Introduction to Computer Networks and Data Communications - Lecture 10

Lecture 10Introduction to Computer Networks and Data CommunicationsSummary of PreviousIn the previous lecture we have learnt,Managing business dataMS Access 2007Purpose and Data OrganizationCreating a DatabaseTableFormQueryReportSummary of PreviousData PresentationPurpose and Types of presentationsMicrosoft Power PointA New presentationDesign TemplatesAnimationSlide MasterAdding PicturesWorking With TextGraphs and Charts4Today’s TopicsIntroduction to TelecommunicationsBasic Components of Communications Telecommunications Media Rate of data transferDefine the basic terminology of computer networksNetwork TopologyClassification of Computer NetworksNetwork DevicesRecognize the individual components of the big picture of computer networksToday’s Topics Computer Network LayoutsMicrocomputer-to-local area networkMicrocomputer-to-InternetLocal area network-to-local area networkPersonal area network-to-workstationLocal area network-to-metropolitan area networkLocal area network-to-wide area networkToday’s TopicsSensor-to-local area networkSatellite and microwaveCell phonesComputer terminal / microcomputer-to-mainframeSummary7IntroductionEveryone is using a computer network today.Mass transit, interstate highways, 24-hour bankers, grocery stores, cable television, cell phones, businesses and schools, and retail outlets support some form of computer networkWhat is Telecommunication?Transmission of different forms of data such as text, audio, video, images, graphics It occurs between one set of electronic devices over media to another set of geographically separated electronic devices.Basic Components of CommunicationsSender: Person or device sending the messageReceiver: Person or device receiving the messageMedium: What carries the message from sender to receiverSender PersonReceiver PersonChannel/Medium A short distance of airMessage VoiceFace-to-face CommunicationSender Telephone, Computer, Video ConferencingChannel/Medium Various Types of Electronic MediaMessage Voice, Data Video, etc.Receiver Telephone, Computer, Video ConferencingTelecommunicationsTelecommunications MediaCommunications media - the paths, or physical channels, in a network over which information travels.Wired communications media - transmit information over a closed, connected path. Wireless communications media - transmit information through the air.Telecommunications MediaTelecommunication – Rate of data transferData transmission channels (bps)narrow bands: 5-30voice bands: 1,000-9,600broad bands: 100,000Computer Networks16What is Computer Network?Computer network is an interconnection of computers and computing equipment using either wires or radio waves over small or large geographic areasNetwork Topology – Connecting ComputersThe network topology defines the way in which computers, printers, and other devices are connected. A network topology describes the layout of the wire and devices as well as the paths used by data transmissions. Bus TopologyCommonly referred to as a linear bus, all the devices on a bus topology are connected by one single cable.Bus TopologyRing TopologyA network configuration in which computers are arranged in the form of a ring using twisted-wire, coaxial cable, or fiber optics. Messages are transmitted in one direction to all devices between the sending node and the receiving node.Ring TopologyStar TopologyA topology in which a central host computer receives all messages and then forwards the message to the appropriate computer on the network.Star TopologyMesh TopologyThe mesh topology connects all devices (nodes) to each other for redundancy and fault tolerance. It is used in WANs to interconnect LANs and for mission critical networks like those used by banks and financial institutions. Implementing the mesh topology is expensive and difficult. Classification of Computer NetworksDifferent Types of Network ExistsLocal area network Networks that are small in geographic size spanning a room, floor, building, or campusTypesMetropolitan area network Networks that serve an area of 1 to 30 miles, approximately the size of a typical cityMANMAN networks are generally good for businesses and organizations that have multiple locations around a city. A bank may also take advantage of a MAN.TypesWide area networka large network that encompasses parts of states, multiple states, countries, and the worldTypesPersonal area network a network of a few meters, between wireless devices such as PDAs, laptops, and similar devicesTypesVoice networka network that transmits only telephone signals (almost extinct)Data network a network that transmits voice and computer data (replacing voice networks)32Computer Network Popular TermsData communications – the transfer of digital or analog data using digital or analog signalsTelecommunications – the study of telephones and the systems that transmit telephone signals (becoming simply data communications)Popular TermsNetwork management – the design, installation, and support of a network, including its hardware and softwareNetwork cloud – a network (local or remote) that contains software, applications, and/or data34The Big Picture of NetworksNetworks are composed of many devices, including:Workstations (computers, tablets, wireless phones, etc)ServersNetwork hubs and switches Routers (LAN to WAN and WAN to WAN)Telephone switching gear35The Big Picture of Networks (continued)Network DevicesWorkstations They are personal computers/microcomputers (desktops, laptops, net books, hand held, etc.) where users resideServers, They are the computers that store network software and shared or private user filesNetwork DevicesSwitches, They are the collection points for the wires that interconnect the workstationsRouters, They are the connecting devices between local area networks and wide area networksA SwitchA Switch with Network PortsRJ-45 and Network CablesA Network RouterComputer Network Layouts41Basic Layouts of Communication networksMicrocomputer-to-local area networkMicrocomputer-to-InternetLocal area network-to-local area networkPersonal area network-to-workstationLocal area network-to-metropolitan area network42Local area network-to-wide area networkSensor-to-local area networkSatellite and microwaveCell phonesComputer terminal / microcomputer-to-mainframeBasic Layouts of Communication networks43Highly common throughout business and academic environments, and now homesTypically a medium- to high-speed connectionComputer (device) requires a NIC (network interface card)NIC connects to a hub-like device (switch)Micro Computer to Local Area Network Layout44Microcomputer-to-Local Area Network Layout (continued)Micro computer to LANGaming Competition46Microcomputer-to-Internet LayoutPopular with home users and small businessesFor some, a dial-up modem is used to connect user’s microcomputer to an Internet service providerTechnologies such as DSL and cable modems are replacing modems47Microcomputer-to-Internet Layout (continued)Dialup Connections49Local Area Network-to-Local Area Network LayoutFound in systems that have two or more LANs and a need for them to intercommunicateA bridge-like device (such as a switch) is typically used to interconnect LANs50Local Area Network-to-Local Area Network Layout (continued)Hardware that connects computers to one another on a local network.51Personal Area Network-to-Workstation LayoutInterconnects wireless devices such as PDAs, laptops and notebooks, and music playback devicesUsed over short distances such as a few meters52Personal Area Network-to-Workstation Layout (continued)Example54Local Area Network-to-Metropolitan Area Network LayoutUsed to interconnect companies (usually their local area networks) to networks that encompass a cityHigh-speed networks Typically, this interconnection uses only fiber-optic links55Local Area Network-to-Metropolitan Area Network Layout (continued)56Local Area Network-to-Wide Area Network LayoutOne of the most common ways to interconnect a user on a LAN workstation to the Internet (a wide area network)A router is the typical device that performs LAN to WAN connectionsRouters are more complex devices than switchesData Communications and Computer Networks: A Business User's Approach, Sixth Edition57Local Area Network-to-Wide Area Network Layout (continued)58Wide Area Network-to-Wide Area Network LayoutHigh-speed routers and switches are used to connect one wide area network to anotherThousands of wide area networks across Pakistan, many interconnected via these routers and switches59Sensor-to-Local Area Network LayoutNot all local area networks deal with microcomputer workstationsOften found in industrial and laboratory environmentsAssembly lines and robotic controls depend heavily on sensor-based local area networks60Sensor-to-Local Area Network Layout (continued)61Satellite and Microwave LayoutTypically long distance wireless connectionsMany types of applications including long distance telephone, television, radio, long-haul data transfers, and wireless data servicesTypically expensive services but many companies offer competitive services and ratesNewer shorter-distance services such as Wi-Max62Satellite and Microwave Layout (continued)63Cell Phone LayoutExpanding market across the world specially Pakistan.Third generation services available in many areas and under many types of plans with fourth generation services starting to appearLatest generation includes higher speed data transfers (100s to 1000s of kilobits per second)64Cell Phone Layout (continued)65Terminal/Microcomputer-to-Mainframe Computer LayoutPredominant form in the 1960s and 1970sStill used in many types of businesses for data entry and data retrievalFew dumb terminals left today, e.g. Telnet66Terminal/Microcomputer-to-Mainframe Computer Layout (continued)67One More LayoutAn Additional Basic layout – telephone-to-networkTelephone systems are ubiquitous and now carry more data than voiceVoice over IP – telephone-to-LAN via gateway or telephone to gateway via DSL/cableSummaryWe have been discussed aboutTelecommunication essentialsComputer NetworksDefinitionTopologyClassificationLayoutsWe have understood that using network we can perform day to day business functions.Depending upon the types and nature of business we want to set up our computer network.