Computer Networks and
Internets
Unit 1
Introduction
,• ''Computer Network'' is a collection of autonomous
computers interconnected by a single technology.
Two computers are said to be interconnected if they
are able to exchange information.
• The word data refers to information presented by
the parties. Data communications are the exchange
of data between two devices via some form of
transmission medium such as a wire cable. For data
communications to occur, the communicating
devices must be part of a communication system
made up of a combination of hardware (physical
equipment) and software (programs).
, 4 fundamental characteristics
1.Delivery. The system must deliver data to the correct destination.
Data must be received by the intended device or user and only
by that device or user.
2. Accuracy. The system must deliver the data accurately. Data that
have been altered in transmission and left uncorrected are
unusable.
3. Timeliness. The system must deliver data in a timely manner. Data
delivered late are useless. In the case of video and audio, timely
delivery means delivering data as they are produced, in the same
order that they are produced, and without significant delay.
4. Jitter. Jitter refers to the variation in the packet arrival time. It is
the uneven delay in the delivery of audio or video packets. For
example, let us assume that video packets are sent every 3D ms. If
some of the packets arrive with 3D-ms delay and others with 4D-
ms delay, results in poor video quality.
, Components of a data communication system
1.4
Internets
Unit 1
Introduction
,• ''Computer Network'' is a collection of autonomous
computers interconnected by a single technology.
Two computers are said to be interconnected if they
are able to exchange information.
• The word data refers to information presented by
the parties. Data communications are the exchange
of data between two devices via some form of
transmission medium such as a wire cable. For data
communications to occur, the communicating
devices must be part of a communication system
made up of a combination of hardware (physical
equipment) and software (programs).
, 4 fundamental characteristics
1.Delivery. The system must deliver data to the correct destination.
Data must be received by the intended device or user and only
by that device or user.
2. Accuracy. The system must deliver the data accurately. Data that
have been altered in transmission and left uncorrected are
unusable.
3. Timeliness. The system must deliver data in a timely manner. Data
delivered late are useless. In the case of video and audio, timely
delivery means delivering data as they are produced, in the same
order that they are produced, and without significant delay.
4. Jitter. Jitter refers to the variation in the packet arrival time. It is
the uneven delay in the delivery of audio or video packets. For
example, let us assume that video packets are sent every 3D ms. If
some of the packets arrive with 3D-ms delay and others with 4D-
ms delay, results in poor video quality.
, Components of a data communication system
1.4
