1.\" 2.\" Copyright (c) 2009 Sam Leffler, Errno Consulting 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD$ 27.\" 28.Dd August 4, 2009 29.Dt IEEE80211_BMISS 9 30.Os 31.Sh NAME 32.Nm ieee80211_bmiss 33.Nd 802.11 beacon miss support 34.Sh SYNOPSIS 35.In net80211/ieee80211_var.h 36.Pp 37.Ft void 38.Fn ieee80211_beacon_miss "struct ieee80211com *" 39.Sh DESCRIPTION 40The 41.Nm net80211 42software layer provides a support framework for drivers that includes 43handling beacon miss events in station mode. 44Drivers can dispatch beacon miss events that are recognized in hardware or 45.Nm net80211 46can detect beacon miss if the driver dispatches received beacon frames 47through the normal receive path. 48Software beacon miss support is especially useful when multiple vaps 49are operating and any hardware beacon miss support is not available 50(e.g. operating as an access point together with one or more station 51mode vaps). 52.Pp 53Drivers should dispatch beacon miss events recognized in the driver with 54.Fn ieee80211_beacon_miss . 55This causes some number of ProbeRequest frames to be sent to the 56access point to check if the association is still alive. 57If no response is received and roaming mode is set to 58.Dv IEEE80211_ROAMING_AUTO 59then 60.Nm net80211 61will try to re-associate and if that fails 62trigger a scan to look for the access point or another suitable AP. 63When the 64.Nm net80211 65state machine is being operated manually, e.g. by 66.Xr wpa_supplicant 8 , 67then applications are notified of the state change and are responsible 68for handling the work of scanning for a new access point. 69The number of beacon miss events (without a ProbeResponse) is user 70settable with the 71.Dv IEEE80211_IOC_BMISSTHRESHOLD 72request. 73.Pp 74Software beacon miss detection is enabled per-vap by setting the 75.Dv IEEE80211_FEXT_SWBMISS 76flag. 77Typically this is done when a vap is setup 78when the 79.Dv IEEE80211_CLONE_NOBEACONS 80option is supplied to the clone operation. 81But drivers may also force this when they know they need help detecting 82beacon miss. 83When beacon miss is detected in software the event is dispatched without 84driver involvement. 85Note that software beacon miss handling is not limited to station mode; 86it can be used in any operating mode where beacons from a peer station 87are received. 88.Sh SEE ALSO 89.Xr wpa_supplicant 8 , 90.Xr ieee80211 9 , 91.Xr ieee80211_vap 9 92