From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-x22d.google.com (mail-oi0-x22d.google.com [IPv6:2607:f8b0:4003:c06::22d]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 12BCF3B25E; Mon, 16 May 2016 00:07:26 -0400 (EDT) Received: by mail-oi0-x22d.google.com with SMTP id v145so250926624oie.0; Sun, 15 May 2016 21:07:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-transfer-encoding; bh=5JE0+/4gaH7g+uuDGLIxRi+Kx51FMYfqtWDK2yLpibc=; b=Iiy2tjqkE6r2DLQwUuIhnCKJJC0eOHzS0vtquNV8nAqDIReu5N+32BPqsZC0ytHaDa sApQp9Lsx2d/FFtkZG5CDIiyaPYAdbhxPQ+X6VFMhPVK23GeAFLgqbbXbOTYV7nUw14S I7ubT9L3HWREJE0zQ3vSHq40vxldZ6PtXGYbiv42KVE3IIk0txVmfv/pDrtT9GW2IO0j xPAm3gNEMXbW/7ebY7KJX7aHXdnjG4+YHroHHgDc8NRBJHcwjFvbo80mLiHwR0SnmdvN E84WJyAteuaA4lcuUPO8VdEnJzQBVBs+Jpta624wJj42x8n1OliMfiPE168U14A5htQN fdRw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-transfer-encoding; bh=5JE0+/4gaH7g+uuDGLIxRi+Kx51FMYfqtWDK2yLpibc=; b=No3DjsTqJd525rs6WjW1nv8qxGq+a8botnOR0S77ze/WTiAW81HY0q2nWi8zTnV9DW AasZ8vsmwa+zjkS1fPcLXPmBf2VhYAYcJ3qw5eNEnQnZPI3xVL8MpE7j6rgL8rlQgjIL tRjCQTzrpzxM+am+4cfmlwXZprWV+FLH8WlNT/qYRdF63ClR+OjsrNwDbFD/XDMHsY6E PyWn4FDO/upJpGtgAvQXF3bFqabP8GDOV60tsTKz1t4fR8muokCV8D8T70VJvFzF6was aFd8bDj+7MKhw5HZPqZM1rOW3B3rTJlwMTi+dM9oih2tUrLBiyWXgpYImZsW8axLwQdq If0A== X-Gm-Message-State: AOPr4FXyq/napUYy9qEipJaDmbUSBYKgxOpxD+sWeutGEj9oVEP8HlXQd0QizQqx53Mb7Qkgj4D7+CAAXa0uaA== MIME-Version: 1.0 X-Received: by 10.202.186.193 with SMTP id k184mr16317943oif.66.1463371645486; Sun, 15 May 2016 21:07:25 -0700 (PDT) Received: by 10.202.229.210 with HTTP; Sun, 15 May 2016 21:07:25 -0700 (PDT) In-Reply-To: References: Date: Sun, 15 May 2016 21:07:25 -0700 Message-ID: From: Dave Taht To: Aaron Wood Cc: make-wifi-fast@lists.bufferbloat.net, "cerowrt-devel@lists.bufferbloat.net" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Cerowrt-devel] [Make-wifi-fast] what is the right way to do, and rationale, for wifi channel scans? X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 16 May 2016 04:07:26 -0000 The discussion on the g+ thread for the channel scan issue got hot and heavy, here: https://plus.google.com/u/0/107942175615993706558/posts/WA915Pt4SRN On Fri, May 13, 2016 at 8:19 PM, Aaron Wood wrote: > wpa_supplicant? I've seen some atrocious behavior from wpa_supplicant in > the past (especially the closed-source versions from some chipset > companies). > > One reason it's likely to be scanning is that it's looking for alternate = APs > for the same SSID, which are "better". > > I saw one implementation that would do an all-channel wildcard ssid scan > (elicting a response from every AP in range), and then would proceed to s= can > every channel for just the ssid it was configured to use (hardcoded in th= e > wifi config). Why it was doing a broadcast for all APs, I don't know. B= ut > once you get enough APs in a small enough area, that behavior causes a > broadcast storm as the probe responses (all at 1Mbps) flood the air, and > then cause other STAs to miss beacons, and re-scan, and it death-spirals > from there. > > -Aaron > > On Fri, May 13, 2016 at 5:19 PM, Dave Taht wrote: >> >> I finally tracked down the source of many of the anomalies I'd >> seen thus far... channel scans. >> >> For the related rant, see: >> >> http://blog.cerowrt.org/post/disabling_channel_scans/ >> >> Still haven't been able to kill it off entirely. >> >> -- >> Dave T=C3=A4ht >> Let's go make home routers and wifi faster! With better software! >> http://blog.cerowrt.org >> _______________________________________________ >> Make-wifi-fast mailing list >> Make-wifi-fast@lists.bufferbloat.net >> https://lists.bufferbloat.net/listinfo/make-wifi-fast > > --=20 Dave T=C3=A4ht Let's go make home routers and wifi faster! With better software! http://blog.cerowrt.org