Glossary

The smallest unit of data sent over a network. A packet includes a header with addressing information, and the data itself.

The maximum rate (in bits per second or some multiple thereof) at which data is transmitted in a data transmission link. The data rate may or may not be equal to the baud rate.

A term used for twisted-pair cable that is used in networks to carry data signals. Data-grade media has a higher frequency rating than voice-grade media used in telephone wiring does. Data-grade cable is considered Category 3 or higher cable.

(1) The interface that electronic equipment uses to communicate with a modem or other serial device. This port is often called the computer

A unit of data larger than or equal to a packet. Generally it is self-contained and its delivery is not guaranteed.

Also known as D type/ D Sub/ D type Sub miniature
D type connectors are used as serial port connectors.

The D refers to the shape of the connector. A D9W connector for instance as you can see below means it is a 9 pin connection interface.

This connector also commonly comes as a 15 way or 25 way although can go up to a 72 way.

Standard 15-pin connector used with Ethernet transceiver cables.

Standard 25-pin connector used with serial and parallel ports.

Standard 9-pin connector used with Token Ring and serial connections.

The total resistance of a conductor from the near end to the far end and back. For a single conductor, it is just the one-way measurement doubled. For a pair of conductors, it is the resistance from the near end to the far end on one conductor and from the far end to the near end on the other.

A standard unit used to express a relative measurement of signal strength or to express gain or loss in optical or electrical power. A unit of measure of signal strength, usually the relation between a received signal and a standard signal source. The decibel scale is a logarithmic scale, expressed as the logarithmic ratio of the strength of a received signal to the strength of the originally transmitted signal. For example, every 3dB equals 50 percent of signal strength, so therefore a 6dB loss equals a loss of 75 percent of total signal strength. See Chapter 1 for more information.

A set of waveguides having the same propagation constant for all specified frequencies.

The difference in propagation delay between the fastest and slowest pair in a cable or cabling system. See Chapter 1 for more information on delay skew.

In fiber optics, equal to the difference between the indexes of refraction of the core and the cladding divided by the index of the core.

A network access method used by Hewlett-Packard