Wireless interface bandwidth limit

[opty77]

At least on Linux e.g. cat /sys/class/net/wlan0/speed doesn't work because the driver(s) doesn't implement get_link_ksettings(), most probably due to difficulties (some below).

So I started thinking about developing a method to obtain a limit based on highest MCS supported for a band which might work for a fixed-configuration AP (access point) but not so well for STAs (clients) whose configuration may change dramatically in a short while, too fast for BandwidthDetectionInterval in minutes.

One could just take the highest limit amongst all supported bands but those may vary too much, e.g. TP-Link Archer TX3000E:

• 574 Mbps - 2SS 2.4GHz 802.11ax (40MHz chan., 1024QAM),
• 2402 Mbps - 2SS 5GHz 802.11ax (160MHz chan., 1024QAM) = AX3000 class

I'm asking whether any interest exists and I should continue or rather give up and set a limit manually?

[vergoh]

Somehow I recall having seen a wireless interface report that correctly in the past and I was expecting this to be mainly a driver related limitation, bug or other kind of issue. However, after resurrecting an old laptop for testing this with its integrated card, that Intel Centrino (using kernel 6.11.0) doesn't provide a readable speed in /sys/class/net. A Raspberry Pi 3 doesn't have it either so maybe I remember this wrong or mix it with some other type of interface.

Xfce's connection information and iwconfig are still able to pick up the active connection speed from somewhere suggesting it would be accessible somehow without having to do other tricks for getting similar information. It could probably worth checking which interface those are using to see if it could be usable also for vnStat or would there possible be a too large dependency chain if it being worth having.

My current suggestion would be setting MaxBWwlan0 to some sensible value. It doesn't need to be exact, it's just a failsafe after all to avoid unexpected counter rollovers and resets to be counted as actual traffic.

[opty77]

On Linux you could make use of Netlink but it looks pretty complex to me. On *BSD I found just possible attempt to port Netlink to FreeBSD.

Honestly as I was afraid, setting MaxBW* according to manufacturer specifications seems like the only option now but one has to keep that in mind e.g. when upgrading hardware.