NDISDUP+wwan for Huawei devices using the new 'huawei_cdc_ncm' driver

[Dan Williams]

On Wed, 2013-11-27 at 14:33 +0100, Bjørn Mork wrote:
> Thomas Schäfer <tschaefer at t-online.de> writes:
> > Am Montag, 25. November 2013, 19:05:29 schrieb Aleksander Morgado:
> >
> >> For reference, the specific changes to run NDISDUP in the /dev/cdc-wdm
> >> port are now in the following branch upstream:
> >>   aleksander/huawei-ndisdup-cdc-wdm
> >
> > Thanks for the info. I have a question about IP and DNS-configuration. For qmi 
> > and mbim-devices you get (additionally) the configuration via 
> > mm-bearer-qmi.c and mm-bearer-mbim.c 
> > Is there a similar way via AT?
> > Especially for (IPV6) DNS-resolver-servers? 
> > (for both types of AT-connect: 
> > Ericsson: AT*ENAP, 
> > Huawei: at^ndisdup)
> 
> I'm wondering the same wrt Ericsson.  I have a F5521gw, which seems to
> connect just fine using an IPV6 PDP context.  But I cannot get the
> allocated prefix out of it.  There are no replies to SLAAC Router
> Solicitations or DHCPv6 solicits.
> 
> The best I can get is this, which shows the DNS servers (the global
> addresses) and most likely the interface identifier on the
> point-to-point link (guessing that is the interface part of the LL
> address):
> 
>  AT*E2IPCFG?
>  *E2IPCFG: (1,"fe80:0000:0000:0000:0000:000b:5380:d201")(3,"2001:4600:0004:0fff:0000:0000:0000:0054")(3,"2001:4600:0004:1fff:0000:0000:0000:0054")

If you assign that IPv6 LL address to the interface, does it start
giving you RAs or start allowing DHCPv6?  Ericsson modules were pretty
good about standards stuff, so maybe they actually enforce that both
sides know the right IPv6LL address?

Also note that only 36xx and 55xx modules have *E2IPCFG; the 3507 does
not.  We didn't bother with E2IPCFG in ModemManager because the modules
support DHCP.  Unfortunately there's nobody from ericsson around anymore
to tell us about IPv6...

Tore and I tested IPv6 with Ericsson devices a while back.  In my case,
I successfully got RAs from a 5521gw.  Tore's old contact at Ericsson
said: "the F5521gw can work as a local PCO to DHCPv6 "bridge" by
intercepting and changing RA (set o-flag) and then responding to DHCPv6
Information-Request for DNS"

Further quoting Tore: "Another thing worth noting here is the link-local
IPv6 address included in PCO. 3GPP specs says you *must* use that
link-local address. That's not a problem with PPP since that's the one
you get from IPV6CP, but for fake Ethernet it's a problem, since there
you typically start out (before the PDP is even up) with an incorrect
link-local address that's derived from some invented Ethernet MAC
address."

Which makes me think that the E2IPCFG LL address from above should be
assigned to the interface before trying anything IPv6 related...

Dan

> Which is all nice etc, but pretty useless without knowing my allocated
> prefix.  There is probably some other command which should be used, but
> which one?
> 
> Tip:  "AT*" will list all supported commands on Ericsson modems.
> 
> 
> 
> Bjørn
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