe
r-O
pticC
a
ble 500 K
bps-10 G
bps H
igh

19. 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

20. 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

21. 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

22. 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

23. Figure 1-9

24. Moving Bits through the Network
Analog Signal
1
0
Digital Signal
1 1 1
0 0 0
digital analog digital
Computer Modem Modem Computer
telephone lines

25. 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)

26. Thank you