Glossary of NGI Terms
Networking Fundamentals
network
A computer network is an interconnected (i.e. able to exchange information) collection of computers. These computers may or may not be autonomous (two computers are autonomous if neither can forcibly start, stop or control the other).
internet (or internetwork)
An internet is a collection of interconnected networks (not to be confused with the Internet, the term used to describe the specific worldwide network thta is widely used to connect universities, government offices, companies, and of late, private individuals).
open systems interconnection (OSI) reference model
A model of communications between cooperating devices (such as computers on a computer network). It defines a seven-layer architecture of communication functions.
physical layer
Layer 1 of the OSI model; concerned with the electrical, mechanical, and timing aspects of signal transmission over a medium.
data link layer
Layer 2 of the OSI model; this layer provides service to transfer data between nnetwork layer (see below) entities, usually in adjacent nodes. This layer detects and possibly corrects errors that may occur in the physical layer.
network layer
Layer 3 of the OSI model; this layer is responsible for routing data (network packets) through and between communication networks.
transport layer
Layer 4 of the OSI model; this layer reliable, transparent transfer of data between network endpoints.
packet
A packet is a group of bits for transmission over a computer network. It consists of both data and control (such as destination address) information. Usually refers to network layer data.
intermediate system
A device used to connect two networks of an internet and permit communication between end systems attached to different networks.
router
An intermediate system used to connect two networks that may or may not be similar. It makes use of an internet protocol present in each host and every other router of the networks. It operates at the network layer.
switch
A switch is a device with n input lines and m output lines (m and n may or may not be equal) which is capable of routing packets from any input line to any output line. Switches operate at the data link layer or at the network layer (in which case they perform essentially the same functions as routers).
TCP/IP
The Transmission Control Protocol (TCP) is a transport layer protocol; the Internet Protocol (IP) is a network layer protocol. These two protocols are commonly used together. They form the foundation on which the Internet and the World Wide Web have grown.
multicast
Multicast is a mode of transmission in a computer network where a single packet can be addressed and sent to a subset of other machines connected to the same internet.
haptics
Haptics is concerned with allowing humans to interact with machines in general, but in particular with computers using the sense of touch and kinesthesia.
LAN
A local area network (LAN) is a communication network that provides interconnection of a variety of data communicating devices within a small area.
WAN
A wide area network (WAN) is a communication network that spans a large geographical area, often a country or continent.
VPN
A private network is composed of computers owned by a single organization that share information specifically with each other. A virtual private network (VPN) is a secure, private network created over a public network such as the Internet. A VPN can be created using software, hardware, or a combination of the two.
encryption
The conversion of plaintext or data into unintelligible form by means of a reversible translation, based on a translation table or algorithm.
authentication
A process used to verify the integrity of transmitted data, especially a message.
bandwidth
Network bandwidth is the amount of data that can be transmitted over the network in a fixed amount of time. It is usually expressed in bits per second, or bytes per second.
throughput
Throughput between two network entities is the amount of data transferred from one entity to the other in a specified amount of time. It can also be thought of as average bandwidth use.
latency, or delay
The amount of time it takes a packet to travel from source to destination.
jitter
Jitter is the variation or variability of network delay.
priority
The preferential rating of a packet in a network that is used to decide contention between packets for a network resource.
quality of service
Quality of service (QoS) means providing consistent, predictable data delivery service. The focus of QoS is providing predictable service during periods of congestion.