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计算机网络专业英语 习题 T2.docx

发布：2025-05-06约1.53千字共1页下载文档
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WirelessLocalAreaNetwork?(WLAN)

A?wirelesslocalareanetwork?(WLAN)isa?wirelesscomputernetwork?thatlinkstwoormoredevicesusingawirelessdistributionmethodwithina?limitedarea?suchasahome,school,computerlaboratory,orofficebuilding.Thisgivesuserstheabilitytomovearoundwithinalocalcoverageareaandstillbeconnectedtothenetwork,andcanprovideaconnectiontothewider?Internet.MostmodernWLANsarebasedon?IEEE802.11?standards,marketedunderthe?Wi-Fi?brandname.

WirelessLANshavebecomepopularinthehomeduetoeaseofinstallationanduse,andincommercialcomplexesofferingwirelessaccesstotheircustomers,oftenforfree.?NewYorkCity,forinstance,hasbegunapilotprogramtoprovidecityworkersinallfiveboroughsofthecitywithwirelessInternetaccess.

The?IEEE802.11?hastwobasicmodesofoperation:?infrastructure?and?adhoc?mode.In?adhoc?mode,mobileunitstransmitdirectlypeer-to-peer.Ininfrastructuremode,mobileunitscommunicatethroughan?accesspoint?thatservesasabridgetoothernetworks(suchas?Internet?or?LAN).

SincewirelesscommunicationusesamoreopenmediumforcommunicationincomparisontowiredLANs,the802.11designersalsoincludedencryptionmechanisms:?WiredEquivalentPrivacy?(WEP,nowinsecure),?Wi-FiProtectedAccess?(WPA,WPA2),tosecurewirelesscomputernetworks.Manyaccesspointswillalsooffer?Wi-FiProtectedSetup,aquick(butnowinsecure)methodofjoininganewdevicetoanencryptednetwork.

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