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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