Practical TCP/IP and Ethernet Networking- P2: The transmitter encodes the information into a suitable form to be transmitted over the communications channel. The communications channel moves this signal as electromagnetic energy from the source to one or more destination receivers. The channel may convert this energy from one form to another, such as electrical to optical signals, whilst maintaining the integrity of the information so the recipient can understand the message sent by the transmitter | Contents Preface xvii J Introduction to communications Data communications 1 Transmitters receivers and communication channels 2 Interface standards 2 Coding 3 Protocols 3 Some commonly used communications protocols 3 Types of communication channels 4 Analog communication channels 4 Communications channel properties 4 Signalattenuation 4 Channel bandwidth 6 Noise 7 Data transmission modes 8 Direction of signal flow 8 Synchronization of digital data signals 9 Asynchronous transmission 10 Synchronous transmission 11 Encoding methods 12 Manchester 12 Differential Manchester 12 RZ return to zero 12 NRZ non-return to zero 13 MLT-3 13 4B 5B 13 Error detection 14 Cyclicredundancycheck CRC 14 2 Networking fundamentals 15 Overview 15 Network communication 16 Circuitswitching 17 Packet switching 17 Datagrams and virtual circuits 17 Types of networks 18 Local area networks LANs 18 Wide area networks WANs 18 Metropolitan area networks MANs 19 vi Contents Couplingratio 19 Virtual private networks VPNs 20 The open systems interconnection model 20 Open and closed systems 20 The open systems interconnection reference model OSI model 21 OSI layer services 25 Application layer 25 Presentation layer 26 Session layer 26 Transportlayer 26 Network layer 27 Data link layer 27 Physicallayer 28 Interoperability and internetworking 28 Protocols and protocol standards 30 IEEE ISO standards 31 Network topologies 33 Broadcastandpoint-to-pointtopologies 33 Logical and physical topologies 34 Bus topology 35 Star topology 36 Ring topology 36 Other types of topology 38 Star-wiredringtopology 38 Distributedstartopology 38 Meshtopology 39 Treetopology 39 .
