COMMUNICATION AND NETWORK CONCEPTS

MOHNISH SAHUPGT (C.S.)

INTRODUCTION

• NETWORK:-Collection of large number of separate but interconnected computers.

• GOAL:- a)Resouce Sharing.b)Reliability.c)Cost Factor.d)Communication Medium.

EVOLUTION OF NETWORKING• ARPANET:-Advance Research Project Agency

NETwork is planted in 1969 to connect computers at U.S. defense & different universities.

• NSFnet:-National Science Foundation in 1980 was started to make a high capacity network for academic & engineering research.

• INTERNET:-In 1990 the internetworking of ARPANET,NSFnet & other private networks resulted into Internet.

• INTERNET:-It is inter connection of large and small networks around the globe.

• Protocol:-It is common set of rules communication over internet.

• TCP:-Transmission Control Protocol is responsible for dividing & reassembling the file into packets on the source & destination computer.

• IP:-It is responsible for handling the address of destination computer so that each packet is routed to its proper destination.

• Interspace:-It is client/server software that allows users to communicate online real time.e.g FACEBOOK,TWITTER,WHATSAPP etc.

• NODES or WORKSTATIONS:-It refers to the computers that are attached to a network.

• SERVER:-A computer that facilitates the sharing of data, software, and hardware resources on network is termed as a server.

a)Dedicated Server b) Non-Dedicated ServerNIU (NETWORK INTERFACE UNIT):-It is a device that is attached to each of the workstations

SWITCHING TECHNIQUES• CIRCUIT:-In this techniques physical connection

between two computers is established then data are transmitted.

• MESSAGE:-In this source computer sends data to the switching office first, which stores the data in its buffer. It then look for free link to another office and then send. It is also known as store ad forward.

• PACKET:-It transfer a fixed size of packet which can be transmitted across the network is specified. All the packet are stored in main memory.

TRANSMISSION MEDIATwisted pair:-The wires come in pairs, are twisted around each other. Twisting reduce cross talk.Advantages:-It is physically flexible. It can be easily connected, easy to install and maintain.Disadvantages:-Because of high attenuation, it is incapable carrying a signal over long distances without the use of repeaters.Its low bandwidth capabilities make it unsuitable for broadband applications. Min speed of 1Mbps max of 10 Mbps.

Coaxial Cable• This type of cable consists of a solid wire core

surrounded by one or more wire shields, each separated by some kind of plastic insulator. Inner core carries the signal, and the shield provides the ground.

• Advantage:-It can be used for broadband transmission. Offer higher bandwidth upto 400 Mbps.

• Disadvantage:-Not compatible with twisted pair

Optical Fibers

• It consist of thin strands of glass material which re constructed that they carry light from a source at one end to other. The bandwidth of the medium is potentially very high.

• It consist of three pieces:-1)Core 2)Cladding 3)Protective coating.

• Advantages:-It is immune to electrical and magnetic interference. It can be used for broadband transmission where several channels are handled in parallel.

MICRO WAVE• Microwave signals are used to transmit data without

the use of cables. It consists of a transmitter, receiver and atmosphere. In this parabolic antennas are mounted on towers to send a bead to other antennas tens of kilometers away. The higher the tower, greater the range. It transmit in line of sight transmission.

• It have ability to communicate over oceans.• Signals may split up and propagate by slightly

different paths to the receiving antenna. It is susceptible to weather effects like rains, thunder storms etc.

RADIO WAVE

• It use continuous sine waves, each different radio signal uses a different sine waves frequency and that is how they are all separated. The receiver receives the radio waves and decodes the message from the sine wave it receives. Both the transmitter and receiver use antennas to radiate and capture the radio signal.

• Advantages:-It offers mobility.• Disadvantages:-Radio wave communication is an

insecure, susceptible to weather and storms etc.

Satellite

• Satellite communication is special case of microwave relay systems. The earth station consists of a satellite dish that functions as an antenna and communication equipment to transmit and receive data from satellites passing overhead.

• Advantages:-Area coverage through this transmission is quite large.

• Disadvantages:-Technical limitations preventing the deployment of large, high gain antennas on the satellite platform.

Infrared & Laser• It transmits data through the air and can propagate

throughout a room but will not penetrate walls.• Laser requires direct line of sight. It is unidirectional

but has much higher speed than microwaves. The laser transmission is point to point transmission, typically between buildings.

Communication terminology• Channel-It is a medium to carry information.• Baud-It is unit of measure for information carrying

capacity.• BPS-It refers to the speed at which data transfer is

measured.• Bandwidth-It refers to the difference between the

highest and lowest frequencies of transmission channel. High bandwidth channels are called broadband. Lower is called narrowband.

TYPES OF NETWORKS• LAN-Small networks that are confined to an office,

building or a factory. The key purpose of a LAN is to serve its users in resource sharing.

• MAN-It is spread over a city. Cable tv networks that are spread over a city.

• WAN-It is spread across countries. The largest WAN in existence is the Internet.

TOPOLOGIES• The pattern of interconnection of nodes in a

network is called topologies.It is set according to:-CostFlexibilityReliabilityTopologies are:-1) STAR 2)BUS 3)RING 4)MESH 5)TREE 6)GRAPH

NETWORK DEVICES• MODEM:-It is device that allows us to connect and

communicate with other computers via telephone lines.

• RJ-45:-Registered Jack-45 is an eight-wire connector, which is commonly used to connect computers.

• Ethernet card:-It is LAN architecture developed by xerox corporation. It used bus topologies and can transfer data upto rates of 10Mbps.

• Hub:-It is used to connect several computers together

• SWITCH:-A switch is a device that is used to segment networks into different subnetworks called subnets. It is responsible for filtering.

• Repeater:-It is device that amplifies and restores signals for long distance transmission.

• Bridge:-This device lets you link two networks together.it is smart enough to know which computers are on which side of the bridge, so they only allow those messages that need to get to the other side to cross the bridge.

• Router:-It handles different protocols, It uses logical address.

• Gateway:-It is used to connects dissimilar networks. It expands the functionality of routers by performing data translation and protocol conversion. It connect local and external networks with completely different structures.

LAN DESIGN• 80-20 RULES• LAN HARDWARES• FLOODING• SPANNING TREE• MEDIA

COMMUNICATION PROTOCOLS

• A protocol means the rules that are applicable for a network. It defines standardized formats for data packets, techniques for detecting and correcting errors and so on.

• HTTP:-Hyper Text Transfer Protocol is set of rules for transferring hypertext on www.

• FTP:-File Transfer Protocol is a standard for exchange of files across internet.

• TCP/IP:-Transmission Control Protocol/Internet Protocol is a layered set of protocols. It is base communication protocol, IP uses numeric IP addresses to join network segments and TCP provides reliable delivery of messages between networked computers.

• SLIP:-Serial Line Internet Protocol is for delivering IP packets over dial-up lines.

• PPP:-Point to Point Protocol is for transmitting IP packets over serial lines.

WIRELESS/MOBILE COMPUTING• GSM:-Global System of Mobile • SIM:-Subscriber Identification Module• CDMA:-Code Division Multiple Access• WLL:-Wireless in Local Loop• 3G and EDGE:-Third Generation and Enhanced Data

rates for Global Evolution.• SMS:-Short Message Service• Email:-Electronic Mail• Voice-Mail• Chat• Video Conferencing

INTERNETWORKING TERMS AND CONCEPTS

• WWW• TELNET• WEB BROWSER• WEB SERVER• WEBSITES,WEB ADDRESS AND WEB PAGES• URL AND DOMAIN NAMES• WEB HOSTING• WEB 2.0• HTML• XML• DHTML• WEB SCRIPTING

OPEN SOURCE BASED SOFTWARES• FREE SOFTWARE• OPEN SOURCE SOFTWARE• GNU• FSF• OSI• W3C• PROPRIETORY SOFTWARE• FREEWARE• SHAREWARE

NETWORD SECURITY• AUTHORIZATION• AUTHENTICATION• ENCRYPTED SMART CARDS• BIOMETRIC SYSTEMS• FIREWALL• COOKIES• HACKERS AND CRACKERS• CYBER LAW• CYBER CRIMES• IPR(Intellectual Property)

VIRUSES• Computer virus is a malicious program that requires

a host and is designed to make a system sick. They are:-

• File infectors, Boot sectors, Macro viruses.• Trojan Horses• Worms• Virus Prevention

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