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OReilly building wireless community networks 2nd edition ISBN 0596005024









TableofContents
Index
Reviews
ReaderReviews
Errata

BuildingWirelessCommunityNetworks,
SecondEdition
ByRobFlickenger

Publisher :O'Reilly
PubDate :June2003
ISBN :0-596-00502-4

Pages :182
Slots :1


BuildingWirelessCommunityNetworksis
aboutgettingpeopleonlineusingwireless
networktechnology.The802.11bstandard
(alsoknownasWiFi)makesitpossibleto
networktowns,schools,neighborhoods,
smallbusiness,andalmostanykindof
organization.Allthat'srequiredisa
willingnesstocooperateandshareresources.
Thefirsteditionofthisbookhelped
thousandsofpeopleengageincommunity


networkingactivities.Thisrevisedand
expandededitionaddscoverageonnew
networkmonitoringtoolsandtechniques,
regulationsaffectingwirelessdeployment,
andIPnetworkadministration,includingDNS
andIPTunneling.










TableofContents
Index
Reviews
ReaderReviews
Errata

BuildingWirelessCommunityNetworks,
SecondEdition
ByRobFlickenger

Publisher :O'Reilly
PubDate :June2003
ISBN :0-596-00502-4
Pages :182
Slots :1


Copyright

Preface
NewinThisEdition

Audience




Organization




CommentsandQuestions

TypographicalConventions
Acknowledgments


Chapter1.WirelessCommunityNetworks
Section1.1.WhyNow?

Section1.2.TheWISPApproach




Section1.3.TheCooperativeApproach
Section1.4.AboutThisBook


Chapter2.DefiningProjectScope
Section2.1.TheStandards

Section2.2.HardwareRequirements





Section2.3.SiteSurvey




Section2.4.802.11bChannelsandInterference
Section2.5.TopographicalMapping101


Chapter3.NetworkLayout
Section3.1.Layer1(Physical)Connectivity

Section3.2.WiredWireless




Section3.3.VitalServices



Section3.5.Summary

Section3.4.SecurityConsiderations


Chapter4.UsingAccessPoints
Section4.1.AccessPointCaveats

Section4.2.TheAppleAirPortBaseStation




Section4.3.AccessPointManagementSoftware




Section4.5.ConfiguringDialup




Section4.7.Bridging




Section4.9.Roaming

Section4.4.LocalLANAccess
Section4.6.NATandDHCP
Section4.8.WEP,MACFiltering,andClosedNetworks
Section4.10.ChannelSpacing


Chapter5.Host-BasedNetworking
Section5.1.AnatomyofaWirelessGateway


Chapter6.Long-RangeNetworking
Section6.1.TopoMaps102:GeographicalDiversity

Section6.2.AntennaCharacteristicsandPlacement


Chapter7.OtherApplications
Section7.1.Software

Section7.2.Point-to-PointLinks




Section7.3.Point-to-MultipointLinks




Section7.5.RedundantLinks




Section7.7.SecurityConcerns




Section7.9.FunwithIP

Section7.4.Home-BrewAntennas
Section7.6.Repeaters
Section7.8.NoCatAuthCaptivePortal
Section7.10.InClosing


Chapter8.RadioFreePlanet
Section8.1.SeattleWireless

Section8.2.UniversalWireless





Section8.3.TheFuture


Chapter9.RadioFreeSebastopol
Section9.1.OSCON2000

Section9.2.TheCampus




Section9.3.Coffee,Coffee,Coffee




Section9.5.SeattleWireless




Section9.7.TheCommunityTakesNotice



Section9.9.AndSoOn

Section9.4.OnlineFromHome,NoStringsAttached
Section9.6.NoCat
Section9.8.ThePortlandSummit


AppendixA.RegulationsAffecting802.11Deployment
SectionA.1.Disclaimer

SectionA.2.AbstractandObjectives




SectionA.3.IntroductiontotheTechnology




SectionA.5.PowerLimits




SectionA.7.Interference




SectionA.9.HumanExposuretoRadioFrequencyRadiation




SectionA.11.TheFuture:GoodNewsandBadNews



SectionA.13.Conclusions






SectionA.4.RegulationsandLawsAffecting802.11NetworkDeployment
SectionA.6.EquipmentLimitationsandCertification
SectionA.8.BroadbandAUPs
SectionA.10.LawsConcerningAntennasandTowers
SectionA.12.WhatCanYouDo?

AppendixB.PathLossCalculations
AppendixC.SimpleSchemeManagement
Colophon
Index


Copyright©2003,2002O'Reilly&Associates,Inc.
PrintedintheUnitedStatesofAmerica.
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NutshellHandbook,theNutshellHandbooklogo,andthe
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Wherethosedesignationsappearinthisbook,andO'Reilly&
Associates,Inc.wasawareofatrademarkclaim,the
designationshavebeenprintedincapsorinitialcaps.The
associationbetweentheimageofaCarolinaparakeetandthe
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Whileeveryprecautionhasbeentakeninthepreparationofthis
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theinformationcontainedherein.


Preface
BuildingWirelessCommunityNetworksisaboutgettingpeople
connectedtooneanother.Wirelesstechnologyisbeingused
rightnowtoconnectneighborhoods,businesses,andschoolsto
thevastandnebulousentityknownastheInternet.Oneofthe
goalsofthisbookistohelpyougetyourcommunity
"unplugged"andonline,usinginexpensiveoff-the-shelf
equipment.
Asecondary,butcriticalgoalofthisbookistocometoterms
withexactlywhatismeantbycommunity.Itmightreferto
yourcollegecampus,wheremanypeopleowntheirownlaptops
andwanttosharefilesandaccesstotheInternet.Yourideaof
communitycouldencompassyourapartmentbuildingor
neighborhood,wherebroadbandInternetaccessmaynoteven
beavailable.Thisbookisintendedtogetyouthinkingabout
whatisinvolvedingettingpeopleinyourcommunityconnected
together,anditwilldemonstrateworkingexamplesofhowto
maketheseconnectionspossible.


NewinThisEdition
ThemostimportantadditiontothisbookistheinclusionofTim
Pozar'sexcellentpaper,"RegulationsAffecting802.11
Deployment."Timisamicrowavecommunicationsengineerand
hamradiooperator,andhehasdoneterrificworkinexploring
thelabyrinthineFCCPart15regulations.Hispaperhelpsusall
tounderstandexactlywhatisrequiredtooperatewireless
equipmentlegallyintheUnitedStates.
Iwillalsotakealookatrelevanttechnologiesthathave
recentlyenteredthewirelessnetworkingworld,including
802.11a,802.11g,and802.1x.While802.11bisstillwidely
regardedasthechampiontechnologyofthecommunity
wirelessnetworkingeffort,thesenewertechnologiesarepoised
tobringinterestingnewcapabilitiestonetworkingprojects
everywhere.
Inaddition,Idiscussanumberoffunnewhome-brew
equipmentandsoftwaredesignsthathavecometolight,and
evaluatesomenewsecuritytools(andchallenges).In
particular,theHostAPdriverhasgraduatedtonear-production
quality,andcanprovideaveryflexiblealternativetotraditional
APs.Moreonthatlater.


Audience
Thisbookdescribessomesolutionstothecurrent(butrapidly
changing)problemofbuildinganopenwirelessnetworkfor
communityuse.Itisnotintendedtobeadesignguidefor
wirelesscompaniesandISPs,thoughIhopetheyfindthe
informationinituseful(andatleastalittlebitentertaining).
Thisbookisintendedforthetechnicaluserwhoisinterestedin
bringingwirelesshigh-speednetworkaccesstowhereverit's
needed.ThiscouldincludeextendingInternetconnectivityto
areaswhereothertypesofaccess(suchasDSLandcable)
aren'tavailable.Itmightalsoincludesettingupaccessata
school,wherestructureswerebuiltlongbeforeanyonethought
aboutrunningcablesandlinesintoclassrooms.Thisbook
shouldalsobeusefulforpeopleinterestedinlearningabout
howdozensofgroupsaroundtheplanetareprovidingwireless
accessintheirowncommunities.Thestoryofwirelessnetwork
accessisstillinitsinfancy,butisalreadyfulloffascinating
twistsandturns(neverminditspotential!).Ihopeto
communicatewhatI'velearnedofthisstorytoyou.


Organization
Earlychaptersofthisbookintroducebasicwirelessconcepts
andessentialnetworkservices,whilelaterchaptersfocuson
specificaspectsofbuildingyourownwirelessnetwork.
Experiencedusersmayprefertoskiparoundratherthanread
thisbookfromcovertocover,sohere'sanoverviewofeach
chapter:
Chapter1,givesabriefhistoryofthestateofwireless
connectivity,andsomeideas(andwarnings)abouthow
thingsmightproceed.
Chapter2,isanoverviewofmanyimportantlogistical
considerationsyouwillfaceindesigningyourownnetwork,
anddescribessometoolsthatmaymakeyourjobeasier.
Chapter3,providesadetaileddescriptionofcriticalnetwork
componentsthatyouwillneedtoprovideyourusers.
Networkdesignandsecurityconsiderationsarealso
addressed.
Chapter4,detailshowtouseWirelessAccessPoint
hardwareeffectivelyinyournetworkingproject.
Chapter5,isastep-by-stepguidetobuildingyourown
AccessPointusingLinux,inexpensivePChardware,and
conventionalwirelessclientcards.
Chapter6,isaboutextendingyourrange.Itlooksatusing
topographicmappingsoftwaretoevaluatelongdistance
links,andexaminesthemyriadantennas,cables,
connectorsyouarelikelytoencounter.Italsoprovidesa
simplemethodforcalculatingtheusablerangeofyourgear.


Chapter7,investigatessomereallyexotic(anduseful!)
applicationsof802.11b.Itincludespracticalpointersfor
settinguppoint-to-pointlinks,somesimplerepeaters,
assemblinga2.4GHzantennafromordinaryhousehold
objects,andlotsofotherfunhackery.We'llalsoseean
implementationofadynamic"captiveportal"firewallusing
opensource(http://www.opensource.org)software.
Chapter8,isaresourceguidetosomeofthemajorplayers
inthewirelessnetworkaccessrevolution.Hereyou'llfind
outhowpeopleallovertheglobearemakingubiquitous
wirelessnetworkaccessareality,allintheirfreetime.
Chapter9,isthe(brief)historyofmyownexperiencesin
settingupawirelesscommunitynetworkinSebastopol,CA
(andinmeetingdirectlywiththeheadsofsomeofthe
biggestcommunityeffortsintheU.S.).
AppendixAcontainsTimPozar'spaper,"Regulations
Affecting802.11Deployment."
AppendixBprovidesapathlosscalculationtable.
AppendixCoffersashellscriptthatmakesnetworkscheme
managementeasier.


TypographicalConventions
Thefollowingtypographicalconventionsareusedinthisbook:
Italic
Usedtointroducenewterms,toindicateURLs,variablesor
user-definedfilesanddirectories,commands,file
extensions,filenames,directoryorfoldernames,andUNC
pathnames.
Constantitalic
Usedtoshowvariablesforwhichacontext-specific
substitutionshouldbemade.

Indicatesatip.

Indicatesawarning.


CommentsandQuestions
Pleaseaddresscommentsandquestionsaboutthisbooktothe
publisher:
O'Reilly&Associates,Inc.
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Sebastopol,CA95472
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(707)829-0104(fax)
Thereisawebpageforthisbook,whichlistserrata,examples,
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http://www.oreilly.com/catalog/wirelesscommnet2
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emailto:
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Acknowledgments
IwouldliketothanktheO'ReillyNetworkTeam,myparents,
andespeciallyCatfortheirendlessencouragementandkeeping
mesane(and,insomecases,evensensible).
Also,mysincerethankstoSchuylerErle,AdamFlaherty,Nate
Boblitt,andJimRosenbaumforhelpingtoturntheNoCatidea
intoanactuallivingproject.ThanksaswelltoMattPeterson,
MattWestervelt,AdamShand,TerrySchmidt,andthecountless
otherpioneersofultra-hyper-connectivity.
Thanksgotothereviewerswhoreadearlydraftsandmade
comments:MikeBertsch,SimsonGarfinkel,JustinLancaster,
NicholasMaddix,andMattPeterson.Thanksalsogotoallthe
peopleatO'Reilly&Associateswhoturnedthismanuscriptinto
afinishedbook.


Chapter1.WirelessCommunity
Networks
Ayearisaneternityinnetworking.
Anonymous
Inthetimesincethefirsteditionofthisbookwaspublished,
millionsofwirelessnetworkingcomponentshaveshippedinto
theeagerlywaitinghandsofconsumers.We'veseenconsumergradewirelessequipmentpricesfalldramaticallyasmoreand
moremanufacturersintegratewirelessintotheirownproducts.
Articlesaboutvariousaspectsofwirelessnetworkinghave
madeinternationalnews,includingstrangetalesof
WarChalking,WarDriving,andPringlescan-wieldingSecret
Serviceagents(asreportedat
http://www.securityfocus.com/news/899).Wirelessaccessis
nowavailableinmanycoffeehouses,parks,schools,offices,and
homes.
Whatisitaboutwirelessnetworkingthathassomanypeople
workedintosuchafrenzy?Ibelievethatpeople'sfascination
withwirelessissimpletounderstand.Wirelessdatanetworking
isprobablythemost"magical"technologytoevolveinrecent
times.Thinkofit:byinstallinganinexpensivePCcard,your
laptopcansuddenlysendandreceivedataataveryhigh
speed,toanyoneinrange,eventhroughwalls!Manylaptops
havedispensedwiththePCcardaltogether,andseemto
magicallyjust"be"online.Combinedwiththepowerofthe
Internet,yourtinybattery-poweredcomputercannow
communicateglobally,whereveranotherwiseinvisiblewireless
networkhappenstoexist.Morethananyothernetworking
technology,peoplejustthinkit'scooltousewireless(never
mindthatitisextremelyuseful,cheap,andcandothingsthat
wirednetworkswillneverbeabletodo).


Inthepastyearandahalf,wehavealsoseenmorethanafew
wirelessstart-upscomeandgo.Wirelessnetworkingmaybe
cheapandeasyfortheindividual,butithascertainlyprovento
befarfroma"slam-dunk"businessforwould-bewirelessISPs.
Inthesametimeperiod,theprojectlistatPersonalTelco
(availableontheirsiteat
http://www.personaltelco.net/index.cgi/WirelessCommunities)
hasgrowntofivetimesthesize,nowlistingover250active
communitynetworkingefforts.Whilepublicwirelessnetworks
haven'tyetproventobeastunningcommercialsuccess,
somethingiscertainlyhappeningwithwireless.Thisbookisan
explorationofmanyaspectsofthatsomething.


1.1WhyNow?
Inrecenttimes,thevelocityoftechnologydevelopmenthas
exceeded"blur"andisnowmovingatspeedsthatdefy
description.Internettechnologyinparticularhasmade
astoundingstridesinthelastfewyears.Whereonlyafewshort
yearsago56Kbpsmodemswerealltherage,manytechheads
nowfindthemselvescomplainingabouthowslowtheir
company'sT1connectionseemscomparedtotheir6MBpsDSL
connectionathome.
Neverbeforehavesomanyhadfreeandfastaccesstosomuch
information.Asmorepeoplegetatasteofmillisecondresponse
timesandmegabitdownloadspeeds,theyseemtoonlyhunger
formore.Inmostplaces,theservicethateveryoneisitching
forisDSL,orDigitalSubscriberLineservice.Itprovides
relativelyhighbandwidth(anywherefrom128Kbpsto6Mbps)
overstandardcoppertelephonelines,ifyourinstallationis
withinaboutthreemilesofthetelephonecompany'sCO,or
centraloffice(thisisatechnicalconstraintofthetechnology).
DSLisgenerallypreferredovercablemodems,becauseaDSL
connectionprovidesguaranteedbandwidth(atleasttothe
telephonecompany)andthusisnotdirectlyaffectedbythe
traffichabitsofeveryoneelseinyourneighborhood.Itisn't
cheap(ranginganywherefrom$40to$300permonth,plusISP
andequipmentcharges),butthatdoesn'tseemtobe
discouragingdemand.
Telephonecompanies,ofcourse,arecompletelyenamoredwith
thisstateofaffairs.Infact,theintensedemandforhighbandwidthnetworkaccesshasledtosomuchbusinessthat
enormousleadtimesforDSLinstallationsaretheruleinmany
partsofthecountry.Inmanyareas,ifyouliveoutsideofthe
perceived"market"justbeyondrangeoftheCO,leadtimesare
sometimesquotedat"twotothreeyears"(marketingjargonfor
"never,butwe'lltakeyourmoneyanywayifyoulike").Worse


thanthat,inthewakeofwidespreadmarketconsolidation,
somecustomerswhowerequitehappywiththeirDSLservice
arefindingthemselvesstrandedwhentheirlocalISPgoesout
ofbusiness.[1]
[1]Onecurrentlycirculatingmemedeemsastrandedcustomer"Northpointed,"inhonorofthe
ISPNorthPoint.net,whichwentoutofbusinessinMarchof2001,leavingthousandswithout
access.

Whatarethealternativesforpeoplewhodesirehigh-speed
Internetaccess,butaren'twillingtowaitforcompaniesto
packageasolutionforthem?Thetelephonecompaniesownthe
copper,andthecablecompaniesownthecoax.
Communitywirelessnetworksnowprovideeasy,inexpensive,
high-bandwidthnetworkservicesforanyonewhocaresto
participate.
Approvedin1997bytheIEEEStandardsCommittee,the
802.11specificationdetailstheframeworknecessaryfora
standardmethodofwirelessnetworkedcommunications.It
usesthe2.4GHzmicrowavebanddesignatedforlow-power,
unlicensedusebytheFCCintheU.S.in1985.802.11provided
fornetworkspeedsofoneortwomegabits,usingeitheroftwo
incompatibleencodingschemes:FrequencyHoppingSpread
Spectrum(FHSS),orDirectSequenceSpreadSpectrum
(DSSS).
InSeptemberof1999,the802committeeextendedthe
specification,decidingtostandardizeonDSSS.Thisextension,
802.11b,allowedfornew,moreexoticencodingtechniques.
Thispushedupthethroughputtoamuchmorerespectable5.5
or11Mbps.WhilebreakingcompatibilitywithFHSSschemes,
theextensionsmadeitpossiblefornewequipmenttocontinue
tointeroperatewitholder802.11DSSShardware.The
technologywasintendedtoprovide"campus"accesstonetwork
services,allowingatypicalrangeofabout1,500feet.Aswe'll
seeinChapter2,afewnewimportantprotocolshavebeen


approvedthatpushavailablewirelessbandwidthevenhigher:
allthewayupto54Mbps(butmoreonthatlater).Whilethese
developmentsarecertainlyimportant,theratificationandwide
acceptanceof802.11binlate1999iswidelyregardedasthe
startofthepopularwirelessnetworkingphenomenon.
Itdidn'ttakelongforsomesharphackertypes(and,indeed,a
fewCEOandFCCtypes)torealizethatbyusingwirelessclient
gearinconjunctionwithstandardradioequipment,effective
rangecanextendtomorethan20milesandpotentiallyprovide
thousandsofpeoplewithbandwidthreachingDSLspeeds,for
minimalhardwarecost.Connectivitythatpreviouslyhadto
creepupmonopoly-heldwirescannowflyinthroughthewalls
withsignificantlyhigherperformance.Andsinceconsumergradewirelessequipmentusesunlicensedradiospectrum,fulltimeconnectionscanbesetupwithoutpayingadimeinairtime
orlicensingfees.
Whiletrumpingthetelcoandcablecompanieswithoff-the-shelf
magicalhardwaremaybeanentertainingfantasy,howwell
doeswirelessequipmentdesignedtoserveafewlocalclients
actuallyperformintherealworld?Howcanitbeeffectively
appliedtoprovidegeneralizedaccesstotheInternet?

1.1.1TheProblem
Anobviousapplicationforwirelessistoprovidetheinfamous
"lastmile"networkservice.Thistermreferstothestretchthat
sitsbetweenthosewhohavegoodaccesstotheInternet(ISPs,
Telcos,andcablecompanies)andthosewhowantit
(consumers).Thissortofarrangementrequireswireless
equipmentatbothendsofthestretch(forexample,atanISP's
siteandataconsumer'shome).
Unfortunately,thenatureofradiocommunicationsatmicrowave
frequenciesrequireslineofsightforoptimalperformance.This


meansthatthereshouldbeanunobstructedviewbetweenthe
twoantennas,preferablywithnothingbutavalleybetween
them.Thisisabsolutelycriticalinlong-distance,low-power
applications.Radiowavespenetratemanycommonmaterials,
butrangeissignificantlyreducedwhengoingthroughanything
butair.Althoughincreasingtransmissionpowercanhelpget
throughtreesandotherobstructions,simplyaddingamplifiers
isn'talwaysanoption,astheFCCimposesstrictlimitson
power.(WewillreturntothissubjectindetailinChapter7.)
Speakingofamplifiers,arelatedtechnicalobstacletowireless
nirvanaishowtodealwithnoiseintheband.The2.4Ghzband
isn'treservedforusesolelybywirelessnetworkinggear.Ithas
tosharethebandwithmanyotherdevices,includingcordless
phones,wirelessX-10cameras,Bluetoothequipment,burglar
alarms,andevenmicrowaveovens!Usingamplifierstotryto
"blast"one'swaythroughinterveningobstaclesandabovethe
backgroundnoiseisthesocialequivalentofturningyour
televisionuptofullvolumesoyoucanhearitinyourfrontyard
(maybealsotohearitaboveyourringingtelephoneand
barkingdog,ormaybeevenyourneighbor'sloudtelevision...).
Ifdataisgoingtoflowfreelyovertheair,therehastobeahigh
degreeofcoordinationbetweenthosewhosetitup.Asthe
airwavesareapublicresource,thewirelessinfrastructure
shouldbebuiltinawaythatbenefitsthemostpeoplepossible,
forthelowestcost.Howcanwirelessnetworkingeffectively
connectpeopletoeachother?


1.2TheWISPApproach
Visionsoflicense-free,monopoly-shattering,high-bandwidth
networksarecertainlydancingthroughtheheadsofsome
business-mindedindividualsthesedays.Onthesurface,itlooks
likesoundreasoning:ifpeopleareconditionedintobelieving
that6MbDSLcosts$250permonthtoprovide,thenthey'll
certainlybewillingtopayatleastthatmuchforan11Mb
wirelessconnectionthatcostspenniestooperate,particularlyif
it'scleverlypackagedasanupgradetoabrandnamethey
alreadyknow.Thetemptationofhighprofitsandlowoperating
costsseemstohaveonceagainallowedmarketingtogiveway
togoodsense.Thus,the"WirelessDSL"phenomenonwasborn.
(Whoneedsanactualtechnologywhenyoucanmarketan
acronym,anyway?)
Inpractice,manyWISPs[2]arefindingoutthatit'snotassimple
asthrowingsomeantennasupandrakinginthecash.Tostart
with,trueDSLprovidesafull-duplex,switchedline.MostDSL
linesareasymmetric,meaningthattheyallowforahigher
downloadspeedattheexpenseofsloweruploadspeed.This
differenceishardlynoticeablewhenmostofthenetworktraffic
isincoming(i.e.,whenusersarebrowsingtheweb),butitis
present.Evenwiththelow-speeduploadlimitation,afullduplexlinecanstilluploadanddownloaddatasimultaneously.
Would-bewirelessprovidersthatbuildonconsumer-grade
wirelesstechnologyarelimitedtohalf-duplex,shared
bandwidthconnections.Thatmeansthattoactuallyprovidethe
samequalityofserviceasawiredDSLline,theywouldneed
fourradiosforeachcustomer:twoateachend,usingonefor
upstreamandonefordownstreamservice.Ifthenetwork
infrastructureplanistoprovideafew(orevenafewdozen)
wirelessaccesssitesthroughoutacity,thesewouldneedtobe
sharedbetweenalloftheusers,furtherdegradingnetwork
performance,muchlikethecablemodemnightmare.Additional


accesssitescouldhelp,butaddingequipmentalsoaddsto
hardwareandoperatingcosts.
[2]WirelessInternetServiceProviders.No,Ididn'tmakethatoneup.

Speakingofaccesspoints,whereexactlyshouldtheybe
placed?Naturally,theantennasshouldbelocatedwhereverthe
greatestexpectedcustomerbasecanseethem.Unlessyou've
triedit,Iguaranteethisistrickierthanitsounds.Trees,metal
buildings,chain-linkfences,andthenaturallayoftheland
makeantennaplacementaninterestingchallengefora
hobbyist,butanightmareforanetworkengineer.Aswe'llsee
later,anantennasiteatleastneedspowerandasturdymastto
mountequipmenton,and,preferably,italsohasaccesstoa
wiredbackbone.Otherwise,evenmoreradiogearisneededto
providenetworkservicetothetower.
Supposethatmarketinghassufficientlydupedwould-be
customersandclaimstohaveenoughtowersitestomake
offeringnetworkservicesatleastapossibility.Nowimagine
thataprospectivecustomeractuallycalls,requestingservice.
HowdoestheWISPknowifserviceispossible?WithDSL,it's
straightforward:lookupthecustomer'sphonenumberinthe
centraldatabase,figureoutabouthowfartheyarefromthe
CO,andgivethemanestimate.Unfortunately,noknown
databasecantellyouforcertainwhatagivenaddresshasline
ofsightto.
Aswe'llseelater,topographicalsoftwarecanhelpperformsome
preliminaryworktohelpruleoutthedefiniteimpossibilities.
Sometopographicalpackagesevenincludetreeandground
clutterdata,althoughthesetendtobeconsiderablymore
expensive(andofdubiousrealvalue,unlesstheyareup-todate).Usingsuchsoftware,wemightevenbeabletoupgrade
thepotentialcustomertoa"maybe."Ultimately,however,the
onlywaytoknowifaparticularcustomercanreachtheWISP's
backboneoverwirelessistosendoutatechwithtestgear,and


tryit.
SonowthepoorWISPmustbepreparedto"rollatruck"for
newinstallations,makingon-sitecallstopeoplewhoaren't
evencustomersyet.Ifthey'relucky,techniciansmightevenget
atestshottowork.Atthispoint,finally,equipmentcanbe
installed,contractssigned,andthecustomercangetonlineat
somethingalmostresemblingDSL.Thatis,beonlineuntilabird
perchesontheantenna,oranewbuildinggoesupinthelink
path,ortheleavescomeoutinthespringandblockmostofthe
signal(atwhichpoint,Iimaginethecustomerwouldbe
referredtothefineprintonthatcontract).
Ithinkyoucanbegintoseeexactlywherethebottomlineis
goinginthissortofarrangement.TheprivateWISPapproachis
filledwithunanticipated(andexpensive)challengesitcomesto
solvingtheproblemofubiquitousaccessonalargescale.What
hopedoesour"wirelesseverywhere"visionhaveinlightofall
ofthepreviouslymentionedproblems?Perhapsamassively
parallelapproachwouldhelp...


1.3TheCooperativeApproach
Thedifficultiesofacommercialapproachtowirelessaccess
existbecauseofasinglesocialphenomenon:thecustomeris
purchasingasolutionandisthereforeexpectingareasonable
levelofservicefortheirmoney.Inacommercialventure,the
WISPisultimatelyresponsibleforupholdingtheirendofthe
agreementorotherwisecompensatingthecustomer.
The"lastmile"problemhasaverydifferentoutlookifeach
memberofthenetworkisresponsibleforkeepinghisown
equipmentonline.Likemanyideaswhosetimehascome,the
communityaccesswirelessnetworkphenomenonisunfolding
rightnow,allovertheplanet.Peoplewhoarefedupwithlong
leadtimesandhighequipmentandinstallationcostsare
poolingtheirresourcestoprovidewirelessaccesstofriends,
family,neighbors,schools,andremoteareasthatwilllikely
neverseebroadbandaccessotherwise.AsdifficultastheWISP
nightmareexamplehasmadethisideasound,people
everywherearelearningthattheydon'tnecessarilyneedtopay
theirduestothetelcotomakeastonishingthingshappen.They
arediscoveringthatitisindeedpossibletoprovideveryhigh
bandwidthconnectionstothosewhoneeditforpenniesnot
hundredsofdollarsamonth.
Ofcourse,peoplewhoareexpectedtorunawirelessgateway
needaccesseithertohighlytechnicalinformation,ortoa
solutionthatisnomoredifficultthanplugginginaconnector
andflippingaswitch.Whilebringingcommonexperiences
togethercanhelpfindaneasysolutionmorequickly,onlya
relativelysmallpercentageofpeopleonthisplanetknowthat
microwavecommunicationsareevenpossible.Evenfewerknow
howtoeffectivelyconnectawirelessnetworktotheInternet.
Aswe'llseelater,ubiquityiscriticalifwideareawirelessaccess
isgoingtobeusable(eventothetechnoüber-elite).Itisin
everyone'sbestinteresttocooperate,sharewhattheyknow,


andhelpmakebandwidthaspervasiveastheairwebreathe.
Thedesiretoendthisseparationof"thoseintheknow"from
"thosewhowanttoknow"ishelpingtobringpeopleawayfrom
theircomputerscreensandbackintotheirlocalneighborhoods.
Inthelastyear,hundredsofindependentlocalgroupshave
formedwithaverysimilarunderlyingprinciple:getpeople
connectedtoeachotherforthelowestpossiblecost.Websites,
mailinglists,communitymeetings,andevenIRCchannelsare
beingsetuptoshareinformationaboutextendingwireless
networkaccesstothosewhoneedit.Whereverpossible,
ingeniouslysimpleandinexpensive(yetpowerful)designsare
beingdrawnupandgivenaway.Thousandsofpeopleare
workingonthisproblemnotforapersonalprofitmotive,butfor
thebenefitoftheplanet.
ItisworthpointingoutherethatISPsandtelcosareinnoway
threatenedbythistechnology;infact,Internetservicewillbein
evengreaterdemandaswirelesscooperativescomeonline.The
differenceisthatmanyenduserswillhaveaccesswithoutthe
needtoteardowntreesanddigupstreets,andmanyothers
mayfindthatnetworkaccessinpopularareaswillbeprovided
gratis,asacommunityserviceoronacooperativetrustbasis,
ratherthanasacorporatecommodity.
Wirelessnetworkscanalsobeatremendousbooninhelpingto
fightcensorship(bothintentionalandaccidental).Intraditional
wirednetworks,thoseresponsiblefortheexistenceofthe
networkcanexertahighdegreeofcontroloverwhathappens
"ontheirwires."Throughborderfirewalls,proxies,packet
filters,andcleverrouting,theultimatenetworkcontentthatis
availabletoanindividualcanbemanipulatedtoanalmost
infinitedegree.Evenwell-intentionedadministratorswhomight
blockaportorservice"forthegoodofthenetwork"can
unintentionallyrestricttheflowofinformationforperfectly
legitimateusers.
Therulesareverydifferentwhenthewiresaretakenaway.


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