Information Workbook

Information Information Level 2

Students Handbook

Class X

2013-2014

Technology

CENTRAL BOARD OF SECONDARY EDUCATIONShiksha Kendra, 2, Community Centre, Preet Vihar, Delhi-110092 India

Information Technology Level -2

CLASS

X

Students Handbook2013-2014

Information Information Level 2

Technology

CENTRAL BOARD OF SECONDARY EDUCATIONShiksha Kendra, 2, Community Centre, Preet Vihar, Delhi-110092 India

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Information Technology Level - 2Students Handbook - Class XPRICE: `First Edition 2013, CBSE, IndiaCopies:

Published By : The Secretary, Central Board of Secondary Education,Shiksha Kendra, 2, Community Centre, Preet Vihar, Delhi-110092Design, Layout : Multi Graphics, 8A/101, WEA Karol Bagh, New Delhi-110005Phone: 011-25783846Printed By :

"This book or part thereof may not be reproduced byany person or agency in any manner."

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THE CONSTITUTION OF INDIAPREAMBLE

1WE, THE PEOPLE OF INDIA, having solemnly resolved to constitute India into a [SOVEREIGN SOCIALIST SECULAR DEMOCRATIC REPUBLIC] and to secure to all its citizens :

JUSTICE, social, economic and political;

LIBERTY of thought, expression, belief, faith and worship;

EQUALITY of status and of opportunity; and to promote among them all 2FRATERNITY assuring the dignity of the individual and the [unity and integrity of the Nation];

IN OUR CONSTITUENT ASSEMBLY this twenty-sixth day of November, 1949, do HEREBY ADOPT, ENACT AND GIVE TO OURSELVES THIS CONSTITUTION.

THE CONSTITUTION OF INDIAChapter IV A

FUNDAMENTAL DUTIES

ARTICLE 51A

Fundamental Duties - It shall be the duty of every citizen of India-

(a) to abide by the Constitution and respect its ideals and institutions, the National Flag and the National Anthem;

(b) to cherish and follow the noble ideals which inspired our national struggle for freedom;

(c) to uphold and protect the sovereignty, unity and integrity of India;

(d) to defend the country and render national service when called upon to do so;

(e) to promote harmony and the spirit of common brotherhood amongst all the people of India transcending religious, linguistic and regional or sectional diversities; to renounce practices derogatory to the dignity of women;

(f) to value and preserve the rich heritage of our composite culture;

(g) to protect and improve the natural environment including forests, lakes, rivers, wild life and to have compassion for living creatures;

(h) to develop the scientific temper, humanism and the spirit of inquiry and reform;

(i) to safeguard public property and to abjure violence;

(j) to strive towards excellence in all spheres of individual and collective activity so that the nation constantly rises to higher levels of endeavour and achievement;

1(k) who is a parent or guardian to provide opportunities for education to his/her child or, as the case may be, ward between age of six and forteen years.

1. Subs, by the Constitution (Forty-Second Amendment) Act. 1976, sec. 2, for "Sovereign Democratic Republic (w.e.f. 3.1.1977)

2. Subs, by the Constitution (Forty-Second Amendment) Act. 1976, sec. 2, for "unity of the Nation (w.e.f. 3.1.1977)

1. Ins. by the constitution (Eighty - Sixth Amendment) Act, 2002 S.4 (w.e.f. 12.12.2002)


The national curriculum Framework, 2005, recommends that childrens life at school must be linked to their life outside the school. This principle make a departure from the legacy of bookish learning which continues to shape our systems and caused a gap between the school home, community and the workplace.The student workbook on information Technology (IT) is a part of qualification package developed for the implementation of National Vocational Education Qualification Framework (NVEQF), an initiative of Ministry of Human Resource Development (MHRD), Government of India to set common principles and guidelines for a nationally recognised qualification system covering the schools vocational education and training institutions, technical education institutions, college and universities. It is envisaged that the NVEQF will promote transparency of qualifications, cross-sect oral learning, student qualifications, thus encouraging life-long learning.This student workbook, which forms a part of vocational qualification package for students who have passed class IX or equivalent examination, was created by group of experts. The IT-ITes skill development council approved by the national occupation standards (NOS). The national occupation standards are a set of competency standards and guidelines endorsed by the representatives of IT industry for recognized and assessing skills and assessing skills and knowledge needed to perform effectively in the workplace.The CBSE has developed materials (units) for the vocational qualification package in IT/ITes sector for NVEQF levels 1 to 4; level 2 is equivalent to class X. Based on Nos occupation related core competencies (Knowledge, skills and abilities) were identified for development of curriculum and learning modules (units).This student workbook attempts to discourage rote learning and to bring about necessary flexibility in offering of courses necessary for breaking the sharp boundaries between different subjects areas. The workbook attempts to enhance this endeavour by giving higher priority and space to opportunities for contemplation and wondering, discussion in small groups and activities requiring hands on experience. Any suggestions, feedback from the readers for improvement in the future editions of the volume shall be heartily welcomed.Vineet JoshiChairman, CBSE

Preface


ContentsPrefaceAcknowledgement

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Networking Fundamentals

Digital Documentation - Advanced Word Processing

Digital Data Analysis - Advanced Operations on Spreadsheet

Advanced Digital Presentation

Digital Content Creation - Web Designing Fundamentals (HTML)

Computer Systems Care

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Unit Code Unit Title

ITCC-201 Networking FundamentalsEvolution of Networking and Need for NetworkingTransmission of Data through different Switching TechniquesData Communication TerminologiesTransmission Medium and Network DevicesNetwork Types and LayoutsITDC-202 Digital Documentation - Advanced Word ProcessingReviewing and editing documents with Track ChangesConnecting Data from Spreadsheet with the Document using Mail Merge FeatureObject Embedding and LinkingLanguage CorrectionSecuring DocumentITDC-203 Digital Data Analysis - Advanced Operations on SpreadsheetManaging Multiple Spreadsheets and WorkbooksOrganising and handling Spreadsheet DataCreating ChartsCreating and Using MacrosSecuring SpreadsheetsITDC-204 Advanced Digital PresentationStandardization of SlidesMultimedia Components in PresentationUsing TablesUsing ChartsPresentation DeliverySecuring Presentation


ITDC-205 Digital Content Creation - Web Designing Fundamentals (HTML)Basics of Webpage and HTMLHTML - Basic TagsParagraphs and TablesWeb Page LayoutFormsMultimedia Content in WebPagesITOC-206 Computer Systems CareHardware Safety and SecuritySoftware Safety, Security and Care


1.1 Evolution of Networking and Need for NetworkingAs you know, networking is widely used for accessing and sharing information; examples include web browsing, downloading & uploading, file sharing, printer sharing, etc. Today networking is popular with private and business users across the globe.In today's world, it can be extremely difficult to live without networks, since resource sharing (printers, shared folders etc) and Internet connectivity have become an integral part of our daily activities.A computer network, often simply referred to as a network, is a collection of computers and other hardware components interconnected by communication channels that allow sharing of resources and information.Networking is widely used for sharing of resources and information & for communication purposes. Networks can also help in reducing costs; for example you can buy a single printer and share it across multiple users.Network consists of one or more computers or devices connected in order to provide and access resources. Resources include a range of devices (example, Printer, CDROM, Hard Drives, etc.) and services (example, web service, mail service, etc.).Networks based on size are classified into LAN & WAN.LAN: Local Area Network refers to group of computers networked within a limited geographical area such as schools, colleges, offices, etc.WAN: Wide Area Network refers to computers networked across geographical areas, in other words they connect LAN's between different locations. For example, computers or devices in a branch office could connect to the computer networks at the head office through telephone lines or satellites.This session introduces you to the basic fundamental concepts of networking and Internet and using different types of Internet connection.

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Networking Fundamentals

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There are several ways to form a network as listed below:Use a cross-over cable (also referred to as Peer-to-peer cable)Use Serial and Parallel portsUse BluetoothUse Wi-Fi (for more than two computers)Use Hub or Network Switch (for more than two computers)SOHO Router or Wi-Fi Router (Commonly found in home & small business networks)Networks are designed using the following architecture:

Networks in which all computers have an equal status are called peer to peer networks. Generally in such a network each terminal has an equally competent CPU.

Peer-to-Peer Network

Networks in which certain computers have special dedicated tasks, providing services to other computers (in the network) are called client server networks. The computer(s) which provide services are called servers and the ones that use these services are called clients.

Client-Server Network

Note: Clients are referred to as "Service Requestors" and Servers as "Service Providers". Any machine that request a service is called as the client and machines that fulfill the requests is called the client.

Ways to form a computer Network

Peer-to-peer (P2P)

Client- Server

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Networks can have a combination of both Client/Server models and Peer-to-Peer.For example, you may be using a centralized mail server and/or access files from other machines in the network.The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks. Internet is one of the most useful technologies of modern times which help us in our daily, personal and professional life. Internet is widely used by students, educational institutes; scientist and professionals to gather information for research and general information. Businesses use the Internet to access complex databases such as financial database. The Internet is the largest encyclopedia for all age groups. The Internet helps in maintaining contact with friends and relatives who live across different locations via Internet chatting systems and email software. Internet is also becoming a major source of entertainment for the general public. Intranet refers to private computer network used by organizations for sharing resources; Intranets can be simple within a building or very large spread across the globe connected through various networking technologies. Intranets help employees of an organization to locate information much faster resulting in increased productivity. Though popularly referred to a company's internal website or portal, Intranet usually employs other protocols such as POP3, SMTP, FTP, etc. and may even offer a variety of services (you will read more about these in later sessions).Extranet is a computer network used outside the Intranet. For example, an organization may allow a vendor to view or access their resources such as their internal website for updating a product catalog or training material. However, this is highly restricted to Internet users (public). Extranets are usually accessed using VPNs (you will read more about this protocol later).World Wide Web (abbreviated as WWW or W3, commonly known as the Web), is a

Internet

Intranet

Extranet

World Wide Web

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system of interlinked hypertext documents accessed via the Internet. With a web browser, one can view web pages that may contain text, images, videos, and other multimedia, and navigate between them via hyperlinks. Information is stored on web servers referred to as web pages are retrieved by using a web browser such as Firefox on the local computer. A Web Browser is software used to view websites and acts as an interface between the user and the World Wide Web. A Web server is a computer that stores web sites and their related files for viewing on the Internet. Some of the advantages associated with networking are:

Data Sharing: One of the most important uses of networking is to allow the sharing of data. Users can send text files, spread sheets, documents, presentations, audio files, video files, etc. to other users. Hardware Sharing: Hardware components such as printers, scanners, etc. can also be shared. For example, instead of purchasing 10 printers for each user, one printer can be purchased and shared among multiple users thus saving cost. Internet Access Sharing: You can purchase a single Internet connection and share it among other computers in a network instead of purchasing multiple Internet connection for each computer. This is very commonly found in Internet caf (browsing centres), schools, colleges, companies, etc. Usage of network based applications such as web browsers, email clients, chat application, audio & video calling, etc is another advantage.

Data can be transferred over a network using the following techniques:Circuit Switching: In this method, a dedicated path is established between the endpoints before the data is transferred. Once a dedicated path is established, no other devices can use the circuit. Example: Dial-Up, ISDN.Packet Switching: In this method, data is divided into blocks referred to as packets. Multiple packets can be sent via different paths allowing more than two devices to communicate at the same time. Modes of operation can be connectionless or connection-oriented.

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In connectionless mode, packets have source & destination address for routing that may take different paths. Example: Ethernet, IP, UDP.In connection-oriented mode, connection is defined (a virtual circuit is created) before a packet is transferred. Packet switching supports variable packet sizes. Example: X.25, Frame Relay, TCP.Cell Switching: Cell switching method is similar to that of packet switching but has a fixed size for the cells transmitting data. Cell switching is efficient when large amounts of data need to transferred. Example: ATM.

Having talked of data transfer and the Internet, have you ever wondered how sitting in one corner of the world, you get information from another distant area in a few seconds? In very simple language, let's see what happens to a piece of data, say a Web page, when it is transferred over the Internet: The data is broken up into bits of same sized pieces called packets. A header is added to each packet explaining where the data has come from, where it should end up and where it fits in with the rest of the packets. Each packet is sent from computer to computer until it finds its destination. Each computer on the way decides where next to send the packet. All packets may not take the same route. At the destination, the packets are examined. If any packets are missing or damaged, a message is sent asking for them to be re-sent. This continues until all packets have been received intact. The packets are now reassembled into their original form. All this done in seconds! To access the Internet, you need an active internet connection. You need to gather and understand your requirement carefully before subscribing to an internet connection plan. In this exercise, you will learn how to choose an Internet connection. Some of the common questions that help you in your decision are: What is the purpose of getting this connection? Will you use the connection regularly?

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Data transfer on the Internet

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How much data will be downloaded on an average per month? How much speed do you need? What technology is available in your particular area? What are the different plans available from the ISP? Is there any limitation or catch for the selected plan? To access Wi-Fi, you need an access point with an active Internet connection. Usually when you subscribe to an Internet connection, the ISP provides options to purchase or rent a Wi-Fi router that can act as both an internet connectivity device and an access point for Wi-Fi connectivity. Setting up a Wi-Fi network requires technical expertise; however, you can access the Wi-Fi network by connecting to an access point that is already setup for use. On computers that run Windows XP, you can view the list of wireless networks available by using the following procedure: Right-Click on the Wireless Icon in the system tray and Click View Available Wireless Networks.

Windows XP will display the list of available Wi-Fi networks; you can choose any of the connection from the list. Select by Double-clicking on the name displayed in the list.Note: You may be prompted to enter a password if the selected network is secure. You will receive a confirmation that you are connected to a wireless network. Now the system is ready to be used for network related applications such as Firefox, Chrome, Skype, etc.

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In a network, communication happens between devices or computers through electrical, optical or radio-wave signals. Methods of signaling are widely categorized into baseband and broadband.Baseband: Data is sent as digital signals by using entire bandwidth of the media (Single Channel), supporting single communication at a time. Signals are sent over co-axial, twisted pair or fiber optic cables. Baseband supports higher transfer rates as compared to broadband; however, baseband is limited with distance. Baseband uses TDM (Time Division Multiplexing) to send multiple signals over a single cable. Example: Ethernet, Token Ring & FDDI.Broadband: Data is send as analog signals by using portion of a bandwidth. Broadband supports use of multiple signals at different frequencies (multiple channels). Signals are split into channels by using FDM (Frequency Division Multiplexing). Example: xDSL, where telephone lines are used for both voice (telephone) calls and data (Internet connectivity).

Baseband vs. Broadband

Channel operation refers to the mode of communication between connected devices or computers. Channel operation can be simplex, half-duplex or fullduplex. Simplex is a one way communication, similar to that of a radio. Halfduplex is a two way communication but only one way at a time, similar to that of a walkie-talkie. Full-duplex is two way simultaneous communication (data can be received and sent at the same time), similar to that of a telephone.When multiple devices or computers are connected in a network, they use multiple signals that are combined at the source and separated at the destination by use of a

Terminolgies and Technologies

Signaling Methods

Channel Operation

Multiple Signaling Methods

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FrequencyFrequency

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technique called multiplexing. For multiplexing, a device called the multiplexer is used for multiplexing / demultiplexing signals. Types of multiplexing include:TDM (Time Division Multiplexing) is a method in which multiple signals are combined and send over a single transmission media such as wires or radio waves. This is achieved by use of time sharing; multiple signals are transmitted for a defined amount of time in cycles. For example, a device sends and receives signals every alternate second.FDM (Frequency Division Multiplexing) is a method in which multiple signals are transmitted at different frequencies. Multiple signals can be sent at the same time over a single channel using this technique. For example, a device sends multiple signals at the same time using different frequencies similar to that of a radio (FM) or cable TV and the end device receives by tuning in to a particular channel.

To use the Internet, you need an Internet connection. Internet connections are provided by Internet Service Providers such as Bharat Sanchar Nigam Limited (BSNL), Airtel, MTS, Vodafone, Tata Docomo, etc. An Internet service provider (ISP) is an organization which provides you with access to the Internet via a dial-up (using modem) or direct (hard wired) or wireless connection. Choosing connectivity depends on the availability of a particular technology, speed and connection type in your area. Usually small and medium business users, home users use connectivity types such as DSL, cable modem, dial-up, broadband wireless, WiMAX or 3G. Medium to large business users or customers with more demanding requirements may use high speed connectivity such as DSL (High Speed), ISDN, etc. modem is a device that converts digital computer signals into a form (analog signals) that can travel over phone lines. It also re-converts the analog signals back into digital signals. The word modem is derived from its function MOdulator/ DEModulator.

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Getting access to the Internet

Internet Service Provider

Modem


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Channel access methods refer to how devices communicate using a shared medium such as bus networks, star networks, ring networks, hub networks & wireless networks. When multiple devices or computers are used in a shared medium, a pre-defined method of transmission needs to be defined. Channel access methods in circuit switching networks include FDM, TDM, etc and in packet switching networks include CSMA/CD, CSMA/CA, Token passing, etc.Ethernet is a family of computer networking technologies for local area networks (LANs) and has largely replaced competing wired LAN technologies. Ethernet standard defines how communication happens between network interface cards, hub, switches, repeaters, etc. Devices on Ethernet networks use frames or Ethernet frames for communication. IEEE 802.3 standard defines the Media Access Control (MAC) portion of the data link layer and the physical layer of the OSI model. Ethernet protocols are covered by this standard.CSMA/CD (Carrier Sense Multiple Access/Collision Detect) as per IEEE 802.3 standard is a mechanism that defines how transmission takes place in a network.Only one device in the collision domain may transmit at any one time, and the other devices in the domain listen to the network before sending any packets in order to avoid data collisions. Collisions also decrease network efficiency on a collision domain. If two devices transmit simultaneously, a collision occurs, and both devices device will wait for a random amount of time before attempting to transmit again.Collision domains are found in a hub environment where each host segment connects to a hub that represents only one collision domain and only one broadcast domain. Modern wired networks use a network switch to eliminate collisions. By connecting each device directly to a port on the switch, either each port on a switch becomes its own collision domain (in the case of half duplex links) or the possibility of collisions is eliminated entirely in the case of full duplex links. Collision domains are also found in wireless networks such as Wi-Fi.; CSMA/CA is used in wireless networks.Carrier sense multiple access with collision avoidance (CSMA/CA) is a network multiple access method in which nodes attempt to avoid collisions by transmitting

Channel Access Methods

Ethernet

CSMA/CD

CSMA/CA

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only when the channel is sensed to be "idle". It is particularly important for wireless networks, where the collision detection of the alternative CSMA/CD is unreliable due to the hidden node problem.Token passing is a channel access method where a signal called a token is passed between nodes that authorize the node to communicate. The most well-known examples are token ring and ARCNET.When multiple computers or devices are connected in a network, signals can be addressed as unicast, multicasts or broadcasts. Unicast refers to one-to-one communication, for example signal is sent from one computer to another.Multicast refers to one-to-may communication, for example signal from one computer or device is sent to selective set of computers or devices. Broadcast refers to one-to-all communication, for example single from one computer or device is sent to all devices and computers in a network.There are different types of Internet Connectivity available today; it can be widely categorized into wired and wireless access. Following table is a summary of different types of Internet connectivity categorized into wired and wireless:

Dial-Up WiredDSL WiredCable Internet Access Wired3G WirelessWiMAX WirelessWi-Fi Wireless Some of the commonly used Internet connectivity are:

Dial-up: Dial-up Internet access is a form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a connection to an Internet service provider (ISP) via telephone lines using a device called MODEM. Users dial a particular number provided by the ISP and gain access to the Internet.

Token Passing

Addressing methods

Types of Common Internet Connectivity

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Dial-up connections are extremely slow and in most cases, it is replaced by a high speed connection such as DSL or Cable Modem. DSL: Digital subscriber line(DSL) provide Internet access by transmitting digital data over wires of a local telephone network. DSL service is delivered along with wired telephone service on the same telephone line. On the customer premises, a DSL filter removes the high frequency interference, enabling simultaneous use of the telephone and data transmission. For using a DSL connection, you need a DSL modem and a subscription. Cable Internet Access: Cable Internet Access is a form of broadband Internet access that uses the cable television infrastructure. Cable Internet Access is provided through existing cable TV networks; this is similar to DSL that is provided over existing telephone lines. 3G: 3G, short for 3rd Generation is a set of standards used for mobile devices and mobile telecommunication services and networks. High-Speed Downlink Packet Access (HSDPA) is 3G mobile telephony communications protocol that allows higher data transfer speeds and capacity. If support for 3G is available on your mobile phone, you can subscribe to the 3G connectivity with your ISP in order to get high speed Internet connection on your phone. WiMAX: WiMAX (Worldwide Interoperability for Microwave Access) is a wireless communications standard designed to provide mobile broadband connectivity across cities and countries through a variety of devices. WiMAX is a long range system, covering many kilometres and is typically used where DSL or Cable Internet Access cannot be used; this could be difficulty in laying out cables for home or offices located in remote locations but need access to the Internet. WI-Fi: Wi-Fi is a popular technology that allows an electronic device such as computers or mobile phones to exchange data wirelessly over a network, including high-speed Internet connections. Wi-Fi devices such as personal computer, smartphones, video game console, etc. can connect to a network resource such as Internet through a device called the Wireless Access Point (WAP). Wi-Fi is used here cables cannot be run (such as old buildings, outdoor areas) to provide network and Internet access. Wi-Fi can also be used where users require mobile connectivity. Wi-Fi connectivity is used in home & offices, hotels, college & school campus typically for Internet Access. Shopping malls, coffee shops, resorts mostly offer free or paid Wi-Fi access to the Internet for their customers.

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Types of Cables for Internet

Twisted-pair Ethernet cables can be wired "straight-through" or "Crossover".To connect a network interface card to a switch, hub or router, straight-through or patch cables are used.To connect similar devices (network interface card on computer to another network interface on another computer, hub to hub or switch to switch), crossover cables are used.Fiber Optic: A fiber optic cable is a cable containing one or more optical fibers. Fiber-Optic cables are ideal for transmitting data over very long distances at great speeds as light is used for the medium for transmission. Fiber optic cables are not susceptible to any EMI, Near-end Crosstalk (NEXT), or Far-end Crosstalk (FEXT).Note that you require special network interface cards & network switch that support the fiber optic interface which is usually expensive and common only in large enterprise networks or locations that are susceptible to EMI such as factories that use heavy machineries.Fiber-Optic cables consist of a high quality glass or plastic strands and a plastic jacket made of Teflon or PVC that protects the cable.Two types of Fiber-Optic cable exist: Single-Mode Fiber (SMF) used for longer distances and Multi-Mode Fiber (MMF) used for shorter distances. Signals are transmitted as light signals from source to destination. Either LED or Laser is used. In multi-mode fiber, light signals are transmitted in numerous dispersed path (single-mode fiber use single light source) and making it un-suitable for long distance transmissions.

1. Core, 2. Cladding, 3. Buffer, 4. Jacket Fiber Optic Cable In some cases, plenum rated cables are used that have a special jacket to protect against fire and emit less smoke than normal cables. However, this is rare and often seen only in industrial or manufacturing sites.


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Network Hardware

On computers that have support for networking, a list of utilities is available to configure and troubleshoot network related issues. Often referred to as TCP/IP utilities, these utilities are bundled along with the operating system. Though the names of the utilities could vary in spelling, the underlying function is almost the same across operating systems. Given below is a list of utilities (with simple description) You will learn more about them in later sessions.

IPCONFIG Internet Protocol Configuration UtilityGETMAC View MAC or Physical Address of an NICPING Test network connectivityTRACERT Trace Route from source to destinationARP Resolve IP address to MAC addressHost name View computer name or hostnameNETSTAT View TCP/IP statisticsNbtstat View NetBIOS over TCP/IP statisticsNslookup View DNS related informationRoute View or modify routing tablePathping Trace packets and view detailed packet informationNote: Use /? for additional help/syntax for each command listed here. For example to know more about IPCONFIG, type IPCONFIG /?Network devices such as NIC, hub, bridge, switch & routers are devices that help computers to network and communicate. There are a variety of network devices equipped with a wide range of functions.Network cards are devices that connect computers to the network. Network cards are both Layer 1 (Physical) & 2 (Data Link) devices as they provide physical access to the medium and also provide physical addressing through the MAC Address.

TCP/IP Utilities

Network Interface Card (NIC)

Utility Description

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Network Interface Cards are available for desktop, laptop and server computers.A variety of interface such as PCI, CardBus, USB are available today. Most desktops, laptops, servers and motherboards have built-in NIC.

View Network Interface card installed on a computerA hub is a device that connects multiple computers using a twisted-pair cable. Hubs operate at Layer 1 (Physical). The number of computers that can be connected to a hub depends on the number of ports available (typically 4 to 8). Whenever it receives data from one port, the hub broadcast data to all the devices connected to it, leading to collisions. Hence hubs are referred to as multiport repeaters. Since the evolution of SOHO routers and network switches, hubs are rarely used and considered obsolete.Bridge is a device that can connect network segments and separate network traffic based on broadcasts. Bridges examine the frames and selectively transfer frames according to their MAC address. Bridges operate at Layer 2 of the OSI Model.Switch is a device that allows multiple computers to be connected using twisted pair cable. Switches (operating at Level 2 - OSI) manage traffic based on MAC (Media Access Control) addresses and are efficient in large networks. Switches are intelligent as they can build a table of MAC Addresses of all the devices connected to ports on the switch and create a virtual circuit for each attached device. Once a packet is received, it is analyzed and forwarded to only the destined station with matching MAC address based on the table.

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Switch

PCI Ethernet Card for usein Desktops Cardbus Ethernet Card foruse in older laptops USB Ethernet Card (USB Ethernet converter)


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Using switches can eliminate collision as each port in the switch acts as a collision domain. Since switches isolate collision domains, they are referred to as multiport bridges. When forwarding frames, switches use Store and forward, cut through, Fragment free or Adaptive switching methods.Unlike a hub that uses half-duplex communication, a network switch can send and receive at the same time (full-duplex mode) resulting in faster performance.Number of computers that you can connect to a switch depends on the number of ports available (Typically 4 or 8 on SOHO switches designed for use in home and small business networks and 8 - 32 or 64 on switches designed for use in an enterprise network.). The networks can be extended by adding additional switches usually cascaded from the primary switch. Switches designed for larger networks are cascaded through a special port called the Uplink port.

Simple Small Office Home Office Network Setup

An Enterprise network with a variety of networking devices

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Categories of switches include:Unmanaged switches are network switches used typically for homes or small offices requiring no administrative configuration.Managed switches are widely used in enterprise networks and ISP's. These need to be configured by the network administrator before it is used in a network.

A single layer-2 network can be partitioned to create multiple distinct broadcast domains, enabling data to be exchanged only between the computers within the domain. This is referred to as VLAN or Virtual LANs. This is created for two primary reasons:to reduce collisionsto implement security.For example if all the computers in an organization are connected to a single switch, you can isolate them by creating VLAN's for each department resulting in restricted access across departments with maximum access between computers within departments. VLANs can be configured only on Managed switches.

Separate VLANs for marketing & finance team connected to a single switch

PoE describes a standardized system to provide electrical power supply through Ethernet cables; generally, UTP cables carry only signals necessary for data communication. Switches that have support for PoE are generally expensive and in some cases only limited number of Ethernet ports are capable of supporting PoE.Advantages of PoE include the ability to provide power up to 25 watts and distance factor that allows devices to be connected up to 100 meters from the switch.

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Power over Ethernet

VLAN 1, Marketing Team VLAN 2, Finance Team


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Routers are Layer 3 devices that allow packets to be routed to different logical networks. Routers can discover and transfer packets based on routing table that are pre-determined or self-discovered. Routing tables are either managed by an administrator by manually defining the routes or automated through special configuration to exchange the routing tables with other routers on a logical network. Most common type of routers includes the SOHO router used at home or small office for sharing Internet connection; sophisticated routers are widely used in enterprise networks and ISP's. Similar to SOHO switches, SOHO routers do not need to be configured and routers designed for use in large networks require to be configured before they can be used.

In general, a combination of several routers and switches are used in large networks. Notable manufacturers of routers include Cisco, Nortel Networks, Avaya, HP, Dell, Huawei, etc.Routing is the process of selecting paths in a network when sending or receiving packets across computers or devices. Imagine if you are planning to send a parcel to someone; the parcel will travel through different offices, change routes if roadblocks are detected and finally be delivered to the recipient. Similarly when you browse the internet or send an email, packets take different routes (from your computer to your ISP, from your ISP to the next ISP, etc.) until it reaches its destination.Also referred to as a residential gateway, SOHO (Small Office Home Office) routers are devices designed for use in small to medium sized networks. Most SOHO routers have combinations of a switch, DSL or cable modem and an access point for Wi-Fi connectivity. These devices are used for two primary purposes:Connecting desktops & laptops across home or office.

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Sharing a single Internet connection across desktops & laptops.Some models include support for connecting peripherals such as printers, USB hard disk drives, etc. through USB ports.Wireless network refers to a computer network that is not connected by any cables. Typically Wireless networking is used where wired connectivity is not possible or feasible due to technology costs or availability. Wireless telecommunications networks are implemented and administered using a transmission system called radio waves. This implementation takes place at the physical level (layer) of the OSI model network structure.

Wireless personal area network (WPANs) interconnect devices within a relatively small area usually within a person's reach. For example, usage of Bluetooth to connect a mobile phone to a laptop.Wireless metropolitan area network (WMANs) is a wireless network that connects several wireless LANs. WiMAX is a type of Wireless MAN and is described by the IEEE 802.16 standard.Wireless wide area network (WWANs) is a wireless network that covers large areas, such as one between neighboring towns and cities, or city and its suburbs. This network can connect branch offices of business or function as a public internet access system. The wireless connections between access points are usually point to point microwave links using parabolic dishes on the 2.4 GHz band, rather than Omnidirectional antennas used with smaller networks. Omnidirectional antennas are types of antenna that radiates radio waves equally in all directions. Omnidirectional antennas oriented vertically are widely used for nondirectional antennas as they radiate equally in all horizontal directions.

Note: Though there are a variety of Wireless Networks, this course focuses only on Wireless LAN.

Instant messaging (IM) is a form of communication over the Internet that offers an

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Introduction to Wireless Networking, RF Communication

Types of wireless networks

Binder1.pdf02 Information Technology Level - 2 (Unit - 1 & 4)03 Information Technology Level - 2 (Unit - 5 & 6)

Binder1.pdf02 Information Technology Level - 2 (Unit - 1 & 4)03 Information Technology Level - 2 (Unit - 5 & 6)

Information Workbook

Documents

Transcript of Information Workbook