libqmi, LTE RAT link dropout, reconnect, surveillance etc.

Aleksander Morgado aleksander at
Thu Apr 14 14:04:48 UTC 2022


> Trying to understand how to deal with various network errors that result
> in some sort of disconnection.
> I've seen situations where the networks seems to drop a client when it's
> crowded or some other errors occur.
> How does one deal with situations like these? Detection? Fallback?
> Reconnections etc?
> Does libqmi provide any detection mechanism or reconnection mechanism
> that discovers network errors (not just automatic connect on powerup?).

Network-initiated disconnections are reported via the "WDS Packet
Service Status" indications. The program making use of libqmi to run
the WDS Start Network connection attempt should make sure to monitor
those indications to know if the connection is still up
asynchronously. Otherwise, you can always query explicitly with "WDS
Get Packet Service Status" requests periodically, if you cannot listen
to indications.

Reconnection by itself is not handled by libqmi, although you could
try enabling autoconnect so that the modem handles that for you. That
comes with issues of its own, e.g. when to refresh IP settings in the
net interface and such, though.

ModemManager can help handle some of these things as it does monitor
"WDS Packet Service Status" indications and reports bearer
disconnections asynchronously


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