Renewal of IP config.

[Markus Gothe]

Thx... So I guess maybe in a (close?) future it can become a real-life scenario and then MBIM is prepared for this. Or if a teleco configures things arbitrary. ;-)

//M

Den 26 mar 2015 22:14 skrev Bjørn Mork <bjorn at mork.no>:
>
> Dan Williams <dcbw at redhat.com> writes: 
> > On Thu, 2015-03-26 at 20:22 +0100, Markus Gothe wrote: 
> >> Does the modemmanager handle the case where a new IP configuration is handed out? Have we seen any cases like that??? 
> >> 
> >> Sierra Wireless had a lease time of 50 years (sic!) in their old sierra_net.c built-in DHCP-server. 
> >> 
> >> AFAIK this is not an issue over PPP since it is just a tunneling protocol. But what about packet switched networks, like LTE? 
> >> 
> >> GPT might be the keyword here... I heard  that some early techs like iBurst etc used ethernet over the air in the backhaul. 
> > 
> > ModemManager itself simply retrieves the IP configuration details from 
> > the modem and passes them to the IP configuration manager (eg, 
> > NetworkManager or something else) when the bearer is connected.  If 
> > there is any kind of "ip config changed" signal that the modem emits, 
> > then MM should listen to that, but I'm not aware of anything at the 
> > AT/MBIM/QMI/etc level.  Instead that's usually handled at the IP+ layers 
> > via DHCP or SLAAC. 
>
> MBIM supports reconfiguration: 
>
> 10.5.20 MBIM_CID_IP_CONFIGURATION 
> .. 
> Unsolicited Event: 
> InformationBuffer contains MBIM_IP_CONFIGURATION_INFO.  Whenever the 
> MBIM function obtains updated IP configuration information, it must 
> issue an Unsolicited Event to inform the host about the new value(s). 
>
> But I don't think it's currently possible to change address(es) of an 
> LTE PDN connection.  At least that's my understandig of how it works, 
> based on a very slack reading of RFC6459.  Quoting: 
>
>
> 5.1. IPv4 Address Configuration 
>
>
>    The UE's IPv4 address configuration is always performed during PDP 
>    context/EPS bearer setup procedures (on layer 2).  DHCPv4-based 
>    [RFC2131] address configuration is supported by the 3GPP 
>    specifications, but is not used on a wide scale.  The UE must always 
>    support address configuration as part of the bearer setup signaling, 
>    since DHCPv4 is optional for both UEs and networks. 
>
> 5.2. IPv6 Address Configuration 
>
> .. 
>
>    Renumbering without closing the layer-2 connection is 
>    also not possible.  The lifetime of the /64 prefix is bound to the 
>    lifetime of the layer-2 connection even if the advertised prefix 
>    lifetime is longer than the layer-2 connection lifetime. 
>
>
>
> Bjørn