About the Presentations

CNIT 276Module 1Module 1Why Use Networks?NetworkGroup of computers and devicesConnected by transmission mediaStand-alone computerNot connected to other computersUses local software and dataAdvantages of networksDevice sharing by multiple usersSaves money and timeCentral network managementModule 1Peer-to-Peer NetworksDirect computer communicationEqual authorityIndividual resource sharingMay share resourcesMay prevent access to resources

Module 1Peer-to-Peer Networks (contd.)AdvantagesSimple configurationLess expensiveCompared to other network modelsDisadvantagesNot flexibleNot necessarily secureNot practical for large installationsModule 1Client/Server NetworksServerCentral computerFacilitates communication and resource sharingClientsPersonal computersAlso known as workstationsCentral resource sharing controlled by serverSharing data, storage space, devices

Module 1Client/Server Networks (contd.)Advantages relative to peer-to-peer networksUser credential assigned from one placeMultiple shared resource access centrally controlledCentral problem monitoring, diagnostics, correction capabilitiesOptimized to handle heavy processing loadsCan connect many computers on a networkModule 1LANs, MANs, and WANsLAN (local area network)Network confined to a relatively small space1980sLANs became popular as peer-to-peer basedTodayLarger and more complex client/server networkMAN (metropolitan area network)Connects clients and servers from multiple buildingsUses different transmission media and technology than LAN

Module 1LANs, MANs, and WANs (contd.)WAN (wide area network)Connects two or more geographically distinct LANs or MANsUses different transmission methods and media than LANNetwork connectionSeparate offices in same organizationSeparate offices in different organizationsSimple Physical TopologiesPhysical topologyPhysical network nodes layoutDoes not specify:Device typesConnectivity methodsAddressing schemesFundamental shapesBus, ring, starHybridModule 19BusBus topologySingle cableConnects all network nodesPhysical mediumCoaxial cableModule 110A terminated bus topology networkModule 1Courtesy Course Technology/Cengage Learning

11RingRing topologyNode connects to nearest two nodesCircular networkClockwise data transmissionOne direction (unidirectional) around ringActive topologyWorkstation participates in data deliveryData stops at destinationPhysical mediumTwisted pair or fiber-optic cablingModule 112Ring (contd.)DrawbacksMalfunctioning workstation can disable networkNot very flexible or scalableModule 1

A ring topology networkCourtesy Course Technology/Cengage Learning13StarStar topologyNode connects through central deviceRouter or switchPhysical mediumTwisted pair or fiber-optic cablingSingle cable connects only two devicesAdvantageFault tolerantFlexibleModule 114Star (contd.)Most popular fundamental layoutModern Ethernet networks based on star topologyModule 1A star topology networkCourtesy Course Technology/Cengage Learning

15OSI ModelModule 1Table 2-1 Functions of the OSI layersCourtesy Course Technology/Cengage Learning

16TCP/IP ModelLayerDescriptionApplicationThe Application layer corresponds to the Session, Presentation, and Application layers of the OSI model. Protocols associated with the Application layer include FTP, HTTP, Telnet, Smtp, DNS, and SNMP.Host-to-hostThe Host-to-host layer is comparable to the Transport layer of the OSI model and is responsible for error checking and reliable packet delivery. Protocols associated with the Host-to-host layer includeTransport Control Protocol (TCP) and User-Datagram Protocol (UDP).InternetThe Internet layer is comparable to the Network layer of the OSI model. It is responsible for moving packets through a network. Protocols associated with the Internet layer include Address Resolution Protocol (ARP), Internet Control Message Protocol (ICMP), and Internet Group Management Protocol (IGMP).Network AccessThe Network Access layer corresponds to the functions of the Physical and Data Link layers of the OSI model. It is responsible for describing the physical layout of the network and how messages are formatted on the transmission medium.Module 1The TCP/IP model incorporates the general concepts and structure of the OSI model. The layers of the TCP/IP model are as follows:Module 1

Figure 4-1 The TCP/IP model compared with the OSI modelCourtesy Course Technology/Cengage Learning18