Network Topologies
2-4 Network Configuration
Infrastructure Wireless LAN for Roaming Wireless PCs
TheBasicServiceSet(BSS)definesthecommunicationsdomainforeachaccesspointandits
associatedwirelessclients.TheBSSIDisa48‐bitbinarynumberbasedontheaccesspoint’s
wirelessMACaddress,andissetautomaticallyandtransparentlyasclientsassociatewiththe
accesspoint.TheBSSID
isusedinframessentbetweentheaccesspointanditsclientstoidentify
trafficintheservicearea.
TheBSSIDisonlysetbytheaccesspoint,neverbyitsclients.Theclientsonlyneedtosetthe
ServiceSetIdentifier(SSID)thatidentifiestheservicesetprovided
byoneormoreaccesspoints.
TheSSIDcanbemanuallyconfiguredbytheclients,canbedetectedinanaccesspoint’sbeacon,or
canbeobtainedbyqueryingfortheidentity ofthenearestaccesspoint.Forclientsthatdonot
needtoroam,settheSSIDforthewireless
cardtothatusedbytheaccesspointtowhichyouwant
toconnect.
Awirelessinfrastructurecanalsosupportroamingformobileworkers.Morethanoneaccess
pointcanbeconfiguredtocreateanExtendedServiceSet(ESS),asshowninFigure 2‐3.Byplacing
theaccesspointsso
thatacontinuouscoverageareaiscreated,wirelessuserswithinthisESScan
roamfreely.AllwirelessnetworkcardadaptersandRBT‐4102s,withinaspecificESS,mustbe
configuredwiththesameSSID.
Figure 2-3 Infrastructure Wireless LAN for Roaming