UNIT-1 DCCN Notes

 

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This document provides an introduction to Data Communication and Computer Networks, starting with the fundamentals of data communication, which is the exchange of data between two devices via a transmission medium. The effectiveness of a data communications system relies on delivery, accuracy, timeliness, and jitter. The five key components of a data communication system are the message, sender, receiver, transmission medium, and protocol. Communication between devices can be classified by data transmission mode: simplex (unidirectional), half-duplex (both transmit/receive, but not simultaneously), or full-duplex (both transmit/receive simultaneously). The document also covers network concepts, including criteria like performance, reliability, and security. Key network categories, such as Local Area Networks (LANs), Metropolitan Area Networks (MANs), and Wide Area Networks (WANs) are outlined. Furthermore, it details network physical structures, discussing point-to-point versus multipoint connections and the four basic topologies: mesh, star, bus, and ring.

The specific topics covered are:

• OSI Model (Open Systems Interconnection): A layered framework for the design of network systems that allows communication between all types of computer systems, consisting of seven separate but related layers.
• TCP/IP Protocol Suite (Transmission Control Protocol/Internet Protocol): A hierarchical protocol made up of interactive modules, originally defined with four layers: host-to-network, internet, transport, and application.
• Data Transmission and Modes: The transfer of binary data across a link, which can be accomplished in either parallel (multiple bits simultaneously) or serial (one bit at a time) modes, with serial transmission further categorized as asynchronous, synchronous, and isochronous.
• Multiplexing: The set of techniques that allows the simultaneous transmission of multiple signals across a single data link, including Frequency-Division Multiplexing (FDM), Wavelength-Division Multiplexing (WDM), and Time-Division Multiplexing (TDM).
• Switching: A better solution than fully meshed or star topologies for large networks, where interlinked nodes called switches create temporary connections between two or more devices, with traditional methods including circuit switching, packet switching, and message switching.