NetworKing Terms

10base-2

The version of Ethernet that uses thin coaxial cable. The name is derived from the speed of the network (10Mbps), the signaling type (baseband), and the maximum cable length (almost 200 meters).

10base-T

The version of Ethernet that uses twisted-pair cabling. The name is derived from the speed of the network (10Mbps), the signaling type (baseband), and the cable type (twisted pair).

100base-T

An extension to the 10base-T standard describing twisted-pair networks that operate at 100Mbps.

802.3

The IEEE standard that describes the CSMA/CD medium access method used in Ethernet networks.

802.5

The IEEE standard that describes the medium access method used in Token Ring networks.

ADSI (Analog Display Services Interface)

A service allowing voice mail to be viewed on your PC screen. Instead of pressing number keys on the telephone to access voice mail functions, you can use your PC to view and control incoming voice mail. A special communications server on the network handles the incoming voice mail.

ADSL (Asymmetrical Digital Subscriber Line)

A high-speed modem technology that provides data services, such as Internet access, over existing telephone lines. ADSL has a downstream (to the subscriber) data transfer rate of at least 1.5Mbps. Subscribers located within two miles of the telephone office can attain downstream speeds as high as 6.2Mbps. Upstream data rates vary from 16Kbps to 640Kbps, depending on line distance. See also asymmetrical transmission.

ANSI (American National Standards Institute)

A private organization involved with setting US standards, often referred to as ANSI standards.

anonymous FTP (Anonymous File Transfer Protocol)

A protocol that allows users to transfer files between TCP/IP-connected computers. A user will log in to an FTP server using anonymous as the user ID and guest as the password. This process gets a user into a special, usually restricted, area of the FTP server.

AppleTalk

A seven-layer protocol stack designed by Apple Computers that allows the sharing of files and printers and the sending of traffic between computers. Its primary design goal was to give the AppleTalk user a simple plug-and-play environment in which the user does not need to be concerned with the details of network configuration.

Application layer

Layer 7 of the seven-layer OSI model. The application layer is responsible for interfacing with the user and directing input from the user to the lower OSI layers. It is the part of the OSI model the user interacts with directly.

ARP (Address Resolution Protocol)

A protocol, described in RFC 826, used to determine the hardware address of another computer on a network. ARP is used when a computer may know the destination computer's IP address, but does not know the destination computer's hardware address. The sender broadcasts an ARP packet and the device that recognizes its own IP address responds with the unknown hardware address.

ASCII (American Standard Code for Information Interchange)

A character set in which each letter, number, or control character is made up of a 7-bit sequence. The term ASCII is sometimes erroneously used when referring to Extended ASCII, an 8-bit character set.

Asymmetrical Transmission

A transmission method developed to overcome the high cost of high-speed full-duplex transmission. In essence, a line's bandwidth is broken up into two subchannels: the main channel and the secondary channel. The main channel contains the majority of the line's bandwidth, the secondary channel contains only a small portion. The unequal division of bandwidth results in an unequal data transfer rate, but allows service providers to overcome signal-coupling problems in large telephone cable plants.

Asynchronous Communications

A type of data transmission in which each character transmitted (8 bits) is framed by a start and stop bit. These two control bits delineate the beginning and end of a character. Though there is more flexibility with asynchronous transmission, it is much less efficient because the addition of the control bits increases the packet size by 25percent.

AT Command Set

The modem command set developed by Hayes, Inc. that has become the de facto standard for programming modems.

ATM (Asynchronous Transfer Mode)

A high-speed connection-oriented switching technology that uses 53-byte cells (packets) to simultaneously transmit different types of data, including video and voice. ATM is an attractive technology because it provides dedicated bandwidth at speeds ranging from 25Mbps to 655Mbps.

AUI (Attachment Unit Interface)

The cable that attaches from a MAU or transceiver to a computer. The AUI cable consists of 15-pin D-shell type connectors, female on the computer end and male on the transceiver end.

Authentication

The computer security process of verifying a user's identity or the user's eligibility to access network resources. See also public key encryption.

Autonomous System

A group of routers or networks that fall under one network administrative organization. Autonomous systems usually run on a single routing protocol.

B-Channel

A 64Kbps ISDN channel used to transmit voice or data. The standard BRI connection contains two B-channels, for a total uncompressed capacity of 128Kbps.

Backbone

A network that interconnects individual LANs and that typically has a higher capacity than the LANs being connected. One exception is a T-1 backbone connecting a WAN connecting two 100Mbps Ethernet LANs at either end of the backbone. In this case, the LANs have a much higher capacity than the backbone.

Backoff

From CSMA/CD, when a collision occurs on a network, the computer sensing the collision calculates a time delay before trying to transmit again. This time delay is referred to as backoff.

Balun

An impedance-matching device used when connecting different types of cable to each other. For example, a balun is required to connect twisted pair cable to coaxial cable on an Ethernet network.

Bandwidth

The width of the passband or the difference between the highest and lowest frequencies in a given range. For example, the human voice has a passband of approximately 50Hz to -15,000Hz, which translates to a bandwidth of 14,950Hz.

baseband

A type of transmission that uses digital signals to move data. Because the signal is digital, the entire bandwidth of the cable is used.

BER (Bit Error Rate)

The ratio of received bits that are in error. Diagnostic cable-checking tools sense BER by transmitting a stream of data on one end of a cable and reading the output from the other end.

Best-Effort Delivery

A network function where an attempt is made at delivering data; however, if an error such as line failure occurs, it does not attempt recovery. There is no mechanism in best-effort delivery to buffer data then retransmit it once the failure has been resolved.

BISDN (Broadband ISDN)

The next generation of ISDN service. BISDN is a fiber-optic-based service using asynchronous transfer mode (ATM) over SONET-based transmission circuits. The service is designed to handle high-bandwidth applications, such as video, at rates of 155Mbps, 622Mbps, and higher.

BONDING (Bandwidth ON Demand INteroperability Group)

An ISDN consortium name and the technique of inverse multiplexing they developed. Data is broken up into a stream of frames, each stream using a portion of the total available bandwidth. If your ISDN configuration has two B-channels, each with 64Kbps, your equipment will allow a data rate of 128Kbps by splitting the data.

BOOTP (BOOTstrap Protocol)

A protocol designed to allow diskless workstations to boot onto an IP network. A single BOOTP message contains many pieces of information needed by a workstation at startup, such as an IP address, the address of a gateway, and the address of a server. A workstation that boots up requests this information from a BOOTP server.

Lot more Terms Coming soon