Computer Networks

COMPUTER NETWORKS

A computer network is any set of computers or devices connected to each other with the ability to exchange data.

Definition:Computer network means an interconnected collection of autonomous computers.

Being interconnected means the ability to exchange data via transmission media (either via cable or wireless). Autonomous means self-governing. If computer A can forcibly start/stop/control computer B, then computer A and B are not autonomous.

Classification on the Basis of Functional Relationships(Network Architecture)

Computer networks may be classified according to the

functional relationships which exist among the elements of the network:

Active NetworkingClient-serverPeer-to-peer(workgroup) architecture.

Classification on the Basis of Connection Method. Computer networks can be classified

according to the hardware and software technology that is used to interconnect the individual devices in the network, such as:

Optical Fiber.Ethernet.Wireless LAN

Computer networks may be classified according to the Network Topology upon which the network is based

Bus Topology.Ring Topology.Star topology.Extended Star

Topology.Mesh Topology.

Classification on the basis of Scale.Personal Area Networks(PAN)Local Area Networks(LAN)Wide Area Network(WAN)Metropolitan Area Network(MAN)Campus Area Network (CAN)

Personal Area Network (PAN) :

A computer network used for communication among computer devices close to one person.

Examples of devices that are used in a PAN are Printers, Fax Machines, Telephones, PDAs and Scanners.

Metropolitan Area Network(MAN) A MAN consists of a group of LANs, which may be spread across

an area of the size of a city. - It would normally consist of a number of buildings each with a central

hub that connects to the MAN network.

Campus Area Network(CAN) CAN is a computer network made up of an interconnection of

local area networks (LANs) within a limited geographical area. It can be considered one form of a metropolitan area network, specific to an academic setting.

In the case of a university campus-based campus area network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls.

LOCAL AREA NETWORK

LANs in turn may be plugged into larger networks, such as larger LANs or wide area networks (WANs), connecting many computers within an organization to each other and/or to the Internet.

Local area networks (LANs) are computer networks ranging in size from a few computers in a single office to hundreds or even thousands of devices spread across several buildings.

They function to link computers together and provide shared access to printers, file servers, and other services.

Advantages of LAN Resource sharing capability allows storage space and network

peripherals, such as printers, to be shared by workstations, reducing hardware requirement, expenses and improving productivity.

Standard PC hardware is used for network workstations and servers, which provide a great deal of design flexibility, easy maintenance and cost efficiency.

Common applications are network aware, which significantly help in user

transition time when relocating to different network environments. Additionally, network licensing is substantially less expensive than that of stand-alone licensing.

Through file sharing, users can easily transfer files to one another, in order

to improve productivity. Shared file access allows multi-user access to user applications.

Advantages of LAN With centralized data storage, LANs offer the ability to place shared data

on a single server within a central location. This reduces the cost incurred by loss of any data during system failure.

LANs offer centralized security, which allows control over access to the network and its resources. Depending on an organization's requirements, this functionality is customizable to help protect sensitive data from loss, destruction, theft, or unauthorized disclosure.

Communication to other users is also provided through a messaging system. It is the basis for implementing sophisticated systems

WIDE AREA NETWORKSWIDE AREA NETWORKSA wide area network (WAN) is a telecommunications

network, usually used for connecting computers, that spans a wide geographical area. WANs can by used to connect cities, states, or even countries.

WANs are often used by larger corporations or organizations to facilitate the exchange of data, and in a wide variety of industries, corporations with facilities at multiple locations have embraced WANs. Increasingly, however, even small businesses are utilizing WANs as a way of increasing their communications capabilities.

Wide Area networks. WANs are either point-to-point, involving a direct connection between

two sites, or operate across packet-switched networks, in which data is

transmitted in packets over shared circuits.

Point-to-point WAN service may involve either analog dial-up lines, in which a modem is used to connect the computer to the telephone line, or dedicated leased digital telephone lines, also known as "private lines." Analog lines are suitable for batch data transmissions, such as non-urgent order entry and point-of-sale transactions. Dedicated digital phone lines permit uninterrupted, secure data transmission at fixed costs.

Point-to-point WAN service providers include both local telephone companies and long distance carriers. Packet-switched network services are typically chosen by organizations which have low volumes of data or numerous sites, for which multiple dedicated lines would be too expensive.

Importance and Advantages of Wide Area Networks

Two great advantages of WAN are allowing secure and fast data transmission between the different nodes in the network. The data transmission is also reliable and inexpensive. 

Big organizations and companies, which have several branches all over the world, are the ones who greatly benefit from WANs, as WANs enable them to easily communicate with their partners or employees around the globe. WAN have had a great impact on e-business, which has became so popular in this Internet age.

Business Applications

Of Computer Networks

MARKETING APPLICATIONSMARKETING APPLICATIONSOrder Entry SystemThe primary objectives of an order processing system

are to :

Provide accurate and timely recording of customer’s orders.

Initiate production of an order.Initiate the shipping of orders.Maintain a record of back-ordered items.Produce sales analysis reports.

The Documents are normally issued in QuadruplicateThe Documents are normally issued in Quadruplicate:

A copy goes to the warehouse for shipping.A copy is sent with the goods.A copy is kept for record.A copy goes to accounts to authorize computerized

invoicing A copy serves as a customer acknowledgement .

Point-of-Sale and Stock ManagementThe system offers a wide range of benefits:

Stock levels can be kept to a minimum.Stores can gain better control over demand

projections.When combined with electronic funds

transfer(EFT) , these systems can help stores give better service to customers. Out-of-stock situations can occur less often, and customer loss is minimized.

Fast-Food Distributor Depends on Networks For Swift Services.

Reservation Systems Reservation Systems are important applications because

up to the minute information needs to be provided to customer almost instantaneously from a single central database.

•Telemarketing.

The Telephone allows salespeople to initiate contacts, offer products and services , or follow up on sales costs without incurring travel costs or travel time.

It also lets salespeople reach many more customers in a given time period than they could through other means.

•Teleshopping. TV has become an important component in teleshopping. Customers can

order directly from products displayed or advertised by using a toll-free number.

FINANCIAL APPLICATIONSFINANCIAL APPLICATIONS

Electronic Funds Transfer (EFT)EFT covers a wide range of transaction services ,

including:

Banking Services.Funds transfer between accounts at the same bank or at

different banks.Stockbrokerage activities.Retail ATM services.Business Transactions involving funds transfer between

accounts , short term investments , and overdraft limit arrangements.

The potential advantages of EFT includes:

Immediate or overnight transfer of funds from the customer’s bank account to the good or service provider’s bank account , thereby improving company’s cash flow.

Online credit authorization, hence reducing bad-debt problems.

A reduced need for customers to carry cash .

Foreign exchange and Investment Services.FINANCIAL SERVICES INCLUDE :FINANCIAL SERVICES INCLUDE :

Interest rate for local , onshore , and offshore time deposits.

Mortgage investment rates.Business investment rates and services.Foreign exchange rates and cross-rates.Stock market information.Online business news.Statistical information, financial analysis , and market

trends.

MANUFACTURING APPLICATIONSMANUFACTURING APPLICATIONSJust-in-Time Systems. With Just-in-Time inventory systems a firm shares

production information with suppliers by means of a network , enabling the suppliers to deliver materials just as

needed.

Rapid Access to Up-to-Date Organizational Information.

Other Applications include:TeleconferencingElectronic Diaries and Calendaring.Electronic Messaging. News Services, Bulletin Boards , and Public

Databases.

SOCIAL ISSUES The widespread use of computer networks introduces several

social , ethical and political problems.

A popular feature of many networks are newsgroups or bulletin boards where people can exchange messages with like-minded individuals. As long as subjects are restricted to technical topics or hobbies like gardening not too many problems will arise .

The trouble comes when news groups are set up on topics that people actually care about , like politics , religions , gender etc. Views posted to such groups may be deeply offensive to some people

Another important aspect is employee rights versus employee rights. Many employers have claimed the right to read and possibly sensor employee messages , including messages sent from a home terminal after work.

Not ALL employees agree with this.

Computer networks offer the potential for sending anonymous messages.

Computer networks allow ordinary citizens to distribute their views in

different ways and to different audiences ….This newly found freedom brings a lots of unsolved social , political and ethical issues.

“In all large corporations, there is a pervasive fear that someone, somewhere

is having fun with a computer on company time. Networks help alleviate that fear.”

John C. Dvorak

Thank You!!!