[Networkmanager] Multiple connections for the same device

[Jan Lübbe]

On Tue, 2023-07-11 at 08:19 +0200, Fabio Porcedda wrote:
> > > > > > I mean gsm type device. I would like to activate multiple connection profiles for the same gsm device at the same time.
> > > > > > Sometimes it is useful to have multiple active  apn for the same broadband device enabled at the same time because each apn can have different capabilities.
> > 
> > 
> > Good luck - the "modems" do not have the capability to connect to more than a single APN simultaneously with a multi-APN device (shich I know of none).
> 
> Modems do have this kind of capability, for example It's possible using ModemManager with a modem that support MBIM or QMI, e.g.:
> 
> mmcli -m <modem_id> --create-bearer="apn=<apn1>,multiplex=required"
> mmcli -m <modem_id> --create-bearer="apn=<apn2>,multiplex=required"
>  
> mmcli -m <modem_id> -b <bearer1_id> --connect
> mmcli -m <modem_id> -b <bearer1_id>
> ip addr add <bearer1_adddres>/<bearer1_prefix> dev <bearer1_interface> 
> ip link set <bearer1_interface> up
> ip route add <bearer1_network>/<prefix> dev <bearer1_interface>
>  
> mmcli -m <modem_id> -b <bearer2_id> --connect
> mmcli -m <modem_id> -b <bearer2_id>
> ip addr add <bearer2_adddres>/<prefix> dev <bearer2_interface> 
> ip link set <bearer2_interface> up
> ip route add <bearer2_network>/<prefix> dev <bearer2_interface>

This seems like it could be represented in NM as a separate device that can be
created on demand. Existing examples of this are MACsec, macvlan and VLAN. They
would have the modem device as parent and have their own connection.

Regards,
Jan