Help in establishing multiple simultaneous APNs: mmcli create/connect bearer

[Aleksander Morgado]

Hey

>> > However, after approximately five minutes of using and examining these interfaces, I noticed the second bearer connection had failed with an unknown error and mbimmux0.2 had been removed from the list of interfaces:
>> > user at ubuntu22a:~/Documents$ mmcli -m 0 -b 1
>> >   --------------------------------------
>> >   General    |                     path: /org/freedesktop/ModemManager1/Bearer/1
>> >              |                     type: default
>> >   --------------------------------------
>> >   Status     |                connected: no
>> >              |    connection error name: org.freedesktop.ModemManager1.Error.MobileEquipment.Unknown
>> >              | connection error message: Unknown error
>> >              |                suspended: no
>> >              |              multiplexed: no
>> >              |               ip timeout: 20
>> >   --------------------------------------
>> >   Properties |                      apn: apnname2
>> >              |                  roaming: allowed
>> >              |                  ip type: ipv4
>> >              |             allowed-auth: pap
>> >              |                     user: apnuser2
>> >              |                 password: apnpass2
>> >   --------------------------------------
>> >   Statistics |                 duration: 294
>> >              |                 attempts: 2
>> >              |           total-duration: 578
>>
>> No idea why that error happens. That's likely an error reported by the
>> modem itself and we're converting it to "Unknown" ourselves, but there
>> is probably more info about the specific error happening in the MM
>> debug log itself. You should look in the MM debug log and look for a
>> MBIM indication reporting that disconnection at that time, and see if
>> there's a better error description there. It could be that the modem
>> reports Unknown itself, I wouldn't be surprised to be honest.
>
>
> When the second bearer fails, I see something similar to the following in /var/log/syslog (Modem number received a value of 2 this time, rather than the 0 of my earlier experiments above):
> Mar 18 12:10:55 ubuntu22a ModemManager[709]: [/dev/cdc-wdm0] Received message...#012>>>>>> RAW:#012>>>>>>   length = 80#012>>>>>>   data   = 07:00:00:80:50:00:00:00:00:00:00:00:01:00:00:00:00:00:00:00:A2:89:CC:33:BC:BB:8B:4F:B6:B0:13:3E:C2:AA:E6:DF:0C:00:00:00:24:00:00:00:02:00:00:00:03:00:00:00:00:00:00:00:01:00:00:00:7E:5E:2A:7E:4E:6F:72:72:73:6B:65:6E:7E:5E:2A:7E:00:00:00:00
> Mar 18 12:10:55 ubuntu22a ModemManager[709]: [/dev/cdc-wdm0] Received message (translated)...#012>>>>>> Header:#012>>>>>>   length      = 80#012>>>>>>   type        = indicate-status (0x80000007)#012>>>>>>   transaction = 0#012>>>>>> Fragment header:#012>>>>>>   total   = 1#012>>>>>>   current = 0#012>>>>>> Contents:#012>>>>>>   service = 'basic-connect' (a289cc33-bcbb-8b4f-b6b0-133ec2aae6df)#012>>>>>>   cid     = 'connect' (0x0000000c)#012>>>>>> Fields:#012>>>>>>   SessionId = '2'#012>>>>>>   ActivationState = 'deactivated'#012>>>>>>   VoiceCallState = 'none'#012>>>>>>   IpType = 'ipv4'#012>>>>>>   ContextType = '7e5e2a7e-4e6f-7272-736b-656e7e5e2a7e'#012>>>>>>   NwError = '0'
> Mar 18 12:10:55 ubuntu22a ModemManager[709]: <debug> [1647627055.057091] [modem2] received notification (service 'basic-connect', command 'connect')
> Mar 18 12:10:55 ubuntu22a ModemManager[709]: <debug> [1647627055.057105] [modem2] session ID '2' was deactivated: Unknown error
> Mar 18 12:10:55 ubuntu22a ModemManager[709]: <debug> [1647627055.057111] [modem2] bearer '/org/freedesktop/ModemManager1/Bearer/2' was disconnected.
> Mar 18 12:10:55 ubuntu22a ModemManager[709]: <debug> [1647627055.057117] [modem2/mbimmux2.2/net] port now disconnected
> Mar 18 12:10:55 ubuntu22a NetworkManager[620]: <info>  [1647627055.0589] device (mbimmux2.2): state change: unavailable -> unmanaged (reason 'unmanaged', sys-iface-state: 'removed')
> Mar 18 12:10:55 ubuntu22a ModemManager[709]: <info>  [1647627055.073236] [modem2/bearer2] connection #1 finished: duration 264s
>
> Any further interpretation of these log entries? I suspect this is the "unknown" that was predicted.
>

Yeah, in the NwError = '0' field.

> The second bearer never stays connected for more than a few minutes. Duration of my last four tries was 264, 247, 331, and 246 seconds. Is there any way I could determine whether the network, modem, Modem Manager, or Network Manager is the one tripping here? Anywhere else to look for more information?
>

It's either the modem or the network, MM/NM have nothing to do with
that disconnection.

>> >
>> > After it fails, running “sudo mmcli -m 0 -b 1 --connect” then “sudo ip link set mbimmux0.2 up” puts things back in business. I did not expect to have to keep checking and then stand it back up when it fails.
>> >
>>
>> MM does not do any reconnection logic by itself, because reconnections
>> may involve IP reconfiguration. All that should be done by upper
>> layers, the actual network management tool should do it.
>>
>
>  After it fails, running “sudo mmcli -m 0 -b 1 --connect” then “sudo ip link set mbimmux0.2 up” always seems to work and the second bearer will be operational for another 5 minutes or so.

Have you tried to make sure traffic goes through that 2nd connection
when you do this? maybe the network detects there's no traffic and
drops it? wild guess

-- 
Aleksander
https://aleksander.es