NDISDUP+wwan for Huawei devices using the new 'huawei_cdc_ncm' driver

[Dan Williams]

On Mon, 2013-11-25 at 20:00 +0100, Thomas Schäfer wrote:
> Am Montag, 25. November 2013, 19:05:29 schrieb Aleksander Morgado:
> 
> > For reference, the specific changes to run NDISDUP in the /dev/cdc-wdm
> > port are now in the following branch upstream:
> >   aleksander/huawei-ndisdup-cdc-wdm
> 
> Thanks for the info. I have a question about IP and DNS-configuration. For qmi 
> and mbim-devices you get (additionally) the configuration via 
> mm-bearer-qmi.c and mm-bearer-mbim.c 
> Is there a similar way via AT?
> Especially for (IPV6) DNS-resolver-servers? 
> (for both types of AT-connect: 
> Ericsson: AT*ENAP, 
> Huawei: at^ndisdup)

It depends on whether the device implements vendor-specific AT commands
to do this.  Most vendors don't support IPv6 with their AT command.  Of
the vendor-specific commands, IIRC only Altair, Icera, and Huawei
support IPv6 on *some* devices.

Note that a few devices support IPv6 via PPP (eg Nokia 21M) but
obviously you get horrible speed when using PPP, and DNS servers may not
be relayed at all.

The "correct" way, according to all the standards, would be to provide
IPv6 Router Advertisements over the pseudo-ethernet port once the
connection has been started via AT/MBIM/QMI/whatever.  These can include
your router address, the network prefix, DNS servers, and search
domains.  This can even be done over PPP.  But almost no firmware does
this, and when they do, they do it very, very badly.

Dan