[systemd-devel] Mobile broadband modems support in systemd-networkd

[Manuel Wagesreither]

Hi Bruce,

Am Fr, 20. Aug 2021, um 22:01, schrieb Bruce A. Johnson:
> Mantas' and Ulrich's responses gave me insights to dig more. Neither the 
> mbim-cli nor ModemManager sets the IP address on the interface, and some 
> kind of agent needs to do that.
> 
> When I start the connection using ModemManager, I am able to retrieve 
> addresses that mmcli displays like the below. If I manually assign the 
> IPv4 address to the interface and set up the route, I'm able to send 
> traffic to and from other nodes. I haven't yet looked into how 
> ModemManager communicates this info to NetworkManager or how things like 
> a change of address are handled. As I see it, these addresses aren't 
> really static, because the IPv6 addresses are different from one mobile 
> session to the next.
> 
> > --------------------------------
> >   IPv4 configuration |     method: static
> >                      |    address: 6.147.139.XXX
> >                      |     prefix: 30
> >                      |    gateway: 6.147.139.YYY
> >                      |        dns: 10.177.0.34, 10.177.0.210
> >                      |        mtu: 1500
> >   --------------------------------
> >   IPv6 configuration |     method: static
> >                      |    address: 2607:fb90:648f:2648:a5b3:8146:95aa:2955
> >                      |     prefix: 64
> >                      |    gateway: 2607:fb90:648f:2648:68d8:1c67:a27:b968
> >                      |        dns: fd00:976a::9, fd00:976a::10
> >                      |        mtu: 1500
> >   --------------------------------
> I took a closer look at what's going on with systemd-networkd, and I 
> found whether I use ModemManager or mbim-cli to connect to the mobile 
> network, the .network file will be processed, but _only after I restart 
> systemd-networkd_.

I'm not 100% sure this applies to all the applications in the systemd ecosystem (like systemd-networkd), but systemd is reloading .unit, .service, .mount and all the other files there are only after a `systemctl daemon-reload`. That's the intended behaviour. Just wanted to mention this. Can't comment on anything else, though, as I have no clue either. But I'm interested in this topic and am silently monitoring this thread.

Regards, Manuel