100BaseT – The general name for any of three 100 Mbps Ethernet variants that have just been made a standard by an IEEE 802.3 subcommittee (802.3u). 100BaseT Ethernet is one of the candidates trying to become the standard 100 Mbps Ethernet. This version was developed and proposed originally [... ]

4B/5B Encoding – 4B/5B encoding is a data-translation scheme that serves as a preliminary to signal encoding in FDDI (Fiber Distributed Data Interface) networks. In 4B/5B, every group of four bits is represented as a five-bit symbol. This symbol is associated with a bit pattern that [... ]

Authentication – In network security and other operations, authentication is the process of determining the identity and legitimacy of a user, node, or process. Various authentication strategies have been developed. Among the simplest are the use of user IDs and passwords. A relatively new authentication scheme, called digital signatures [...]

Backbone Network – A backbone network is one with a central cabling scheme (the backbone) to which other networks are attached. Nodes in one network can talk to nodes in other networks by sending packets across the backbone network. The networks attaching to the backbone are known as access networks. Access networks may [...]

Bandwidth – Bandwidth refers to the amount of data a cable can carry; measured in bits per second (bps) for digital signals, or in hertz (Hz) for analog signals such as sound waves. An analog bandwidth is computed by subtracting the lower frequency from the higher one. For example, the bandwidth of the human voice is roughly 2,700 Hz (3,000 – 300). A larger bandwidth means [...]

Channel – A channel is a physical or logical path for a signal transmission. Two particularly important channels in networking are the communications channel and the disk channel. A communications channel is a path through which data or voice can be transmitted; for example, in a network or a telephone call. In telecommunications, a single cable may be able to provide multiple [...]

Collision Detection and Avoidance – In an Ethernet network, a collision is the simultaneous presence of signals from two nodes on the network. A collision can occur when two nodes each think the network is idle and both start transmitting at the same time. Both packets involved in a collision are broken into fragments and must be [...]

IP address – 32-bit address assigned to hosts using TCP/IP. An IP address belongs to one of five classes (A, B, C, D, or E) and is written as 4 octets separated by periods (dotted decimal format). Each address consists of a network number, an optional subnetwork number, and a host number. The network and subnetwork [...]

Protocol – A protocol is a set of predefined rules that govern how two or more processes communicate and interact to exchange data. The processes can be on the same machine or on different machines. For example, a transport-layer program on one machine uses a protocol to talk to the program’s counterpart on another machine. Protocols are generally associated with particular services or tasks, such as data packaging or packet [...]

UTP – unshielded twisted-pair. Four-pair wire medium used in a variety of networks. UTP does not require the fixed spacing between connections that is necessary with coaxial-type connections. There are five types of UTP cabling [...]

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