How does routeros decide which frequency to use when AP is set to auto?
Does it scan and look for the frequency with the least noise? (If so; How often does it perform such scan?)
Does the connected clients affect the frequency selection in any way? If there are two AP’s at same frequency (your own and one of your neighbors network), the neighbors AP may be out of range for AP (inside your house). But when you’re outside in your yard the neighbors AP may interfere so much with your AP that your laptop struggles with connection. Would the auto channel selection switch to another frequency in such case? If so, how would it know that the laptop would prefer another frequency when the current frequency seems to be the best at the APs location?
It only scans once. It finds the frequency with the least number of other devices and sets it. That’s all it does.
So it is not about signal levels and band utilisation and such things? Just about the number of other devices? OMG!
Yes, this is only based on number of networks in each frequency. It is only for home users that don’t know which frequency to use.
Then it is clear now why I always finally set the frequency manually because automatic selection performed worse than expected.
There is normally only one problem with automatic frequency selection, and it is that it would not
adhere to your channel spacing method. I.e. when selecting manually you would use only
channels 1-6-11 or 1-6-13 and then the automatic selection puts it on channel 8,
for example. That will result in worse performance than just using channel 6 all the time.
The reason I asked is that a customer is in a location where channels are crowded. Even in the 5ghz band its hard to find channels. I’ve never used auto channel. At this place there may be channels available where the AP is located, but once moving 5m away the same channel is filled with other networks. The result is that what looks good at the AP is not usable at the client. Thats what makes the channel selection so hard.
To make it even worse neighbors are randomly changing channels so that even when I have found channels that performs well, my customers wlan start to perform bad after a while. In april they changed to cisco AP’s, set them to auto channel, and their channel-issue has not reoccurred. I don’t know how cisco decides channels, but it seems to be working.
Cisco have the clear channel technology.
Basically the Cisco AP is monitoring the channel if it detects a lot of interference it changes channels automatically.
Maybe that could be something for Mikrotik to implement as well?
is there a way of monitoring the channel and if it detects a lot of interference it changes channels automatically?
Or even some script that periodically scanned and could change channels if some aspect went over some threshold.
Anyone know how to restart the channel scanning process? Just as it does on boot?
One way could be to schedule a reboot. Preferably outside office hours.
Does the AP scan only at boot up, or would it scan any time the wireless is enabled? As in a script to disable/enable wireless at a selected time each day?
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when you disable/enable interface it will run channel select procedure.
Nordex, thanks for responding.
Would this be a recommended thing to do in a relatively high density environment? Run the script at 4am daily or some such thing, or weekly? I’m referring primarily to a single AP in a system, not multiples where you could end up with overlap.
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Running it at 4AM has the disadvantage that the situation at that time may not be representative.
Some access points in the neighborhood could be turned off at that time.
Anyway, once congestion is so high that you need to change channels the end is near. There are only 3 channels.
It is better to invest in a 5 GHz AP then.
Old thread, but it looks like a solution has arrived! I have not tested though, and it’s not mentioned in the wiki.
ROS: 6.40.3
Capsman → Channel → reselect interval
The name sounds like something we’ve been looking for.
Seems like this cannot be set on a wlan interface not controlled by capsman.
It’s shocking to hear that the implementation is that weak. But then again can’t say I’m surprised based on it’s performance. Why oh why would you not make use of the frequency usage scanner as a minimum to find a channel that has the lowest usage and best noise floor combination?
One reason would be that (at least on some models) you have only one receiver so you cannot look around to see
what is going on on the other channels while still communicating with your clients. That would mean that there would
be an interruption just to check if another channel is less crowded, something some customers maybe would not like.
A more modern AP could be able to use a second or third chain to scan while still being connected, so that may not
always be a valid reason.
There seams to be a bit more to it unfortunately.
One could theoretically use frequency-monitor or snooper to get an idea for how populated the other channels are to make an informed decision. But once you start going down this path you’ll quickly see that these functions have been nerfed to make it practically impossible to make your own smart channel selection script. Frequency monitor does not support “do” or save to file so you can’t get any of it’s data out. Same type of issues with swoop. Either it is massively under-featured, or it’s been intentionally removed to prevent users from writing their scripts that actually do what one expects in 2018. On the forum there is evidence that it once supported “do” so it seems like this was intentionally removed, which makes me lean towards the latter argument where they don’t want us to do this.