NETWORKING

DATA COMMUNICATIONS

•      This course provides a broad introduction to the fundamentals of data communications and network technology. It teaches the users basic networking concepts and skills. It also provides an understanding of data communication standards. Further, it provides an overview of how data is transferred in a real-world network environment

Static vs. Dynamic Web Application

Ø Text Books: Stallings, W. (2007) Data and Computer Communications, 8^th education. Pearson Education International.

Ø Reference Books: Leon-Garcia, A and Widjaja, I (2004) Communica8on Networks: Fundamental Concepts and Key

How to access the Web?

•      Once you have your Internet connection, then you need special software called a browser to access the Web

•      Browser : is a special program used to locate, retrieve and display content on the www including Web pages, images, video and other files

Client/Server Structure of the Web

•      Web is a collection of files that reside on computers, called Web servers,

•       Web servers are located all over the world and are connected to each other through the Internet

•      When you use your Internet connection to become part of the Web, your computer becomes a Web client in a worldwide client/server network

•      A Web browser runs on your computer to make it work as a web client

Web-based systems architectures

•      Browser(client) requests for a particular web page(HTML file)

•      The sever locates the file and send it to the browser

•      The browser(client) display the file

Introduction to Networks

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

Data communication system components

Five components of data communication

•         Message

–        Is the information(data) to be communicated.

–                 (text, numbers, pictures, sound, video or any combination of these)

•          Sender

–        Is the device that sends the data message.

–                 (computer, workstation, telephone handset, video camera)

•          Receiver

–        Is the device that receives the message.

–                 (computer, workstation, telephone handset, video camera)

•         Medium

–        Is the physically path by which a message travels from sender to receiver.

–                 (twisted pair wire, coaxial cable, fiber- optic cable, laser , or radio waves(terrestrial or satellite microwave))

•          Protocol

 Is a set of rules that govern data communication

Direction of Data Flow

•         Is used to define the direction of signal flow between two link devices

•         Simplex

ü Unidirectional, as on a one-way street (keyboard, monitor)

•         Half-Duplex

ü Each station can both transmit and receive, but not at the same  time

•         Full-Duplex

ü Both stations can transmit and receive simultaneously

WHAT IS COMPUTER NETWORKS

•      A network is a set of devices (often referred to as nodes) connected by communication links in order to communicate and share resources.

•      A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network.

•      Computers may connect to each other by either wired or wireless media.

Classification of Computer Networks

Computer networks are classified based on various factors. They includes:

•      Geographical span

•      Inter-connectivity(topology)

•      Connection Method

•      Architecture

Geographical span

•      Computer networks may be classified according to the scale

ü Local area network (LAN)

ü Metropolitan area network (MAN)

ü Wide area network (WAN)

Geographical span-Local area network (LAN)

•      LAN connects networking devices with in short span of area, i.e. small offices, home, internet cafes etc

•      spanned inside a building and operated under single administrative system

•      It uses TCP/IP network protocol for communication between computers

•      LAN provides a useful way of sharing the resources between end users. The resources such as printers, file servers, scanners, and internet are easily sharable among computers

•      LAN can be wired,wireless, or in both forms at once.

Geographical span- Metropolitan Area Network(MAN)

•      MAN generally expands throughout a city such as cable TV network

•      Metro Ethernet is a service which is provided by ISPs

•      This service enables its users to expand their Local Area Networks.

•      For example, MAN can help an organization to connect all of its offices in a city.

•      MAN works in between Local Area Network and Wide Area Network

•      MAN provides uplink for LANs to WANs or internet

Geographical span- Wide Area Network (WAN)

•      WAN connection between computers over large geographical areas that may comprise a country, a continent, or even the whole world

•      Dedicated transoceanic cabling or satellite uplinks may be used to connect this type of global network

•      These networks provide connectivity to MANs and LANs

•      The Internet itself is the biggest example of WAN 

By network topology

•      Network topology is the arrangement of the various elements (links, nodes, etc.) of a computer network

•      Topologies may define both physical and logical aspect of the network

•      There are several common physical topologies

•      Bus Network

•      Star Network

•      Ring Network

•      Mesh Network

•      Star-Bus Network

Tree or Hierarchical Topology Network

Network Architecture

•      Computer networks may be classified according to the functional relationships which exist between the elements of the network

•      There are two type of network architecture :

ü Client-Server

ü Peer-to-Peer Architecture

By Connection Method

•      Computer networks can also be classified according to the hardware technology that is used to connect the individual devices in the network such as Optical fibre, Ethernet, Wireless LAN.