Re: Network with same ssid question

[Marcel Holtmann <marcel@holtmann.org>]

Hi Michael,

>>>>> suppose you have 3 access point with different signal strength on a
>>>>> network, the best will be connman select access point in the area
>>>> 
>>>> This selection is done by the wpa_supplicant/iwd, not by ConnMan.
>>> 
>>> the wpa_supplicatan using wpa_cli show all the network so connman
>>> can create several services with the same ssid name. The logic to what
>>> service to connect is can not be done even in connman
>> 
>> actually iwd does select the best possible AP and will also roam between them in case one AP tells iwd that a different AP is preferable or even if it gets asks to move bands. That is all done inside iwd. It is impossible to do sitting on top of wpa_supplicant.
>> 
> This depends on the tsf of the latest scan and how cache is managed
> and on hardware too.

no, it is impossible since wpa_cli only gets parts of the required information. So you are just out of luck. Trust me on this since the code in iwd to manage networks and roaming and band steering and so on is actually complex. Source code is available, feel free to check for yourself.

> 
>> Keep in mind that one physical AP broadcasting on 2.4 GHz and 5 GHz is already two BSSIDs with the same SSID. The client (like iwd) has to roam between the two bands.
>> 
> 
> That was already clear but this is a different use case because you
> know that both are part of the same access point.

Actually you don’t know that. They are two independent BSSIDs as well.

> 
>>>>>>> IIRC, ConnMan merges those together and only exposes it one Service.
>>>>>> 
>>>>>> is_duplicated the one that merges them? I think that in scenario when
>>>>>> multiple access point
>>>>>> are present we should not do it. I have seen that even iwd does not
>>>>>> show duplicated. Is that correct?
>>>> 
>>>> wpa_supplicant or iwd? I can't remember the wpa_supplicant details here.
>>>> For iwd, all these stuff is done in iwd. Not ConnMan.
>>> 
>>> I have tested iwctl and wpa_cli. The first one show only one ssid the second one
>>> all the access point. iw scan show all of them
>> 
>> The wpa_cli shows BSSIDs and so does iw. You see every single BSSID broadcasting. iwd works on networks. Every BSSID with the same SSID and matching security settings gets merged into a network. As it is meant to be done by the WiFi spec.
>> 
> 
> Ok, now it's clear. So iwd re-use the same password. Do you know if
> wpa_supplicant does the same?

I lost track of what wpa_supplicant does. We always found that whatever it does it is half-baked. You have to think about it this way, the main user is a human sitting in front of wpa_cli and typing commands. iwd is meant to just work. You provide the passphrase (or other credentials) and it does the job of keeping you connected.

Regards

Marcel