Specifications

Configuring Access Points
RoamAbout Mobility System Software Configuration Guide 9-47
Changing the Preamble Length
Bydefault,802.11b/gradiosadvertisesupportforframeswithshortpreamblesandcansupport
frameswithshortorlongpreambles.
An802.11b/gradiogeneratesunicastframestosendtoaclientwiththepreamblelengthspecified
bytheclient.An802.11b/gradioalwaysusesalongpreambleinbeacons,proberesponses,
and
otherbroadcastormulticasttraf fic.
Generally,clientsassumeaccesspointsrequirelongpreamblesandrequesttouseshortpreambles
onlyiftheaccesspointwithwhichtheyareassociatedadvertisessupportforshortpreambles.You
candisabletheadvertisementofsupportforshortpreamblesbysettingthepreamblelengthvalue
tolong.In thiscase,clientsassumethattheaccesspointsupportslongpreamblesonlyandthe
clientsrequestlongpreambles.
Changingthepreamblelengthvalueaffectsonlythesupportadvertisedbytheradio.Regardless
ofthepreamblelengthsetting(shortorlong),an802.11b/gradioacceptsandcangenerate

802.11b/gframeswitheithershortorlongpreambles.
Ifanyclientassociatedwithan802.11b/gradiouseslongpreamblesforunicasttraffic,theaccess
pointstillacceptsframeswithshortpreamblesbutdoesnottransmitanyframeswithshort
preambles.Thischangealsooccursiftheaccesspointoverhearsabeacon
froman802.11b/gradio
onanotheraccesspointthatindicatestheradiohasclientsthatrequirelongpreambles.
Thedefaultpreamblelengthvalueisshort.Thiscommanddoesnotapplyto802.11aradios.
Tochangethepreambleleng th advertisedby802.11b/gradios,usethefollowingcommand:
set radio-profile name preamble-length {long | short}
Example
Toconfigure802.11b/gradiosthatusetheradioprofilerp_longtoadvertisesupportforlong
preamblesinsteadofshortpreambles,typethefollowingcommand:
RBT-8100# set radio-profile rp_long preamble-length long
success: change accepted.