Compare MC7430 based on qmi_wwan and GobiNet

Bjørn Mork bjorn at
Fri Sep 9 07:59:34 UTC 2016

dailijin <dailijin126 at> writes:

> Hi All,
> I just now test Sierra dev kit and driver, the MC7430 can work and get
> IP via dhclient, Does this indicate the modem work on 802-3 protocol?

No, but the GobiNet driver will add and strip the ethernet header, so it
appears so to the host.  This is similar to what e.g. cdc_mbim does for
MBIM functions.

We had an informal vote for or against that model before implementing
the qmi_wwan raw-ip support, and it was rejected. If anything, I regret
having pushed for doing it in cdc_mbim.  And I definitely regret having
chosen 802-3 as the default mode for qmi_wwan.  We would have been much
better off with raw-ip from the beginning, and just rejected the
ethernet illusion.  But time machines are currently too expensive for me

> Before somebody told me the MC7430 only can work with raw-ip mode,


> so need use udhcpc include dhclient to get IP,

Correct for qmi_wwan, since it does not fake an ethernet interface in
raw-ip mode.

As you have found out, there are ways to make dhclient work too since
the modem does run a DHCP server.  One method is making the driver add
dummy headers.  Another method is making dhclient accept that there is
no header

> I want to test MC7430 modem work on 802-3 mode with qmi_wwan driver,
> but always set data packet as 802-3 fail. Does anyone know how to do
> this?

Not supported by the MC7430.  Just ask Sierra Wireless.


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