[Networkmanager] Preventing unnecessary and unwanted WiFi roaming

[Thomas Haller]

On Thu, 2023-11-02 at 15:51 +0100, Bjørn Mork wrote:
> 
> Well, enough ranting for today I guess :-)
> 

Hi Bjørn,


thanks for the insightful write up.


> So why does wpa_supplicant decide to switch APs?  Turns out it has a
hard coded limit 5 Mbps throughput limit:

Maybe all that needs to improve, is to adjust that value... Maybe the
5Mbps should be relative to the overall estimated throughput (e.g.
20%).

> better if we could just say that any estimated throughput over 200
Mbps (or whatver) is good enough.

Or that. Or a combination of both.


Other than that, NetworkManager should just configure the most suitable
"bgscan" option. The hard part is deciding on what the best strategy
is, to work for general cases. I don't believe this should be made
configurable to users. At most, we find several useful bgscan
strategies and an option like `wifi.roaming-
behavior=default|EAGERLY|NORMAL|CONSERVATIVE|ALMOST_NEVER|NEVER".
NetworkManager already chooses different bgscan values,  effectiveley
auto-selecting NORMAL, ALMOST_NEVER and NEVER.

> Why is that a hard coded policy deep inside wpa_supplicant?

I think NetworkManager should only tell supplicant the general (high-
level) roaming behavior, and how that is implemented, is up to
supplicant.


"simple:" indeed sounds like a naive approach, and there is room for
improvement. The question is, how exactly the strategy should be
improved.


Thomas