creating new adhoc networks fails with ipw2200

Dan Williams dcbw
Tue Jun 27 21:24:13 PDT 2006

On Tue, 2006-06-27 at 19:25 -0700, Jouni Malinen wrote:
> On Tue, Jun 27, 2006 at 03:14:22PM -0400, Dan Williams wrote:
> > I seem to have run into a problem with this.  While I can create the
> > network setup using something like the following.  I don't intend to
> > join an _existing_ network; I want to create a totally new adhoc
> > network.
> That's not how IEEE 802.11 defines IBSS.. No new IBSS should be created
> if there are existing stations using the same SSID.

Correct; I want to create a new IBSS using a new SSID.  I don't
particularly care about existing networks at all, just creating a new

> > wpa_supplicant will never return a successful connection event until I
> > set the frequency/channel on the card using 'iwconfig'.  This is with
> > ipw2200.  Is this the way it's supposed to work?  I don't think so, but
> > please correct me if I'm wrong.
> It would be up to the driver to notify that the connection is completed.
> I have done only limited testing of adhoc networks with Linux drivers,
> though.

It appears that ipw2200 (at least) only notifies that connection is
completed when the frequency gets set.  The driver doesn't autopick a
frequency; of course I need to tell it which frequency to use.  Once I
do that, it sends the association event correctly, and wpa_supplicant
completes the connection correctly.  The _only_ missing bit here is the
ability to set the frequency for a new IBSS using wpa_supplicant.

> > One solution to this problem is to add a new configuration option to
> > wpa_ssid for "frequency", and add the config parsing logic to
> > ctrl_iface.c and the dbus side of things too.  If frequency was
> > specified, wpa_supplicant would direct the card to lock to that
> > frequency before any connection attempt and would unlock the frequency
> > after disassociation.
> This has actually already been implemented and is somewhere on my
> things-to-merge list.. However, that frequency is _not_ for locking the
> channel to avoid joining an existing network, it is for giving the new
> channel for the case where no existing network is available.

Yes; that's what I'd like.  Is there a patch somewhere that I can
evaluate?  There's already code in the drivers for setting the
frequency, but it's limited to cases where the MLME stuff is done in
userspace, and those bits aren't in the codepath for normal uses.


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