From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp118.iad3a.emailsrvr.com (smtp118.iad3a.emailsrvr.com [173.203.187.118]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 591933CB4E for ; Sat, 24 Mar 2018 16:52:43 -0400 (EDT) Received: from smtp31.relay.iad3a.emailsrvr.com (localhost [127.0.0.1]) by smtp31.relay.iad3a.emailsrvr.com (SMTP Server) with ESMTP id 17E5222E06; Sat, 24 Mar 2018 16:52:43 -0400 (EDT) X-SMTPDoctor-Processed: csmtpprox beta Received: from smtp31.relay.iad3a.emailsrvr.com (localhost [127.0.0.1]) by smtp31.relay.iad3a.emailsrvr.com (SMTP Server) with ESMTP id 1298722E22; Sat, 24 Mar 2018 16:52:43 -0400 (EDT) Received: from app45.wa-webapps.iad3a (relay-webapps.rsapps.net [172.27.255.140]) by smtp31.relay.iad3a.emailsrvr.com (SMTP Server) with ESMTP id 0314B22E06; Sat, 24 Mar 2018 16:52:43 -0400 (EDT) X-Sender-Id: MAILER-DAEMON Received: from app45.wa-webapps.iad3a (relay-webapps.rsapps.net [172.27.255.140]) by 0.0.0.0:25 (trex/5.7.12); Sat, 24 Mar 2018 16:52:43 -0400 Received: from deepplum.com (localhost.localdomain [127.0.0.1]) by app45.wa-webapps.iad3a (Postfix) with ESMTP id E4F3240194; Sat, 24 Mar 2018 16:52:42 -0400 (EDT) Received: by mobile.rackspace.com (Authenticated sender: dpreed@deepplum.com, from: dpreed@deepplum.com) with HTTP; Sat, 24 Mar 2018 16:52:42 -0400 (EDT) Date: Sat, 24 Mar 2018 16:52:42 -0400 (EDT) From: "dpreed@deepplum.com" To: "Dave Taht" Cc: "Rich Brown" , make-wifi-fast@lists.bufferbloat.net MIME-Version: 1.0 Content-Type: text/plain;charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Message-ID: <1521924762.93563937@mobile.rackspace.com> X-Mailer: mobile/4.1.4 X-Mailman-Approved-At: Sat, 24 Mar 2018 17:15:07 -0400 Subject: Re: [Make-wifi-fast] =?iso-8859-1?q?Latency_spikes_every_few_minutes?= =?iso-8859-1?q?=3F?= X-BeenThere: make-wifi-fast@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 24 Mar 2018 20:52:43 -0000 My understanding, which may be wrong, is that a channel scan requires liste= ning for either a packet or a beacon on each channel. Beacons being the lon= gest you have to wait. But adding up across all the 5 GHz channels + 2.4 GH= z channels, assuming most are unused, you get real long delays! A better idea would be listening for beacons with a simple secondary receiv= er. That receiver could be a variable bandwidth front end, so it could list= en on adjacent channel groups at the same time, in parallel with the normal= stuff. It would be even easier if you were only interested in newer and louder sig= nals than the current one, because you could just open the channel filter b= andwidth (getting worse SNR) and use SDR to sample for louder signals, if a= ny. Conceptually, what you probably want is good hints about what fallback chan= nel you might switch to. Channel scanning one at a time is a poor, poor alg= orithm for that. And even for fixed stations, propagation varies -- turn on a fan in the roo= m causing time varying multipath distortion, or open a metal filing cabinet= drawer. So a fallback is useful to have for quick association switching. H= owever, the ideal thing at that point is to be associated simultaneously wi= th multiple APs or mesh peers, and maybe even have DHCP leases with fallbac= k nets. -----Original Message----- From: "Dave Taht" Sent: Fri, Mar 23, 2018 at 5:15 pm To: "Rich Brown" Cc: "Rich Brown" , make-wifi-fast@lists.bufferbloa= t.net Subject: Re: [Make-wifi-fast] Latency spikes every few minutes? On Fri, Mar 23, 2018 at 2:12 PM, Rich Brown wrote: > Hi folks, > > My Google-fu is weak today. I know that someone described the reason that= some Wifi sees big latency spikes every few minutes. I remember it being r= elated to an AP scanning something, for some reason, but that's all I remem= ber. Could someone refresh my brain? Thanks. http://blog.cerowrt.org/post/disabling_channel_scans/ > > Rich > _______________________________________________ > Make-wifi-fast mailing list > Make-wifi-fast@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/make-wifi-fast --=20 Dave T=C3=A4ht CEO, TekLibre, LLC http://www.teklibre.com Tel: 1-669-226-2619 _______________________________________________ Make-wifi-fast mailing list Make-wifi-fast@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/make-wifi-fast --=20 Reed Online Ltd is a company registered in England and Wales. Company=20 Registration Number: 6317279. Registered Office: Academy Court, 94 Chancery Lane, London WC2A 1DT.