SECTION2"FeaturesandFunctionalOverview
2-66710Access PointUser’sGuide
Flooding Configurations
StandardLANbridgesfloodframesonall portswhenthe
destinationaddress isunknown.Additionally,many
networkprotocolsusemulticastaddressingfor connection
andstatuscommunications.Amulticastframeisaspecial
type of framedestinedformorethanonephysicaladdress.
Standardbridgesalwaysfloodmulticastframes.
Mostwireless mediasupportedintheaccess pointoperate
atlowermediaspeedsthanEthernet.Indiscriminate
floodingfroma busyEthernetbackbonetoawireless
mediumcanconsumeasubstantialportionoftheavailable
wireless bandwidth.Thisreduces systemperformance even
thoughfloodedframesarefrequentlynotintendedfor
stationsonagivenwireless segment.
Toallowperformancetuning,theaccesspointprovides
separatefloodingcontroloptionsforboth unicast(single
physicaladdress)andmulticastframes.Access points
servingasdesignatedbridgesconnectingwiredLAN
segmentsmaybeconfiguredtousedifferentflooding
settingsthanaccess points servingonlywireless stations.
Twoofthewireless mediasupportedintheaccess point—
synthesizedUHF(S-UHF)and900 MHz—providereliable
attachmechanisms, whichguarantee thatwireless stations
arealwaysintheaccess point’sforwardingdatabase.
Unicastfloodingisnever requiredforthesestations.
TheWireless LANInteroperabilityForum(WLIF)2.4GHz
optionalsoprovidesareliableattachmechanismfor
stationsusingtheNORANDRNetworkLayer(NNL)
terminalemulation networkprotocol.Multicastflooding
levelsaresetforindividualnetworksbasedontheneedsof
wireless stationstoreceivemulticastframes.Fornetworks
withIPwireless stationsonly,theProxyARPServer
providesanoptionto enablingmulticastflooding.