Subject: Re: [PATCH 2/3] mac80211: create a STA entry for a WDS interface
 after receiving a beacon
From: Johannes Berg <johannes@sipsolutions.net>
To: Felix Fietkau <nbd@openwrt.org>
Cc: linux-wireless@vger.kernel.org, linville@tuxdriver.com
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Date: Wed, 01 Jun 2011 13:02:11 +0200
Message-ID: <1306926131.3867.8.camel@jlt3.sipsolutions.net> (sfid-20110601_130218_126167_5FBE6CAC)
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On Wed, 2011-06-01 at 12:53 +0200, Felix Fietkau wrote:
> On 2011-06-01 6:17 AM, Johannes Berg wrote:
> > On Tue, 2011-05-31 at 22:22 +0200, Felix Fietkau wrote:
> >>  On 2011-05-31 10:06 PM, Johannes Berg wrote:
> >>  >  On Tue, 2011-05-31 at 21:39 +0200, Felix Fietkau wrote:
> >>  >>   On 2011-05-31 9:32 PM, Johannes Berg wrote:
> >>  >>   >   On Tue, 2011-05-31 at 21:16 +0200, Felix Fietkau wrote:
> >>  >>   >>    When a STA entry is created too early, a lot of essential information
> >>  >>   >>    required for rate control is missing.
> >>  >>   >
> >>  >>   >   I don't understand how you can rely on beacons for WDS.
> >>  >>   You usually set up WDS links between APs on the same channel, each
> >>  >>   running both a normal AP vif and a WDS vif. The remote AP's beacons are
> >>  >>   then used to detect the capabilities of the peer.
> >>  >
> >>  >  I don't think we can rely on "usually" unless we also enforce that
> >>  >  somehow. Otherwise this link will basically be dead. There's nothing
> >>  >  that requires you to add WDS to an AP interface only after all.
> >>  I don't think using WDS without APs makes any sense. Since WDS alone
> >>  does not use beacons or probe requests, there's nothing else that would
> >>  ensure that rate information, HT capabilities, etc. get exchanged.
> >
> > I just don't like the fact that you can create a non-functional WDS
> > interface by adding it when there's no AP interface.

> Actually, I just noticed that ieee80211_assign_perm_addr forces you to 
> use the MAC address of an existing AP interface for a WDS interface, 
> same as for an AP VLAN interface. So the requirement to also have an AP 
> mode interface is not new.

No, it just uses that since it can use the same address -- there's no
requirement anywhere that the AP must exist.

johannes