自动频率选择机制DFS

最新推荐文章于 2025-06-13 08:50:27 发布

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博客内容提及了dmesg中频繁出现的AP频宽变化信息，这可能导致网络延迟和不稳定性增加。尽管ping操作未显示网络中断，但对延迟敏感的应用可能受到影响。文章建议检查WiFi环境的抗干扰能力及路由器设置，特别是AP的频宽设置，可能需要从“自动”调整为“20/40MHz”以减少此类信息的影响。

突然发现，dmesg中出现很多的这样信息，首先想到的是，难道网络在不停重启？ping www.xfyun.cn ping baidu.com

实验结果表明，ping操作并没有断掉过。也就是说，wifi并没有断掉过。

wlan0     Link encap:Ethernet HWaddr 00:15:00:64:e9:4c
          inet addr:192.168.1.43 Bcast:192.168.1.255 Mask:255.255.255.0
          inet6 addr: fe80::215:ff:fe64:e94c/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:120210 errors:0 dropped:0 overruns:0 frame:0
          TX packets:22166 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
说明一直在XTROBOT上面连接着。另一片转载博文提示会有更多的延迟和不稳定。这种情况在对网络延迟要求比较高的情况下，也许是致命的，要重点关注wifi环境抗干扰和路由器设置方法。延迟测量

[83679.389798] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 2 (2437/0 MHz)

[83680.312782] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 1 (2427/0 MHz)
[83683.387769] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 2 (2437/0 MHz)
[83685.335602] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 1 (2427/0 MHz)
[83686.360838] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 2 (2437/0 MHz)
[83688.308749] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 1 (2427/0 MHz)
[83690.358747] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 2 (2437/0 MHz)
[83706.351390] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 1 (2427/0 MHz)
[83708.401667] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 2 (2437/0 MHz)
[83709.324148] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 1 (2427/0 MHz)
[83711.374428] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 2 (2437/0 MHz)
[83712.399730] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 1 (2427/0 MHz)
[83713.424733] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 2 (2437/0 MHz)
[83715.371221] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 1 (2427/0 MHz)
[83723.368868] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 2 (2437/0 MHz)
[83724.392587] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 1 (2427/0 MHz)
[83725.419980] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 2 (2437/0 MHz)
[83728.392052] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 1 (2427/0 MHz)
[83730.442672] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 2 (2437/0 MHz)
[83731.365786] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 1 (2427/0 MHz)
[83733.415367] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 2 (2437/0 MHz)
[83734.440567] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 1 (2427/0 MHz)
[83735.365763] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 2 (2437/0 MHz)
[83740.386420] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 1 (2427/0 MHz)
[83742.437846] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 2 (2437/0 MHz)
[83743.461830] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 1 (2427/0 MHz)
[83744.384471] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 2 (2437/0 MHz)
[83745.408299] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 1 (2427/0 MHz)
[83749.406543] wlan0: AP 88:25:93:5a:f0:25 changed bandwidth, new config is 2427 MHz, width 2 (2437/0 MHz)

From the code, this is just an info message:

sdata_info(sdata,
"AP %pM changed bandwidth, new config is %d MHz, width %d (%d/%d MHz)\n",
ifmgd->bssid, chandef.chan->center_freq, chandef.width,
chandef.center_freq1, chandef.center_freq2);

and you are probably getting it because you have enabled: CONFIG_MAC80211_MESSAGE_TRACING

What dose this message mean? Dose the AP change its bandwidth?

Does it have any affects to STA? Or can we ignore it?

There might be a "channel width" setting in your AP, and possibly it is set as "Auto". You can try changing it to "20/40MHz" and confirm if you see the message.

If the station couldn't have supported this, then you would've got a message like:
"AP changed bandwidth in a way we can't support - disconnect"

文件:ClipCapIt-131021-173234.PNG