From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp118.ord1d.emailsrvr.com (smtp118.ord1d.emailsrvr.com [184.106.54.118]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 3A5503B2A4 for ; Fri, 11 Jun 2021 21:40:02 -0400 (EDT) X-Auth-ID: karl@auerbach.com Received: by smtp15.relay.ord1d.emailsrvr.com (Authenticated sender: karl-AT-auerbach.com) with ESMTPSA id 74EA660123; Fri, 11 Jun 2021 21:40:01 -0400 (EDT) Reply-To: karl@cavebear.com To: Mike Puchol , starlink@lists.bufferbloat.net, davecb@spamcop.net References: <950B8EAF-90B9-41A6-951D-91821F591D41@teklibre.net> <01a7bed2-6f49-3d7d-eb5a-209031ee8070@gmail.com> From: Karl Auerbach Organization: IWL Message-ID: <9368429e-5043-b9b7-b9af-b44c842a4dd9@cavebear.com> Date: Fri, 11 Jun 2021 18:40:00 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Classification-ID: 5c6c2ce5-61cf-41e8-861a-45950fa995a8-1-1 Subject: Re: [Starlink] Fwd: Microstate Accounting and the Nyquist problem 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: Sat, 12 Jun 2021 01:40:02 -0000 Measuring things across network is indeed made a lot easier if we have a solid, precise, synchronized clock at the end points. (I would have thought that Starlink would have had a built-in clock based on the resonance of the heavy isotope of Elonmuskium.) HP once upon a time had a patent on using GPS to get that time sync for doing network measurements.  But that was in the 1980's. One hopes that that patent has long since faded into dust. (Not long ago I wrote a fairly simple tool that runs on Linux on cheap hardware, I call it "C-Clamp" that wraps around a device or network (such as a satellite uplink and downlink) and sends packets to itself and collects numbers so it can generate statistics about the amount of delay, its stability (are there bursts, and if so, how big and how often), losses, etc etc.  Since it has a single clock it can get some fairly high precision time measurements.)  I thought it would be fun to slap one of these around two Starlink dishes located at the same location (or within a distance I could cross with a single Ethernet cable.) I've long been intrigued by all the interesting stuff that astronomers derive by watching deviations of periodic or predictable events.  There's an astrophysicist at UC Santa Cruz who apparently is interested, as am I, whether we can apply those techniques to measuring paths on networks. For one project I was going to buy a big bag of ESP32s (fun little systems-on-a-chip) and use them as network pulsars that would emit a predictable pattern of packets of various size, times (and intervals, sometimes bunched together sometimes widely separated.)  A receiver could lock onto the pattern and from the dissonance between the emission times and the reception times could intuit things about the path. I understand that RIPE has done something like this.     --karl--