about scan and probe request

belle.shi at yy.com belle.shi
Fri Oct 23 00:25:26 PDT 2009

dear all,
    is there anyone who read the standard "Part 11: Wireless LAN Medium
Access Control (MAC) and Physical Layer (PHY) Specifications" ?
    and i spend two month to read the stardard, and i read a few code 
of wpa_suppliant and wpa_gui,there is one question: the scan have two 
mode:active or passive,but when i run the wpa_gui, there is only scan 
button, in the standard the scan request is like
MLME-SCAN.request (
but there are only three MAC frame formats:data frame, control frame 
and Management frame, and there is no scan frame, there is only a Probe 
Request frame,    so i am stumped, what's the relationship between 
MLME-SCAN.request and Probe Request frame, is the MLME-SCAN.request and 
Probe Request frame only in different layer? but the items is also 
different, the MLME-SCAN.request have:(
BSSType, BSSID, SSID,  ScanType, ProbeDelay,  ChannelList,  
MinChannelTime,   MaxChannelTime), but the  Probe Request frame body 
only have two parts:  SSID
and Supported rates.     and in my view, i think the active scan is to 
send Probe Request frame, and the passive scan to receive the beacon 
frame, is it right?
     thanks for advance!!

More information about the Hostap mailing list