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

[Bjørn Mork]

Arjen Smit <smit.arjen at gmail.com> writes:

> This question actually does extend to IPv6, here also via the available
> control protocol (QMI/AT/etc) the connection is initiated.  It is the modem
> firmware that runs a SLAAC client process to receive a /64 prefix.  Then
> the data interface on the host is able retrieve that prefix (via a
> SLAAC/DHCPv6 client procedure (depending on the modem firmware
> capabilities) from the modem. Also here the alternative option exists to
> retrieve the IPv6 prefix (+ other items like Ipv6DNS, MTU size, or even PD
> - (e.g quectel AT+QIP6CFG="PD_addr") via the control interface from the
> modem and apply the result to the data interface.
>
> What is the modem manager approach in this ? It looks like always the data
> interface needs to use DHCP/SLAAC kind of client processes. As I prefer to
> be independent of specific modem firmware (DHCP) server processes (which
> are often outdated/have limited DHCP options supported) I am interested to
> understand  the pros/cons of the above approach (and the modem manager
> support of this approach).


I'm extremely interested in generic solutions to this problem.  My
understanding is that we can only make one side of the client <-> network
generic.

If you want to use DHCPv6 agaist a generic network, then you depend on a
specific modem firmware implementation.  There is no way for MM to
inject link local packets on the gtp link.  And there is no universal
proxying/relaying of DHCPv6 in modem firmware.  Is this correct?

If correct, which modem firmwares and methods are there supporting
DHCPv6-PD?

That Quectel command looks very promising.  But are there similar
solutions for e.g Sierra Wireless modems?  Others?

Using routed DHCPv6 wrapped in DHCPv6 relay-forward messages would allow
a generic client solution regardless of modem firmware. But it becomes
very network dependent since you'd need a co-operating PGW and
DHCPv6-server.

Interesting in hearing about such deployments, if anyone knows of one.

Generally:  Are there anyone actually using DHCPv6-PD on a mobile
network? I.e outside the lab. How do you do that?


Bjørn