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

[Dan Williams]

On Fri, 2013-11-29 at 19:51 +0100, Bjørn Mork wrote:
> Bjørn Mork <bjorn at mork.no> writes:
> 
> >> 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...
> >
> > I have a F3507g and H5321gw (NCM only and not upgradable) too.  Will
> > test them if/when I can find the time.
> 
> I am probably doing something wrong.  I have the same problem with both
> the F3507g and the H5321gw: No RAs, no DHCPv6, and AT*E2IPCFG only
> gives a LL address (only on the H5321gw of course - the F3507g doesn't
> support this command as you noted).  And I cannot find any way to use
> this LL address.

I tried the 3607gw and could only get an IPv6 address once.  The other
times I got disconnected immediately after being disconnected
("AT*E2NAP: 0,36").  I think this device has older firmware, but I've
never been able to upgrade it, since it's a Toshiba module but I don't
have a Toshiba, and thus haven't ever gotten Windows drivers to
recognize the device.

But here's what I did with the 5521gw:

ifconfig wwan1 up
wireshark on wwan1
AT+CFUN=1
AT+CGDCONT=3,"IPV6","epc.tmobile.com"  (firmware doesn't support IPV4V6)
AT*E2NAP=1  (for connection notifications)
(wwan1 has no IP addresses yet)
AT*ENAP=1,3

wait for AT*E2NAP: 1 response, then boom wireshark finds some packets.
They are:

:: -> ff02::1:ffec:200  Neighbor solicitation for feec:200
feec:200 -> ff02::2     Router solicitation from 02:80:37:ec:02:00
feec:200 -> ff02::2     Router solicitation from 02:80:37:ec:02:00
feec:201 -> ffec:200    Router advertisement from 02:80:37:ec:02:01

AT*E2IPCFG?
*E2IPCFG:
(1,"fe80:0000:0000:0000:0000:0022:b2d6:8101"),(3,"fd00:976a:0000:0000:0000:0000:0000:0009")

ifconfig wwan1 gives me:
inet6 2607:fb90:17:540c:80:37ff:feec:200/64
inet6 fe80::80:37ff:feec:200/64
ether 02:80:37:ec:02:00

The router advertisement isn't very interesting, except that it does
have the O bit set (no other bits set), router lifetime 65535, Prefix
information 2607:fb90:17:540c::/64, and the A flag set.  Lifetimes for
the prefix are set to infinity.  Source link-layer address is
02:80:37:ec:02:01.

Then I tried to go to www.google.com, and the module crashed.

So anyway, you are correct, it doesn't appear that the module cares at
all about the IPv6LL address that it reports with E2IPCFG.

> I observed one very strange thing on the F3507g: It sends gratious ARPs
> for an IPv4 LL address when an IPV6 PDP type connection is established.
> That was a bit surprising.

I see the gratuitous ARPs too.

Dan