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NAME

     ieee80211_bmiss — 802.11 beacon miss support

SYNOPSIS

     #include <net80211/ieee80211_var.h>

     void
     ieee80211_beacon_miss(struct ieee80211com *);

DESCRIPTION

     The net80211 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)