table of contents
IEEE80211_BMISS(9) | Kernel Developer's Manual | IEEE80211_BMISS(9) |
NAME¶
ieee80211_bmiss
—
802.11 beacon miss support
SYNOPSIS¶
#include
<net80211/ieee80211_var.h>
void
ieee80211_beacon_miss
(struct
ieee80211com *);
DESCRIPTION¶
Thenet80211
software layer provides a
support framework for drivers that includes handling beacon miss events in
station mode. Drivers can dispatch beacon miss events that are recognized in
hardware or net80211
can detect beacon miss
if the driver dispatches received beacon frames through the normal receive
path. Software beacon miss support is especially useful when multiple vaps are
operating and any hardware beacon miss support is not available (e.g.
operating as an access point together with one or more station mode vaps).
Drivers should dispatch beacon miss events recognized in the driver with
ieee80211_beacon_miss
(). This causes some
number of ProbeRequest frames to be sent to the access point to check if the
association is still alive. If no response is received and roaming mode is set
to IEEE80211_ROAMING_AUTO
then
net80211
will try to re-associate and if
that fails trigger a scan to look for the access point or another suitable AP.
When the net80211
state machine is being
operated manually, e.g. by wpa_supplicant(8),
then applications are notified of the state change and are responsible for
handling the work of scanning for a new access point. The number of beacon
miss events (without a ProbeResponse) is user settable with the
IEEE80211_IOC_BMISSTHRESHOLD
request.
Software beacon miss detection is enabled per-vap by setting the
IEEE80211_FEXT_SWBMISS
flag. Typically this
is done when a vap is setup when the
IEEE80211_CLONE_NOBEACONS
option is
supplied to the clone operation. But drivers may also force this when they
know they need help detecting beacon miss. When beacon miss is detected in
software the event is dispatched without driver involvement. Note that
software beacon miss handling is not limited to station mode; it can be used
in any operating mode where beacons from a peer station are received.
SEE ALSO¶
wpa_supplicant(8), ieee80211(9), ieee80211_vap(9)August 4, 2009 | Debian |