Hi Forest,
On 12/05/2012 08:54 PM, Forest Bond wrote:
Hi Marcel,
Thanks for your message.
On Thu, Dec 06, 2012 at 12:12:26AM +0100, Marcel Holtmann wrote:
Hi Forest,
If the device has retained parameters for a previously defined IP
context, is is probed via AT+CGDCONT?.
this is really not a good idea. The AT+CGDCONT? settings are on a per
device basis. That is not how oFono actually works. It operates on a per
SIM card basis. And since you do not know to what SIM card these
previous settings apply to, the only sensible thing to do is to ignore
them.
Okay, I was not aware of this. But surely the common case (i.e. the only one
I've personally seen) is to have a single SIM card per device, and under those
limited circumstances it is safe to assume that the settings are valid for that
SIM. Would it be reasonable to implement such a fallback for this more limited
case?
I admit your approach did make me chuckle for being so unorthodox :)
However, I think your perception is slightly wrong, there are people who
switch sim cards like crazy (e.g. frequent travelers) so this form of
provisioning is not really a good idea in those cases.
You do know that oFono does keep its settings per SIM card persistent.
So no matter what device you enter that SIM card into, the settings will
be available the next time you try to connect. So it is a one time
configuration option.
Yes, I do know this. But it's just not a great fit for our use case.
We're using ConnMan and oFono to manage networking for computing appliances
(e.g. interactive kiosks and digital signs). These are typically deployed in
fleets of anywhere from 10 to 10,000 units. Clearly we do not want to manually
configure an APN for each machine. ;)
Ideally, we try to use a single configuration for the entire fleet to keep the
fleet easy to manage. But for a variety of business and technical reasons,
multiple service providers may be used within a given fleet. So we can't simply
provision a single APN for the entire fleet. What we really want is to be able
to plug a modem into the machine and it will Just Work.
So we'd like to choose the right APN based solely on information from the modem.
I've observed that modems tend to arrive with an IP context pre-configured
(including the correct APN). I assume the service provider sets this as part of
some internal provisioning process. Perhaps it is not safe to assume that this
will be the case with the majority of devices and/or providers. On the other
hand, if it is, it seems sensible to make use of that data.
The alternative to pulling the data from the device is to provide a mechanism
for specifying the APN policy for a particular fleet. (At least in theory the
APN selection policy can vary from one fleet to the next.) I assume this would
be implemented as a custom provisioning plugin that either hard-codes the policy
for the fleet, or provides a configuration mechanism that is flexible enough to
accommodate the needs of most fleets (probably using a provider -> APN mapping,
assuming we can guess the provider e.g. using the mobile-broadband-provider-info
database).
I'm getting lost, why is the default mobile-broadband-provider-info
plugin not good enough? And why don't you simply create your own
database based on the providers you are targeting? To me it seems like
you need X entries for all X providers you have. Unless the settings
vary within a given provider somehow?
Regards,
-Denis
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