AT+ECM for connection management, QNCM rx_framing and le16 length prefixed IP tx_framing

Bjørn Mork bjorn at
Sat Mar 22 11:27:24 PDT 2014

Bjørn Mork <bjorn at> writes:

> And I wonder if this modem maybe speaks QMI and
> can be configured for an already known framing that way.  Better have
> that checked out first I guess.

Stupid me.  The dump was full of QMI as well.  I just missed them
because I was trusting that Ilya's wireshark dissector would identify
them for me.  But it didn't because it is tuned for usbmon dumps, not
for usbpcap dumps.

The QMI commands showed up fine after changing local_off from 64 (usbmon
URB header) to 28 (usbpcap USB header) in the dissector.

So this is definitely a QMI device, although the Windows driver use it
in a strange way.  The connection is managed with the AT+ECM command,
but some properties are still set up using QMI.  There are also WDS
commands in the dump, like for example "Set IP Family Preference".  The
odd framing is probably what's configured using service 0x1a.

I assume all this is optional and that we can let qmi_wwan and MM handle
it as any other QMI deivce. Let's start there in any case.


More information about the ModemManager-devel mailing list