network is a group of two or more computers or communicating devices that are able to communicate...

NETWORK

NETWORKNetwork is a group of two or more computers or communicating devices that are able to communicate with each other.The computers on a network may be linked through cables, telephone lines, radio waves or satellites. 1Sunil Kumar Sahu,Lecturer RCET1Computer networks allow people to:

Exchange information (for example, databases, documents, and graphics) via connected workstations. Share resource equipment (for example, computers, printers and scanners). Use shared applications (for example, spreadsheets and word processing programs). Collaborate and communicate electronically.2Sunil Kumar Sahu,Lecturer RCETA computer network comprises the following components: A minimum of at least 2 computers. Cables that connect the computers to each other, although wireless communication is becoming more common.A network interface device on each computer (this is called a network interface card or NIC).A Switch used to switch the data from one point to another. Hubs are outdated and are little used for new installations.Network operating system softwareComponents of networks3Sunil Kumar Sahu,Lecturer RCETNetwork CriteriaPerformanceMostly measured by throughput and delayReliabilityThe frequency of failureRecovery time from a failureSecurityProtecting data from unauthorized accessDamage1.4Sunil Kumar Sahu,Lecturer RCET Depending upon the geographical area covered by a network, it is classified as:

Local Area Network (LAN) Metropolitan Area Network (MAN) Wide Area Network (WAN) Personal Area Network (PAN)Different Types of Networks5Sunil Kumar Sahu,Lecturer RCETLANLAN stands for Local Area Network.A LAN is group of computers and networks devices connected together usually within same building.LAN is high speed and inexpensive.It uses guided media.Waves are guided along solid medium such as twisted pair cable/coaxial cable/fiber optic cable.Ex. University,school,computer lab etc.Speed of LAN is 100 to 1Gbps.Is limited in size, typically spanning a few hundred meters,and no more than a mile.It Has lower cost compared to MANs or WANs.

6Sunil Kumar Sahu,Lecturer RCETLANs can be either wired or wireless. Twisted pair,coax or fibre optic cable can be used in wired LANs.Nodes in a LAN are linked together with a certain topology. These topologies include: Bus Ring Star7Sunil Kumar Sahu,Lecturer RCETLocal Area Network

8Sunil Kumar Sahu,Lecturer RCET9Local Area Networks

9Sunil Kumar Sahu,Lecturer RCET9This is Figure 7.11.*07/16/96*##Advantages of LAN SpeedCostSecurityE-mailResource Sharing10Sunil Kumar Sahu,Lecturer RCETDisadvantages of LAN Expensive To Install Requires Administrative Time File Server May Fail Cables May Break11Sunil Kumar Sahu,Lecturer RCETMANMAN stands for Metropolitan Area Network.A MAN is larger network that usually span several building in the same city or town.A MAN is optimized for a larger geographical area than a LAN, ranging from several blocks of buildings to entire cities.Is larger than a LAN, but smaller than a WAN.Slow in compare to LAN and inexpensive.Connected with Fiber Optics Cable. Used may be guided or may be unguided media.Ex.-cable tv, or large companies with multiple buildings etc.

12Sunil Kumar Sahu,Lecturer RCET

13Sunil Kumar Sahu,Lecturer RCETWANWAN stands for Wide Area Network.WAN covers a large geographic area such as country, continent or even whole of the world.A WAN is two or more LANs connected together.A WAN is confined within the bounds of state or country.A WAN is generally slow and relatively expensive.The Internet is an example of WAN.Use unguided media i.e.Waves are propagated through atmosphere.WAN Connected using Internet,Satellite or ISDN land line.


15Sunil Kumar Sahu,Lecturer RCETPANPAN stands for PERSONAL AREA NETWORK.A PAN is a network that is used for communicating among computers and computer devices (including telephones) in close proximity of around a few meters within a room.PANs can be wired or wireless16Sunil Kumar Sahu,Lecturer RCET

PAN17Sunil Kumar Sahu,Lecturer RCETWhat is I N T E R N E T ?The largest network of networks in the world.

18Sunil Kumar Sahu,Lecturer RCETWhat is I N T E R N E T ?A network of networks, joining many government, university and private computers together and providing an infrastructure for the use of E-mail, bulletin boards, file archives, hypertext documents, databases and other computational resources.19Sunil Kumar Sahu,Lecturer RCETVinton Cerf

Father of InternetCo-designer of the TCP/IP networking protocol.

20Sunil Kumar Sahu,Lecturer RCETApplications Of InternetDownload programs and filesE-MailVoice and Video ConferencingE-CommerceFile SharingInformation browsingSearch the web addresses for access through search engine Chatting and many more21Sunil Kumar Sahu,Lecturer RCETDisadvantages of InternetTheft of personal information such as name, address, credit card number etc.Virus threats nothing but a program which disrupts the normal functioning of your system.Spamming refers to receiving unwanted e-mails in bulk, which provide no purpose and needlessly obstruct the entire system.Pornography This is perhaps the biggest threat related to childrens healthy mental life. A very serious issue concerning the Internet.

22Sunil Kumar Sahu,Lecturer RCETApplications of an Intranet Human resources managementSales and marketingProduction and operationsAccounting and financeHelp organizations move from a calendar- or schedule-based document-publishing strategy to one thats based on events or need Reduce the costs and time of document production 23Sunil Kumar Sahu,Lecturer RCETInternet ServicesElectronic Mail (e-mail)World Wide WebTelnetFile Transfer Protocol (FTP)Internet TelephoneWeb TV/RadioInternet Relay ChatNews GroupsVideo conferencing24Sunil Kumar Sahu,Lecturer RCETElectronic Mail (e-Mail)Distributes e-mail messages and attached files to one or more electronic mailboxes.

Eg:- e-mail [email protected] [email protected] 25Sunil Kumar Sahu,Lecturer RCETElectronic Mail (e-Mail)thomas @ mes . edu . in

murugan @ mesmarampally . org OrganizationType of OrganizationName of PersonCountry26Sunil Kumar Sahu,Lecturer RCETElectronic Mail (e-Mail)Different e-mail service providers

G-Mail

Yahoo Mail

Hot Mail


28Sunil Kumar Sahu,Lecturer RCETWorld Wide Web (W W W)Most important service provided by Internet.

An internet-based hypermedia initiative for global information sharing.

Developed in 1989 by Tim Berners-Lee of the European Particle Physics Lab (CERN) in Switzerland. 29Sunil Kumar Sahu,Lecturer RCETTim Berners-Lee

Father of W W W.

The inventor of HTML.

Invented W W W while working at CERN, the European Particle Physics Laboratory. 30Sunil Kumar Sahu,Lecturer RCETSearch EnginesFor searching information on the Internet.

GoogleYahooAltavista31Sunil Kumar Sahu,Lecturer RCET

32Sunil Kumar Sahu,Lecturer RCETImpact of InternetEducation

Health Care

Business33Sunil Kumar Sahu,Lecturer RCETIntranetIt is an internal network that is setup internally for companies and can be accessed by employees for the purpose of standard documents or information and many items of information and data.34Sunil Kumar Sahu,Lecturer RCETTable 7.2The Internet versus Intranets

The Internet versus IntranetsEXTRANETA network based on Web technologies that links selected resources of the intranet of a company with its customers, suppliers, or other business partners.36Sunil Kumar Sahu,Lecturer RCETExtranetsAdvantages of extranets:CoordinationFeedbackConsumer satisfactionCost reductionExpedited communication

37Sunil Kumar Sahu,Lecturer RCETTRANSMISSION MODE The term transmission mode defines the direction of the flow of information between two communication devices i.e.It tells the direction of signal flow between the two devices. 38Sunil Kumar Sahu,Lecturer RCET Transmission Modes The term transmission mode refer to the manner in which data is sent over the underlying medium.Transmission modes can be divided into two fundamental categories:1. Serial2.ParallelFigure 9.1 gives an overall taxonomy of the transmission modes.

3939Sunil Kumar Sahu,Lecturer RCET39 A Taxonomy of Transmission Modes 4040

Sunil Kumar Sahu,Lecturer RCET40 Parallel Transmission Parallel transmission allows transfers of multiple data bits at the same time over separate mediaIn general, parallel transmission is used with a wired medium that uses multiple independent wires.Furthermore, the signals on all wires are synchronized so that a bit travels across each of the wires at precisely the same time.Figure 9.2 illustrates the concept of parallel transmission.

41Sunil Kumar Sahu,Lecturer RCET414.42Figure 4.32 Parallel transmission

Sunil Kumar Sahu,Lecturer RCET42 Parallel Transmission A parallel mode of transmission has two important advantages: High speed: it can send N bits at the same time

Match to underlying hardware: Internally, computer and communication hardware uses parallel circuitry.

4343Sunil Kumar Sahu,Lecturer RCET43PARALLEL TRANSMISSIONDisadvantage- there is a significant disadvantage: cost. Parallel transmission requires n communication lines (wires in the example) just to transmit the data stream. Because this is expensive, parallel transmission is usually limited to short distances.44Sunil Kumar Sahu,Lecturer RCET Serial Transmission Serial transmissionsends one bit at a timewe need only one communication channel rather than n to transmit data between two communicating devicesFigure 9.3 illustrates the configuration

4545Sunil Kumar Sahu,Lecturer RCET454.46Figure 4.33 Serial transmission

Sunil Kumar Sahu,Lecturer RCET46Serial TransmissionThe advantage of serial over parallel transmission is that with only one communication channel, serial transmission reduces the cost of transmission over parallel by roughly a factor of n.Since communication within devices is parallel, conversion devices are required at the interface between the sender and the line (parallel-to-serial) and between the line and the receiver (serial-to-parallel).

47Sunil Kumar Sahu,Lecturer RCETSerial TransmissionSerial transmission occurs in one of three ways: 1. asynchronous 2. synchronous 3. isochronous.48Sunil Kumar Sahu,Lecturer RCETASYNCHORONOUS TRANSMISSIONSends only one character at a time (one byte of data at a time)Synchronize two devices using Start Bit and Stop Bit.Start bit refers to the start of the data. Usually 0 is used for start bit.Stop bit indicates the end of data, more than one bit can be used for end.

49Sunil Kumar Sahu,Lecturer RCET4.50Figure 4.34 Asynchronous transmission

Sunil Kumar Sahu,Lecturer RCET50SYNCHRONOUS TRANSMISSIONData sent at one time multiple bytes.Start and stop bit not used.Gap between data units not present.Data transmission speed fast.Cost high.Transfer of data between two computer.Synchronization between sender and receiver required.51Sunil Kumar Sahu,Lecturer RCET4.52Figure 4.35 Synchronous transmission

Sunil Kumar Sahu,Lecturer RCET52IsochronousIn isochronous transmission we cannot have uneven gaps between frames.Transmission of bits is fixed with equal gaps.In real-time audio and video, in which uneven delays between frames are not acceptable,synchronous transmission fails. For example, TV images are broadcast at the rate of 30 images per second;. If each image is sent by using one or more frames, there should be no delays between frames. For this type of application, synchronization between characters is not enough; the entire stream of bits must be synchronized. The isochronous transmission guarantees that the data arrive at a fixed rate.53Sunil Kumar Sahu,Lecturer RCETTypes of TRANSMISSION MODEA communications channel is classified as one of three types:(depending on the direction of transfer)SimplexFull-DuplexHalf-Duplex

54Sunil Kumar Sahu,Lecturer RCETSimplex

In simplex mode, the communication is unidirectional, as on a one-way street. Only one of the two devices on a link can transmit; the other can only receive (see Figure).Keyboards and traditional monitors are examples of simplex devices. The keyboard can only introduce input; the monitor can only accept output. The simplex mode can use the entire capacity of the channel to send data in one direction.

55Sunil Kumar Sahu,Lecturer RCETHalf-Duplex

In half-duplex mode, each station can both transmit and receive, but not at the same time. :When one device is sending, the other can only receive, and vice versa.Ex. -Walkie-talkies and CB (citizens band) radios are both half-duplex systems.56Sunil Kumar Sahu,Lecturer RCETFull-Duplex

In full-duplex mode (also called duplex), both stations can transmit and receive simultaneously.One common example of full-duplex communication is the telephone network.When two people are communicating by a telephone line, both can talk and listen at the same time.The full-duplex mode is used when communication in both directions is required all the time.


58Sunil Kumar Sahu,Lecturer RCET59ConnectingIn a local network (office, building, campus), computers a usually connected via dedicated links, such as:Twisted pair wire Coaxial cableFiber-optics cableBut what if we want to connect from home?Telephone-linesCable TVwireless

Sunil Kumar Sahu,Lecturer RCETTERMINOLOGY


61Sunil Kumar Sahu,Lecturer RCET62Dial-up access uses a telephone modem, DSL service uses a DSL modem, cable access uses a cable modem, and satellite service uses a satellite adapter.The connection links:Are used to transmit data between the computers on the network. The links could be: wires (cables, telephone-lines), or even wireless (radio transmitters, satellites).Sunil Kumar Sahu,Lecturer RCET



65Sunil Kumar Sahu,Lecturer RCETTYPES OF INRENET CONNECTIONDIAL UPDSLLEASED LINEISDNCABLE CONNECTIONWIRELESS CONNECTION66Sunil Kumar Sahu,Lecturer RCET67Connecting via Telephone LinesProblem:Telephone systems were build to carry voice as analog data, but computers use digital (binary) data.Solution:At the sending end the data is converted to analog signal (modulate).At the receiving end: the analog signal is converted back to digital data (demodulate).The device that does this is called a modem.Bandwidth: up to 56 KbpsSunil Kumar Sahu,Lecturer RCET




71Sunil Kumar Sahu,Lecturer RCETDSLIt is composed of several subcategories.ADSL (Asymmetric Digital Subscriber Line),SDSL (Symmetric Digital Subscriber Line),HDSL (High-data-rate Digital Subscriber Line). ADSL technology is a transport that allows faster flow of information downstream than upstream.while SDLS supports one speed regardless of upstream or downstream flow. 72Sunil Kumar Sahu,Lecturer RCETSpeed: ADSL supports data rates from 1.5 to 9 Mbps when receiving data (known as the downstream rate). And from 16 to 640 Kbps when sending data (known as the upstream rate). SDSL supports data rates up to 3 Mbps.Cost: The cost of the modem can range from $200 to $300.73Sunil Kumar Sahu,Lecturer RCET

74Sunil Kumar Sahu,Lecturer RCETLeased LinesA leased line is a telephone line that is rented directly from the telephone company, and sometimes is referred to as direct connections to the Internet.75Sunil Kumar Sahu,Lecturer RCET


77Sunil Kumar Sahu,Lecturer RCET78ISDN(Integrated Service Digital Network)ISDN uses fully digital signals over copper phone wire, a standard telephone line. This means there is no conversion from digital to analog and back again in the manner that an analog modem works.Telephone companies are now also offering ISDN connections (Integrated Services Digital Network)Communications links capable of handling digital signals.Can also be used for normal telephone calls, a device called Terminal Adaptor (TA) converts the analog telephone signal to/from a digital signal.Bandwidth: 128KbpsSunil Kumar Sahu,Lecturer RCET






84Sunil Kumar Sahu,Lecturer RCETCABLE CONNECTIONWhereas ISDN and DSL have become popular by taking advantage of copper telephone lines, cable is another broadband option which takes advantage of another setup found in homes-cable TV. A cable modem uses the cable TV providers hybrid Fiber/Co-ax infrastructure as a shared data network.All of the devices connected to the neighborhood co-ax network talk and listen to each other.85Sunil Kumar Sahu,Lecturer RCET

86Sunil Kumar Sahu,Lecturer RCETCable ConnectionSpeed: Cable TV systems were originally designed to deliver large amounts of bandwidth (TV pictures and audio) from the head end (central distribution point) to the user (TV sets).Theoretically cable modes can operate at speeds of up to 50 Mbps for downloading, 10 Mbps for uploading.But practically, these can deliver 1 Mbps to 10 Mbps for downloading and 200 Kbps to 2Mbps for uploading.Cost: Installation costs $100 or more. Monthly fees are between $40 to $6087Sunil Kumar Sahu,Lecturer RCET

88Sunil Kumar Sahu,Lecturer RCET89Cable ModemA device called a cable modem allows to transmit data via a cable TV connection:Does modulate the digital signals so can be transmitted (but without interfering with the TV picture).NeedsCable TV outletA cable modem (rental included in monthly fee)A network card in your computer.Advantages:Dedicated connection (don't have to dial in). Bandwidth: up to 45 Mbps (but shared by all users on cable)Sunil Kumar Sahu,Lecturer RCET90Cable Modem Setup

Sunil Kumar Sahu,Lecturer RCETTwisted-pair cable

91Sunil Kumar Sahu,Lecturer RCETTwisted-pair cableA twisted pair consists of two conductors (normally copper), each with its own plastic insulation, twisted together.One of the wires is used to carry signals to the receiver, and the other is used only as a ground reference.If the two wires are parallel, the effect of these unwanted signals is not the same in both wires because they are at different locations relative to the noise or crosstalk sources (e.g., one is closer and the other is farther).By twisting the pairs, a balance is maintained. For example, suppose in one twist, one wire is closer to the noise source and the other is farther; in the next twist, the reverse is true.Twisting makes it probable that both wires are equally affected by external influences (noise or crosstalk). This means that the receiver, which calculates the difference between the two, receives no unwanted signals.Page 22992Sunil Kumar Sahu,Lecturer RCETTypes of Twisted-pair cable

93Sunil Kumar Sahu,Lecturer RCETApplications

Common in building for digital signaling used at speed of 10s Mb/s (CAT3) and 100Mb/s (CAT5) over 100s meters. Common for telephone interconnection at home and office buildingsLess expensive medium; limited in distance, bandwidth, and data rate. Frequency range100Hz-5MHz

94Sunil Kumar Sahu,Lecturer RCETCoaxial CableCoaxial cable (or coax) carries signals of higher frequency ranges than those in twisted pair cable.

95Sunil Kumar Sahu,Lecturer RCETFrequency range

100 KHz-500MHz

96Sunil Kumar Sahu,Lecturer RCETCategories of coaxial cables


A section of RG-59 cable with its end stripped.A: outer plastic sheathB: copper braid shieldC: inner dielectric insulatorD: copper core

98Sunil Kumar Sahu,Lecturer RCETFiber-opticsA fiber-optic cable is made of glass or plastic and transmits signals in the form of light.

99Sunil Kumar Sahu,Lecturer RCETFiber-opticsOptical fibers use reflection to guide light through a channel. A glass or plastic Core is surrounded by a cladding of less dense glass or plastic. The difference in density of the two materials must be such that a beam of light moving through the core is reflected off the cladding instead of being refracted into it.100Sunil Kumar Sahu,Lecturer RCETFiber-optics

101Sunil Kumar Sahu,Lecturer RCETApplicationsFiber-optic cable is often found in backbone networks because its wide bandwidth is cost-effective.

102Sunil Kumar Sahu,Lecturer RCETAdvantagesSPEED: Fiber optic networks operate at high speeds - up into the gigabits.

BANDWIDTH: large carrying capacity.

DISTANCE: Signals can be transmitted further without needing to be "refreshed" or strengthened.

RESISTANCE: Greater resistance to electromagnetic noise such as radios, motors or other nearby cables.

MAINTENANCE: Fiber optic cables costs much less to maintain.103Sunil Kumar Sahu,Lecturer RCETDisadvantagesInstallation and maintenance.Fiber-optic cable is a relatively new technology. Its installation and maintenance require expertise that is not yet available everywhere.

Unidirectional light propagation.Propagation of light is unidirectional. If we need bidirectional communication, two fibers are needed.

Cost.The cable and the interfaces are relatively more expensive than those of other guided media. If the demand for bandwidth is not high, often the use of optical fiber cannot be justified.104Sunil Kumar Sahu,Lecturer RCETWireless Internet ConnectionWireless Internet, or wireless broadband is one of the newest Internet connection types. Instead of using telephone or cable networks for your Internet connection, you use radio frequency bands. Wireless Internet provides an always-on connection which can be accessed from anywhere.105Sunil Kumar Sahu,Lecturer RCETThere are several wireless options, available for special Internet access applications.They can be extremely useful for some Internet users.Cellular modems: Much the way a regular modem interfaces the PC to the Internet over standard phone lines, cellular modems can perform a similar function over cellular phones. These are slow (usually 9600 bps) and expensive (because cellular phone time is still expensive), but they offer the freedom to allow the user to access the Internet from virtually anywhere.106Sunil Kumar Sahu,Lecturer RCETSatellite:IoS short for Internet over Satellite allows a user to access the Internet via a geostationary satellite that orbits the earth. A geostationary satellite is a type of satellite placed at a fixed position above the earth's surface. Because of the large distances between home and satellite, signals must travel from the earth up to the satellite and back again. It causes a slight delay between the request and the answer.107Sunil Kumar Sahu,Lecturer RCET This technology is a method by which Internet content is downloaded to a satellite dish and then transmitted directly from the dish to the users PC. Download speeds are typically about 600 kbps.This option may be particularly appealing to those who already have a satellite dish for TV purposes,With two-way satellite .or uploading and downloading-- internet access, the satellite company serves as the ISP, and the cost is around $40 to $ 70 per month.Satellite dishes capable of carrying Internet data cost around $250. Unlike its cable and telephone counterparts, satellite technology is not faced with the problem of pulling wire through the desert and over mountains108Sunil Kumar Sahu,Lecturer RCETSatellite Connection



111Sunil Kumar Sahu,Lecturer RCETSunil Kumar Sahu,Lecturer RCET112EMAIL ARCHITECTURETo explain the architecture of e-mail, we give four scenarios. We begin with the simplest situation and add complexity as we proceed. The fourth scenario is the most common in the exchange of e-mail.

Refer book- data comm and networking page 861112Sunil Kumar Sahu,Lecturer RCET113Topics Discussed in the Section First Scenario Second Scenario Third Scenario Fourth Scenario113Sunil Kumar Sahu,Lecturer RCET114

Figure 23.1 First scenario

114Sunil Kumar Sahu,Lecturer RCET115When the sender and the receiver of an e-mail are on the same mail server,we need only two user agents.

Note115Sunil Kumar Sahu,Lecturer RCET116

Figure 23.2 Second scenario

116Sunil Kumar Sahu,Lecturer RCET117When the sender and the receiver of an e-mail are on different mail servers,we need two UAs and a pair of MTAs (client and server).

Note117Sunil Kumar Sahu,Lecturer RCET118

Figure 23.3 Third scenario

118Sunil Kumar Sahu,Lecturer RCET119When the sender is connected to the mail server via a LAN or a WAN, we need two UAs and two pairs of MTAs (client and server).

Note119Sunil Kumar Sahu,Lecturer RCET120Figure 23.4 Fourth scenario

120Sunil Kumar Sahu,Lecturer RCET121When both sender and receiver are connected to the mail server via a LAN or a WAN, we need two UAs, two pairs of MTAs (client and server), and a pair of MAAs (client and server). This is the most common situation today.

Note121Sunil Kumar Sahu,Lecturer RCET122Figure 23.5 Push versus pull

122Sunil Kumar Sahu,Lecturer RCET123Figure 23.6 Format of an email

123Sunil Kumar Sahu,Lecturer RCET124Figure 23.7 E-mail address

124PROTOCOLS GOVERNNING THE WEBPROTOCOL:-A protocol is a set of rules that govern data communications. It represents an agreement between the communicating devices. Without a protocol, two devices may be connected but not communicating, just as a person speaking Frenchcannot be understood by a person who speaks only Japanese.A protocol defines what is communicated, how it is communicated, and when it is communicated. The key elements of a protocol are syntax, semantics, and timing

Refer book page -56125Sunil Kumar Sahu,Lecturer RCETThe Defence Advance Research Projects Agency (DARPA) originally developed Transmission Control Protocol/Internet Protocol (TCP/IP) to interconnect various defence department computernetworks.

The Internet, an international Wide Area Network, uses TCP/IP to connect government and educational institutions across the world. TCP/IP is also in widespread use on commercial and private networks126Sunil Kumar Sahu,Lecturer RCETTCP/IP PROTOCOL SUITTCP/IP protocol suit used in the Internet was developed prior to OSI model. It has 5 layers.1.Physical layer2.Datalink layer3.Network layer 4.Transport layer5.Application layer

The first 4 layer provide physical standards,Network interface,internetworking and transport function that correspond to the first 4 layer of OSI model.The three tomost layers in OSI model are represented in TCP/IP by single layer i.e. Application layer.Refer book page 79


Protocol(TCP) and User Datagram Protocol (UDP).

At the network layer, the main protocol defined by TCP/IP is theInternetworking Protocol (IP); there are also some other protocols that support data movement in this layer.128Sunil Kumar Sahu,Lecturer RCET

129Sunil Kumar Sahu,Lecturer RCETPhysical and Data Link Layers:-At the physical and data link layers, TCP/IP does not define any specific protocol. It supports all the standard and proprietary protocols. A network in a TCPIIP internetworkcan be a local-area network or a wide-area network.

Network Layer:-At the network layer (or, more accurately, the internetwork layer), TCP/IP supports the Internetworking Protocol. IP, in turn, uses four supporting protocols: ARP, RARP, ICMP, and IGMP.

130Sunil Kumar Sahu,Lecturer RCETInternetworking Protocol (IP)The Internetworking Protocol (IP) is the transmission mechanism used by the TCP/IP protocols. It is an unreliable and connectionless protocol-a best-effort delivery service. The term best effort means that IP provides no error checking or tracking.IP transports data in packets called datagrams, each of which is transported separately.

Address Resolution Protocol

The Address Resolution Protocol (ARP) is used to associate a logical address with a physical address.ARP is used to find the physical address of the node when its Internet address is known.131Sunil Kumar Sahu,Lecturer RCETReverse Address Resolution ProtocolThe Reverse Address Resolution Protocol (RARP) allows a host to discover its Internet address when it knows only its physical address.

Internet Control Message ProtocolThe Internet Control Message Protocol (ICMP) is a mechanism used by hosts and gateways to send notification of datagram problems back to the sender. ICMP sends query and error reporting messages.

Internet Group Message ProtocolThe Internet Group Message Protocol (IGMP) is used to facilitate the simultaneous transmission of a message to a group of recipients.132Sunil Kumar Sahu,Lecturer RCETTransport LayerTraditionally the transport layer was represented in TCP/IP by two protocols: TCP and UDP. IP is a host-to-host protocol, meaning that it can deliver a packet from onephysical device to another. UDP and TCP are transport level protocols responsiblefor delivery of a message from a process (running program) to another process. A new transport layer protocol SCTP, has been devised to meet the needs of some newe applications.User Datagram ProtocolThe User Datagram Protocol (UDP) is the simpler of the two standard TCP/IP transport protocols. It is a process-to-process protocol that adds only port addresses, checksum error control, and length information to the data from the upper layer.133Sunil Kumar Sahu,Lecturer RCETTransmission Control ProtocolThe Transmission Control Protocol (TCP) provides full transport-layer services to applications. TCP is a reliable stream transport protocol. The term stream, in this context, means connection-oriented: A connection must be established between both ends of a transmission before either can transmit data.Stream Control Transmission ProtocolThe Stream Control Transmission Protocol (SCTP) provides support for newer applications such as voice over the Internet.134Sunil Kumar Sahu,Lecturer RCETApplication LayerThe application layer in TCPIIP is equivalent to the combined session, presentation, and application layers in the OSI model Many protocols are defined at this layer. Like1.SMTP2.FTP3.TELNET4.DNS.6.TFTP5.SNMP and etc.135Sunil Kumar Sahu,Lecturer RCETIntroduction to WebWeb featuresClent/ServerHTTPHyperText Markup LanguageURL addresses

Web server - a computer program that is responsible for accepting HTTP requests from clients and serving them HTTP responses

Web application - a dynamic extension of a web or application server.

Web Applications Basics136Sunil Kumar Sahu,Lecturer RCETWeb Applications & ComponentsTwo types of web applications:Presentation-oriented (HTML, XML pages)Service-oriented (Web services)

Web components provide the dynamic extension capabilities for a web server:Java servletsJSP pagesWeb service endpoints137Sunil Kumar Sahu,Lecturer RCETWeb Application Interaction[client] sends an HTTP request to the web server

[web server] HTTP request HTTPServletRequest

This object is delivered to a web component, which can interact with JavaBeans or a DB to generate dynamic content

[web component] generates an HTTPServletResponse or pass the request to another web component

[web server] HTTPServletResponse HTTP response

[web server] returns HTTP response to the client138Sunil Kumar Sahu,Lecturer RCETWeb Application Interaction

139Sunil Kumar Sahu,Lecturer RCETWeb ComponentsServlets - Java classes that dynamically process requests and construct responses.

JSP pages - text-based documents that execute as servlets but allow a more natural approach to creating static content

Appropriate usageServlets - service-oriented applications, control functionsJSP - generating text-based markup (HTML, SVG, WML, XML)140Sunil Kumar Sahu,Lecturer RCETJava Web Application TechnologiesJava Servlet technology is the foundation of all the web application technologies

141Sunil Kumar Sahu,Lecturer RCETWeb ContainersWeb components are supported by the services of a runtime platform called a web container.

Web container services: request dispatching security concurrencylife-cycle managementnaming, transactions, email APIs142Sunil Kumar Sahu,Lecturer RCETWeb Container ExamplesNon-commercialApache TomcatJetty

CommertialSun Java System Application Server BEA WebLogic ServerOracle Application ServerWebSphere

Open sourceJBoss

143Sunil Kumar Sahu,Lecturer RCETDeploymentWeb components have to be installed or deployed to the web container

Aspects of web application behaviour can be configured during application deployment

The configuration information is maintained in a XML file called a web application deployment descriptor144Sunil Kumar Sahu,Lecturer RCET

network is a group of two or more computers or communicating devices that are able to communicate...

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