From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sainfoin-smtp-out.extra.cea.fr (sainfoin-smtp-out.extra.cea.fr [132.167.192.228]) (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 B5B283B29E for ; Thu, 31 Aug 2023 04:56:49 -0400 (EDT) Received: from pisaure.intra.cea.fr (pisaure.intra.cea.fr [132.166.88.21]) by sainfoin-sys.extra.cea.fr (8.14.7/8.14.7/CEAnet-Internet-out-4.0) with ESMTP id 37V8ums5053235 for ; Thu, 31 Aug 2023 10:56:48 +0200 Received: from pisaure.intra.cea.fr (localhost [127.0.0.1]) by localhost (Postfix) with SMTP id 67C89203E70 for ; Thu, 31 Aug 2023 10:56:48 +0200 (CEST) Received: from muguet2-smtp-out.intra.cea.fr (muguet2-smtp-out.intra.cea.fr [132.166.192.13]) by pisaure.intra.cea.fr (Postfix) with ESMTP id 5FD84203E6D for ; Thu, 31 Aug 2023 10:56:48 +0200 (CEST) Received: from [10.8.32.70] (is156570.intra.cea.fr [10.8.32.70]) by muguet2-sys.intra.cea.fr (8.14.7/8.14.7/CEAnet-Internet-out-4.0) with ESMTP id 37V8umBe044259 for ; Thu, 31 Aug 2023 10:56:48 +0200 Message-ID: <22b7ab5d-1dba-0d4b-eb9d-83e2e9ab57ea@gmail.com> Date: Thu, 31 Aug 2023 10:56:48 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.14.0 Content-Language: fr To: starlink@lists.bufferbloat.net References: From: Alexandre Petrescu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Subject: Re: [Starlink] a puzzling starlink uplink trace 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: Thu, 31 Aug 2023 08:56:49 -0000 Le 30/08/2023 à 20:07, Dave Taht via Starlink a écrit : > In the attached 5 minute plot from a few days ago (I can supply the > flent.gz files if anyone wants them), I see a puzzling spike at T+155s > to nearly 90ms of baseline latency, then down to 20ms. 20ms? A latency of 20ms might come if these low altitude starlink sats (70km or so) pass by there? Or maybe I dont see quite well these sat altitudes. Alex > No degree of > orbital mechanics can apply to this change, even factoring in an over > the horizon connection, routing packets on the ground through LA to > seattle, and back, or using a couple ISLs, can make this add up for > me. A combination of all that, kind of does make sense. > > The trace otherwise shows the sawtooth pattern of a single tcp flow , > a loss (sometimes catastrophic) at every downward bandwidth change. > > An assumption I have long been making is the latency staircase effect > (see T+170) forward is achieving the best encoding rate at the > distance then seen, the distance growing and the encoding rate falling > in distinct steps, with a fixed amount of buffering, until finally > that sat starts falling out of range, and it choses another at T+240s. > > But jeeze, a 70ms baseline latency swing? What gives? I imagine > somehow correlating this with a mpls enabled traceroute might begin to > make some sense of it, correlated by orbital positions.... > > > > _______________________________________________ > Starlink mailing list > Starlink@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/starlink