Chapter 1- Introduction to Computer Networks and Data Communications

Frame

A cohesive unit of raw data. A package of data created at the data link layer of the OSI model.

Local Area Network (LAN)

A communication network that interconnects a variety of data communication devices within a small geographic area and broadcasts data at high data transfer rates with very low error rates.

Server

A computer that stores the network software and shared or private user files.

Switch

A device that is a combination of a hub and a bridge; it can interconnect multiple workstations, but can also filter out frames, thereby providing segmentation of the network.

Client/Server System

A distributed computing system consisting of a server and one or more clients that request information from the server.

Network Layer

A layer in the OSI model and TCP/IP protocol suite that is responsible for creating, maintaining, and ending network connections.

Session Layer

A layer of the OSI model that is responsible for establishing sessions between users and for handling the service of token management.

Presentation Layer

A layer of the OSI model that performs a series of miscellaneous functions that need to be carried out in order to present the data package properly to the sender or receiver.

TCP/IP Protocol Suite

A model of communications architecture that incorporate the TCP/IP protocols and has surpassed the OSI model in popularity and implementation.

Personal Area Network (PAN)

A network that involves wireless transmissions over a short distance, such as a few meters.

Metropolitan Area Network (MAN)

A network that serves an area of 3 to 30 miles - approximately the area of a typical city.

Logical Connection

A non-physical connection between sender and receiver that allows an exchange of commands and responses.

Workstation

A personal computer or microcomputer where users perform computing work.

Computer Terminal

A relatively non-intelligent device that allows a user to input data into a system or displays data from the system.

Protocol

A set of hardware and/or software procedures that allows communication to take place within a computer or through a computer network.

Wireless

A shorthand term often used to denote the transmission of signals without the use of wires.

Token Management

A system that controls who talks during the current session by passing a software token back and forth.

Open Systems Interconnection (OSI) Model

A template that consists of seven layers and defines a model for the operations performed on a computer network.

Network Architecture

A template that outlines the layers of hardware and software operations for a computer network and its applications.

Telnet

A terminal emulation program for TCP/IP networks, such as the Internet, that allows users to log in to a remote computer.

Voice Network

A type of network that is designed to support standard telephone calls.

Hypertext Transfer Protocol (HTTP)

An Internet protocol that allows Web browsers and servers to send and receive World Wide Web pages.

Simple Network Management Protocol (SNMP)

An industry standard created by the internet Engineering Task Force; it was originally designed to manage Internet components, but is now also used to manage wide area network and telecommunications systems.

Computer Network

An interconnection of computers and computing equipment that uses either wires or radio waves over small or large geographic areas.

Data Network

An interconnection of computers that is designed to transmit computer data.

Simple Mail Transfer Protocol (SMTP)

An internet protocol for sending and receiving e-mail.

Wide Area Network

Interconnection of computers and computer related equipment that performs a given function or functions, typically uses local and long-distance telecommunications systems, and can encompass parts of states, multiple states, countries, and even the world.

File Transfer Protocol (FTP)

One of the first services offered on the Internet, its primary functions are to allow a user to download a file from a remote site to their computer, and to upload a file from their computer to a remote site.

Synchronization Point

Some form of backup points that are inserted into a long transmission to serve as markers from which retransmission can be started, in case of error or failures.

Physical Connection

The actual connection between sender and receiver at the physical layer where the digital content of a message (actual 1's and 0's) is transmitted.

Convergence

The coming together of multiple communication concepts to form a single point.

Nodes

The computing devices that allow workstations to connect to the network and that decide which route a piece of data will follow next.

Network Management

The design, installation, and support of a network and its hardware and software.

Router

The device that connects local area networks to a wide area network and at various transfer points within a wide area network.

Technological Convergence

The joining of two or more Technologies into a single device.

Protocol Convergence

The joining of two or more protocols into a single protocol.

Transport Layer

The layer of software in the TCP/IP protocol suite and OSI model that provides a reliable end-to-end network connection

Data Link Layer

The layer of the OSI model that is responsible for transforming the network-layer data into a cohesive unit called a frame.

Physical Layer

The lowest layer of the OSI model; it handles the transmission of bits over a communications channel.

Network Access Layer

The lowest layer of the TCP/IP protocol suite; it defines both the physical medium that transmits the signal, and the frame that incorporates flow and error control.

Industrial Convergence

The merging of two or more companies into a single company.

Cloud

The network sub structure of nodes (routers and switches) at high-speed links.

Encapsulation

The process by which control information is added to a data packet as it moves through the layers of a communication module such as the OSI model or the TCP/IP protocol suite.

Compression

The process of manipulating data such that it fits into a more compact space.

Internet Protocol (IP)

The software that prepares a packet of data so that it can move from one network to another on the Internet or within a set of networks in a corporation.

Application Layer

The topmost layer in the OSI model and the TCP/IP protocol suite; where the network application resides.

Data Communications

The transfer of digital or analog data using digital or analog signals.

Sub-Network

The underlying physical system of nodes and communications links that support a network.

TCP/IP

Transmission Control Protocol/Internet Protocol.

Multiplexing

Transmitting multiple signals on one medium at essentially the same time.