Huawei E3131 and the ignored at^ndisdup command

[Aleksander Morgado]

On 30/06/13 14:59, Enrico Mioso wrote:
> Hello guys!
> I'm happy to be now a member of this list! I read some messages in the
> archives and understood that I _should_ subscribe! :)
> 

Yes, thanks for doing that :)

> I have an Huawei E3131 device - it reuses the E398 ID, and similar
> disfunctions.
> First of all - this hardware version doesn't support LTE, and has been
> boughton Italy. the "ati" commands reports:
> Manufacturer: huawei
> Model: E3131
> Revision: 21.157.41.01.1037
> +GCAP: +CGSM,+DS,+ES
> 
> 
> at^hwver says:
> ^HWVER:"CH2E303SM"
> at^vertime says:
> ^VERTIME:Apr 19 2012 15:16:47
> 
> So it seems a pretty recent firmware version.
> As you know for sure, the device actually has the same ID as the E398,
> see attached lsusb; and is handled by the option driver (for the serial
> ports) and the cdc_ncm driver (for the wwan interface).
> 
> Even in this case, the commands:
> at^ndisdup
> or
> at^ndisconn
> returns an "OK" message, but the modem will not ever try to connect to
> the network.
> ModemManager, in a debug session, ended up using the 2plain ppp
> connection".
> I wanted to inform you all about the fact that:
> - I have the device
> - I can help in testing
> 
> And hoping someone has some ideas about this.
> 
> thank you all for your help!


According to Huawei, the only modems supporting NDISDUP in a Linux-based
system are those exposing a standard ECM/NCM interface, i.e. with the
following setup:
 * bInterfaceClass=02
 * bInterfaceSubclass=06
 * bInterfaceProtocol=00
or
 * bInterfaceClass=02
 * bInterfaceSubclass=0d
 * bInterfaceProtocol=00

In these modems, dialling is done through NDISDUP in the AT (PCUI) port.

Other modems exposing a wwan interface but without those
class/subclass/protocol values are supposed to support NDISDUP through
the NCM port with endpoint 0, but that is unsupported for now. There are
also newer Huawei modems labelled as 'hi-link' (like the E303), which
are supposedly auto-configured, but I haven't played with these yet. So
for now, NDISDUP is used in those modems that we know for sure it is
supported.

In short, having the NDISDUP command supported by the AT interpreter in
the modem doesn't mean it will actually do anything with it.


-- 
Aleksander