Download ITT04103-Lecture-1

ITT 413
Basics of Data Communication
Overview
 Assessment Plan
Coursework – 40%
Final Exam – 60%
 Course Content
Introduction
What is Computer Communication?
Computer?
Communication?
Elements of Computer communication
 Sender
 Receiver
 Message
 Medium
 Protocols
 Sender: The sender is the device that sends the message (data). It can be a
computer, workstation, mobile handset or a video camera
 Receiver: The receiver is the device that receives the message . It can be a
computer, workstation, mobile handset or television
 Message: The message is the information (data) to be communicated. It can be
a text message, number, picture, sound, video or a combination of these
 Medium: The transmission medium is the physical path by which a message
travels from sender to receiver. It could be a cable (twisted pair), fiber optic or
air
 Protocol: A protocol is a set of rules that govern computer communication. It
present an agreement between communicating devices. A protocol define
what is communicate, how it is communicated and when it is communicate
Key elements of a protocol are: Syntax, Semantic and Timing
Syntax:
Syntax refer to the structure or format of the data,
meaning the order in which they are presented
Semantics: Semantics refers to the meaning of the section of bits.
How is a particular pattern to be interpreted? and what action is to
be taken based on that interpretation?
Timing: Timing refers to two characteristics: when data should
be sent and how fast they should be sent
Transmission Modes
The direction of a signal between two devices is defined by a
transmission mode. Or The transmission mode defines the
direction of a signal between two devices
 Simplex
 Half-Duplex
 Full-Duplex
Simplex
In the simplex mode the communication is unidirectional. Only one
can send data and other can receive. No any other possibility is
available. A remote is an example of simplex mode.
Example of Simplex Communication
• For example, in TV and radio broadcasting, information flows only from the
transmitter site to multiple receivers.
• Commercial radio and television broadcast (not two-way radio such as
walkie-talkies)
• Garage door openers
• Baby monitors
• Wireless microphones
• Radio controlled models
• Public address systems
• Surveillance cameras
• Pagers
• Communication between a mouse and a computer
• Internet multicast
• Radio navigation beacons and radiolocation services such as GPS
• Telemetry
• Printers
Half-Duplex Transmission
Half Duplex Mode: In the Half-duplex (sometimes it is called an
alternating connection or semi-duplex) mode, the data can be
transmitted from one direction to the other. The terminals have
ability to either receives or sends out the data. However, sending
and receiving can not be done at same time. For example; FAX (it
can sends or receives letter but not in same time) and Walkie-
talkie is an example of half duplex transmission
Full-Duplex Transmission
Full Duplex Mode: In full duplex mode both devices can send and
receive data at the same time. It has two way traffic at the same time
or its like a two lane bridge on a two-lane highway. Online
communication such as MSN-hotmail, Yahoo messanger, google
talk, facebook chatt-room and Skype telephone are the one of the
examples of software, which are in full-duplex and also the
telephone network (example landline and mobile) is an example of
full duplex mode.
Categories of Networks
A network is a set of devices (nodes) connected by media links. A
node can be a computer , printer, or any other devices capable of
sending and /or receiving data generated by another node in the
network
LAN
LAN is usually privately owned and interconnect devices in a single office,
building, or campus (see the figure below)
MAN
MAN is designed to extend over an entire city. It may be single network such as
cable television network , or it may be a means of connecting a number of
LANs into a large network so that resources can be shared. For example,
UDSM with many campuses mliman, kunduchi, and DCE .
WAN
WAN provides a long-distance transmission of data, voice, image and video
information over large geographical area that may comprises a country, a
continent , or even the whole world. For example the internet
LAN COMPONENTS

LAN is the combination of hardware and software.

Hardware is the part of the network that is tangible whereas Software is
the collection of programs that allows the use of network
Hardware:

Stations

Transmission media

Connecting Devices
Software:
Software run on a LAN can be divided into two larger groups: Network
operating system (NOS) and application programs
Network Operating system (NOS) : is a program that allows logical
connection of the stations and devices to the network. It allows users to
communicate and share resource. Some examples of network operating
systems include Novell NetWare, Microsoft Windows NT, Microsoft
Windows 2000, Microsoft Windows XP, Sun Solaris, Linux.
Application Programs
•
Application programs allow users to solve special problems
•
In this case applications is either the program you are using or the data you
are working with or both reside on a network.
•
Network applications use a client-server architecture, where the client and
server are two computers connected to the network. The server is
programmed to provide some service to the client.
•
The client is typically a desktop, laptop or portable device like an smart
phone. The server can be any of these, but is typically a computer in a data
center.
Examples of network applications are: E-mail, The Web, Instant Messaging,
P2P file sharing, File Transfer between two accounts on two computers
(FTP) Multi-user networked games, Streaming stored video clips, Internet
Phone, Real time video conferencing
•
Client/Server Model with Dedicated Servers
Client/Server Model with a General Server
LAN Applications
Common applications of LAN are office networks and industry network
Office Networks: LANs are used for sharing resources such as hardware,
software and data.
Hardware – example printer
Software – example accounting package (program)
Data – example bank customer’s information
Industry Network : This is suitable for automated manufacturing and
production. For example, a LAN can be used in the automobile industry
such as TOYOTA to coordinate different activities such as controlling
robots, material handling , or warehouse inventory