Sierra EM7455 LTE drop connection after a while

IoT Modules MC/EM Series
1

Hello guys
i have an issue when using Sierra EM7455 LTE on Ubuntu 18.04 kernel 4.15.0-72 raw ip mode

im trying to establish connection and im using qmicli (1.22.0 version) commnads:

1: “qmicli -d /dev/cdc-wdm0 --set-expected-data-format=raw-ip”
2: “qmicli -d /dev/cdc-wdm0 --wds-start-network=“apn=internetg,ip-type=4” --client-no-release-cid”

then i can see in “qmicli -d /dev/cdc-wdm0 --wds-get-current-settings”
for exmple
[/dev/cdc-wdm0] Current settings retrieved:
IP Family: IPv4
IPv4 address: 10.210.105.53
IPv4 subnet mask: 255.255.255.252
IPv4 gateway address: 10.210.105.54
IPv4 primary DNS: 194.90.0.11
IPv4 secondary DNS: 212.143.0.11
MTU: 1500
Domains: none

i can alos see in AT!SCACT? that it is : !SCACT: 1,1

but after copule of hours i see that !SCACT: 1,0 and the output of “qmicli -d /dev/cdc-wdm0 --wds-get-current-settings” is error: couldn’t get current settings: QMI protocol error (15): ‘OutOfCall’

i see in atthat :
+CGCONTRDP: 1,5,internetg,10.133.205.175,194.90.0.11,212.143.0.11

  AT!SCACT?
  !SCACT: 1,0

meanig that the ip has change (im not using static ip APN service ) but its not reflacting to the qmicli commands

pls if someone can advice , thanks in advance!!

here is more dump of maybe relevet AT commands :

ATI
Manufacturer: Sierra Wireless, Incorporated
Model: EM7455
Revision: SWI9X30C_02.24.05.06 r7040 CARMD-EV-FRMWR2 2017/05/19 06:23:09
MEID: 35907306077906
IMEI: 359073060779067
IMEI SV: 12
FSN: LF815621960110
+GCAP: +CGSM

OK

AT!PCINFO?
State: Online
LPM voters - Temp:0, Volt:0, User:0, W_DISABLE:0, IMSWITCH:0, BIOS:0, LWM2M:0, OMADM:0, FOTA:0
LPM persistence - None

OK Temperature: 45
Reset Counter: 1 Mode: ONLINE
System mode: LTE PS state: Attached
LTE band: B3 LTE bw: 20 MHz
LTE Rx chan: 1400 LTE Tx chan: 19400
LTE CA state: NOT ASSIGNED
EMM state: Registered Normal Service
RRC state: RRC Idle
IMS reg state: No Srv

PCC RxM RSSI: -57 RSRP (dBm): -91
PCC RxD RSSI: -62 RSRP (dBm): -95
Tx Power: 0 TAC: 03A4 (932)
RSRQ (dB): -13.8 Cell ID: 0038431F (3687199)
SINR (dB): 2.2

OK
AT!PCTEMP?
Temp state: Normal
Temperature: 45.00 C

OK
AT!PCVOLT?
Volt state: Normal
Power supply voltage: 3296 mV (ADC: 35850)

OK
AT+CPIN?
+CPIN: READY

OK
AT!IMPREF?
!IMPREF:
preferred fw version: 02.24.05.06
preferred carrier name: GENERIC
preferred config name: GENERIC_002.026_000
current fw version: 02.24.05.06
current carrier name: GENERIC
current config name: GENERIC_002.026_000

OK
AT+COPS?
+COPS: 0,0,“Cellcom IL Cellcom”,7

OK
AT+CGDCONT?
+CGDCONT: 1,“IP”,“internetg”,“0.0.0.0”,0,0,0,0

OK

2

someone can help maybe?

3

the NTWK can drop the connection for a number of reasons.
The modem will re-attach and acquire a new IP - this is normal.
The host should handle such cases and re-establish the session between the host & modem.

James

4

thanks for the replay!

how can i identifay those cases? or the host shout handle it automateclly?
if not , what should be done to restore connection ?

5

Maybe you can write a IP/DNS lookup program to check the network connectivity periodically.

6

When you bring up the connection between the modem & host (AT!scact=1 or QMI), the modem is notifies the host via a QMI unsolicited call.
GobiNet driver monitors these interface up/down calls and the link up/down msg will be propagated to upper layers.

For example you can monitor linkup/down with ethtool:

root@nano:/home/sierra# ethtool enp0s20u6i8
Settings for enp0s20u6i8:
Current message level: 0x00000007 (7)
drv probe link
Link detected: no
root@nano:/home/sierra# ethtool enp0s20u6i8
Settings for enp0s20u6i8:
Current message level: 0x00000007 (7)
drv probe link
Link detected: yes

James