skip-dfs-channels option is not available for some time in the wireless menu. However, it’s still accessible when setting up CAPsMAN, even the new one that was introduced in RouterOS 7.13.
The wiki page about it says the following:
skip-dfs-channels (10min-cac | all | disabled)
Whether to avoid using channels, on which channel availability check (listening for presence of radar signals) is required.
10min-cac - interface will avoid using channels, on which 10 minute long CAC is required
all - interface will avoid using all channels, on which CAC is required
disabled (default) - interface may select any supported channel, regardless of CAC requirements
While I understand how all and 10min-cac values work, I’m not quite sure how disabled is affecting the channel selection. Does it bypass the CAC requirements and use the channels without scanning them first or does it comply with regulations and uses DFS and CAC where requested by the law?
I just want to know if there is any chance to bypass the legal requirements in the newer versions of the RouterOS; I hope there isn’t and the people that are violating the law are just using some older versions of the RouterOS. In my country - Czech Republic - there are several APs that interfere with weather radars and by looking at their MACs it’s always Routerboard or Ubiquiti.
I hope this was not discussed earlier, i tried to search through the forum first. If that is the case, I apologize for my bad vision )
The problem with DFS is that at some installation locations even though a fixed channel is selected where for sure there is no active radar, DFS still detects it. Then the channel changes to a random other number, also the channels where there IS radar. So it ends up hopping around all the time.
This “forces” people to turn off the DFS and when they are not observing the local radar situation they cause interference.
It is a difficult problem to solve… manufacturers are not allowed to have some customization options to adjust the sensitivity of the detection.
Also some of the (cheap) hardware simply cannot cope with radio environments where a lot of strong signals are present.
Yeah, I know that. For that reason, I usually use “all” option to skip all DFS channels. It doesn’t leave much room for channels without interference and power balance through the entire spectrum, but it’s still better than with DFS channels on, I think.
For indoor that is fine. But the interference is normally from outdoor use (links) where you normally want to use DFS-guarded channels because you can use more power there.
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