What is WiFi DFS?
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- เผยแพร่เมื่อ 2 ส.ค. 2024
- What's DFS in WiFi you ask? Let's talk about Dynamic Frequency Selection and what it does. I try to explain it, let me know if this helped.
Sources: WiFi Alliance and CWNA Study Guide
00:00 - Intro
00:30 - What is DFS?
00:50 - Dry Erase Board Beginning
09:15 - Wrap Up
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Willie this video was looong time coming.
In Czech Republic, Slovakia and I presume the rest of the EU, if you deploy outside placed APs, it's mandatory to use DFS channels. This is a huge headache with UniFi They jump, however, if they were to jump, say, to channel 52 and I deployed, say UAP-AC-M outside, I am suddenly not in compliance, because channel 52 is indoors only. There used to be a selection box, back in a day, where you could disable indoor only channels for outside installations, but it's gone now. Meanwhile AirMax devices can have preset fallback channel. Ubiquiti would stand to benefit from pooling their ideas a little. Sure, ISP gear is ISP gear, but WiFI is WiFi!
For sparse home environments where you have only a few neighbor APs, you can might be able to tell your router to exclude DFS channels but still auto-select channels. Of course, this only works if your have a single router or your other APs negotiate with the main router. My Verizon Fios router and extender have this option and they include DFS channels by default.
This is a wonderful explanation! Appreciate your work.
For quick info: I recommend setting the video playback speed to 1.25x or 1.5x as the video lacks editing, and feels drawn out.
If you're looking for a summary
(Yes, I know this video is 2 yrs+ old)
(DFS have longer channel acquisition times compared to non-DFS channels sometimes as little as 60 seconds and up to 10 mins to make sure the channel is not occupied)
Rural areas: with fewer 'disruptions' and less 'noise,' enabling DFS channels should generally be fine. However, there is a possibility of channel switching if a radar system starts using the DFS channel, which may cause issues for devices that cannot handle frequent channel changes.
High populated areas: utilizing DFS channels can provide access to less congested channels, resulting in potentially better performance. However, there is also a higher chance of being kicked off those channels if there is a heavier presence of prioritized radars, which can lead to interruptions in the 5GHz connection.
Personal Opinion: Don't use DFS if you don't need to. In rural areas, channel congestion should be minimal, and in highly populated areas, DFS channels will probably be as reliable or congested as public channels.
Apologies for the long comment and my complaints about the video layout. Hopefully, this recap helps someone understand the topic better. Thank you Willie Howe for the overview!
Thank you for the detailed explanation!
Great info here, thanks!
Awesome content
Thanks a lot. This information is helpful please make more video about latency
off or on
Hi, Awesome video. indeed useful. As I research on channel switch announcements, I have a few questions to clarify.
1. If an AP is enabled with DFS, I usually observe, it starts with channel 52(being Europe) and keeps this channel during its uptime as long as there are no radars or interference. Is this correct?
2. If DFS is enabled, with a single operating channel, the AP can communicate with multiple devices simultaneously using the feature OFDMA (main channel divided into partial channels if 802.11 ax used). In this case, how can we identify the frequency of partial or sub channels. Any idea?
3. In our personal home networks, if the AP is enabled with DFS, will it continously scans for radars or such interference? I understand that the scan (channel availability check) will happen only when it boots for first time. Is this correct?
4. DFS feature is not available or applicable to 2.4. ghz. Is this correct?
I would be thankful, if you could clarify my doubts. thank you in advance.
What will happen if we change from the DFS channel to nondfs channel?
Ok I think I am gonna stop using DFS, I have seen these alerts in my unifi dashboard and am close to a small airport lol
Is DFS for AP’s concern? As a STA (client), it should not worry about. Right?
some reason none of my 5G devices can connect to my network because it says I'm connected on 48 but DFS is waiting.
How do I resolve this? WIFI AI is off.
I've changed the channel multiple times and nothing works
if there is no airports near me i shouldnt have problems with radars right?
Need help with neighbor deathorising my wifi
Thanks for this tidbit. If someone happens to live on a rural street close to a speed trap, would a speed radar kick the AP off and cycle the check mode?
@@WillieHowe that makes a lot of sense now. Thanks 👍
No, speed radar works in X band (8-12Ghz), K band (18-27Ghz), or Ka band (33.4-36Ghz)
In Germany it's "Deutsche Flugsicherung". The agency for air safety.
The conclusion is that you should not use a 5 GHz WiFi with DFS, if you want a reliable connection, as a replacement for the network cables in a home.
first
OK, so the moral of the story is stay the hell away from DFS channels got it