generic-unspecified Bearer End

Sat Feb 23 12:33:21 UTC 2019

I've analysed the following sequence of events against a control plane
packet capture provided by AT&T, I believe this capture is between the core
and the tower and not the tower and device, it uses the GTPv2 protocol.

In the log you'll find below my device is assigned an IP at 22:17:55. The
capture shows many release access bearer requests and responses as well as
modify bearer request and response messages following this. I believe this
is normal operation for a mobile device as it moves in and out of standby
mode. No disruption of connectivity is seen as monitored on the device. At
22:33:34 the network sends a delete bearer request message to the device,
This is seen as the bearer call end message in the device logs at 22:33:34.
A new session is initiated immediately by the device and the received IP
address seen in the logs matches with the capture.

>From what I see in the captures the issues with connectivity seem to be on
the radio network side and not related to the modem behaviour.

I'd welcome any feedback you can offer on my analysis.

Feb 19 22:17:54 ModemManager[932]: <info>  bearer call end reason (1):
'generic-unspecified'
Feb 19 22:17:54 ModemManager[932]: <info>  bearer verbose call end reason
(3,1028): [cm] (null)
Feb 19 22:17:54 ModemManager[932]: <info>  Modem
/org/freedesktop/ModemManager1/Modem/0: state changed (connected ->
registered)
Feb 19 22:17:55 ModemManager[932]: <info>  Modem
/org/freedesktop/ModemManager1/Modem/0: state changed (registered ->
connecting)
Feb 19 22:17:55 ModemManager[932]: <info>  QMI IPv4 Settings:
Feb 19 22:17:55 ModemManager[932]: <info>      Address: 10.x.x.133/30
Feb 19 22:17:55 ModemManager[932]: <info>      Gateway: 10.x.x.134
Feb 19 22:17:55 ModemManager[932]: <info>      DNS #1: 8.8.8.8
Feb 19 22:17:55 ModemManager[932]: <info>      DNS #2: 8.8.4.4
Feb 19 22:17:55 ModemManager[932]: <info>         MTU: 1430
Feb 19 22:17:55 ModemManager[932]: <info>  Modem
/org/freedesktop/ModemManager1/Modem/0: state changed (connecting ->
connected)
Feb 19 22:33:34 ModemManager[932]: <info>  bearer call end reason (1):
'generic-unspecified'
Feb 19 22:33:34 ModemManager[932]: <info>  bearer verbose call end reason
(3,1028): [cm] (null)
Feb 19 22:33:34 ModemManager[932]: <info>  Modem
/org/freedesktop/ModemManager1/Modem/0: state changed (connected ->
registered)
Feb 19 22:33:35 ModemManager[932]: <info>  Modem
/org/freedesktop/ModemManager1/Modem/0: state changed (registered ->
connecting)
Feb 19 22:33:35 ModemManager[932]: <info>  QMI IPv4 Settings:
Feb 19 22:33:35 ModemManager[932]: <info>      Address: 10.x.x.59/29
Feb 19 22:33:35 ModemManager[932]: <info>      Gateway: 10.x.x.60
Feb 19 22:33:35 ModemManager[932]: <info>      DNS #1: 8.8.8.8
Feb 19 22:33:35 ModemManager[932]: <info>      DNS #2: 8.8.4.4
Feb 19 22:33:35 ModemManager[932]: <info>         MTU: 1430
Feb 19 22:33:35 ModemManager[932]: <info>  Modem
/org/freedesktop/ModemManager1/Modem/0: state changed (connecting ->
connected)

-JohnF

On Fri, Feb 22, 2019 at 10:17 AM John Marrett <johnf at zioncluster.ca> wrote:

> I am experiencing intermittent issues with session disconnects on a
> private APN on the AT&T network. When experiencing the issue we see "bearer
> call end reason (1): 'generic-unspecified'" in the ModemManager logs.
>
> I'm running Modem Manager version 1.8.0 with custom control scripts, we
> aren't presently using Network Manager. The modem is a Sierra Wireless
> MC7354 running SWI9X15C_05.05.58.00 r27038 carmd-fwbuild1 2015/03/04
> 21:30:23. Rebooting the modem (cold boot) and restarting the embedded
> system driving it (including a modem reboot) do not affect the behaviour.
> This specific site observed the problem for three days last week, it then
> worked properly for two days and resumed the disconnection after 72 hours
> of clean behaviour. There are three other devices located at this same
> site. Two of them have shown no issues in the past two weeks, one followed
> a similar pattern to this one for the first period of session disconnects
> but did not resume with the other unit.
>
> AT&T indicates that the modem itself is disconnecting from the network and
> that the disconnect is not tower or network initiated. I have received
> control plane packet captures that I intend to compare with these logs to
> confirm the behaviour details this weekend, but wanted to see if anyone on
> the list could offer any guidance.
>
> I would like to run in debug mode but I can't restart the ModemManager
> process remotely without an unacceptable risk of connection loss. If
> there's a way to enable debug mode on the running Modem Manager process I
> could get much more detailed info from the site.
>
> Thanks very much for your help, I'm ready to provide any information
> required, logs follow,
>
> -JohnF
>
> Feb 22 15:20:18 device ModemManager[932]: <info>  bearer call end reason
> (1): 'generic-unspecified'
> Feb 22 15:20:18 device ModemManager[932]: <info>  bearer verbose call end
> reason (3,1028): [cm] (null)
> Feb 22 15:20:18 device ModemManager[932]: <info>  Modem
> /org/freedesktop/ModemManager1/Modem/0: state changed (connected ->
> registered)
> Feb 22 15:20:19 device ModemManager[932]: <info>  Modem
> /org/freedesktop/ModemManager1/Modem/0: state changed (registered ->
> connecting)
> Feb 22 15:20:20 device ModemManager[932]: <info>  QMI IPv4 Settings:
> Feb 22 15:20:20 device ModemManager[932]: <info>      Address:
> 10.x.x.225/30
> Feb 22 15:20:20 device ModemManager[932]: <info>      Gateway: 10.x.x.226
> Feb 22 15:20:20 device ModemManager[932]: <info>      DNS #1: 8.8.8.8
> Feb 22 15:20:20 device ModemManager[932]: <info>      DNS #2: 8.8.4.4
> Feb 22 15:20:20 device ModemManager[932]: <info>         MTU: 1430
> Feb 22 15:20:20 device ModemManager[932]: <info>  Modem
> /org/freedesktop/ModemManager1/Modem/0: state changed (connecting ->
> connected)
> Feb 22 15:35:58 device ModemManager[932]: <info>  bearer call end reason
> (1): 'generic-unspecified'
> Feb 22 15:35:58 device ModemManager[932]: <info>  bearer verbose call end
> reason (3,1028): [cm] (null)
> Feb 22 15:35:58 device ModemManager[932]: <info>  Modem
> /org/freedesktop/ModemManager1/Modem/0: state changed (connected ->
> registered)
> Feb 22 15:35:59 device ModemManager[932]: <info>  Modem
> /org/freedesktop/ModemManager1/Modem/0: state changed (registered ->
> connecting)
> Feb 22 15:35:59 device ModemManager[932]: <info>  QMI IPv4 Settings:
> Feb 22 15:35:59 device ModemManager[932]: <info>      Address: 10.x.x.35/29
> Feb 22 15:35:59 device ModemManager[932]: <info>      Gateway: 10.x.x.36
> Feb 22 15:35:59 device ModemManager[932]: <info>      DNS #1: 8.8.8.8
> Feb 22 15:35:59 device ModemManager[932]: <info>      DNS #2: 8.8.4.4
> Feb 22 15:35:59 device ModemManager[932]: <info>         MTU: 1430
> Feb 22 15:35:59 device ModemManager[932]: <info>  Modem
> /org/freedesktop/ModemManager1/Modem/0: state changed (connecting ->
> connected)
> Feb 22 15:51:08 device ModemManager[932]: <info>  bearer call end reason
> (1): 'generic-unspecified'
> Feb 22 15:51:08 device ModemManager[932]: <info>  bearer verbose call end
> reason (3,1028): [cm] (null)
> Feb 22 15:51:08 device ModemManager[932]: <info>  Modem
> /org/freedesktop/ModemManager1/Modem/0: state changed (connected ->
> registered)
> Feb 22 15:51:09 device ModemManager[932]: <info>  Modem
> /org/freedesktop/ModemManager1/Modem/0: state changed (registered ->
> connecting)
> Feb 22 15:51:09 device ModemManager[932]: <info>  QMI IPv4 Settings:
> Feb 22 15:51:09 device ModemManager[932]: <info>      Address: 10.x.x.85/30
> Feb 22 15:51:09 device ModemManager[932]: <info>      Gateway: 10.x.x.86
> Feb 22 15:51:09 device ModemManager[932]: <info>      DNS #1: 8.8.8.8
> Feb 22 15:51:09 device ModemManager[932]: <info>      DNS #2: 8.8.4.4
> Feb 22 15:51:09 device ModemManager[932]: <info>         MTU: 1430
> Feb 22 15:51:09 device ModemManager[932]: <info>  Modem
> /org/freedesktop/ModemManager1/Modem/0: state changed (connecting ->
> connected)
>
>
>
>
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