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Chapter 1 , Computer networking and telecommunication, Communication:- communication is the process of transferring message from one point to another. It is derived from latin word “Communicare” which means to share., Telecommunication:- telecommunication is the transmission of message over a significant distance through the use of mediums such as landline phone, mobile phone, television, etc., Data Communication:- the process of transferring data, information and voice between two or more devices through wire or wireless media is known as data communication., Elements of data communication:, 1.Sender:- Which creates the message to be transmitted., 2. Medium:- Which carries the message., 3. Receiver:- Which receive the message., 4. Protocol:- The set of rule and formats under which data transmission takes place between sender and receiver.

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#Mode of data Transmission, The way of transmitted data from one location to another location is called data transmission., Ways or mode of data transmission;, Simplex Mode:- Simplex mode communication is a mode of transmission in which data flows in one direction only. Eg TV, Radio, etc., Duplex Mode:- Duplex mode communication is a mode of transmission in which data flows in the both direction., Half Duplex:- Half duplex mode communication is mode of transmission in which data flows in the both direction, but only in one direction at a time. Eg, Walkie- Talkie., Full Duplex:- Full duplex communication is a mode of transmission in which data is transmitted in the both the directions simultaneously on the same time. Eg, Telephone .

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Difference between simplex mode and duplex mode of communication

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Analog and Digital Signal, #Analog Signal:- An analog signal is continuous signal that have any analog values limited range and it operated in the analog system. Eg, Speedometer, analog watch, etc., Analog signal denoted by:, , , #Digital signal:- a signal that determine the value in binary format i.e. (0 and 1 ) digital signals are discrete type in which digit are two level i.e. lower and upper level. Eg, Calculator, mobile, computer, etc., Digital signal denoted by:

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#Modem:- The combination of modulator and demodulator is called modem. Which allows the computer to send and receive data through telephone lines. It modulates the digital signal (‘0’ and ‘1’) into analog signal similarly, it demodulates the analog signal back into digital signal., #Bit:-it stand for binary digit that is the smallest data measuring unit in communication system., #Bandwidth:- The amount of data transmitted per second through the communication channel is called bandwidth. The bandwidth of digital signal is measured in bits per second(bps) where as the bandwidth of analog signal is measured in cycle per second(cycle/sec) or Hertz.

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#Communication media (Transmission Media):- A transmission media is the channel through which data, information and files are transferred from one point to another in the form of electromagnetic signals., Medium, , Types of Communication media:-, Wired communication Media/Guided media/Bounded, Wireless communication media/ unguided media/unbounded, Wired communication media/Guided media/Bounded, This types of communication media used wire such as twisted-pair cable, coaxial cable, fiber-optic cable, etc. to transfer data among computer., i) Twisted-Pair cable:- It is widely used in telephone lines. that consist of copper wire twisted in to pairs with each wire insulated with plastic., Sender, Receiver

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They are two type of twisted pair cable, Unshielded Twisted Pair(UTP), , , b) Shielded Twisted Pair(STP), , ii) Coaxial Cable:- a transmission line that consists of a tube of electrically conducting material surrounding a central conductor held in place by insulators and that is used to transmit telephone, television, and Internet signals called coaxial cable.

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iii) Fiber-Optic Cable:- it uses glass or plastic threads(fibers) to transmit data. In this cable data are transferred in the form of light along the optic fiber at the speed of light. It is more powerful and occur less data error than coaxial and twisted pair cable.

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b) Wireless communication media/ unguided media/unbounded, The communication uses radio signals or infrared signals for transmitting and receiving data is known as wireless communication media., Microwave System:- in the microwave system, a high frequency radio signals are used to transfer data through the space. Its signal can travel only straightway and they can not bend. the hills and mountains can block the signal so they are mounted on very high tower., Radio wave System:- it consists of pressure variations in matter, such as air or water, sound will not travel through a vacuum. Radio waves, like visible lite , infrared , ultraviolet, x-rays and gamma rays, are travel through a vacuum. Its range of 500 – 1600 KHz for AM (Amplitude Modulation)stations, or 86 – 107 MHz for FM(frequency Modulation) stations.

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iii) Communication satellite:- A communication satellite is an artificial satellite placed in outer space for the purpose of telecommunications.

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iv) Bluetooth Technology:- It is a wireless technology that connects electronic devices while they are close to each other. Bluetooth creates PAN(Personal Area Network) to transmission data in short distance 5-10 meter. Eg, laptop, printer, Digital Camera, etc., v) Infrared(IR) Transmission:- IR is a wireless transmission medium that sends signals using infrared light waves. Its frequencies between 300 GHz to 400 GHz. IR used in short distance (no more than 5 meters). Its wave can not pass through solid object, like wall. Eg, remote control used in TV, AC, etc., vi) Laser Transmission:- It use thin laser to transfer data up to few kilometers. Laser beams are unidirectional and they can not go through rain or thick fog. A photo detector and laser is set on both sender and receiver side.

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v) Wi-Fi Technology(Wireless- Fidelity):- wi-fi is a popular wireless technology that uses radio waves to provide wireless high speed network connection. It uses both single-carrier direct-sequence spread spectrum radio technology and multi-carrier Orthogonal Frequency-Division Multiplexing(OFDM) radio technology. , , #Difference between guided media and unguided communication media:

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#Computer Network:- Computer network is the interconnection of several computer, so that they can communicate, share information and data., #Service provided by the computer network:, File services:- it include file transfer, storage, data migration, file update etc., Printing services:- It produce shared access to valuable printing devices., Message services:- it provide email, voice mail and coordinate object oriented application facilitates., Application services:- it allow to centralize high profile application to increase performance and ability., Database service:- it coordinates the distributed data and replication., Terms Used in Computer Network:, a) Client:- clients are the network computers on which users run application . It is less powerful than server. It has own processor, memory and storage and can perform own task and processing.

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b) Server:- A server is a computer on the network which control and manages other computer on the network. That provide service to the clients in response to their request. And they are more powerful than client., , , c) Node:-Node is any network device that is attached to a network and that can receive , generate, process or forward information. Eg: Modem, Hub, Bridge or Switch, etc. , , , d) Work Station:- The computer that is generally developed to run different type of heavy and the professional software for the sake of networking is called workstation. Workstation computer often run Unix or Linux operating system.

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#Advantage and Disadvantage of Computer Network:, #Advantage:, Information can share easily., It can share peripheral devices such as printer, hard disk etc., It can share software between member workstations., It helps to keep information reliable and up-to-date and if one person in the networks updates the data it is instantly available to other., It provide backup of function., It give the facility locking records which leads the multiple users to simultaneously access a file without corrupting the data., #Disadvantage of computer network:, Computer virus spreads mostly through network., Fear or misappropriation of data., The initial setup cost is very high., Cyber crime may be occurred.

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#Component of computer Network:, They are two components of computer network are:, 1. Hardware Components:, Computer = a) Server b) Clients, , ii) Network connecting device :, Network cable b) Hub c) Switch d) Repeater e) Media Connectors , f) Network Cable g) Bridge h) Gateway i) Router, , Software Components:, Network Operating System(Windows-NT, Windows 2000, Novell Netware, Windows-XP, Linux, etc.), Network Protocol ( TCP/IP, HTTP, SMTP, etc.), Device Driver, etc

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Hardware components:, Computer: it is used to send and receive information in the network. Some computers in the network act as client, some act as server and other act as ISP(Internet Service Provider)., , Network Interface Card(NIC): it is a network connecting device that is also known as network adapter. It is placed on the expansion slot of the motherboard. And It connect a computer in a network.

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c) Hub:- It is a network connecting device used in LAN(Local Area Network). It joins multiple computers together. The information sent from one computer to another passes through the hub. A hub can’t identify the source or intended destination of the information it receives, so it sends the information to all the computers connected to it. It can send or receive message but can’t do both at a same time so it works slower than switches or routers.

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d) Switch: it is a network connecting device the joins multiple computers together within one LAN(Local Area Network). It can be identify the intended destination of the information that they receive. Switches can send and receive information at the same time so they work faster than hubs.

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e) Router, It is a network connecting device that connects wired or wireless network together. , Router can determine the best path for sending data and filtering broadcast traffic to the local segment. So it is called router., Router always used in a complex network situation because that provide better traffic management than other device.

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f) Bridge:- This device is used to join different networks or two segments with in a same protocol. it reduce the amount of traffic on a LAN by dividing two segments. they are operated at the data link layer (layer 2) of the OSI( Open System interconnection) model., g) Gateway:- This device is used to join two different networks having different protocols. It make communication possible between different architecture and environments. , h) Repeater:- it is a networking device that increase the length of network by amplifying weak signals. Repeater take a weak signal from the computers and regenerates the signal to maintain its integrity while traveling along a longer media. They are simply devices that sit on the network and boost the data signals that they received., i) Media Connectors:- it is used to connect communication media with network devices. They provide data communication through network adapter. There are different types of media connectors such as RJ-45(Registered Jack-45), BNC(British Naval Connector/Bayonet Naur Connector), T-Connector, Terminal, etc.

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2. Software Components:-, Network Software:- A special types of software which is used to control and manage all the resources used in computer network is called network software. For example, Novell netware , NOS(Network Operating System)., communication protocol:- it is a set of rules and procedures that governs data communications among different computers in the network is called Protocol. It considered what is communicate, how communicate and when communicate. NCP(Network Control Protocol) is the first protocol and later, the TCP/IP is developed & it is still use today., Some Protocols Are:, TCP/IP(Transmission Control Protocol), FTP(File Transfer Protocol), HTTP(Hypertext Transfer Protocol), IMAP(Internet Message Access Protocol), NNTP(Network News Transfer Protocol), POP(Post office Protocol), SMTP(Simple Mail Transfer Protocol), TFTP(Trivial File Transfer Protocol, a simple file transfer Protocol), PPP(Point to Point Protocol), IPX/SPX(Internetwork Packet Exchange/ Sequence Packet Exchange), Net BEUI(Network Bios extended User Interface)

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C) Device Driver:- it is a program and software that controls and manage the hardware devices. It enables the computer to use any device and run successfully. Without driver, we are not able to work with hardware devices.

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Types of Network:-, LAN(Local Area Network), MAN(Metropolitan Area Network), WAN(Wide Area Network), , LAN(Local Area Network):- , The network which is limited to a, small area such as a room a building , or a school and connects limited , number of computer is called LAN. , Advantage:, It covers limited area(Few Kilometers)., its processing is very high(10 to 100 mbps)., It uses guided transmission media.

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b) MAN(Metropolitan Area Network):- The medium sized network that covers the area larger than a LAN but smaller than WAN is called MAN. Eg:- City or Region, Advantage:- , It covers large area than LAN., It uses cable or wireless communication media., It connects multiple LAN in different location , by using Ethernet Technology., It is owned by single or multiple organization., Its speed is slow than LAN(128kbps to 1 Gbps).

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c) WAN(Wide Area Network):- The network that spans globally and connects large number of computer around the world is called WAN., Advantage:-, It is not restricted to a geographical location. It covers whole world., It use satellite and microwave system to communicate., It is owned by multiple organization., Its speed is very slow than MAN , and LAN., It is very expensive to setup.

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Network Architecture:- the architecture that describe how the computers on the network interact and communicate with other., Types of network architecture:, Client – Server Network Architecture, Peer-to-Peer Network Architecture., , Client- Server Architecture:- This network mode in which there is at least one server and other clients is called client server mode. Client always send request to the server and server response there request. There are different types of server such as: File server, Printer server, Message server, application Server, Web server etc. , Advantage of Client Server Network:, It covers large area., It reduce the network traffic., It centralizes the network management , and security to the server.

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Disadvantage of Client Server Network:- , Too many request from the clients and overload can lean to breaking- down of server system., If server fails, the whole network goes to down., It is very expensive to install and manage., It needs professional manpower to maintain., b) Peer –To-Peer Network Architecture:- This types of network, all the computers function both as a client and a server, in which, each computers have equal responsibilities of providing and using resources. It has no centralized data storage., Advantage of a Peer-To-Peer Network Architecture, All the resources are shared by all the peers(clients)., If failure of one peer doesn’t affect the functioning, of other peers., It is less expensive than Client server network.

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Disadvantage of a Peer-To-Peer Network:, The whole system is decentralized thus it is difficult to administer., Security system is very less., Data recovery or backup is very difficult., , # Network Topology /LAN Topology:- the arrangement and connection patterns of computers in the network is called topology.it is cabling structure or geographical arrangement of computer in LAN., Types of Topology/LAN topology:-, Bus or Linear topology, Star Topology, Ring Topology , Mesh Topology, Tree Topology

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Bus Topology or Linear topology:- this type of topology, all the nodes are connected to the single cable by the help of interface connectors. The centralized cable is the backbone of the network and is known as Bus., Advantage of Bus Topology:, it is easy to setup., It is cheaper than other topologies., It is widely used in small networks., Disadvantage of Bus topology:, If main cable has any problem, , whole network breaks down., There are maximum chance, of collision of data., It is difficult to detect fault.

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b) Star Topology:-in this topology, all the computer are connected to the central device(Hub, Switch)., Advantage of Star Topology:-, It provide better performance, than bus topology., New node can be added easily, without affecting the network., It is centralized management, and monitoring., Failure of one node or link doesn’t, affects the rest of network., Disadvantage of Star Topology:, If the central device fails, the entire network is break down., New node can be added to dependent on capacity of the central device.

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c) Ring Topology:-, This topology, all the nodes are connected to each-other in such a way that they make a closed circular loop(ring pattern)., This network provides equal access for all computers so, if one of the computer fails, it impacts all the computers in the network. There are no chance of data collision because data are travelled in one direction only that is clockwise or anticlockwise. , It uses TOKEN that passes one to next node, which checks if the signal intended to it. If yes, it receives it and passed the empty to into network., Advantage of Ring Topology:-, The collision of data is very less., It is not need to server to control., Each computer has equal access to resources., Disadvantage of Ring Topology:, It is slower., If one workstation or port goes down, the , entire network gets affected.

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Thank you!!!