Hello Bjørn,

Very informative email. You are spot on, it was the NCM/MBIM problem.

After following your suggestions, the wwan card now works perfectly.

For some reason, NetworkManager (or maybe nm-applet) did not pick up the
interface after loading cdc_nbm. A reboot seems to have solved that.

Thank you very much!

Dan


On Mon, Apr 15, 2013 at 5:19 PM, Bjørn Mork <[email protected]> wrote:

> Dan Irwin <[email protected]> writes:
>
> > Hello,
> >
> > I have a dell 3g "wwan" 5560 card in my laptop, which is detected, but
> does
> > not connect to the Internet. The card appears as wwan0 to my system.
> >
> > ModemManager seems to open ttyACM1 and ttyACM2 (but not ttyACM0), and
> > dhclient is started on wwan0.
> >
> > After sending DHCPDISCOVER 4 times, NetworkManager seems to give up.
> >
> > I'm not sure what is meant to happen here. I assume the card negotiates
> > with the network, and present's an ethernet interface (and presumably a
> > dhcp server) to the OS. However, something somewhere is broken.
> >
> > This configuration appears to work in Windows 7, and I think it also
> worked
> > in Fedora 17, but I'm not 100% sure.
> >
> > Short of re-installing F17, is there anything obvious I should look for?
>
> I believe the Dell 5560 is a re-branded Ericsson F5321?  If this is a
> new laptop, or you have recently upgraded the wwan firmware, then you
> may have hit the "NCM/MBIM problem".
>
> Do you have this parameter, and is it set to yes?:
>
>  bjorn@nemi:~$  grep . /sys/module/cdc_ncm/parameters/prefer_mbim
>  Y
>
> If so, then the problem may be solved by
>
>  echo N >/sys/module/cdc_ncm/parameters/prefer_mbim
>
> followed by unbinding the modem from cdc_mbim and rebinding it to
> cdc_ncm.  Which should happen automatically if you "unplug" and replug
> it (I know it's an internal module, but this might still be possible
> using rfkill).
>
> Or just unload the drivers and reload them to test:
>
>  modprobe -r cdc_mbim
>  modprobe cdc_ncm prefer_mbim=N
>
>
> If this works, then you may want to add a config workaround until MM
> support for MBIM is ready. Put something like this into a new
> /etc/modprobe.d/avoid-mbim.conf file:
>
>  options cdc_ncm prefer_mbim=N
>
>
> (Note that you probably do want to remove this again when the MBIM
> support is available, because that will enable MM to better manage your
> modem).
>
>
> > I can provide logs, if needed.
>
> That would be good to confirm my wild guesses.  Preferably including
> enough kernel logs to see which drivers are binding to the device.
>
>
> Bjørn
>
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