Help in establishing multiple simultaneous APNs: nmcli and multiple connection keyfiles

[Aleksander Morgado]

Hey,


>
> I attempted to use mmcli 1.18.6 and nmcli 1.36.0 with network manager and keyfiles to create multiple simultaneous connections to two different APNs with a USB cellular modem on an Ubuntu Jammy Jellyfish 22.04 system. The ModemManager.service file had the debug and test-multiplex-requested options activated on the ExecStart line.
>
> Short summary of results:
>
> This sequence of commands (sudo nmcli con reload, sudo nmcli --wait 300 con up id conn1,  sudo nmcli --wait 300 con up id conn2) did not produce multiple simultaneous packet data network connections, but rather the second connection displaced the first.
>

Hum... you are right here, and I think I totally mixed it.
NetworkManager probably runs an explicit disconnect of all bearers in
the modem before attempting a new connection. Something to improve in
NM I'd say, we may need NM also to know about the multiplex needs of a
given device, and allow having multiple connections over the same
single device. When I tested all this a while ago, I used NM for
testing, but all those tests were checking the complex process of
getting one multiplexed connection up, not more than one :) When
testing and validating multiple multiplexed connections I used a
different small tester program that used MM APIs directly.

So, yes, for testing all this you should probably play with mmcli and
manual IP/route settings setup :/

-- 
Aleksander
https://aleksander.es