From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dispatch1-us1.ppe-hosted.com (dispatch1-us1.ppe-hosted.com [67.231.154.184]) (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 4F74C3B29E for ; Tue, 13 Jul 2021 14:06:58 -0400 (EDT) X-Virus-Scanned: Proofpoint Essentials engine Received: from mx1-us1.ppe-hosted.com (unknown [10.110.51.172]) by mx1-us1.ppe-hosted.com (PPE Hosted ESMTP Server) with ESMTPS id 720A22A0067; Tue, 13 Jul 2021 18:06:57 +0000 (UTC) Received: from mail3.candelatech.com (mail2.candelatech.com [208.74.158.173]) by mx1-us1.ppe-hosted.com (PPE Hosted ESMTP Server) with ESMTP id 033B814007E; Tue, 13 Jul 2021 18:06:56 +0000 (UTC) Received: from [192.168.100.195] (50-251-239-81-static.hfc.comcastbusiness.net [50.251.239.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail3.candelatech.com (Postfix) with ESMTPSA id 6869A13C2B1; Tue, 13 Jul 2021 11:06:34 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 mail3.candelatech.com 6869A13C2B1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=candelatech.com; s=default; t=1626199594; bh=/6cdpWmSswchu4g5kvydMEFPF8SnD+9a1CBVZAAjd7I=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=RtDIgYp9iNrpNWFcCdUuXJM31u+Qb6HzBmX+OGYCpYHd6+OgqzEG7ct3BcYzw0aPK uDygq3OOeCbyZ6Ty61oW9DkUfu8xIdsJLs+qC2ECEt7xDNGinzxgRPH3G7ZbmkJjew VSA9Xqp3RDWR7EMp41ukerYDpYOxJpBE60q3iSkk= To: David Lang , "Rodney W. Grimes" Cc: starlink@lists.bufferbloat.net, "David P. Reed" References: <202107131239.16DCdq6D058102@gndrsh.dnsmgr.net> From: Ben Greear Organization: Candela Technologies Message-ID: <616d0497-0d22-b8be-895b-bb57f2e82480@candelatech.com> Date: Tue, 13 Jul 2021 11:06:34 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-MDID: 1626199617-LzAEgfHLYuQH Subject: Re: [Starlink] SatNetLab: A call to arms for the next global> Internet testbed X-BeenThere: starlink@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Starlink has bufferbloat. Bad." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 13 Jul 2021 18:06:58 -0000 On 7/13/21 11:01 AM, David Lang wrote: > On Tue, 13 Jul 2021, Rodney W. Grimes wrote: > >> It wasnt suggested "lowering the bit rate", it was suggested to make the >> packets smaller, which actually does address the hidden transmitter problem >> to some degree as it *would* reduce your air time occupancy, but the damn >> wifi LL aggregation gets in your way cause it blows them back up.  When I >> am having to deal/use wifi in a hidden transmitter prone situation I always >> crank down the Fragmentation Threshold setting from the default of 2346 bytes >> to the often the minimum of 256 with good results. > > The problem is that with wifi at modern data rates, you have a header at a low data rate and then data at a much higher data rate (in extreme cases, a >50x > difference), so the amount of data that you send has a pretty minor difference in the airtime used. So you really do want to send a large amount of data per > transmission to minimize the overhead > > IT's not quite as bad if you have disabled 802.11b speeds on the entire network as that raises the header/housekeeping transmissions from 1Mb/s to 11Mb/s The quiesce period waiting for medium access also takes some time, so that is another reason to try to put lots of frames on air in the same tx operation... David, I'm curious about the rate-ctrl aspect of this. Have you found any implementations of rate-ctrl that try harder to decrease amsdu groupings and/or keep MCS higher (maybe based on RSSI?) in a congested environment to deal better with hidden node problems? Thanks, Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com