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# ieee80211\_bmiss.9

`ieee80211_bmiss` — 802.11 信标丢失支持

## 名称

`ieee80211_bmiss`

## 概要

```c
#include <net80211/ieee80211_var.h>
```

```c
void
ieee80211_beacon_miss(struct ieee80211com *)
```

## 描述

`net80211` 软件层为驱动程序提供了支持框架，包括在站模式下处理信标丢失事件。驱动程序可以调度在硬件中识别的信标丢失事件，或者如果驱动程序通过正常接收路径调度接收到的信标帧，`net80211` 可以检测信标丢失。软件信标丢失支持在多个 vap 同时操作且没有硬件信标丢失支持时特别有用（例如作为接入点与一个或多个站模式 vap 一起操作）。

驱动程序应使用 `ieee80211_beacon_miss` 调度在驱动程序中识别的信标丢失事件。这会导致向接入点发送若干 ProbeRequest 帧以检查关联是否仍然有效。如果未收到响应且漫游模式设置为 `IEEE80211_ROAMING_AUTO`，则 `net80211` 将尝试重新关联，如果失败则触发扫描以查找接入点或另一个合适的 AP。当 `net80211` 状态机被手动操作时（例如由 wpa\_supplicant(8)），应用程序会被通知状态变化，并负责处理扫描新接入点的工作。信标丢失事件的数量（没有 ProbeResponse）可通过 `IEEE80211_IOC_BMISSTHRESHOLD` 请求由用户设置。

通过设置 `IEEE80211_FEXT_SWBMISS` 标志按 vap 启用软件信标丢失检测。通常这在设置 vap 时向 clone 操作提供 `IEEE80211_CLONE_NOBEACONS` 选项时完成。但驱动程序也可以在知道需要帮助检测信标丢失时强制启用。当在软件中检测到信标丢失时，事件调度不需要驱动程序参与。注意，软件信标丢失处理不限于站模式；它可以在接收来自对等站信标的任何操作模式下使用。

## 参见

wpa\_supplicant(8), [ieee80211(9)](/man/man9/ieee80211.9.md), [ieee80211\_vap(9)](/man/man9/ieee80211_vap.9.md)


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