Author: Achyut S.Godbole, “ Data Communications and Networks”, Tata McGraw-Hill Publishing Company Limited, Ninth reprint, 2007

1. R.Anushiya
Assstiant Professor,
P.K.R Arts College for Women, Gobi
Author: Achyut S.Godbole, “ Data Communications and Networks”, Tata McGraw-Hill Publishing
Company Limited, Ninth reprint, 2007

2. Introduction to DCN
Fundamental Concept
Data Communications
Protocols
Standards
Standard Oganizations
Signal Propagation
Analog and digital signals

3. DATA?

4. Data generally are defined as information
that is stored in digital form

6. Communications is the process of
transferring digital information between
two or more points

8. Interconnecting of computer systems that
used for transferring messages from one
place to other

10. Characteristics
1. Correct delivery. The system must deliver
data to the correct destination. Data must be
received by the intended device or user
2. Accurate delivery. The system must deliver
the data accurately.
3. Timely delivery. The system must deliver
data in a timely manner. Data delivered late
are useless

11. Components
1. Message. The message is the information (data) to be
communicated. Popular forms of information include text,
numbers, pictures, audio, and video.
2. Sender. The sender is the device that sends the data message.
It can be a computer, workstation, telephone handset, video
camera, and so on.
3. Receiver. The receiver is the device that receives the
message. It can be a computer, workstation, telephone
handset, television, and so on.
4. Transmission medium. The transmission medium is the
physical path by which a message travels from sender to
receiver. Some examples of transmission media include
twisted-pair wire, coaxial cable, fiber-optic cable, and radio
waves
5. Protocol. A protocol is a set of rules that govern data
communications. It represents an agreement between the
communicating devices.

12. Protocol is a set of rules
The sender and receiver, the two parties must
agree on a common set of rules
It defines by
Syntax (What to communicate) – Structure of
data
Semantics (How to Communicate)- Both are in
same network
Timing (When to Communicate) – Transmission
time

13. An association of organizations, governments,
manufacturers and users form the standards
organizations and are responsible for
developing, coordinating and maintaining the
standards.
They are classified as
Standard creation committees
Forums
Regulatory Agencies

14. 1. International Standard Organization (ISO)
2. International Telecommunications Union-
Telecommunication Sector (ITU-T)
3. Institute of Electrical and Electronics
Engineers (IEEE)
4. American National Standards Institute
(ANSI)
5. Electronics Industry Association (EIA)

15. • User groups, students, industry
perspective, experts come together and
setup a group to address the various
issues and concerns of data
communications technology

16. • FCC (Federal Communications
Commission) is a government appointed
agencies
• This helps to protect general
communication services as radio,
television and wired communication