Attach APN configuration problem

[Aleksander Morgado]

Hey,

>
>
> We're testing a Gl850-based Chromebook Cellular. We found thar some operators need Attach APN.
>
> We found the ModemManager can’t configure Attach APN automatically. Just can configure by  mmcli --3gpp-set-initial-eps-bearer-settings=[] for that.
>
> Let's consider if we can add a table with MCCMNC and Attach APN elements. During the attach phase, ModemManager looks up the table for different MCCMNC to determine if attach APN needs to be configured.
>
> Do you have any relevant suggestions or comments?
>
>


In general MM doesn't do that kind of "autoconfiguration"; it's only a
proxy between the real connection manager program (e.g. NetworkManager
or Chrome's Shill) and the device.

That said, MM currently does something which is more or less
equivalent. For the DW5821e, MM is able to detect and choose the
correct carrier configuration based on the SIM that is currently
inserted. The per-carrier configuration may have the initial EPS
bearer settings for the operator, among other things. This automatic
carrier configuration is done exclusively for this device though, no
other device implements this even if they support QMI PDC, because the
mapping between MCCMNC and carrier config ID is specific for this
module, and is a mapping provided by the manufacturer itself (the same
mapping they use in their Windows setup).

The case of the initial EPS bearer settings, though, is much "broader"
than the per-carrier config selection done in the DW5821e. E.g. can
you guarantee that a single operator (with a single MCCMNC) will have
exactly one initial EPS bearer attach APN for all its users (standard
users, corporate users...)? I don't think you can guarantee that,
because sometimes the attach APN (with/without user auth) is a way for
the operator to get the device registered in a specific subnet in
their network (e.g. for private APNs and such). And if that cannot be
guaranteed, there should also be no automatic selection of the initial
EPS bearer settings either, in my opinion.

The one who should be in charge of configuring these settings should
be a "higher level program", e.g. like GNOME Settings in the GNOME
desktop for example. Not sure which program should be in charge of
that in Chrome OS, though.

-- 
Aleksander
https://aleksander.es