Host data interface IP configuration via DHCP vs via control channel.

Aleksander Morgado aleksandermj at
Mon Nov 7 14:55:17 UTC 2022


> > No, the DHCP server is running in the modem, to ease the configuration
> > process on the host side.  Qualcomm modems have it for sure, there are
> > several other manufacturers that don't.
> > There is no DHCP protocol used in between the modem and the network,
> > IP assignment is done via 3GPP protocols.
> Ah thanks, that clarifies some unrelated matters for me.
> >> Anyway, it's certainly true that DHCP
> >> is not always provided.  But also, with a static IP assignment as it is done
> >> in OpenWrt, there's no mechanism if the IP changes - this can happen due to
> >> expiry of the IP, changing stations (i.e, a moving devicde) or other upstream
> >> network churn.  In such cases, you continue to be connected to the network, but
> >> lose IP connectivity unless you have another mechanism to watch for such changes.
> >
> > If I'm not mistaken, a network-initiated disconnection is reported in
> > such cases (which openwrt git master branch supports), and the modem
> > just needs to re-establish the bearer with a reconnection. If this is
> > not always the case, we should definitely trigger a disconnection of
> > the modem ourselves upon detecting the IP reconfiguration. I'll ask
> > around to see what modems usually do in this regard.
> When was this introduced?

Commit bc754f31cfdb004eefa43038f8f0827922107fc6 in openwrt-packages, I
think it's only in master for now.


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