Quectel: Use DHCP bearer with ECM port

Aleksander Morgado aleksander at aleksander.es
Thu Nov 25 20:20:36 UTC 2021

Hey Sven,

> Where would I have to change the Quectel plug-in in order to use a DHCP bearer if there is a net interface (ECM) associated with a modem. Currently, a PPP bearer is created even if a net interface is available. This is for a BG95 modem which comes with a ECM mode.

I'm afraid this is not as easy as it seems; the change would not be to
just configure to use DHCP on the net interface. When in ECM mode,
you're expected to use some vendor-specific AT commands to bring the
connection up in that interface, before we can request DHCP on it.
When a plugin doesn't implement the vendor-specific AT commands to
bring up ECM interfaces, as in your case, the plugin falls back to

Adding the AT support for that ECM mode would be done through a new
Quectel specific "bearer" object, implementing both connect_3gpp() and
disconnect_3gpp() at least.

If the modem supports QMI or MBIM, using those would anyway be
preferable, as they're fully supported in the codebase already.


More information about the ModemManager-devel mailing list