UMMU
`TK
`5102
`.N49
`2002
`bks
`
`OVER 500,000 SOLD
`
`The Authoritative Resource for
`Telecommunications, Networking,
`the Internet and Information Technology
`
`MORE THAN 20 , 000 TERMS DEFINED
`
`c MPBooks
`
`18th Updated and Expanded Edition
`
`by Harry Newton _
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`

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`NEWTflN’s
`TELEBDIVI
`DIBTIIJNARY
`
`

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`
`NEWTON's TELECOM DICTIONARY
`copyright © 2002 Horry Newton
`email: Harry@HarryNewton.com
`personal web site: www.HorryNewton.com
`business web site: www.Technologylnvestor.com
`
`All rights reserved under International and Pon-American Copyright conventions, including
`the right to reproduce this book or portions thereof in any form whatsoever.
`
`Published by CMP Books
`An imprint of CMP Media LLC.
`12 West 21 Street
`New York, NY 10010
`
`ISBN Numbe~ 1-57820-104-7
`
`February 2002
`
`Eighteenth Edition
`
`For individual orders, and for information on special discounts for quantity orders,
`please contact:
`
`CMP Books
`6600 Silacci Woy
`Gilroy, CA 95020
`Tel: l-800-500-6875 or 408-848-3854
`Fox: 408-848-5784
`Web: www.cmpbooks.com
`Email: cmp@rushorder.com
`
`This book is c,lso sold through www.Amozon.com, www.Fotbrain.com and
`www.BornesAndNoble.com
`
`Distributed to the book trade in the U.S. and Canada by Publishers Group West
`1700 Fourth St., Berkeley, CA 94710
`
`Manufactured in the United States of America
`
`

`

`I.A. "fVL 'n l t,(/ bk '>
`<o-; 7 go7[,
`~Ur
`7- 11 -02
`
`Table of Contents
`
`HELP MAKE THIS DICTIONARY EVEN BETTER
`- We offer a real reward . . .... ..... ... . ... ... ........ .. . ... . . . ......... .. ... .. .... ... V
`
`119 BEST DOLLAR-SAVING TIPS
`- How To Save on Telecom, PC, Internet and Airline Expenses and Best Investment Tips .......... .. . ..... . VII
`
`WHY IS IT SO HARD TO BUY?
`- The logic of call centers, customer cares, and buying on the Internet . ... .. . ....... .. . ............. XV
`
`WHERE'S THE TECHNOLOGY GOING?
`- Cheaper, faster and more relioble are obvious trends but there are other less obvious important ones also. . .. . XVII
`
`DISASTER RECOVERY PLANNING
`- How to Make Sure Your Computing and Telecommunications Still Run ... .. .. .. . . . . . ...... ......... XIX
`
`RULES FOLLOWED IN THIS DICTIONARY
`- How to figure our ordering of terms and our spellings ... .. .. ........ . ...... .. .. . ...... . . . ... XXI
`
`ABOUT THE AUTHOR
`- Harry Newton does have a life outside this dictionary .... ... ... . ....... . .... . ... . .. .. .... . .. XXV
`
`ABOUT THE CONTRIBUTING EDITOR
`· Ray Horak teaches, consults and lives in Paradise . ... . . ... . .. . . . ... .......... ... . ......... XXVII
`
`DICTIONARY
`Dictionary begins with Numbers then goes onto Letters . .. ..... . ..... ... . .. .... ... . .. . . . .. . . .... 1
`
`APPENDIX
`- Industry Standards Organizations and their contact information ....... .. . . .. ... ...... . . . .... .... 850
`- International Calling Codes ............ . ... . ....... .. .. . ......... . .. . ... . .. ...... ... 856
`- Standard Plugs and Connectors ........ . ......... .... ... .. . ..... .... ... . ... . ...... .. 858
`
`Ill
`
`

`

`ond Zilog Z-80, we1e installed in 8-bit computers such os the Apple II, the MSAI 8080, and
`the Commodore 64.
`800 The filst •oreo code' for who! AT&I originol~ called In-WATS seriice. See 800
`Service ond 8NN.
`800 Portability 800 Portability refers to the foct thor you can toke your 800 num(cid:173)
`oer to ony long distnll{e carrier. A case example, once I hod 1·800-llBRARY. For mony
`yeors, tho! number was fllOvieded by AT&T. When portobilty come along, we were oble to
`chonge ~ from AT&T 10 MO ond S1il keep l-8()(HJBRARY, v.M is 800-542·7279. 800
`Portobility is prolicled by a series of complex dotuooses the loco! phone companies, under
`FCC mandate, hove built. BOO Portobilty storied on Moy I, 1993. See BOO Se!vice.
`800 Service A toll con paid for by the coiled party, rather than the colling party. A gener·
`ic ond common te1111 for In-WATS (Wide Areo Telecorrnoonicotions Service) service provided
`by o phone company, whether o l!C (loco! Exchange Carrier) or on IX( (lntereXchonge
`Conierl. In North America ond in Older of their introciJclion, ol lhese llrWATS seriices hove
`800 (1967), 888 (1996), 877 (1998), 866 (2000), or 855 (2001) os thei1 ·oreo
`code." (Note: Future 800 numbers will follow the convention 8NN, whe1e NN ore specific
`numbers vihkh ore identicol. Such 800 selVice is typical~ use.l by merchonls offering to sell
`something such os hotel reselVOtions, clothes, or rentol cars. The ideo of the free seMCe is to
`ootice wslomefs to coD the IUllher, with the theruy being !hot if the col was o toll col ooo
`therefore cost the ruslomef somethi~ he or she miJht be le:ss illcined lo col. Supplieis of
`800 services use vorious Wa/S to cootigure ond bill their 800 services.
`800 SelVice works Ike this: You're somewhere in North Amo~co. You dial 1-800, 1-888,
`1-1177, 1-866 or 1·855 ond seven digiis. The LEC (Local Exchange Co1rie1, i.e., the local
`phone company) C8!1trol office sees the ·1 • ond recognizes the coll os long aistonce. It
`also recognizes the 8NN oreo code ond (J)eries o cenho!ize,l ootubose before processing
`the con further, with the query general~ toking ploce over o 557 (Signomg System 7)
`link. The centrolized dotubose resides on o Service Management System (SMS), which is
`o cen~olized computing ploriorm. The dotobose identifies tile lEC or IX( (lnterExchonge
`Conier) providing the 8NN numbei. Based on thot infom10tion, ond assuming thot the toll(cid:173)
`f,ee numbei is ossocilted with on IX(, the l!C switch rootes the coD to the p1oper IXC.
`Once the IXC hos been hooded the con, it piocesses the 800 number, perhaps trolllloting
`it into a ·1eol" telephone number in order lo 10ute it coneclty. Altemativ~, the IX( Irons·
`kites the 800 number into on internol, nonstandard 1 o-digit numbe1 lo1 further routing to
`the terminating Central Office (CO) ond trunk 01 trunk group.
`As o real-life example, the publisher of this book hos on 800 number, 800UBRARY (or
`800-542-7279). When you coil that oomber, MC! routes !hot number to the firs1 ovoifoble
`channel on the dedicated T· l circuit which leased horn MCI's, ooo conne(ting the MCI New
`York City POP (Point Of Presence) to the (MP New York City office.
`Because BOO long distonce sel'lice is essentially o dotobose lookup and tron~otion service
`for iocoming phone coils, there ore endless 'BOO sel'lices' you con create. You con put
`permonoot instructioos into the company to change the routing patterns boSM on lime of
`day, doy of week, number coned, numbei colnng. Some long distance companies allow you
`to chonge your routing inst111ctions from one minute to another. For example, you might
`hove two coll centers into which 800 phone coils ore pou1ing. When one gels busy, you
`moy tell your long distoll{e company to route oU the 800 ill1boood phone coils to the coll
`cente1, m isn't busy. See Eight Hundred Service and One Number Colling for more,
`especially oD the features you con now get on 800 seJ'li<e.
`In Moy of 1993 the FCC mooooted tho! oil BOO (ond by extmn oil BNNJ oombers become
`"portable." Thot means that custome1s coo toke their BOO telephone number horn one long
`distance company to another, ond still keep the some 800. See also 800 PortobWty.
`800 Services ore known intemotionol¥ os 'fleefone Servi<es.' In other countries the dial(cid:173)
`ing scheme may VOIY, with examples being 0-SOO ond 0-500. Such services also go undei
`the nome ' G1eenfone." In June 1996, the lllH approved the E.169 stundord Universol
`lnternotionol F1eefone Number (UIFN) numbers, also knoW11 os 'Globol BOO." UIFN will
`work oaoss notional boundaries, based on o stondmd numooring scheme of 800, 888 or
`877 plus on &iligit telephone number. See also UIFN and Vanity Numbers.
`802 See 802 Stnndords.
`802 Standards The 802 Stundords ore o set of s1orldords 101 LAN (Local Area
`Network) ond MAN (Metropolitun Areo NetwO!k) data communications developed through
`the IEEE's Project 802. !he two most important stondords ore 802.11 bond 802.1 lo. The
`stondords also indude on overview of recommended networking architectures, approved in
`1990. The 802 stundords follow o ooique numbering cooventioo. A number followed by o
`capitol letter denotes a shnlolone stondoid; a oomber followed by o lower case letter
`
`800 I 802. 1 l a
`
`denotes either o supplement to o stondord, 01 o port of o multiple-numbe1 stondord (e.g., #
`
`802. l & 802.3). The 802 stondords segment the dolo link layer into two subloyers:
`1. A l,ledio Access Conhol (MAO loyer tho! indxfes specific methods for gaining occess to
`the LAN. These methods -
`such os Etnemers rondom access method and Token Ring's
`token passing procedure- ore in the 802.3, 802.5 ond 802.6 standards.
`2. A Lo~col Link Control (LLC) Loyer, desuibed in the 802.2 stondord, that provides for
`connection estoblishment, doto transfer, ond connection terminotion services. LLC spec[ies
`tlvee types of co11VOmic:otions tinks:
`w An Unocknowtedged Connectionless link, where the seoo1119 and receiving devices do not
`set up o connection before transmitting. Instead, messages ore sent on o 'best effort'
`bosis, with no prov~ion for enor detection, error recovePf, or message sequencing. This
`type of link is best suited for op~icotiollS where the higher loyer protocols con provide the
`errOf conection ond functions, or where the loss of broodcost messages is not critical.
`• A Connection-Mode link, where o connection belweerl message source ond destinotioo
`is established prior tu tronsmission. This type of fink works best in opplicotions, such os file
`tonsfer, where large omounls of dota are being tronsmitted ot one time.
`• An Acknowledged Connectionless Link that, os ils name indicates, provides for ocknowl(cid:173)
`edgoment of messages without burdening the receiving devices with mointoining o con(cid:173)
`nedion. For tlis reason, it is most often USM for opplicotions whe!e o cootrol proces:soi
`cornmunicoles Ylith o large number of ~ces with hrrited processing copobitrties.
`802.1 IEEE standard fo, overall architedure of LANs ond inrernetworking. See oU the
`following definitions.
`802. 11 a 802.1 lo is actually on updated, bigger, better, foster version of 802.1 lb
`(also colled Wifi), which is now co11lf11Clrt/ installed in offices, airports, coffee shops, etc.
`lhiny laptops now come with 802. l lb bot1Hn. The newer 802.1 lo, also Oil IEEE slOn(cid:173)
`dord fo1 Ylireless LANs, supports speeds up to 54 Mbps. 802.1 lo IUllS in a 300-1.\Hz otlo(cid:173)
`cotion in the 5 GHz range, which was ollocoted by the FCC in support of UNII (the
`Unlicensed Notionol lnformotion lnfrosnucture). Specificolly, 200 MHz is ollocoted at 5.15·
`5.35 MHz for in-building opplicotions, and 100 MHz at 5.725·5.825 MHz for outdoor use.
`This ollocoted spectTum is divided into three working domains. Al 5.15-5.25 MHz, rnoxi(cid:173)
`mum powei output is reslricted lo 50mW (miniWattsl, 5.25-5.35 to 250mW, and S.725-
`5.825 to 1 Wott. 802. l lo hos been dubbed Wtfi5 (Wireless Fidefity 5 MHz) by the
`Wireless Ethernet Compatibility Alliance (WECA).
`802.1 lo uses Coded Orthogonal frequency Division Multi~exing (COFOM) os the signal
`modulation technique. COFOM sends o stream of dotu symbols in a rnossive~ pa101lel losh(cid:173)
`ion, with multiple subcorriers (i.e., smoD skes of Rf, or Roo10 Spectrum, within the desig(cid:173)
`noted carrier hequency bond. Each conier chonne! is 20 MHz wide, and is sulxfivided inro
`52 subcarrier channels, eoch of which is opproximote~ 300 KHz wide; 48 of the subcor·
`rie1 chonnels ore used for dota nonsrn~sion, ond the remaining four for enor control.
`Through the opplicotion of o coding tecmique, eoch symbol comprises multiple doto biis.
`The specified codiWJ techniques and do1o rotes specified, oil of which must be supported
`by 802.11-comprlOllt products, include BPSK (Binory Phase Shilt Keying) ot 125 Kbps per
`channel for o total of 6 Mbps across oil 48 doto channels, QPSK (Ouod1oture Phase Shilt
`Keying) ot for 250 Kbps per channel for o total of 12 Mbps, ond l 6QAM (l 64evel
`Ouodrolure Amplitude Modulotioo) ot SOD Kbps per channel for o totul of 2 4 Mbps. The
`slOndord also oDows more complex modulation schemes, thot offer increose.l doto rotes.
`C1Jrently, the most complex ond fastest is 640AM (64-level OAM), of 1.125 Mbps per
`channel for a totol of 54 Mbps.
`The symbol rote is slowed down enough that eoch symbol transmission is longer than the
`delay spread. The delay spread is the w1iotion in timing between receipt of the signals
`rnocioted with o given symbol, with the delay spread caused by multipath fading.
`Multipath fading is the phenomenon whereby the Rf signals corrying o given doto symbol
`arrive at the receiver of stightly aillerent times. This is bemuse the signal spreods out horn
`the transmitter, with certain portions of the signol reaching the receiver more 01 less direc~
`ly, while other portions of the signol bounce around off of walls, fumitu1e, your co-wo1k·
`er's pointy head, ond such. Now, each, of the symbols contains multiple bils, vihich ore
`imposed oo ~ through the coding processes identified above. As the mulli~e symbols reoch
`the receiver, they ore sorted out ond decoded, with the decoding proc~ providing some
`odditionol time for the receiver to adjust for the delay spread and to get reody to receive
`the next symbol. Both 802. l la ond 802.1 lb ore designed to be compatible v~th Ethernet
`LANs, using the MAC (Media Access Control) technique of CSMA/CA (Corner Sense
`Multiple Access v.ith Collision Avoidance l.
`tt this sounds great, !hors because fl is great. K this solllds too good to be true, thors
`
`17
`
`

`

`802.11 b / 802. 1 Q
`
`be<ouse it gets a little more complicoted. While the 5 GHz spectrum is pretty clear in the
`US, it's not so readi~ available elsewhere. Military and government installations use par·
`tions of this bond overseas. In Jopon, on~ the 5.15-5.25 MHz spectrum is avoiloble. In
`Europe, the 5.725-5.825 MHz spectrum is already allocated for other uses. In Europe, ETSI
`(European Tele<ommunications Stamkirds Institute) requires that two additional protocols
`be used in conjunction with 802.11 o in mder to protect incumbent applications ond sys·
`terns running over pievious~ allocated shored spectrum. OFS (Dynamic frequency
`Selection) allows the 802.1 lo system to dynamically shift frequency channels and TPC
`CTransmissioo Power Control) reduces the power level. In combination, lhese protocols
`serve to eliminate inte~erence issues wilh incumbent signa~. See o~ 802.1 lb,
`802.11 g, BPSK, CSMA/CA, MAC, OFOM, QAM, OPSK, WECA and Wifi.
`802. 1 lb 802.llb is now the most common wireless local area network. 802.1 lb
`(also called Wifi) is now commonly installed in offices, airports, coffee shops, etc. Many
`laptops now come wilh 802. ll b builtin. 802. llb has been dubbed Wifi (Wireless
`fidelity) by the Wireless Ethernet Compatibility Alliance (WECA). 802.11 b defines both the
`Physical (PHY) and Medium Access Control (IMO protocols. Specifically, the PHY spec
`includes lhree transmission options- one Ir (Infrared), and two RF (Radio frequency).
`802.11 buses DSSS (Direct Sequence Spread Spectrum) modulation.for digitul communi·
`cation. OSSS involves the transmission of a stream of one's and zero's, which is modulat(cid:173)
`ed with the Barker code chipping sequence. Barker code is an 11-bit sequence (e.g.,
`10110111000) that hos odvonloges in wireless transmission. Each bit is encoded inlll on
`l 1-bit Barker code, with eoch resulting data object forming a "chip." The chip is put on a
`carrier frequency in the 2.4 GHz range (2.4-2.483 GHz), and the waveform is modulated
`using one of several techniques. 802.11 systems running at 1 Mbps make use of BPSK
`(Binary Phase Shih Keying). Systems running at 2 Mbps make use of QPSK (Quaternary
`Phase Shift Keying). Systems running at 11 Mbps make use of (CK (Complementary Code
`Keying), which involves 64 unique code sequences, which technique supports six bits per
`code word. The (CK code word is then modulated onto the Rf corner using OPSK, which
`allows another two bits tu be encoded fm each 6-bit symbol. Therefore, each 6-bit sym(cid:173)
`bol contoins eight bits. Power output is limited by the FCC to l watt EIRP (Equivalent
`Isotropically Radiated Power). At this low power level, the physicol distance between the
`transmitting devices becomes on issue, with en0t performance suffering os the di;Wnce
`increoses. Therefore, the devices adopt to longer distances by using o less complex encod(cid:173)
`ing technique, and o resulting lower signaling speed, which translates into a lower dotu
`rate. for example, a system running at 11 Mb~s using CCK and OPSK, might throttle back
`to 5.5 Mbps by halving the signaling rote os the distunces inuease and error pertormance
`drops. As the situation gets worse, it might throttle bock to 2 Mbps using only QPSK, and
`1 Mbps using BPSK. Also to be considered in this equation is the fact that the 2.4 GHz
`range is in the unlicensed ISM (Industrial, Scientific and Medical) bond, which is shored by
`garage door openers, microwave ovens, bor code scanners, cordless phones, Bluetoolh
`IANs, ond o wide variety of other devices. As a result, !his ~ice of spectrum can be heov~
`fy congested at times, and periormonce con drop considerably. 802.11 divides lhe ovai~
`able spectrum into 14 channels. In the US, the FCC allows the use of 11 channels. four
`channels ore ovoilable in Fronce, 13 in the rest of Europe, and only one in Japan. There
`also is overlap beh'leen od[acent channe~ (e.g., channels one and two), which fact further
`affects pertormonce; therefore, any given system must maintain maximum channel sepo·
`ration from other systems in proximity.
`Bolh 802. l lo and 802.11 bare designed to be compatible with Ethernet IANs. 802.11 buses
`a variation of lhe MAC (Media Access Cootrol) technique of CSMA/U.. (Carrier Sense Multiple
`Access with Collision Avoidonce), which is used in some wired Ethernets, as well. A device seek(cid:173)
`ing to transmit ovei lhe shared medium (in this case, a shored RF channel) hstens to the ne}
`work. If it senses no activity over the COfrier frequency for a minimoo, period of time known
`os the DIFS (DCF (Distributed Coordinoted function) lnterfrome Spacing), it requests access
`by ~rst transmitting o RTS (Request To Send) pocket. The RTS pocket indudes both the source
`(i.e., transmitter) ond destination (i.e., intended rnceivei) addresses, lhe duration of the intend(cid:173)
`ed sessioo (i.e., transmission), and the ACK (A(Knowledgernent) associated with it. If the ne~
`work is ovoiloble, the destinatioo device responds with CTS (Clear To Send), repeating both the
`duration ond lhe ACK. All other devices back off lhe network until the session is concluded. If
`lhe netw01k, oo the other hand, is busy, the device waits o period of time equal to the DlfS,
`~us a ranclom number of ~ot times, os colculoteo wilh several bock-off timers. The ' listening·
`process tokes several forms. CAM (Constont Access Method), the default method, involves con(cid:173)
`stant monitoring of the network. Since CAM aeotes o power consumption issue for battery(cid:173)
`powered devices, PAM (Polled fu:cess Mode) con be substituted. PAM coils for all dient devices
`
`to go into sleep rnocle, oil owoktng ot regulcr intervals, at the exact same time, to 6sten for
`nelwork activity. On Jrnuory 3, 2000 the 802.11 technology got another boost when
`Microsoft ond Sturbucks announced that they weie to join forces lo offer wireless access, using
`802.11 b among olher stundards, in most of Starbucks' coffee ou~ets over the next two years.
`The deal, same anolysi, SW/, ~ a further sign thot 802.11 b coold become o serious competi(cid:173)
`tor to better knovm wireless technologies such as Bluetooth, HomeRF, or even next-generation
`cellular nelwO!ks. Apple was Ifie f•st to launch on 802.1 lb product line (called AirPort). All
`Apple computers now include a iluiltin onlenno whkh, in conjooction with a networking cord,
`con excliange dote with o smoll base station plugged inlll o broadband Internet connection up
`to 45 metros (150 feet) oway. Although some PC laptops now come pr~pped with wire(cid:173)
`less hardware, most use~ buy a PCMCIA cord, or PC card, lfmt serves as a wireless modem
`and antenna. See also 802.lla, 802.l lg, Bluetooth, BPSK, Chip, CSIM/CA, DSSS, EIRP,
`Ethernet, HomeRf, MAC, OPSK, Spread Spectn.m, WECA and WHL
`802. 12 Standard fm 1 OOVG-AnylAN. Addresses 100 Mbps demand-priority access
`method physico~loyer ond repe□ter specifkotions. Approved in 1995.
`802.15 A develo~ng IEEE standard for Wireless Personal Area NelwO!ks (WPANs), the
`802.1 5 Working Group (WG) comprises lour Task Groups (TGs). TGl is deriving o WPAN
`slumlord based on the Bluetootn speclticotions. TG2 is developing recommended practices
`ta focilitute the coexistence of 802.15 WPANs and 802.11 WlANs (Wireless local Area
`Netwmks). TG3 is chartered to drah o new standard for high1ate WPANs running ot 20
`Mbps or better. Development is focusing on the 2.4 GHz bond, using OQPSK (Orthogonal
`Quaternary Phase Shih Keying) as the modulation technique. TG4 is charged with investi(cid:173)
`gating a low doto rote WPAN solution running at no more than 200 Kbps in support of appl~
`cations such as wireless interactive toys, sensors, automation, and smart togs and badges.
`802.16 A developing IEEE standard for broadband wireless access. lhe 802.16
`Working Group (WG) is worki~ on a variety of fixed wireless standards intended to serve
`high-speed opplicotions.
`802. 1 B Standard for IAN/WAN management, approved in 1992; along with 802. l k,
`become the basis of ISO/IE( 15802-2.
`802.1 D IEEE stundord for interconnecting lANs lhrough MAC bridges (specifically
`between 802.3, 802.4, and 802.5 networks). The standard was approved in 1990, ond
`wos incorporated into ISO/IE( 10038. Works al the IMC level.
`802.1 E IEEE standard for IAN and MAN load protocols. Approved in 1990, formed the
`basis for ISO/IE( 15802·4.
`802.1 F Stondord for defining network management infmmation specified in 802
`umbrella stondords. Approved ifl 1993.
`802.1 G A developing standard for remote bridging at the MAC layer.
`802.1 H IEEE practices recommended for bridging Ethernet IANs at the MAC layer.
`Approved in 1995.
`802.11 IEEE standard for using FOOi (fiber Distributed Oatu lnterloce) os o MAC-layer
`bridge. Approved in 1992, the stundord was incorporated into ISO/IE( 10038.
`802. lJ IEEE standard for LAN connectivity u~ng MAC-layer bridges. A supplement to
`802.1 D, it was approved in 1996.
`802. 1 K IEEE standard for the discovery and dynamic control of network management
`information. Approved in 1993. In conjunction with 802.18, was the basis for ISO/IE(
`15802-2.
`802.1 MA conformance statement for 802.1 E, it addresses definitions and protocols for
`system load management. Approved in 1993, it was incorporated into 1S0/IEC 15802-4.
`802. IP IEEE extension of 8 02. l D. Specification for the use of MAC layer bridges in filter·
`ing and expediting multicast traffic. Prioritizolion of troffk is accomplished through lhe odd,
`tion of o 3M, priority volue in the frame header. Eight topology-independent priority values
`(Q-7) are specified, with oil eight values mopping directly into 802.4 and 802.6. Switches
`that support 802.lP and 802.10 provide a framework for bandwidth p!ioritizotion.
`Essentially what oll these words mean is that you con as~gn o priority to the type of traf(cid:173)
`fic with IEEE 802.1 p class-of-service ((oS) values ond these allow network devices along
`the way to recognize and del[ver high-priority traffic in o predictable manner. When con·
`gesrion occurs, QoS drops low-priority lraffic to allow delivery of Aigh-priority troffic. See
`also 802.10.
`802. lQ IEEE specification for irnplementution of VIANs in Loyer 2 LAN switches, with
`emphasis on Ethernet. Similar to 802.1 P, priontizotioo of traffic is accomplished through
`on additional four bytes of data in the frame header. Most data fields in this addition to
`lhe header are specific to VIAN operation. Also included is a field which provides the same
`3-bit priority flog specified in 802.1 P's primity111apping scheme. In addition to conven-
`
`18
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`