MC7304 takes minutes to get IP address with DHCP

[Paul Loberg]

Hi Dan.

I did try parsing the output from qmicli -d $DEV
--wds-get-current-settings, but was unable to pass any traffic through the
interface so I suspect the modem is actually not fully online. (I used the
shell code from the patch here:
https://aur.archlinux.org/cgit/aur.git/tree/0003-Added-STATIC_IP-option-to-configure-non-DHCP-network.patch?h=libqmi-qmi-over-mbim-netctl
)

Yesterday I also tested with the Gobi drivers from Sierra Wireless and they
behave exactly the same way, taking forever to get an IP, so now I'm
waiting for support from them.

Thanks,

 -- Paul


On 25 October 2017 at 18:14, Dan Williams <dcbw at redhat.com> wrote:

> On Tue, 2017-10-24 at 12:42 +0200, Paul Loberg wrote:
> > Hi.
> >
> > I am testing a computer with a Sierra Wireless MC7304 modem where I
> > am
> > stuck in debugging why it usually take several minutes to obtain an
> > IP
> > address via DHCP.
> >
> > I'm using libqmi 1.18.0 and a 4.1.35 kernel on Gentoo. To bring up
> > the
> > connection I do (DEV is /dev/cdc-wdm0)
> >
> >  qmicli -d $DEV --wda-set-data-format=802-3
> >  qmicli -d $DEV --wds-start-network=apn='internet' --client-no-
> > release-cid
> >  qmicli -d $DEV --wds-set-autoconnect-settings=enabled,roaming-
> > allowed
> >
> > After this, "qmicli -d $DEV --wds-get-packet-service-status" will
> > show the
> > status as "connected" and qmicli -d $DEV --wds-get-current-settings
> > does
> > show that the connection has been assigned an IP address immediately
> > afterwards.
> >
> > To configure the interface I rely on dhcpcd which I see report
> > "carrier
> > acquired" shortly after I bring up the wwan interface with qmicli and
> > it
> > then start sending DISCOVER requests on the interface. This goes on
> > for
> > many minutes (sometimes as much as 10 minutes) before a DHCP offer is
> > received with the IP that I already observed when doing "qmicli -d
> > $DEV
> > --wds-get-current-settings".
> >
> > What can be causing this? Is it an issue with the mobile broadband
> > provider
> > or related to my system?
> >
> > Would it be safe to parse the output from "qmicli -d $DEV
> > --wds-get-current-settings" and configure the wwan interface using
> > that
> > information? Does any tools exist that does that?
>
> Yes, this is likely what you should do.  Note that new QMI-based
> devices often do no support 802.3 mode and some don't support DHCP, but
> do support --wds-get-current-settings.  It's not too hard to just parse
> that info and run a couple /sbin/ip commands to set up the interface.
>
> Dan
>
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