MC7430 Connection problem

Aleksander Morgado aleksander at
Mon Oct 2 16:36:55 UTC 2017

>> However when I try to connect with the modem to the LTE network it looks as
>> if the modem is successfully attached to the cell but I don't get an IP
>> address on any of my interfaces wwan0 or wwan1.
>> When i run the qmi-network tool I get the following output
>> sudo qmi-network /dev/cdc-wdm0 start
>> Loading profile at /etc/qmi-network.conf...
>>     APN: internet
>>     APN user: unset
>>     APN password: unset
>>     qmi-proxy: no
>> Checking data format with 'qmicli -d /dev/cdc-wdm0 --wda-get-data-format
>> '...
>> Device link layer protocol retrieved: raw-ip
>> Getting expected data format with 'qmicli -d /dev/cdc-wdm0
>> --get-expected-data-format'...
>> Expected link layer protocol retrieved: 802-3
>> Updating kernel link layer protocol with 'qmicli -d /dev/cdc-wdm0
>> --set-expected-data-format=raw-ip'...
>> error: cannot set expected data format: Expected data format not updated
>> properly to 'raw-ip': got '802-3' instead
> This is weird.
> AFAIK, 802-3 does not work on MC7430 ; just raw-ip.

There are 2 things we do here in the qmi-network script (same thing is
done in ModemManager):
  * the first one is asking the modem which is the link layer protocol
it expects, and in this case the modem is telling us it expects
"raw-ip" (MC74xx only support raw-ip)
  * the second one is asking the kernel which is the link layer
protocol it expects, and in this case the kernel is telling us it
expects "802.3" (the default one).

So, we try to tell the kernel it should use raw-ip and that fails.
Which kernel version are you using? The Linux kernel must be >= 4.5
for the raw-ip support to work!

>> Starting network with 'qmicli -d /dev/cdc-wdm0
>> --wds-start-network=apn='internet'  --client-no-release-cid '...
> Maybe add
> --wds-start-network=apn='internet',ip-type=4,autoconnect=yes
> here.
> And maybe try a
> --wds-stop-network=disable-autoconnect
> before the --wds-start-network.

No, don't think autoconnect has anything to do with this.

>> Saving state at /tmp/qmi-network-state-cdc-wdm0... (CID: 35)
>> Saving state at /tmp/qmi-network-state-cdc-wdm0... (PDH: 63159616)
>> Network started successfully
>> If I then try to obtain an ip address I get nothing
>> sudo dhclient -v wwan0
>> Internet Systems Consortium DHCP Client 4.3.1
>> Copyright 2004-2014 Internet Systems Consortium.
>> All rights reserved.
>> For info, please visit
>> Listening on LPF/wwan0/3a:0b:18:73:f4:e1
>> Sending on   LPF/wwan0/3a:0b:18:73:f4:e1
>> Sending on   Socket/fallback
>> DHCPDISCOVER on wwan0 to port 67 interval 8
>> DHCPDISCOVER on wwan0 to port 67 interval 8
>> DHCPDISCOVER on wwan0 to port 67 interval 15
>> DHCPDISCOVER on wwan0 to port 67 interval 14
>> DHCPDISCOVER on wwan0 to port 67 interval 16
>> No DHCPOFFERS received.
>> No working leases in persistent database - sleeping.
>> Any ideas what might be the issue ?

The modem expects raw-ip, and the kernel is expecting 802.3. That's one issue.

The other issue is that dhclient doesn't support interfaces configured
in raw-ip mode (but you'll get there once the kernel matching to
raw-ip happens). You can avoid using DHCP and instead retrieve static
IP settings with --wds-get-current-settings and apply them manually
(ip addr add XXX...) to the network interface.


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