1Introduction to Networking & TelecommunicationsSchool of BusinessEastern Illinois University © Abdou Illia, Fall 2014(August 27, 2014)2Meaning of star symbols Something to which you should pay special attention. Multiple stars are for especially important or difficult material3Learning ObjectivesYou should be able to describe basic Networking Concepts in wide use today: Basic terminology of computer networks Voice and Video Communications Versus Data Communication Circuit Switching Versus Packet Switching Components of a computer network24Computer Network An interconnection of computers and computing equipment using either wires or radio waves over small or large geographic distances“Connect to GHI”ABCDEFGHIJKLMNO5Computer Network Local area network - networks that are small in geographic size spanning a room, building, or campus Metropolitan area network - networks that serve an area of up to 40 miles - approximately the area of a typical city Wide area network - a large network that encompasses parts of states, multiple states, countries, and the world6Why Networking ? Resource sharing– Sharing hardware (printers, processors, etc.)– Sharing software (programs, data files) High reliability– Could set automatic backup of programs and data at different locations– Fault tolerance (if one server is down, another provides service. If a disk fails, a mirror disk may be available) Cost saving Communication tool– Internal email service– Remote Access service37The Language of Computer Networks Voice network - a network that transmits telephone signals Voice communication - Transmission of analog data(specifically spoken words) usually between people Telecommunication - the study of telephones and the systems that transmit telephone signals Data network - a network that transmits computer data Data communication - the transfer of digital or analog datausing digital or analog signals8Voice & Data Communication Originally, There was a Sharp Distinction:– Voice Communication– Data Communication, in which one or both parties is a computer Database Electronic mail World Wide Web Distinction is fading because voice communication is increasingly computer-based9Circuit Switching and Reserved Capacity – Circuit capacity is reserved during duration of each call– At each switch– On each trunk lineCircuitReservedCapacityReservedCapacity410Pros and cons of Reserved Capacity Nothing like the congestion on the Internet Reserved Circuit Capacity is Expensive– Have to pay for it whether you use it or not– Good for voice, because conversations are fairly constant– Bad for data, because most data transmission is bursty; e.g., in World Wide Web, download, then stare at screen for a long time until next download11Packet-Switching Data Networks Packet Switching– Large messages are broken into small pieces called packets (or frames)– Packets are short (averaging a few hundred bytes) because networking devices handle short messages more efficientlyMessagePackets12Packet-Switching Data Networks Multiplexing– Packets from many conversations are mixed (multiplexed) over each trunk lineMultiplexing onTransmission LinePacket Switching513The Big Picture of Networks.14The Big Picture of NetworksWorkstationsPCs or terminals used to receive services form the NetworkServersComputers that store the Network software and shared or private user fileshubs (or switches)Collection points for wires that interconnect WorkstationsBridgesConnecting devices between separate LANsRoutersConnecting devices between LANs and WANsNodesAny computer (or computing device) connected to a network.15Elements of a Simple LANHub or SwitchMedia616Elements of a Simple LANHub or SwitchMediaHub or Switch: Devicethat connect all stationsMedia: Wired or Wireless transmission media used to transfer data.17Elements of a Simple LANClient PCClient PCClient PCs are used byordinary managers andProfessionals. Receive servicesServers provide servicesto client PCs18Elements of a Simple LANFigure 1.5: Small PC Network Built on a LANHub or SwitchBusiness Telephone WireNetworkInterfaceCardNICClientPCSe rv e rNIC: Device that provides a dedicated connection to the network. Includes a physical address called MAC address7191.Station A transmitsto the Hub2.Hub broadcaststo all stationsStation C must wait,or its signal willcollide with Station A'ssignalStationAStationBStationCStationAStationBStationCHub operationHubs split available bandwidth among computers, i.e. with a 100 Mbps hub, the network speed will be 100 Mbps / n (where n is the number of computers)Active hubs include repeater capabilities for regenerating signals.Passive hubs don't regenerate signals. Limited to a 30meter distance apart from computers.(Except sending station)20Switch operationStationCStati onDSwitchStationBStation ATransmitsto Station CSwitch SendsSignal out aSingle Port162345StationAStation BTransmitsSimultaneouslyto Station DSwitches send out a single port: destination port.Most switches can efficiently handle simultaneous transmissionsSwitches provide a full bandwidth to all connected computers.Switching tableMAC Address PortA1-44-D55-1F-AA-4C 1 (Station A)B2-CD-13-5B-E4-65 2 (Station B)C3-2D-55-3B-A9-4F 5 (Station C);;21Summary Questions a) Define the following:– Computer Network  Data communications– Voice Network b) Distinguish between voice and data communications. c) Distinguish between circuit switching and packet switching.  d) List and explain the elements of a Simple Network4,789-1215-822Summary Questions (cont.) What category of network is illustrated here?23Summary Questions (cont.) What category of network is illustrated