Data Communications

Data Communications

Pertains to the actual physical connection of the DTE and DCE.Typically, the signal and control leads are bundled into a cable with a terminator plug, male or female, at each end.DTE and DCE must be of opposite gender.MechanicalData Communication NetworkingNSAre the collection of devices that wishes to communicateMay be in the form of computers, terminals, telephones, or other communicating devicesStationsData are transferred from source to destination through a series of intermediate nodesCircuit-switched network does have a dedicated path which is a connected sequence of physical links between nodesPacket-switched network data are sent out in a sequence of small chunks.

Switch Communication NetworkThere are no intermediate switching nodesPacket radio network stations are w/in transmission range of each other and broadcast directly to each otherSatellite network data are not directly transferred from Tx to Rx but are relayed via satelliteLocal networks it is a communication network which happens to be confined to a small area Broadcast Communication NetworkCOMPUTERCOMMUNICATIONSARCHITECTUREThe exchange of information between computers for the purpose of cooperative actionParamounting concepts of protocols and computer communications architectureImportant elements of protocol are: syntax, semantics and timingComputer CommunicationsNetwork ServicesNetwork ServicesFTFTCommunication NetworkAOPSTSPLayer 7 Application LayerLayer 6 Presentation LayerLayer 5 Session LayerLayer 4 Transport LayerLayer 3 Network LayerLayer 2 Data Link LayerLayer 1 Physical LayerOpen Systems Interconnection ModelDATAENCODINGDIGITAL DATA, DIGITAL SIGNAL

ANALOG DATA, DIGITAL SIGNAL

DIGITAL DATA, ANALOG SIGNAL

ANALOG DATA, ANALOG SIGNALINTERFACINGGeneric Interface to Transmission MediumDigital Data Tx/RxTxn Line Interface DeviceDigital Data Tx/RxTxn Line Interface DeviceSignal and control leadsBit Serial Transmission MediumDCEDTEMechanicalElectricalFunctionalProceduralSignificant Characteristics of Interfacing25-pin connector with specific arrangement of leadsMore negative -3V as binary 1 and more than 3V as binary 0Signal rate of