Message-ID: <4DE61FEA.60903@openwrt.org> (sfid-20110601_131812_724089_1FCA61F6)
Date: Wed, 01 Jun 2011 13:18:02 +0200
From: Felix Fietkau <nbd@openwrt.org>
MIME-Version: 1.0
To: Johannes Berg <johannes@sipsolutions.net>
CC: linux-wireless@vger.kernel.org, linville@tuxdriver.com
Subject: Re: [PATCH 2/3] mac80211: create a STA entry for a WDS interface
 after receiving a beacon
References: <1306869394-83047-1-git-send-email-nbd@openwrt.org>	 <1306869394-83047-2-git-send-email-nbd@openwrt.org>	 <1306870354.29989.1.camel@jlt3.sipsolutions.net>	 <4DE543E2.9070600@openwrt.org>	 <1306872395.29989.3.camel@jlt3.sipsolutions.net>	 <4DE54E16.7000709@openwrt.org>	 <1306901843.3867.2.camel@jlt3.sipsolutions.net>	 <4DE61A11.1070708@openwrt.org> <1306926131.3867.8.camel@jlt3.sipsolutions.net>
In-Reply-To: <1306926131.3867.8.camel@jlt3.sipsolutions.net>
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Sender: linux-wireless-owner@vger.kernel.org

On 2011-06-01 1:02 PM, Johannes Berg wrote:
> 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.
Oh, right. I'll send a follow-up patch that forces a WDS to also have an 
active AP interface before it's brought up.

- Felix