Strange behaviour of Sierra Wireless MC7430

Erik Kazandjian erik.kazandjian at
Tue Oct 17 05:52:45 UTC 2017


The MC7430 does behave very strange when I try to setup ip connectivity 
to it.

When I bring the modem on line *qmicli -d /dev/cdc-wdm0 
--dms-set-operating-mode=online* I see the modem attaching on our cell 
and in the Attach accept message it gets an IP address. That address is 
not automatically added to the wwan0 interface. Verification of the 
nas-serving-system returns the following info

*qmicli -d /dev/cdc-wdm0  --nas-get-serving-system *
[/dev/cdc-wdm0] Successfully got serving system:
     Registration state: 'registered'
     CS: 'attached'
     PS: 'attached'
     Selected network: '3gpp'
     Radio interfaces: '1'
         [0]: 'lte'
     Roaming status: 'off'
     Data service capabilities: '1'
         [0]: 'lte'
     Current PLMN:
         MCC: '1'
         MNC: '1'
         Description: 'Test1-1'
     Roaming indicators: '1'
         [0]: 'off' (lte)
     3GPP location area code: '65534'
     3GPP cell ID: '769'
     Detailed status:
         Status: 'available'
         Capability: 'cs-ps'
         HDR Status: 'none'
         HDR Hybrid: 'no'
         Forbidden: 'no'
     LTE tracking area code: '1'
     Full operator code info:
         MCC: '1'
         MNC: '1'
         MNC with PCS digit: 'no'

However when I try to get information about the IP address using *qmicli 
-d /dev/cdc-wdm0  --wds-get-current-settings* I get

error: couldn't get current settings: QMI protocol error (15): 'OutOfCall'

Until a few days ago this would just return me the assigned IP address. 
If I than start the network (can someone explain me what this does) I 
get the following *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 
Expected link layer protocol retrieved: raw-ip
Device and kernel link layer protocol match: raw-ip
Starting network with 'qmicli -d /dev/cdc-wdm0 
--wds-start-network=apn='internet'  --client-no-release-cid '...
Saving state at /tmp/qmi-network-state-cdc-wdm0... (CID: 35)
Saving state at /tmp/qmi-network-state-cdc-wdm0... (PDH: 62876480)
Network started successfully

If I than ask for the current settings *qmicli -d /dev/cdc-wdm0  
--wds-get-current-settings* I get

  Current settings retrieved:
            IP Family: IPv4
         IPv4 address:
     IPv4 subnet mask:
IPv4 gateway address:
     IPv4 primary DNS:
                  MTU: 1500
              Domains: none

The first thing I noticed is the netmask. I don't know where the modem 
is getting this from but it is definitely not coming from the core 
network. Anyway if I assign to the wwan0 interface I see 
that wwan0 is configured but the Link encap is UNSPEC

wwan0     Link encap:UNSPEC  HWaddr 
           inet addr:  P-t-P: Mask:
           inet6 addr: fe80::d37a:aed3:aeb:4d4/64 Scope:Link
           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
           TX packets:9 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:1000
           RX bytes:0 (0.0 B)  TX bytes:504 (504.0 B)

If I than try to ping from my raspberry pi which has the modem connected 
to a host behind the core network, I see nothing arriving in the GTP 
tunnel on core network, however when I ping from the host behind the 
core network to I get replies from the ping , I even see 
them in both directions going through the GTP tunnel but on my linux 
interface (wwan0) on the rasberry pi I don't see any packet being 
received or transmitted. So it looks as if the Sierra Wireless card is 
responding to the pings but it is not offering its IP capabilities to 
the my Linux.

Does any body has any idea what is going on ?

Kind regards


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