focal (9) ieee80211_beacon_miss.9freebsd.gz

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)