Computer Networks

Introduction to Data Communication

Data communication is the transfer of data from one device to another via some form of transmission medium.A data communications system must transmit data to the correct destination in an accurate and timely manner. The five components that make up a data communications system are the message, sender, receiver, medium, and protocol.

Text, numbers, images, audio, and video are different forms of information.Data flow between two devices can occur in one of three ways: simplex, half-duplex, or full-duplex. A network is a set of communication devices connected by media links. In a point-to-point connection, two and only two devices are connected by a dedicated link. In a multi-point connection, three or more devices share a link.

Topology refers to the physical or logical arrangement of a network. Devices may be arranged in a mesh, star, bus, or ring topology.A network can be categorized as a local area network (LAN), a metropolitan-area network (MAN), or a wide area network (WAN). A LAN is a data communication system within a building, plant, or campus, or between nearby buildings. A MAN is a data communication system covering an area the size of a town or city. A WAN is a data communication system spanning states, countries, or the whole world. An internet is a network of networks.

The Internet is a collection of many separate networks. TCP/IP is the protocol suite for the Internet. There are local, regional, national, and international Internet service providers (ISPs). A protocol is a set of rules that governs data communication; the key elements of a protocol are syntax, semantics, and timing. Standards are necessary to ensure that products from different manufacturers can work together as expected.

The ISO, ITU-T, ANSI, IEEE, and EIA are some of the organizations involved in standards creation. Forums are special-interest groups that quickly evaluate and standardize new technologies. A Request for Comment (RFC) is an idea or concept that is a precursor to an Internet standard.



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