computer networks ppt

WELCOME A POWER POINT PRESENTATION ON

Co-elucidated by

KUMAR ABHISHEK (C.Sc.E)

&

KUMAR MURLIDHAR (E.C.E)

“COMPUTER NETWORKS”

A “Computer Network” is an interconnection of a group of computers. Networks may be Classified by what is called the network layer at which they operate according to basic reference models considered as standards in the industry such as the four-layer Internet Protocol Suite model.

INTRODUCTION

On the basis of “ SCALE ”

TYPES OF NETWORKS

A network covering a small geographic area, like a home, office, or building.

Current LANs are most likely to be based on Ethernet technology.

LOCAL AREA NETWORKS(LAN)

Between LANs and

WANs

Traditional point-to-point and switched networks in WANs

inadequate for growing needs of organizations

Requirement for high capacity private and

public networks at low costs over a large area

METROPOLITAN AREA NETWORK(MAN)

WIDE AREA NETWORK(WAN)

A WAN is a data communications network that covers a relatively broad geographic area (i.e. one city to another and one country to another country) and that often uses transmission facilities provided by common carriers, such as telephone companies.

2.BASED ON “SPAN”

Intranet

Extranet

The “internet”

An INTRANET is a set of

interconnected networks, using

the Internet Protocol and uses Ip-base tools such as web browsers, that is under the control of a single

administrative entity.

An EXTRANET is a network or internetwork that is limited in scope to a

single organization or

entity but which also has

limited connections to the networks

THE INTERNET HISTORY

Evolved from ARPANET, 1969 Advanced Research Projects Agency (ARPA),U.S. Department of Defense.

Began in four locations: UCLA, University of Santa Barbara, the University of Utah, and SRI (Stanford Research Institute)

“WWW “ was developed in Spring 1989, at CERN (the European Laboratory for Particle Physics) by Tim Berners-Lee.

Explosive growth came with first graphically oriented browser, Mosaic, 1993

NETWORK TOPOLOGY1. BUS TOPLOGY Each node is daisy-

chained (connected one right after the other) along the same backbone. Information sent from a node travels along the backbone until it reaches its destination node.

2.RING TOPOLOGY

Similar to a bus network, rings have nodes daisy chained, but the end of the network in a ring topology comes back around to the first node, creating a complete circuit. Each node takes a turn sending and receiving information through the use of a token.

3.STAR TOPOLOGY

In a star network, each node is connected to a central device called a hub. The hub takes a signal that comes from any node and passes it along to all the other nodes in the network.

BASIC TRANSMISSION MEDIA

CONDUCTIVE: twisted pairs and coaxial cables

ELECTROMAGNETIC: microwave

LIGHT: lasers and optical fibers (need clear line of sight)

WIRELESS – inner/ outer space ; satellite (omnidirectional security issues)

THE NETWORK ARCHITECTURE

File Transfer, Email, Remote Login

ASCII Text, Sound (syntax layer)

Establish/manage connection

End-to-end control & error checking (ensure complete data transfer): TCP

Routing and Logical Addressing: IP

Two party communication: Ethernet

How to transmit signal; codingHardware means of sending and receiving data on a carrier

THE OSI REFERENCE MODEL

THE TCP/IP ARCHITECTURE

ASSOCIATED TCP/IP PROTOCOLS & SERVICES

•This protocol, the core of the World Wide Web, facilitates retrieval and transfer of hypertext (mixed media) documents. Stands for the Hypertext Transfer protocol

HTTP•A remote terminal emulation protocol that enables clients to log on to remote hosts on the network.Telnet•Used to remotely manage network devices. Stands for the Simple Network Management Protocol. SNMP

NETWORK SECURITY

• Confidentiality• Integrity• Availability• Authenticity

Security

Requirements

TYPES OF ATTACKS ON A NETWORK

• Eavesdropping on transmissions

• Release of message contents

• Difficult to detect

• Can be prevented

Passive

Attacks

• Masquerade• Replay• Modification of

messages• Denial of service• Easy to detect• Hard to prevent

Active Attacks

SIMPLIFIED MODEL OF SYMMETRIC ENCRYPTION

Ingredients

a) Plain textb) Encryption

algorithmc) Secret keyd) Ciphertexte) Decryption

algorithm

PUBLIC-KEY CRYPTOGRAPHY THE RSA ALGORITHM  Key Generation

 Select p, q p and q both prime, p q Calculate n = p ´ q Calculate f(n) = (p – 1)(q – 1)

Select integer gcd (f(n), e) = 1;

1 < e < f(n)

Calculate d de mod f(n) = 1

Public key KU = {e, n}

Private key KR = {d, n}

Encryption

Plaintext: M < n

Cipher text: C = Me (mod n)

Decryption

Cipher text: C

Plaintext: M = Cd (mod n)

NETWORK MANAGEMENT

Elements of

Network

Management

Fault

Accounting

Performance

Security

LATEST DEVELOPMENTS IN COMPUTER NETWORKING

1.THE INTERNET GRID2.THE GOOGLE WAVES

Grid computing is the combination of computer resources from multiple administrative domains applied to a common task, usually to a scientific, technical or business problem that requires a great number of computer processing cycles or the need to process large amounts of data.

Google Wave is It is a web-based service, computing platform, and communications protocol designed to merge e-mail, instant messaging, wikis, and social networking.

BIBLIOGRAPHY “Computer Networks” By Andrew Tenenbaum. Digital Communication And Networking by Behrouz

A. Forouzan. Communication Networks by Alberto Leon Garcia &

Indra Widjaja. www.google.com, www.dogpile.com, www.ask.co

m, www.compnetworking.about.com