COMPUTER NETWORKS

Prepared by S.Sabari Giri Murugan Faculty G2-Grade KL University

SESSION I Basics of Network & Networking, Advantages of Networking, Types of Networks, Network Terms- Host, Workstations, Server, Client, Node

BASICS OF NETWORK & NETWORKING

What is Data?

What is Communication?

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COMPONENTS IN COMMUNICATION

Hi, how are you?

5 Protocol

4 Medium

3 Receiver2 Sender

1 Message

DATA COMMUNICATION: DEFINITION

Data Communication has two types :1. Local -Local communication takes place when

the communicating devices are in the same geographical area, same building, face-to-face between individuals etc

2. Remote-Remote communication takes place over a distance i.e. the devices are further 4

Transfer of data from one device to another via some form of transmission medium.

EFFECTIVENESS OF A DATA COMMUNICATION CAN BE MEASURED THROUGH THE FOLLOWING FEATURES

Delivery : Delivery should be done to the correct destination.

Timeliness : Delivery should be on time.

Accuracy : Data delivered should be accurate.

Jitter : Variation in packet arrival.

DATA REPRESENTATION

Numbers 8/16/32 bit integers floating point

Text ASCII, Unicode

Images Bit patterns, Graphics formats JPG/GIF/etc

Audio Samples of continuous signal Video Sequence of bitmap images

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PROTOCOLS Protocol

A set of rules governing data communications Syntax

Structure or format of the data Semantics

Interprets the meaning of the bits Knows which fields define what action

Timing When data should be sent and what Speed at which data should be sent or speed at which it is

being received.

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DIRECTION OF DATA FLOW

Simplex: One direction only

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Server Monitor

data flow

Keyboard

data flow

DIRECTION OF DATA FLOWHalf Duplex: Both directions, one at a

time

E.g., walkie-talkies9

data flow at time 1

data flow at time 2

DIRECTION OF DATA FLOWFull Duplex: Both directions

simultaneously

E.g., telephone

Can be emulated on a single communication link using various methods

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data flow

data flow

DIFFERENCE B/W TELECOMMUNICATION & DATA COMMUNICATION?

NETWORK

Topics discussed in this section:Topics discussed in this section:

Définitions

Network Criteria

Physical Structures

Categories of Networks

NETWORK DEFINITION

A A networknetwork is a set of devices (often referred to as is a set of devices (often referred to as nodesnodes) ) connected by communication connected by communication linkslinks. .

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

A link can be a cable, air, optical fiber, or any medium A link can be a cable, air, optical fiber, or any medium which can transport a signal carrying information.which can transport a signal carrying information.

PURPOSE

The purpose of a network is to share resources.

A resource may be: A file A folder A printer A disk drive Or just about anything else that exists on a

computer.

NETWORK CRITERIA A network must be able to meet certain criteria, these are mentioned below: Performance Reliability Scalability

Performance : It can be measured in following ways : Transit time : It is the time taken to travel a message from one device to

another. Response time : It is defined as the time elapsed between enquiry and response.Other ways to measure performance are : Efficiency of software Number of users Capability of connected hardware

CONTD..

Reliability It decides the frequency at which network failure

take place. More the failures are, less is the network's reliability.

Security It refers to the protection of data from the

unauthorized user or access. While travelling through network, data passes many layers of network, and data can be traced if attempted. Hence security is also a very important characteristic for Networks.

PROPERTIES OF GOOD NETWORK

Interpersonal Communication : We can communicate with each other efficiently and easily example emails, chat rooms, video conferencing etc.

Resources can be shared : We can use the resources provided by network such as printers etc.

Sharing files, data : Authorized users are allowed to share the files on the network.

TYPES OF CONNECTIONS Point-to-point-Dedicated link Multipoint (Timeshared)-Shares a single link

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POINT-TO-POINT CONNECTION

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MULTIPOINT CONNECTION

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Wireless

ADVANTAGES OF NETWORKINGConnectivity and Communication Data Sharing Hardware Sharing Internet Access Internet Access Sharing Data Security and Management Entertainment

THE DISADVANTAGES (COSTS) OF NETWORKING Network Hardware, Software and

Setup Costs Hardware and Software

Management and Administration Costs

Undesirable Sharing Illegal or Undesirable Behavior Data Security Concerns

NETWORK CATEGORIES

Local Area Network (LAN)

Wide Area Network (WAN)

Metropolitan Area Network (MAN)

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LOCAL AREA NETWORKS A local area network (LAN) is a computer

network covering a small geographic area, like a home, office, or group of buildings

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WIDE AREA NETWORKS Network providing long-distance

communication over a country, a continent, or the whole world Two or more LANs connected together The Internet is an example

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METROPOLITAN AREA NETWORKS Network extended over an entire city

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Bangkhen Kampangsaen

NETWORK TERMS- HOST, WORKSTATIONS, SERVER, CLIENT, NODEHost: A network host is a computer or other device

connected to a computer network. A network host may offer information resources, services, and applications to users or other nodes on the network. A network host is a network node that is assigned a network layer host address

Workstations: A workstation is a special computer designed

for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems.

CONTD.. Server : computer is a core component of the network,

providing a link to the resources necessary to perform any task.

Client : computers normally request and receive

information over the network client. Client computers also depends primarily on the central server for processing activities