Section 3 B Terms Flashcards
B8ZS
Binary 8-zero substitution. Line-code type, used on T1 and E1 circuits, in which a special code is substituted whenever 8 consecutive zeros are sent through the link. This code is then interpreted at the remote end of the connection. This technique guarantees ones density independent of the data stream. Sometimes called bipolar 8-zero substitution. Compare with AMI. See also ones density.
Back End
Node or software program that provides services to a front end. See also client, front end, and server.
Back End Processor
A computer running an application that supplies data to other computers on demand, but has no user interface.
Back Pressure
Propagation of network congestion information upstream through an internetwork.
Backbone
Referring to the internet, a central network that provides a pathway for other networks to communicate.
Background Task
A computing task that is executing while another task or application is displaying its user interface.
Backoff
The (usually random) retransmission delay enforced by contentious MAC protocols after a network node with data to transmit determines that the physical medium is already in use.
Backplane
The communication channels of a single device’s architecture, such as in a hub or concentrator.
Backup
A copy of a set of files made for replacement purposes in case the original set is damaged or lost.
Backward Compatible
An upgraded component of a computing system that can be used interchangeably with its previous version.
Backward Learning
Algorithmic process used for routing traffic that surmises information by assuming symmetrical network conditions. For example, if node A receives a packet from node B through intermediate node C, the backward-learning routing algorithm will assume that A can optimally reach B through C.
Balanced Configuration
In HDLC, a point-to-point network configuration with two combined stations.
Balun
Balanced/Unbalanced. A device that links together dissimilar wire types and attempts to minimize any negative effects to the signal that would normally result from the dissimilarity.
Band
In analog communications, the range of frequencies over which a communication system operates.
Bandwidth
In analog communications, the difference between the highest and lowest frequencies available in the band. In digital communications, bandwidth is loosely used to refer to the information-carrying capacity of a network or component of a network.
Bandwidth Reservation
Process of assigning bandwidth to users and applications served by a network. Involves assigning priority to different flows of traffic based on how critical and delay-sensitive they are. This makes the best use of available bandwidth, and if the network becomes congested, lower-priority traffic can be dropped. Sometimes called bandwidth allocation. See also call priority.
BARRNet
Bay Area Regional Research Network. Regional network serving the San Francisco Bay Area. The BARRNet backbone is composed of four University of California campuses (Berkeley, Davis, Santa Cruz, and San Francisco), Stanford University, Lawrence Livermore National Laboratory, and NASA Ames Research Center. BARRNET is now part of BBN Planet.
Base address
The lowest address available in an address range.
Baseband
A communication system in which only one signal is carried at any one time.
Baud
Unit of signaling speed equal to the number of discrete signal elements transmitted per second. Baud is synonymous with bits per second (bps), if each signal element represents exactly 1 bit.
Baud Rate
The number of voltage or frequency transitions per second.
BBN
Bolt, Beranek, and Newman, Inc. High-technology company located in Massachusetts that developed and maintained the ARPANET and later, the Internet, core gateway system.
BBN Planet
Subsidiary company of BBN that operates a nationwide Internet access network composed in part of the former regional networks BARRNET, NEARNET, and SURAnet.
Bc
Committed Burst. Negotiated tariff metric in Frame Relay internetworks. The maximum amount of data (in bits) that a Frame Relay internetwork is committed to accept and transmit at the CIR.
B Channel
Bearer channel. In ISDN, a full-duplex, 64-kbps channel used to send user data. Compare to D channel, E channel, and H channel.
Be
Excess Burst. Negotiated tariff metric in Frame Relay internetworks. The number of bits that a Frame Relay internetwork will attempt to transmit after Bc is accommodated. Be data is, in general, delivered with a lower probability than Bc data because Be data can be marked as DE by the network.
Beacon
Frame from a Token Ring or FDDI device indicating a serious problem with the ring, such as a broken cable. A beacon frame contains the address of the station assumed to be down.
BECN
Backward explicit congestion notification. Bit set by a Frame Relay network in frames traveling in the opposite direction of frames encountering a congested path. DTE receiving frames with the BECN bit set can request that higher-level protocols take flow control action as appropriate. Compare with FECN.
Bellcore
Bell Communications Research. Organization that performs research and development on behalf of the RBOCs.
Benchmark
A test performed t compare a computer process in one set of circumstances to another.
BER
- Bit error rate. The ratio of received bits that contain errors. 2. Basic encoding rules. Rules for encoding data units described in the ISO ASN.1 standard.
BGP
Border Gateway Protocol. Interdomain routing protocol that replaces EGP. BGP exchanges reachability information with other BGP systems. It is defined by RFC 1163.
BGP4
BGP Version 4. Version 4 of the predominant interdomain routing protocol used on the Internet. BGP4 supports CIDR and uses route aggregation mechanisms to reduce the size of routing tables.
BIGA
Bus Interface Gate Array. Technology that allows the Catalyst 5000 to receive and transmit frames from its packet-switching memory to its MAC local buffer memory without the intervention of the host processor.
Big-endian
Method of storing or transmitting data in which the most significant bit or byte is presented first. Compare with little-endian.
Binary
- A numerical system using “2” as its base. 2. Data that is encoded or presented in machine-readable form (1’s & 0’s).