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1. Computer Network

2. 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

3. On the basis of “ SCALE ” TYPES OF NETWORKS

4. 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)

5. METROPOLITAN AREA NETWORK(MAN)

6. 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.

7. 2.Based on “span”

8. 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

9. NETWORK TOPOLOGY 1. 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.

10. 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.

11. 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.

12. BASIC TRANSMISSION MEDIA

13. 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; coding Hardware means of sending and  receiving data on a carrier THE OSI REFERENCE MODEL

14. THE TCP/IP ARCHITECTURE

15. ASSOCIATED TCP/IP PROTOCOLS & SERVICES

16. NETWORK SECURITY

17. TYPES OF ATTACKS ON A NETWORK

18. SIMPLIFIED MODEL OF SYMMETRIC ENCRYPTION Ingredients Plain text Encryption algorithm Secret key Ciphertext Decryption algorithm

19. 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 )

20. NETWORK MANAGEMENT

21. LATEST DEVELOPMENTS IN COMPUTER NETWORKING 1.THE INTERNET GRID 2.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.