“ MANAGEMENT INFORMATION SYSTEM ”

“MANAGEMENT INFORMATION SYSTEM”

By

Kishor Deshmukh

Management Information System

UNIT-I

MIS: DEFINATION

The system which provides information for decision making in an organization.

It is also known as Information System, Information & decision system, Computer based information system.

The system which support decision making function in org.

In every org. time goes in data collection, processing, documenting & communicating the people.

MIS plays a role of information generation, communication.

DATA, INFORMATION & SYSTEM

• Generating Information:

Computer-based ISs take data as raw material, process it, and produce information as output.

Examples:

Data : Thermometer readings of temperature taken every hour: 16.0, 17.0, 16.0, 18.5, 17.0,15.5….

Information – today’s high: 18.5 today’s low: 15.5


What Is a System?

System: A set of components that work together to achieve a common goal

Subsystem: One part of a system where the products of more than one system are combined to reach an ultimate goal

Closed system: Stand-alone system that has no contact with other systems

Open system: System that interfaces with other systems



System

Elements

GoalInputs

Processingelements Outputs

Movie

Actors, director, staff, sets, equipment

Filming, editing, special effects, distribution

Finished film delivered to movie studio

Entertaining movie, film awards, profits


Input Processing Output

Organisation

Environment

Feedback


InformationSystem

People Organisation

Technology

External Environment

Role of MIS can be compared to the role of heart in the body.

MIS satisfies the needs through variety of systems such as Query system, Analysis system, Modelling Systems, & Decision Support System.

MIS plays a role of information generation, communication.

It helps in the process of decision making.

It is supported by the use of mgt. tools of planning & control

Role Of MIS

MIS plays very important role.

It creates impact on organization’s functions, performance, & product.

with good MIS support, the mgt. of marketing, finance, production becomes more efficient.

Time required is very less.

The tracking & monitoring of functional targets becomes easy.

Impact Of MIS

Every person in organization is user of MIS.

The people in organization operate at all levels in the hierarchy.

A typical user is a clerk, an assistant, an officer, an executive or a manager.

Each of them has specific task & a role to play in the mgt of business.

MIS has to satisfy the needs of all the person.

MIS & The User

MIS is necessity of all the organization.

To process data from org. & present it in the form of reports.

The information is a product of analysis of data.

System should present information in such a form & format that it creates an impact on its user.

Some modifications & sort of selective approach is necessary.

The norm for an exception is necessary.

MIS: Concept

MIS: Concept

MIS

Business Goals & Mission

Application of Pure & Social Science

Application of Principles & Practices of Management

Use of Database & Knowledge Base

Information Tech. & Enterprise

Software

Supp

ort S

truct

ure

To M

IS

Conceptual View of MIS

MIS: Concept

EIS

Business Information System

Mission Critical

Applications

Functional

Information Applications

Databases & Knowledge Base

Data Processing & Analysis Systems

OLTP, Data & Validation System

Inte

grat

ed In

form

atio

n Sy

stem

Stru

ctur

e

Physical View of MIS

Mgt process is executed through a variety of decision taken at each step of planning, organizing, staffing, directing, coordinating and control.

MIS aids decision making.

Objective of MIS is to provide information for decision support.

Business goals are achieved in most efficient manner.

Decision making is not restricted to a particular level.

A Support To The Management

Steps in mgt. Decision

Planning Selection from various alternatives

Organization Selection of goals, people, resources, method & authority.

Staffing Providing proper manpower

Directing Choosing methods of directing the efforts in the organization.

Coordinating Choice of the tools & techniques for optimum result.

Controlling Selection of exception conditions & providing the decision guidance.

A Support To The Management

Accurate,

Complete,

Economical,

Flexible,

Reliable,

Relevant,

Simple,

Timely

Verifiable,

Accessible,

Secure.

Characteristics Of Valuable Information


UNIT-II

Basics of MIS : Decision making. Decision methods. Behavioral concepts. Organizational decision making. MIS and decision making concepts. Information concepts and classification. Methods of data and information collection. Value of information, organization and information. Human as an information processor. Development of MIS and choice of IT.

Unit-II

Decision: a reasoned choice among alternatives.

Examples: Where to advertise a new product What stock to buy What movie to see Where to go for dinner

Decision Making:-- a process of choosing among alternative courses of action for the purpose of attaining a goal or goals

Decision-Making Concepts

a) Sequential in nature.

b) Exceedingly complex due to risks & trade offs.

c) Influenced by personal values.

d) Made in institutional setting & business environment.

Characteristics of Business Decision Making

Ensures the achievement of the goal. If it is raining it is rational to look for a

cover. The rationality of decision made is not the

same in every situation. It will vary with the organization. Any business decision if review by a share

holder, a customer, an employee will result in different criticism due to difference individual’s rationality

Rational Decision Making

Rational Decision Making

Define the problem Identify the decision criteria Allocate weights to the criteria Develop the alternatives Evaluate the alternatives Select the best alternatives

Steps in Rational Decision Making

Steps in Rational Decision Making

Making a Decision

Define the problem

Identify thecriteria

Develop alternatives

Allocate weights to the criteria

Evaluate thealternatives

Select the best alternative

1.

2.

3.

4.

5.

6.

Ascertaining the problem

Insufficient knowledge

Not enough time to be rational

The environment may not cooperate

Other limitations

The Problems in Making Rational Decisions

Decision making is a process which the decision maker uses to arrive at a decision.

The process is described by Herbert Simon in a model.

Decision Making Process

Herbert Simon’s decision making model

• Simple• Decision process

modeled as a “flow” of events

Decision Making ProcessThis gentleman won a Nobel

Prize!

Intelligence Phase

• Collect raw material• Process & examine• Identify the problem

calling for decision


Design Phase

• Identify the key variables• Create model to aid

decision making.• Identify the alternative

solutions.


Example of Statistical Model-Factory


The model sounds good

Should we be concerned about model?

Choice Phase

• Select one alternative as a decision, based on the selection criteria.

• Selection criteria such as max profit, least cost, least time.


Implementation Phase

• Implement the decision• Monitor• Make adjustments


There are two types of systems based on the managers knowledge about the environment.

Closed decision making system

Open decision making system

Types of Decision Making System

Closed decision making system

Known set of decision alternatives. Outcomes are known. The manager has model or rule. Based on some goal manager can choose

one of them. Eg: examination system to declare pass or

fail, fixed deposits.


Open decision making system

Manager does not Know all the decision alternatives.

Outcome of decision is not known fully. No method, rule or model is available to

study. It is difficult to decide an objective or goal. Eg: Pricing of a new product, plant location


MIS tries to convert every open system into closed system by providing information support.

MIS gives information support so that manager knows more & more about environment.

Goal of MIS

Decision making is a complex situation.

To resolve the complexity, the decisions are classified as programmed & non programmed decisions.

Nature of Decision

Programmed Decision

Decision can be based on a rule, method or even guidelines.

If such rules can be developed then MIS can be designed to make a decision.

The system in such case plays a role of decision maker based on a given rule or method.

Nature of Decision

Non-programmed Decision

Decision which can not be made by using rule or method.

Such decisions are infrequent.

MIS can help to some extent in identifying the problem.

MIS can develop support system in the non-programmed decision making situation.

Nature of Decision

1) Discuss the various activities performed through an MIS in any business organization.

2) What are different types of strategies. Explain it in brief.

3) State the differences between MIS & the computer system.

4) What are the different methods to avoid misuse of information.

Assignment

One manager may not the same as that of other managers.

They differs on the behavioural platform. The manager differ in their approach

towards decision making in the organization.

They can be classified into two categories

• Achievement Oriented

• Task Oriented

Behavioural Concepts in Decision-Making

Achievement Oriented

• Looking for excellence

• Always opt for the best.

• He will be scientific & therefore more rational.


Task Oriented

• Looking of completion of the task somehow.

• Achievement doesn’t matter.


The managers personal values will influenced.

Behaviour is influenced by position he holds.

Behaviour is also influenced by fear & an anxiety.


Methods for Deciding Decision Alternatives

There are different methods to help the manager decide among the alternatives.

There are methods for selection of decision alternatives with the goals.

1) Optimization Techniques.2) Payoff Analysis.3) Decision Tree Analysis.


Optimization Techniques.

Linear Programming, Integer Programming, Dynamic Programming, Queuing Models & so on are examples of optimization techniques.

Computer algorithms and programs are readily available to handle many problems of this class.

The major problem is to construct the model correctly.

Statistical Decision Theory

Decision Theory provides a rational framework for choosing between the different alternatives when the choices are imperfectly known.

The theory provides techniques for mathematically evaluating the outcomes of alternative action in a given situation.

In all cases decision maker has an objectives (eg. Maximize profit)

Two methods: Payoff Matrix & Decision Tree


Payoff Analysis

When all the alternatives & their outcomes are not known with certainty.

The payoff matrix consists of rows for the alternatives or strategies available and columns for the conditions that affect the outcomes.

Each cell contains the payoff (the consequences) in dollars if that strategy is chosen and that state occurs.


Payoff Matrix

S3

S2

S1

States of Nature

Strategies n1 n2 n3 n4


Payoff Analysis Example 1: The Anniversary Problem

You are suddenly driving home from work in the evening when you suddenly recall that your wedding anniversary comes about this time of year. In fact, it seems quite probable, (but not certain), that it is today. You can still stop at the local florist and buy a dozen roses, or you may go home empty-handed and hope the anniversary lies in the future.

What do you do?

Anniversary Problem Payoff Matrix

Possible Outcomes (States of Nature)

DecisionAlternatives(Strategies)

Buy Flowers

Do NotBuy Flowers

It IS YourAnniversary

It IS NOT Your Anniversary

DOMESTICBLISS

SPOUSE SUSPICIOUSAND YOU ARE OUT

$50

SPOUSE IN TEARSAND

YOU IN DOGHOUSE

STATUS QUO

Decision Tree for Anniversary Problem

Buy Flowers

Do NotBuy Flowers

Anniversary

NOTAnniversary

NOTAnniversary

Anniversary

Decision Point

Resolution ofUncertainty

DOMESTICBLISS

$50 LOSS ANDSUSPICIOUS WIFE

DOGHOUSE

STATUS QUO

Planning Models

A planning model is a method for structuring, manipulating & communicating the future plans.

Simple Profit Model:

Sales = input variableCost of Sales = 0.4 x salesGross Margin = sales - cost of salesOperating expenses = input variableProfit before taxes = gross margin - operating expensesTaxes = 0.48 x profit before taxesNet Profit = profit before taxes - taxes

The Role of Models in Decision Making

A major characteristic of decision-making is the use of models.

A model is a simplified representation or abstraction of reality.

It is usually simplified because reality is too complex to copy.

Basis idea is that analysis is performed on a model rather than on reality itself.

Organizational Decision Making

An organization is an arrangement of individuals having different goals.

Each individual having different powers & rights.

Hierarchy of goals which may be conflicting, self defeating & inconsistent.

In case of inconsistent goals, the conflict in the organization increases.

The organizational decision making should help in the resolution of such conflicts.


Dealing with Uncertainty.

The organizations perform in an environment of uncertainty.

Ex. Market uncertainty, the price fluctuation, the changes in govt policy, technology changes are some factors which make the business envt uncertainty.

Org. behaviour towards minimizing the risk in decision making.


Organizational Learning

Learning provides a strength to review the goals.

Learning provides to set goals more correctly.

As the time progresses, the org. may have new set of goals & objectives.

Org. may take a fresh look at the alternatives, outcomes, methods.

Adopting such methods the org builds skills & capabilities in mgt.

MIS & Decision Making

Simon Model

Programmed Decision

Non programmed decision

Closed & Open Decision Making system

Organizational & Behavioural aspects.

Information Concepts

Information is equivalent to the finished goods produced after processing raw material.

The information has a value in decision making.

Information brings clarity & create intelligent human response in the mind


Information has following characteristics.

Improves representation of an entity.

Updates the level of knowledge.

Has a surprise value.

Reduces uncertainty.

Aids in decision making.


Information Presentation

Presentation of information is an art

The data can be collected in best possible manner & processed analytically.

Method of improving communication is message routing.

Knowledge is a power & an intelligent person can misuse this power.

Information: A Quality Product

Information is a product of data processing.

The manager will determine the quality of information.

The quality of information can be measured on the four dimensions

• Utility• Satisfaction• Error • Bias


Utility:

The utility dimension has four facets: • The form,• The time • The access• The possession


Parameters Impacting Quality

Impartiality

Validity

Reliability

Consistency

Age

Classification of Information

Action Versus No-action Information

Recurring Versus Non-recurring Information

Internal Versus External Information

Planning Information

Control Information

Knowledge

Methods of Data & Information Collection

Observation

Experiment

Survey

Subjective Estimation

Transaction Processing Purchased from outside

Publication

Government agencies

Value of Information

General Model of a Human as an Information Processor

A decision maker uses his sensory receptors.


UNIT-III

Applications of MIS : Applications in manufacturing sector, Applications in service sector, Introduction to service, sector, Creating a destructive services, MIS applications in service industries Role of MIS in source industries. DSS: Concepts and philosophy, Deterministic systems and knowledge based expert

systems. MIS and role of DSS. MIS in Enterprise Management System.

Unit-III

Decision support systems are an application of Herbert Simon Model.

DSS is an organized collection of people, procedures, software, databases, and devices used to help make decisions that solve problems

Focus of a DSS is on decision-making effectiveness when faced with unstructured or semistructured business problems

Decision Support System

Components of Decision Support System

Model base: provides decision makers access to a variety of models and assists them in decision making Financial models

• Spreadsheets often used Statistical analysis models Graphical models

• Charts, Maps Project management models

• Timeline tracking of resources and tasks


Database

External database access

Access to the Internet and corporate intranet, networks, and other computer systems

Dialogue manager: allows decision makers to easily access and manipulate the DSS and to use common business terms and phrases.


Fig. Conceptual Model of DSS

Types of DSS

Status Inquiry System It does not call for any elaborate computation,

analysis, choice etc. If the status is known the decision is automatic.

Data Analysis System DSS based on comparative analysis, use of

formula or algorithm.

Information Analysis System In this system, data is analysed & information

reports are generated.

Types of DSS

Accounting System Desirable to keep track of major aspects of

business or function.

Model Based System These systems are simulation models or

optimization models for decision making. The product mix decision, the material mix, the

job scheduling rules & resources are examples.

DSS: Deterministic Systems

There are number of situation where the management has to make the decision based on the business statistics.


System Input Source

System Hardware User

Inquiry Database, Conventional files

Query System

PC, Servers, Clients

Clerk, Assistant

Data Analysis

Database & System

PCs Mainframe or managers

Operations

Information Analysis

Processed Data files

Analysis Programs

Mainframe, Mini

Middle Level Manager

Accounting Transactions, Master files

Transaction Processing System

Mini, Mainframe, Client/Server

Middle & Top Mgt.

Model Based Control

Inventory DB & External Data

Development of OR & Business Models

Mainframe, Mini, Client/Server

Middle & top Mgt.

If the management can design such models duly tested, they can be used by decision makers.

All such tools & models acts as a support system for decision making.

Number of computer based software tools & packages are available.


Typical DSS

DSS

Designed to support organizational decision making

“What-if” analysis• Example of a DSS tool: Microsoft Excel• Text and graphs

Models for each of the functional areas• Accounting, finance, personnel, etc.

Characteristics of Decision Support System

DSS is design specifically to facilitate decision process.

DSS should able to respond quickly to the changing needs of decision makers.

DSS use sophisticated data analysis & modeling tools.

DSS has ability to present knowledge.

DSS can interact directly with decision maker.

DSS offers flexibility, adaptability & quick response.

Introduction to Expert System(ES)

ES are knowledge based systems.

Replicates the thought processes of Human “Experts”.

Follow a structured set of rules . My computer won’t turn on…

Did you press the power button? If no, press it and start again. If yes, is it plugged in? If no, plug it in and try again. If yes, is the monitor on? ………………and so

on.

http://www.tubecad.com/2006/09/blog0080.htm

D. Introduction to Expert Systems (ES)Expert Systems

tend to use branching logic, like this one.

bare


An expert system can replace the expertex. Identify the whale species

An expert system can support the expertex. Paper machine diagnostic system.


Expert System(ES)

Notice that the recommendations still leave the human expert some options.



How is an ES different from a DSS??

DSS Allows decision maker a platform for exploring and evaluating the options

ES Delivers advice/recommendations based on answers to a set of questions

Business examples of ES??.


Knowledge Based Expert System(KBES)

In unstructured situation, two methods of problem solving , generalised or the knowledge based expert system.

Generalised problem solving approach considers the generally applicable constraints, examines all possible alternatives.

The Knowledge based problem solving approach considers specific constraints within a domain, examines limited alternatives within knowledge domain.

Knowledge Based Expert System(KBES)

Considers knowledge as a base.

To build knowledge based system, then• A person with ability to solve the problem

with knowledge based reasoning.• Expert should be able to articulate the

knowledge.

KBES Model

User Control Mechanism

Inference MechanismKnowledge Base

Fig. KBES Model

KBES Model

KBES has three basic components which are necessary to build a system.

Knowledge Base• It is database of knowledge consisting of

facts, rules formulae, experience. Inference Mechanism

• It is a tool to interpret the knowledge available.

User Control Mechanism• It is a tool applied to the inference

mechanism to select, interpret.

Comparison of DSS & MIS

MIS DSSSupport Info about

performanceInfo and modeling to analyze problems

Report Form

Periodic reportsor On Demand

Interactive Inquiries

Format Pre-specifiedFixed format

Flexible and Adaptable

Processing Extract and manipulate data

Analytical modeling of data

DSS Vs MIS

Information System

Information System

MIS: Management Information System

DSS: Decision Support System

EIS: Executive Information System.

Types of Information System

Transaction Processing Systems

Systems designed to handle large volumes of routine transactions.• Were the first computer-based information systems

handling billing, payroll, and supplier payments.


Operations Information Systems

Systems that gather, organize, and summarize comprehensive data in a form of value to managers.• Can help managers with non-routine decisions such as

customer service and productivity.


Decision Support Systems

Provides computer-built models that help managers make better nonprogrammed decisions.

New productive capacity, new product development, launch a new promotional campaign, enter a new market or expand internationally


Executive Support System Sophisticated version of a decision support system

designed to meet the needs of top managers

Group Decision Support System An executive support system that links top managers so

that they can function as a team.


UNIT-IV

Technology in MIS : Data processing Transaction processing Application processing Information System processing TQM of IS.

DBMS: Object Oriented Technologies Client Server Arch. And MIS.

Unit-IV

Data Processing

Data is smallest automic entity in the information system

If the data is proper, its usage will ensure quality output.

Data processing is handling raw material in systematic manner.

The automic data entity is define as a value attached to an attribute which has character, meaning & presentation for understanding to user.• Eg. Date :cha, meaning & presentation.

Data Processing

Data processing means following steps to be implemented before the data is accepted.

• Confirming the character, structure & presentation.

• Checking the value of the data. Eg. Data value specification such as single specific value, range of value.

• If non conformance is seen, point out the error before the processing.

Transaction Processing

After the data has been process the next step is transaction processing.

A transaction is processed with reference to business rules.

The rules may be directly related to transaction or it may have some relation & association with other transaction.

In case, if transaction does not conform to the set of specified conditions governed by the rules, the error is displayed for user to take corrective action.


Computerized systems that perform and record the daily routine transactions


Let us take an example of the goods receipt as a transaction.

The business rules in case of this transaction are:

• The purchase order must be present & open, the receipt as per the scheduled date.

• The supplier has sent the necessary documents such as Exercise Gate Pass, Challan, Sales Tax Form, etc.

• Such other conditions that may be applicable.


Examples :

• Payroll.• Sales & Ordering.• Inventory.• Purchasing, receiving.• Account payable & receivable

Application Processing

Application processing is designed to process more than one type of transaction.

This processing is carried out once the transaction is processed for its validity.

Ex. If the stock level is below reorder level, it would raise purchase requisition.

The application can be design for status updation. Ex:If the number of work orders are on hold for no material to process, then on receipt of the material the affected work order will be released for processing.

Information System Processing

The system processing is at a higher level, over the application processing.

The system is define as the product made up of several applications set in orderly manner to produce a higher level information output.

Ex. Financial system is a product of finance, sales, & purchase accounting applications.

The nature role & type of system is such that its design is very complex & sensitive to the business needs.

TQM of IS

Objective is to assure quality of information.

This can be done by ensuring, verifying & maintaining software integrity.

Quality ensuring the processes & methodologies are correctly choosen.

TQM of IS

The quality of information assures :

• A precise and an accurate information.• A high level response in an interactive

processing.• User friendly operations.• Reliability of information.• An ease of maintenance.

Database Management System

• File organization concepts• Computer system uses hierarchies

• Field: Group of characters• Record: Group of related fields• File: Group of records of same type • Database: Group of related files

• Record: Describes an entity• Entity: Person, place, thing on which we store

information• Attribute: Each characteristic, or quality, describing

entity• E.g. Attributes Date or Grade belong to entity

COURSE


The Data Hierarchy


• Problems with the traditional file processing • Data redundancy and inconsistency

• Data redundancy: Presence of duplicate data in multiple files

• Data inconsistency: Same attribute has different values

• Program-data dependence:• When changes in program requires changes to data

accessed by program• Lack of flexibility• Poor security• Lack of data sharing and availability


Database Collection of Interrelated data is called as

database.


• Relational DBMS• Represent data as two-dimensional tables called

relations or files• Each table contains data on entity and attributes

• Table: Grid of columns and rows• Rows (tuples): Records for different entities• Fields (columns): Represents attribute for entity• Key field: Field used to uniquely identify each record• Primary key: Field in table used for key fields• Foreign key: Primary key used in second table as look-

up field to identify records from original table


Relational Database Tables


• Hierarchical and Network DBMS: Older systems

• Hierarchical DBMS: Models one-to-many relationships

• Network DBMS: Models many-to-many relationships

• Both less flexible than relational DBMS and do not support ad hoc, natural language


• Object-Oriented DBMS (OODBMS)

• Stores data and procedures as objects

• Capable of managing graphics, multimedia, Java applets

• Relatively slow compared with relational DBMS for processing large numbers of transactions

• Hybrid object-relational DBMS: Provide capabilities of both OODBMS and relational DBMS

Inheritance

Declaring subclassesclass B extends A{ . . . } means class B is a

specialization of class A the "is a" relationship exists a B object is an A object

A

B

"is a"

Superclass

Subclass

Inheritance

Other names: superclass also called "parent class" subclass also called "child class"

These names help understand concept of inheritance

Child class inherits characteristics of parent class attributes methods

Inheritance

When we say …class TalkingParrot extends Parrot

{ … } then a TalkingParrot object inherits all

Parrot attributes

(which, in turn, inherits both FlyingBird and

Bird attributes)

In general, descendant classes inherit the attributes of ancestor classes

O-O Design

Identify the problem's objects if an object cannot be represented by an existing

type, design a class to do so if two or more classes share common attributes,

design a hierarchy Identify the operations

If an operation cannot be performed with an existing operator or method define a method to do so store the method within a class hierarchy to enable

inheritance Organize the objects and operations into an

algorithm

O-O Design

Using the extends relationship: A class B should extend another class A if and only if

B "is a" specialized version of A and …

All messages that can be sent to A can be appropriately sent to B

A

B

Client Server ArchitectureThe client/Server architecture is based upon

hardware and software components that interact to form a system.

• Front-end application(Client): Any computer process that requests services from the server.

• Back-end application(Server): Any computer processing providing services to the clients.

• Communications middleware(Middleware): Any computer process through which clients and servers communicate.

Client Server Architecture

Clientprocess

Communicationsmiddleware

network

Databaseserver

SQL

Data Data

SQL

Clients process sends SQL request through

communications middleware.

Middleware routes SQL request to database

server process.

Database server process receives request, validates

it, and executes it.

How components interact?


A network architecture in which each computer or process on the network is either a client or a server.


Components: Clients Servers Communication Networks

Server

Client


Clients Applications that run on computers Rely on servers for

Files Devices Processing power

Example: E-mail client An application that enables you to send and receive e-

mail


Servers Computers or processes that manage

network resources Disk drives (file servers) Printers (print servers) Network traffic (network servers)

Example: Database Server A computer system that processes database queries


Communication Network

Networks Connect Clients and Servers


UNIT-V

MIS and Networks : Network Topology LAN Data Communication ATM Technology

Business Process Reengineering: Introduction BP Process Model of organization Value stream model Delays in BP Relevance of IT MIS and BPR

Unit-V

Networking

What is Network??

What is Wifi??

What is IP??

IP Address & Classes??

Local Area Network(LAN)

A LAN (Local Area Network) is a “Transmission system intended primarily for linking computers and associated devices within a restricted geographical area”.

It covers an area of moderate size, such as an office block, factory or campus.

In practice, its size may range from a few meters to, in rare cases, tens of kilometers.

Local Area Network(LAN)

The raw transmission rate of LANs are high, typically being in the 1-1000 Mbps range.

On LANs, network errors are expected to be relatively few when compared with larger networks.

LANs are relatively inexpensive when compared to the cost of the equipment that connects to it.

Wide Area Network(WAN)

A WAN (Wide Area Network) is a network that is spread over multiple sites (>30Km).

WANs are not limited in size (they can even cross the world).

Public facilities (such as the public switched telephone network) are extensively used.

However, this means that the rate at which data is sent is limited by the bandwidth of these facilities.

WAN vs. LAN

When comparing WANs with LANs, the main difference is in the data transmission rates.

Delay and error rate parameters are also relevant to some applications.

We can view the technical facilities offered by a WAN as a subset of those offered by a LAN.

What a WAN offers is long distance connectivity.

Network Topology

The term topology refers to the way in which the nodes of a network are connected.

The topology of a network will effect its performance (in terms of speed) and its cost (both short and long term).

Cost/resource considerations and the environment in which the network is to be used often determines the choice of topology.

Network Topology A network topology is the way in which a network

is connected up.

The simplest network topology you can have is a single link (i.e. cable, optical fibre, radio or any other means of transmitting data) between two computers.

It may not be a very big network, but technically it is still a network. The computers can exchange data and they are autonomous.

Communication Link

Network Topology

Some common topologies include:

MESH STAR BUS TREE RING BACKBONE

Data Communication

Data communication-

Defined as a subset of telecommunication involving the transmission of data to and from computers and components of computer systems.

• More specifically data communication is transmitted via mediums such as wires, coaxial cables, fiber optics, or radiated electromagnetic waves such as broadcast radio, infrared light, microwaves, and satellites.

Features of Communication

Four things required Sender, receiver, medium, and message

Types of messages File Request Response Status Control Correspondence

Understandability Error Detection


Data Communication Frameworks

Two major data communication frameworks have been developed to help ensure that networks meet business and communication requirements: Open Systems Interconnection (OSI)

reference model developed by the International Standards Organization (ISO)

Transmission Control Protocol/Internet Protocol (TCP/IP) suite









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