fibocom: Minimum PDP context ID

[Aleksander Morgado]

Hey,

> > The CID=2 context was created because we're now explicitly requesting
> > a specific APN in settings. I think that should be fine.
> >
> >> +CGCONTRDP:
> >> 1,5,"internet.gma.iot","10.80.129.7",,"193.181.245.57","193.181.245.58"
> >> +GTRNDIS: 1,2,"10.80.129.7","193.181.245.57","193.181.245.58"
> >> +CGACT: 1,1
> >> +CGACT: 2,0
> >
> > So CID=2 is not being used at all because the runtime state already
> > matches the settings we were requesting. So this is like, we create
> > some specific bearer settings to use in CID=2 but the modem decides to
> > reuse the already connected CID=1 that had the same runtime settings.
> > We should handle this somehow definitely.
>
> Yes, I believe this is what happens. Note, however, that +GTRNDIS?
> expectedly reports CID=2
>

Ah, that's actually better isn't it? It matches the CID of the profile
we created.

> >> However, when configuring different APN for initial and ECM bearer, this
> >> is the behavior after the +GTRNDIS connection:
> >>
> >> +CGDCONT: 1,"IP","gemalto.ericsson.iot","10.118.26.77",0,0,0
> >> +CGDCONT: 2,"IP","internet.gma.iot","10.80.196.82",0,0,0
> >> +CGCONTRDP:
> >> 1,5,"gemalto.ericsson.iot","10.118.26.77",,"193.181.245.57","193.181.245.58"
> >> +CGCONTRDP:
> >> 2,6,"internet.gma.iot","10.80.196.82",,"193.181.245.57","193.181.245.58"
> >> +GTRNDIS: 1,2,"10.80.196.82","193.181.245.57","193.181.245.58"
> >> +CGACT: 1,1
> >> +CGACT: 2,1
> >>
> >
> > All this above is expected, right? I don't see any issue with that.
>
> Agreed. This is what I expected.
>
> > Once the connection attempt has succeeded, we should run an explicit
> > +CGCONTRDP to look for which CID is the one that got really connected
> > matching the APN we requested, and if the CID is different to the one
> > that we thought would be, then internally change the CID value so that
> > the connection checks can go on normally with the correct CID,
> > something like that? What do you think?
>
> That would work I think. Do you then suggest to continue using +CGACT?
> for the connectivity check or switch to +GTRNDIS?
>

If with +GTRNDIS we can simply modify the connectivity check step, I
think that is probably the quickest way forward. If that is not
enough, and we need to involve changing the logic to guess which is
the CID that was really connected at the end, then we could keep
+CGACT. Open to your suggestions here.

> >> When hacking the initial EPS bearer setup into a connection manager
> >> (e.g. NetworkManager), should this be done before or after enabling the
> >> modem device?
>
> I looked into this some more. It seems like it's not possible to set the
> initial EPS settings if the modem is disabled.
>
> > Looks like that would be mixed in the Cinterion plugin? Or maybe the
> > Cinterion modules behave in a different way?
> > Giacinto, what do you think?
>
> Looks like it's mixed up in the cinterion plugin.
>

I see.

-- 
Aleksander