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Jumat, 28 Oktober 2011

Computer Networks - Test Interview Viva Voce

Q1. Define Network with example. Give importance of computer network.

COMPUTER NETWORK
A computer network is a set of two or more computers connected together to share information and other resources. The computers in a network can share:

Data, information and Files
Resources (printers, Cd-Rom Drives, DVD- Rom Drives, CD- Writers, hard disk, modems)
Programs / software

EXAMPLES OF COMPUTER NETWORK

Computer network can be used in an organization's office. Different employees and managers in the office and organization can share common information.
Internet, is also an example of a computer network. Internet is a network of millions of computers connected through phone lines. People can share information, files and talk with one another through internet.
Internet cafe also uses computer network for internet sharing on all computers.
A Computer laboratory in a school or college may use local area network for sharing data and other reources like printers, Cd-Rom drives or hard disks etc.

ADVANTAGES OF COMPUTER NETWORKS

Following are some important advantages of computer networks:

Information Sharing
Data and information can be shared by many users.
Hardware Sharing
Hardware Resources like printer, scanner, CD-ROM drive and hard disk can also be shared.
Money Saving
We can save a lot of money by using the same software and hardware in a network.
Easy and Fast Communication
We can send and receive emails and share files with other people in the company or in any part of the world through network or internet.

Q2. Explain different types of computer networks: (LAN,WAN,MAN).

Main types of computer networks are: 1. LAN - Local-Area Network 2. WAN - Wide-Area Network 3. MAN - Metropolitan-Area Network

LAN (Local Area Network)

LAN stands for Local Area Network. It covers a small area. Most LANs are used to connect computers in a single building or group of buildings. Examples: Following are two examples of LAN: • LAN is used in a computer lab to connect computers. The students can share software, files and data in the lab. • In Internet cafe, many computers can be connected through LAN. These computers can share single connection of Internet.

2)WAN (Wide Area Network)

WAN stands for wide area network. It covers a large area. WAN connects computers in different cities, countries and continents. Computers in WAN are often connected through telephone lines. The largest WAN is the Internet. Examples of WAN • In air ticketing system like PIA, many offices can be joined together using WAN. A person can get a ticket from any office in the country. • A bank with many branches in different cities can connect its branches through WAN. The customer can use his account from any branch.

3)MAN (Metropolitan-Area Network)

A metropolitan area network (MAN) is a network that covers an area of the size of a city. Example: Mobile phones systems often use MAN.

Q3. Differentiate between LAN and WAN.

The differences between LAN and WAN is as follows:

*LAN*		*WAN*
1.	LAN is used to connect computers at one place.		WAN is used to connect computers anywhere in the world.
2.	LAN covers limited area.		WAN can cover more area.
3.	Data transfer speed is very fast in LAN.		Data transfer speed is slow in WAN.

Senin, 07 Desember 2009

Thinking Networks - the Large and Small of it

By Kieran Greer

The book is titled 'Thinking Networks - the Large and Small of it'. The topics covered span from large global networks to small local neural-like networks, hence the title. The book is mainly a research monograph, but it also contains blue sky research suggestions and also some informative or teaching sections. This book tries to cover research areas that look at adding autonomous or reasoning capabilities to information networks. It would be of interest to both academic or industrial researchers looking to build intelligent networks. For example, the telecommunications sector might want to add intelligent services to the Internet or a mobile environment. The book however could be used to build networks that range in size from large Internet-based networks to small local neural network-like structures, and ultimately suggests an architecture on which to build a network that might even begin to 'think'. Some of the research has been proven, while the more ambitious claims or suggestions are for future research.

The book covers areas such as the Internet/p2p/ mobile networks, SOA, Semantic Networks (Semantic Web, Ontologies, Web Services, Grid), AI (including Autonomous systems, Intelligent, Cognitive or Neural Network-like systems, and Bio-inspired networks), XML-based languages and query processes. It is available from different online stores and is also listed on the ACM portal. The technologies that are described in this book are also strongly related to the new 'Cloud Computing' architecture that is being talked about for the Internet.

Kamis, 31 Januari 2008

Download free Computer Networking Ebooks

This posting helps you to get free computer networking ebooks focuses on computer networking, computer network security, requirements for network security, tcp ip protocols, internetworking, osi model, socket programming, internet protocols, ipv6, voice over internet protocol, port authority, port forwarding, wireless networking, home networking, computer networking, client server computing, client server software, virtual private networks, socket programming, tcp/ip protocols, ATM networks asynchronous transfer mode, DNS, Parallel Virtual Machine, Networking fundamentals, SSH secure shell, IPX routing, etc.

You can download free computer networking ebooks from the following links. Visit this free computer networking ebooks.

Rabu, 14 Februari 2007

Netizens On the History and Impact of the Net

By Michael Hauben and Ronda Hauben

Introduction By Thomas Truscott

Netizens: On the Impact and History of Usenet and the Internet is an ambitious look at the social aspects of computer networking. It examines the present and the turbulent future, and especially it explores the technical and social roots of the "Net". A well told history can be entertaining, and an accurately told history can provide us valuable lessons. Here follow three lessons for inventors and a fourth for social engineers. Please test them out when reading the book.

The first lesson is to keep projects simple at the beginning. Projects tend to fail so the more one can squeeze into a year the better the chance of stumbling onto a success. Big projects do happen, but there is not enough time in life for very many of them, so choose carefully.

The second lesson is to innovate by taking something old and something new and putting them together in a new way. In this book the "something new" is invariably the use of a computer network. For example, ancient timesharing computer systems had local "mail" services so its users could communicate. But the real power of E-mail was when mail could be distributed to distant computers and all the networked users could communicate. Similarly, Usenet is a distributed version of preexisting bulletin-board-like systems. The spectacularly successful World Wide Web is just a distributed version of a hypertext document system. It was remarkably simple, and seemingly obvious, yet it caught the world by complete surprise. Here is another way to state this lesson: If a feature is good, then a distributed version of the feature is good. And vice-versa.

The third lesson is to keep on the lookout for "something new", or for something improved enough to make a qualitative difference. For example, in the future we will have home computers that are always on and connected to the Net. That is a qualitative difference that will trigger numerous innovations.

The fourth lesson is that we learn valuable lessons by trying out new innovations. Neither the original ARPAnet nor Usenet would have been commercially viable. Today there are great forces battling to structure and control the information superhighway, and it is invaluable that the Internet and Usenet exist as working models. Without them it would be quite easy to argue that the information superhighway should have a top-down hierarchical command and control structure. After all there are numerous working models for that.

It seems inevitable that new innovations will continue to make the future so bright that it hurts. And it also seems inevitable that as innovations permeate society the rules for them will change. I am confident that Michael Hauben and Ronda Hauben will be there to chronicle the rapidly receding history and the new future, as "Netizens" increasingly becomes more than a title for a book.

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Looking Over the Fence at Networks: A Neighbor's View of Networking Research (2001)

The Internet has been highly successful in meeting the original vision of providing ubiquitous computer-to-computer interaction in the face of heterogeneous underlying technologies. No longer a research plaything, the Internet is widely used for production systems and has a very large installed base. Commercial interests play a major role in shaping its ongoing development. Success, however, has been a double-edged sword, for with it has come the danger of ossification, or inability to change, in multiple dimensions:

Intellectual ossification—The pressure for compatibility with the current Internet risks stifling innovative intellectual thinking. For example, the frequently imposed requirement that new protocols not compete unfairly with TCP-based traffic constrains the development of alternatives for cooperative resource sharing. Would a paper on the NETBLT protocol that proposed an alternative approach to control called “rate-based” (in place of “window-based”) be accepted for publication today?
Infrastructure ossification—The ability of researchers to affect what is deployed in the core infrastructure (which is operated mainly by businesses) is extremely limited. For example, pervasive network-layer multicast remains unrealized, despite considerable research and efforts to transfer that research to products.
System ossification—Limitations in the current architecture have led to shoe-horn solutions that increase the fragility of the system. For example, network address translation violates architectural assumptions about the semantics of addresses. The problem is exacerbated because a research result is often judged by how hard it will be to deploy in the Internet, and the Internet service providers sometimes favor more easily deployed approaches that may not be desirable solutions for the long run.

At the same time, the demands of users and the realities of commercial interests present a new set of challenges that may very well require a fresh approach. The Internet vision of the last 20 years has been to have all computers communicate. The ability to hide the details of the heterogeneous underlying technologies is acknowledged to be a great strength of the design, but it also creates problems because the performance variability associated with underlying network capacity, time-varying loads, and the like means that applications work in some circumstances but not others. More generally, outsiders advocated a more user-centric view of networking research—a perspective that resonated with a number of the networking insiders as well. Drawing on their own experiences, insiders commented that users are likely to be less interested in advancing the frontiers of high communications bandwidth and more interested in consistency and quality of experience, broadly defined to include the “ilities”—reliability, manageability, configurability, predictability, and so forth—as well as non-performance-based concerns such as security and privacy. (Interest was also expressed in higher-performance, broadband last-mile access, but this is more of a deployment issue than a research problem.) Outsiders also observed that while as a group they may share some common requirements, users are very diverse—in experience, expertise, and what they wish the network could do. Also, commercial interests have given rise to more diverse roles and complex relationships that cannot be ignored when developing solutions to current and future networking problems. These considerations argue that a vision for the future Internet should be to provide users the quality of experience they seek and to accommodate a diversity of interests.

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Computer Networks and Internets

Contains various network component specifications and photos with explanation. Following networking topics are covered

Motivation and Tools
Network Programming And Applications
Transmission Media
Local Asynchronous Communication (RS-232)
Long-Distance Communication (Carriers, Modulation, And Modems)
Packets, Frames, And Error Detection
LAN Technologies And Network Topology
Hardware Addressing And Frame Type Identification
LAN Wiring, Physical Topology, And Interface Hardware
Extending LANs: Fiber Modems, Repeaters, Bridges, and Switches
Long-Distance And Local Loop Digital Technologies
WAN Technologies And Routing
Connection-Oriented Networking And ATM
Network Characteristics: Ownership, Service Paradigm, And Performance
Protocols And Layering
Internetworking: Concepts, Architecture, and Protocols
IP: Internet Protocol Addresses
Binding Protocol Addresses (ARP)
IP Datagrams And Datagram Forwarding
IP Encapsulation, Fragmentation, And Reassembly
The Future IP (IPv6)
An Error Reporting Mechanism (ICMP)
UDP: Datagram Transport Service
TCP: Reliable Transport Service
Network Address Translation
Internet Routing
Client-Server Interaction
The Socket Interface
Example Of A Client And A Server
Naming With The Domain Name System
Electronic Mail Representation And Transfer
IP Telephony (VoIP)
File Transfer And Remote File Access
World Wide Web Pages And Browsing
Dynamic Web Document Technologies (CGI, ASP, JSP, PHP, ColdFusion)
Active Web Document Technologies (Java, JavaScript)
RPC and Middleware
Network Management (SNMP)
Network Security
Initialization (Configuration)

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Networking with z/OS and Cisco Routers: An Interoperability Guide

The increased popularity of Cisco routers has led to their ubiquitous presence within the network infrastructure of many enterprises. In such large corporations, it is also common for many applications to execute on the z/OS (formerly OS/390) platform. As a result, the interoperation of z/OS-based systems and Cisco network infrastructures is a crucial aspect of many enterprise internetworks.

This IBM Redbook provides a survey of the components necessary to achieve full interoperation between your z/OS-based servers and your Cisco IP routing environment. It may be used as a network design guide for understanding the considerations of the many aspects of interoperation. We divide this discussion into four major components:

The options and configuration of channel-attached Cisco routers
The design considerations for combining OSPF-based z/OS systems with Cisco-based EIGRP networks
A methodology for deploying Quality of Service policies throughout the network
The implementation of load balancing and high availability using Sysplex Distributor and MNLB (including new z/OS V1R2 support)

We highlight our discussion with a realistic implementation scenario and real configurations that will aid you in the deployment of these solutions. In addition, we provide in-depth discussions, traces, and traffic visualizations to show the technology at work.

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Networking Fundamentals, v4.0

Networks are an interconnection of computers. These computers can be linked together using a wide variety of different cabling types, and for a wide variety of different purposes.

The basis reasons why computers are networked are

to share resources (files, printers, modems, fax machines)
to share application software (MS Office)
increase productivity (make it easier to share data amongst users)

Take for example a typical office scenario where a number of users in a small business require access to common information. As long as all user computers are connected via a network, they can share their files, exchange mail, schedule meetings, send faxes and print documents all from any point of the network.

It would not be necessary for users to transfer files via electronic mail or floppy disk, rather, each user could access all the information they require, thus leading to less wasted time and hence greater productivity.

Imagine the benefits of a user being able to directly fax the Word document they are working on, rather than print it out, then feed it into the fax machine, dial the number etc.

Small networks are often called Local Area Networks [LAN]. A LAN is a network allowing easy access to other computers or peripherals. The typical characteristics of a LAN are,

physically limited ( less than 2km)
high bandwidth (greater than 1mbps)
inexpensive cable media (coax or twisted pair)
data and hardware sharing between users
owned by the user

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Local Area Network Concepts and Products: Routers and Gateways

Local Area Network Concepts and Products is a set of four reference books forthose looking for conceptual and product-specific information in the LAN environment. They provide a technical introduction to the various types of IBM local area network architectures and product capabilities.

The four volumes are as follows:

SG24-4753-00 - LAN Architecture

SG24-4754-00 - LAN Adapters, Hubs and ATM

SG24-4755-00 - Routers and Gateways

SG24-4756-00 - LAN Operating Systems and Management

These redbooks complement the reference material available for the products discussed. Much of the information detailed in these books is available through current redbooks and IBM sales and reference manuals. It is therefore assumed that the reader will refer to these sources for morein-depth information if required.

These documents are intended for customers, IBM technical professionals, services specialists, marketing specialists, and marketing representatives working in networking and in particular the local area network environments.

Details on installation and performance of particular products will not be included in these books, as this information is available from other sources.

Some knowledge of local area networks, as well as an awareness of the rapidly changing intelligent workstation environment, is assumed.

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Internetworking Technology Handbook

What Is an Internetwork?
An internetwork is a collection of individual networks, connected by intermediate networking devices, that functions as a single large network. Internetworking refers to the industry, products, and procedures that meet the challenge of creating and administering internetworks.

History of Internetworking
The first networks were time-sharing networks that used mainframes and attached terminals. Such environments were implemented by both IBM's Systems Network Architecture (SNA) and Digital's network architecture.

Local-area networks (LANs) evolved around the PC revolution. LANs enabled multiple users in a relatively small geographical area to exchange files and messages, as well as access shared resources such as file servers and printers.

Wide-area networks (WANs) interconnect LANs with geographically dispersed users to create connectivity. Some of the technologies used for connecting LANs include T1, T3, ATM, ISDN, ADSL, Frame Relay, radio links, and others. New methods of connecting dispersed LANs are appearing everyday.

Today, high-speed LANs and switched internetworks are becoming widely used, largely because they operate at very high speeds and support such high-bandwidth applications as multimedia and videoconferencing.

Internetworking evolved as a solution to three key problems: isolated LANs, duplication of resources, and a lack of network management. Isolated LANs made electronic communication between different offices or departments impossible. Duplication of resources meant that the same hardware and software had to be supplied to each office or department, as did separate support staff. This lack of network management meant that no centralized method of managing and troubleshooting networks existed.

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Realizing the Information Future - The Internet and Beyond

The potential for realizing a national information networking marketplace that can enrich people's economic, social, and political lives has recently been unlocked through the convergence of three developments:

The federal government's promotion of the National Information Infrastructure through an administration initiative and supporting congressional actions;
The runaway growth of the Internet, an electronic network complex developed initially for and by the research community; and
The recognition by entertainment, telephone, and cable TV companies of the vast commercial potential in a national information infrastructure.

A national information infrastructure (NII) can provide a seamless web of interconnected, interoperable information networks, computers, databases, and consumer electronics that will eventually link homes, workplaces, and public institutions together. It can embrace virtually all modes of information generation, transport, and use. The potential benefits can be glimpsed in the experiences to date of the research and education communities, where access through the Internet to high-speed networks has begu n to radically change the way researchers work, educators teach, and students learn.

To a large extent, the NII will be a transformation and extension of today's computing and communications infrastructure (including, for example, the Internet, telephone, cable, cellular, data, and broadcast networks). Trends in each of these component areas are already bringing about a next-generation information infrastructure. Yet the outcome of these trends is far from certain; the nature of the NII that will develop is malleable. Choices will be made in industry and government, beginning with inv estments in the underlying physical infrastructure. Those choices will affect and be affected by many institutions and segments of society. They will determine the extent and distribution of the commercial and societal rewards to this country for invest ments in infrastructure-related technology, in which the United States is still currently the world leader.

1994 is a critical juncture in our evolution to a national information infrastructure. Funding arrangements and management responsibilities are being defined (beginning with shifts in NSF funding for the Internet), commercial service providers are playi ng an increasingly significant role, and nonacademic use of the Internet is growing rapidly. Meeting the challenge of "wiring up" the nation will depend on our ability not only to define the purposes that the NII is intended to serve, but also to ensure that the critical technical issues are considered and that the appropriate enabling physical infrastructure is put in place.

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PVM: Parallel Virtual Machine - A Users' Guide and Tutorial for Networked Parallel Computing

The PVM project began in the summer of 1989 at Oak Ridge National Laboratory. The prototype system, PVM 1.0, was constructed by Vaidy Sunderam and Al Geist; this version of the system was used internally at the Lab and was not released to the outside. Version 2 of PVM was written at the University of Tennessee and released in March 1991. During the following year, PVM began to be used in many scientific applications. After user feedback and a number of changes (PVM 2.1 - 2.4), a complete rewrite was undertaken, and version 3 was completed in February 1993. It is PVM version 3.3 that we describe in this book (and refer to simply as PVM). The PVM software has been distributed freely and is being used in computational applications around the world.

To successfully use this book, one should be experienced with common programming techniques and understand some basic parallel processing concepts. In particular, this guide assumes that the user knows how to write, execute, and debug Fortran or C programs and is familiar with Unix.

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Senin, 25 Desember 2006

Planning a computer system facility in an intercomputer network

By Barry Wessler

In this talk a computer network is defined to be a set of autonomous, independent computer systems, interconnected so as to permit interactive resource sharing between any pair of systems. An overview of the need for a computer network, the requirements of a computer communication system, a description of the properties of the communication system chosen, and the potential uses of such a network will be described later.

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IEEE/ACM Transactions on Networking (TON)

Volume 14 , Issue SI ( June 2006 ) Special issue on networking and information theory

43 books relating networking

PDF for each topics are available. They are

Introduction to the special issue on networking and information theory
On the θ-coverage and connectivity of large random networks
Scaling properties of statistical end-to-end bounds in the network calculus
On the path-loss attenuation regime for positive cost and linear scaling of transport capacity in wireless networks
Relaying protocols for two colocated users
On the capacity of information networks
Unachievability of network coding capacity
An outer bound for multisource multisink network coding with minimum cost consideration
The encoding complexity of network coding
A unification of network coding and tree-packing (routing) theorems
On average throughput and alphabet size in network coding
The multicast capacity of deterministic relay networks with no interference
Matrix games in the multicast networks: maximum information flows with network switching
On achieving maximum multicast throughput in undirected networks
Algebraic gossip: a network coding approach to optimal multiple rumor mongering
Randomized gossip algorithms
Asymptotic analysis of multistage cooperative broadcast in wireless networks
Raptor codes
Optimal throughput-delay scaling in wireless networks: part I: the fluid model
On the throughput, capacity, and stability regions of random multiple access
Minimum-cost multicast over coded packet networks
Bandwidth- and power-efficient routing in linear wireless networks
A fast lightweight approach to origin-destination IP traffic estimation using partial measurements
Overcoming untuned radios in wireless networks with network coding
Coverage by randomly deployed wireless sensor networks
Statistical location detection with sensor networks
Optimal overload response in sensor networks
Capacity of queues via point-process channels
One-way delay estimation using network-wide measurements
On the scalability of cooperative time synchronization in pulse-connected networks
The feasibility of matchings in a wireless network
On the throughput scaling of wireless relay networks
Fundamental limits and scaling behavior of cooperative multicasting in wireless networks
On outer bounds to the capacity region of wireless networks
Degenerate delay-capacity tradeoffs in ad-hoc networks with Brownian mobility
Separating distributed source coding from network coding
Cycle-logical treatment for "Cyclopathic" networks
On the capacity of multiple unicast sessions in undirected graphs
Decentralized erasure codes for distributed networked storage
Lossy network correlated data gathering with high-resolution coding
Coding on demand by an informed source (ISCOD) for efficient broadcast of different supplemental data to caching clients
Critical node lifetimes in random networks via the Chen-Stein method
Constructions of optical FIFO queues

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The Networking CD Bookshelf

gd.tuwien.ac.at

Following books were included in this networking CD Bookshelf

DNS and BIND - By Cricket Liu & Paul Albitz
TCP/IP Network Administration -By Craig Hunt
Sendmail - By Bryan Costales & Eric Allman
Sendmail Destop Reference - By Bryan Costales & Eric Allman
Building Internet Firewalls - By D. Brent Chapman & Elizabeth D. Zwicky
Practical Unix and Internet Security - By Simson Garfinkel & Gene Spafford

Preface of DNS and BIND

You may not know much about the Domain Name System - yet - but whenever you use the Internet, you use DNS. Every time you send electronic mail or surf the World Wide Web, you rely on the Domain Name System.

You see, while you, as a human being, prefer to remember the names of computers, computers like to address each other by number. On an internet, that number is 32 bits long, or between zero and four billion or so. That's easy for a computer to remember, because computers have lots of memory ideal for storing numbers, but it isn't nearly as easy for us humans. Pick ten phone numbers out of the phone book at random, and then try to remember them. Not easy? Now flip to the front of the book and attach random area codes to the phone numbers. That's about how difficult it would be to remember ten arbitrary internet addresses. And, with IP version 6, it's soon to be a whopping 128 bits long, or between zero and a decimal number with 39 digits.

This is part of the reason we need the Domain Name System. DNS handles mapping between host names, which we humans find convenient, and internet addresses, which computers deal with. In fact, DNS is the standard mechanism on the Internet for advertising and accessing all kinds of information about hosts, not just addresses. And DNS is used by virtually all internetworking software, including electronic mail, remote terminal programs such as telnet, file transfer programs such as ftp, and web browsers such as Netscape Navigator and Microsoft Internet Explorer.............

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Minggu, 17 Desember 2006

Running a Perfect Intranet

By Rich Casselberry, et al.

The Internet has been growing in popularity at a phenomenal rate. Many television ads now contain URLs (Uniform Resource Locators) such as CNN's http://www.cnn.com/ and surveys commonly ask for an e-mail address. An even faster growing phenomenon, though, is the use of the Intranet.

An Intranet is an IP network designed for internal use. The growth of Intranets has been silent but rapid, and is actually where most sales of Web servers are used.

Intranets are used in many types of companies from high-tech computer firms to real estate companies to oil refineries. Everyone can benefit from the technology available.

Intranet technology is used in many different ways. It can be used to set up a central document repository or workgroup server. It can be used to integrate with existing databases, either by writing custom software or using commercial applications. Most database vendors currently have or are working on WWW interfaces to their products.

Intranets can also be used as a client/server combination, allowing quick building of distributed applications. Use of the Web can also allow develop-ers to quickly build cross-platform tools. Because HTML is an open standard, almost any computer will have a browser that can be used as a graphical user interface, or GUI.

Intranet-based tools also allow groupware applications to be integrated. Groupware applications can be built using free software, or commercial applications such as Lotus can be purchased and integrated.

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Managing Multivendor Networks

By John Enck and Dan W. Blacharski

Macmillan Computer Publishing

Lot has happened in the computer world since John Enck wrote the first edition of this book in 1990. The Internet has become wildly popular, which has led to the suprem-acy of TCP/IP; the mainframe is being slowly replaced (or at least augmented) by a distributed, client/server architecture; and high-speed technologies, such as ATM and FDDI, have significantly enhanced the very nature of networking.

John had three goals in writing this book:

To introduce and define the fundamental network architectures of four key computer manufacturers. This information gives executive management a sufficient understanding of the basics for making informed, intelligent decisions about networks and networking strategies.
To help technical management and systems personnel begin the cross-training process. By covering each vendor's systems and networking architectures using the same orientation and organization, this book gives you a common level of understanding and facilitates this horizontal training.
To explore standards and technologies that greatly affect the world of multivendor networking and data communications. Many of these developments result from third-party efforts and serve to define a middle ground on which to build multivendor solutions.

In this edition, I have endeavored to supplant Mr. Enck's comprehensive work with information on some of the latest technologies and to cover some of the changes that have taken place in the networking industry during the past six years.........

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High-Performance Networking Unleashed

Macmillan Computer Publishing

The past decade has been witness to the radical evolution of data networks from their humble origins to their current forms. The original Local Area Networks (LANs), were nothing more than coaxial cabling, strung from terminal servers to desktop terminals whose users were treated to monochromatic text displayed on low-resolution cathode ray tubes (CRTs).

In the mid-1980s, wide area networks (WANs), too, were slow and crude. Terminal servers multiplexed access for dozens of users to 9.6Kbps circuits. These circuits connected users to mainframe-based applications that lay hidden in a remote data center.

Today, LANs have metamorphosed into high-bandwidth, high-performance, local area networks that support bandwidth- and CPU-intensive client applications such as live, interactive voice and videoconferencing, as well as e-mail and some of the more traditional forms of data processing.
WANs, too, have experienced radical, evolutionary change. Today, 9.6Kbps is deemed inadequate for most of the needs of even a single user. Just try to give a user a 9.6Kbps modem for use as anything but a paperweight!

It is important to recognize that the impetus for all these changes has been, and remains, the user's business requirements. The competitive environment of most business entities ensures that any technological innovations that offer competitive advantages--that is, better, cheaper, and/or faster--get accepted. For example, the introduction of the mouse facilitated access to computing by obviating the need for typing skills. Suddenly, almost everyone could use a computer! Personal computers, too, offered countless advantages by distributing intelligence down to the desktop.

Software developers also drove changes by constantly upgrading a dizzying array of increasingly complex products that enabled users to actually use the newly distributed processing power at their fingertips. Together, these innovations quickly made hard-wired connections to terminal servers obsolete.

Into this void came the first generation of LANs. These networks offered almost obscene amounts of bandwidth, such as 1 or 4Mb per second (Mbps), depending on whose network you purchased. Initially, these LANs were used as a more flexible means of connecting users with terminal servers. After all, the users' basic requirements hadn't changed all that much, and the increased bandwidth was more than adequate to support terminal emulation.

Towards the end of the 1980s, this first generation of LANs began to show its age. Once the user community understood that the distributed microprocessors on their desktops could do more than just terminal emulation, their quest for even more bandwidth and for higher performance networking began.

The second generation of LANs were little more than faster versions of their predecessors. 1Mbps Ethernets grew into 10Mbps Ethernets. Similarly, 4Mbps Token Rings were accelerated to 16Mbps. This increase in the clock rates would keep users somewhat satisfied up to the middle of the 1990s.......

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Jumat, 28 Oktober 2011

Q1. Define Network with example. Give importance of computer network.

EXAMPLES OF COMPUTER NETWORK

ADVANTAGES OF COMPUTER NETWORKS

Hardware Sharing

Q2. Explain different types of computer networks: (LAN,WAN,MAN).

LAN (Local Area Network)

2)WAN (Wide Area Network)

3)MAN (Metropolitan-Area Network)

Q3. Differentiate between LAN and WAN.

Senin, 07 Desember 2009

Kamis, 31 Januari 2008

Rabu, 14 Februari 2007

Senin, 25 Desember 2006

Minggu, 17 Desember 2006