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: head/share/man/man9/ieee80211_bmiss.9 233648 2012-03-29 05:02:12Z eadler $ 27.\" 28.Dd April 28, 2010 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 net/if.h 36.In net/if_media.h 37.In netproto/802_11/ieee80211_var.h 38.Pp 39.Ft void 40.Fn ieee80211_beacon_miss "struct ieee80211com *" 41.Sh DESCRIPTION 42The 43.Nm net80211 44software layer provides a support framework for drivers that includes 45handling beacon miss events in station mode. 46Drivers can dispatch beacon miss events that are recognized in hardware or 47.Nm net80211 48can detect beacon miss if the driver dispatches received beacon frames 49through the normal receive path. 50Software beacon miss support is especially useful when multiple vaps 51are operating and any hardware beacon miss support is not available 52(e.g. operating as an access point together with one or more station 53mode vaps). 54.Pp 55Drivers should dispatch beacon miss events recognized in the driver with 56.Fn ieee80211_beacon_miss . 57This causes some number of ProbeRequest frames to be sent to the 58access point to check if the association is still alive. 59If no response is received and roaming mode is set to 60.Dv IEEE80211_ROAMING_AUTO 61then 62.Nm net80211 63will try to re-associate and if that fails 64trigger a scan to look for the access point or another suitable AP. 65When the 66.Nm net80211 67state machine is being operated manually, e.g. by 68.Xr wpa_supplicant 8 , 69then applications are notified of the state change and are responsible 70for handling the work of scanning for a new access point. 71The number of beacon miss events (without a ProbeResponse) is user 72settable with the 73.Dv IEEE80211_IOC_BMISSTHRESHOLD 74request. 75.Pp 76Software beacon miss detection is enabled per-vap by setting the 77.Dv IEEE80211_FEXT_SWBMISS 78flag. 79Typically this is done when a vap is setup 80when the 81.Dv IEEE80211_CLONE_NOBEACONS 82option is supplied to the clone operation. 83But drivers may also force this when they know they need help detecting 84beacon miss. 85When beacon miss is detected in software the event is dispatched without 86driver involvement. 87Note that software beacon miss handling is not limited to station mode; 88it can be used in any operating mode where beacons from a peer station 89are received. 90.Sh SEE ALSO 91.Xr wpa_supplicant 8 , 92.Xr ieee80211 9 , 93.Xr ieee80211_vap 9 94