From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-il1-x12a.google.com (mail-il1-x12a.google.com [IPv6:2607:f8b0:4864:20::12a]) (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 BB4843B2A4 for ; Sun, 12 Dec 2021 19:06:43 -0500 (EST) Received: by mail-il1-x12a.google.com with SMTP id m12so658869ild.0 for ; Sun, 12 Dec 2021 16:06:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=aefGYfyLTS16UnTaJ/Kb6TOxQQgqFduPeUXL7Ne51js=; b=bvAWqlKYMxGe8TRxb5NTt4Ola61XFAAFkWc2Gu2b3MK6SbDpHRbdCVdH2DyzaoU2Te 1hNodSUcXEoiIYi719xbXvyFytI+FzXNEJbAnSXixDrdPGkrqf+0luZb2Pd4LyNVtVe8 MJHrImXaRd+fZAyCcNBFExF/WINLIOTHPR81m9W5SN0q7pyz53A0rd4JFt1PdNw9z5fG QvR+Tif6Vuh6YlZImNx5D7RuJN9UTfxbXgQcK5gKiJDrxF1KAspjT2szVxw+tgEvdok9 qwD+TpfIBVtBQTav0S81X/OVjstWL4PKpP7hoTANEFKgeEXC4wSMrSeDVSk3cUJ3kqzx Cf2A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=aefGYfyLTS16UnTaJ/Kb6TOxQQgqFduPeUXL7Ne51js=; b=SgzpNl379VFw5jV21PKpLgqw9kcQ+5ugLp6pVncgnRVHCKfNuAa6w7BZe2hRVjD2w8 mq7mtJ4zhM/tt1Ncfe8sHYwju3mbwqnmYRPbfDzMRapfoMiRXSsN2bWyu/UiNmIfw7Su kTF+zMBsoqcTiVDPK/NWSe94/rIG5QcXF5lWUrxZQe/96g19E1lgEuOXkUF/25XojavY jqidRkD/lL8fJ8e4iSwESzVvsngnFfd07qF0YRyMm0K/VDCT8L0YbVaQJ3PPpVWyL+Fa JOBaB0plHf2odGCc7J8PKSZYe16Vb9m6EBR1DRUmkuvGPYL/AGod1uPYMjsrxO1hilfS 7Fsg== X-Gm-Message-State: AOAM5332N/fyYw8PfQnyCfnGUSn+idNUfzZBLOnFptCl7SbiQ4Djg6ry DRlYLOdOciQbqbRaFnejXssQZYjIjhQdSkZUdWKPFMUAVAU= X-Google-Smtp-Source: ABdhPJyONrfBxMmffs67NNpAlJ8XkdJSLASX36g1FaVn0e9ZCmN1vzjs33OCY1vr/p6QY62bVn7vqrKXNuxvOymaSZw= X-Received: by 2002:a92:d9c7:: with SMTP id n7mr7088329ilq.88.1639354003029; Sun, 12 Dec 2021 16:06:43 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Dave Taht Date: Sun, 12 Dec 2021 16:06:30 -0800 Message-ID: To: Vint Cerf Cc: starlink@lists.bufferbloat.net Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: Re: [Starlink] some details on the DTN, bundle protocol, and a capacity question 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: Mon, 13 Dec 2021 00:06:43 -0000 On Sat, Dec 11, 2021 at 7:15 PM Vint Cerf wrote: > > I haven't pushed to much further until we get some real data from running= implementations. I also hope we can develop a simulator from which we migh= t derive measurements to compare with actual data and modeled (queueing the= oretic) data. I am just going to ignore the way this thread went for now. What I was mostly asking was what version of dtn was the most promising for an embedded (e.g. cerowrt II) implementation? https://dtn7.github.io/ looks very promising, especially the rust bits. Rust lets me sleep better and we are moving some support for it into openwrt's next release. https://github.com/morgenroth/ibrdtn is undermaintained but was already ported to openwrt, and is lighter weight. There's another one targetted at microcontrollers ( https://upcn.eu/ ), but not the FRAM one we used on a previous space-related project... really liked those FRAMs.... As for the simulator side, what/where are the requirements? I confess to wanting to feed forward the asterank, or celestia, or nasa's new https://eyes.nasa.gov/apps/asteroids/#/asteroids into it another 10 years and plunk 28k nodes into it.... > v > > > On Sat, Dec 11, 2021 at 9:58 PM Dave Taht wrote: >> >> A good deep dive into DTN with vint cerf is here: >> https://www.datacenterdynamics.com/en/analysis/vint-cerfs-interplanetary= -ambitions/ >> >> I went looking for existing source code for it, some here: >> https://projet.liris.cnrs.fr/riot/dtn_implementations_survey.html >> >> From the interview... >> >> Q: "So for store and forward to work, what is the level of storage >> each node needs to the speed of the network?" >> >> VC: That's such a good question. So guess what, I have the same >> question. And I said, 'Okay, where do I go to get an answer to that?' >> And that is the capacity question: What capacity of this DTN network, >> given if I know where the nodes are, and I know what the physics are. >> And I know what the data rates could be. I have a traffic matrix. Do I >> have a network which is capable of supporting the demand? >> >> That's the formulation of the question you're asking. So I went to the >> best possible source for this question, Leonard Kleinrock at UCLA. He >> is the father of the use of queueing theory to analyze store and >> forward networks way back in 1961/62, doing his dissertation at MIT on >> this topic, not in aid of the interplanetary network, but more general >> question on store and forward networking. >> >> And so he did some fantastic work, he broke the back of the problem >> with what was called the independence principle. But he left MIT and >> came to UCLA in the '60s, he was on my thesis committee. And he's >> still very, very active. He's 87, still blasting on. >> >> So I sent him a note saying, look, here's the problem. I've got this >> collection of notes, and I've got a traffic matrix, and I have this >> DTN environment, how do I calculate the capacity of the system so I >> know, I'm not gonna overwhelm it. >> >> And, you know, I figured it would take him a while and maybe find a >> graduate student. So *two days later*, I get back two pages of dense >> math saying, okay, here's how you formulate this problem. Now, I >> didn't get all of the answer. I still don't have all of the answer. >> But I know I have one of the best minds in the business looking at the >> problem." >> >> That was back in august of this year, made any progress? >> >> -- >> I tried to build a better future, a few times: >> https://wayforward.archive.org/?site=3Dhttps%3A%2F%2Fwww.icei.org >> >> Dave T=C3=A4ht CEO, TekLibre, LLC >> _______________________________________________ >> Starlink mailing list >> Starlink@lists.bufferbloat.net >> https://lists.bufferbloat.net/listinfo/starlink > > > > -- > Please send any postal/overnight deliveries to: > Vint Cerf > 1435 Woodhurst Blvd > McLean, VA 22102 > 703-448-0965 > > until further notice > > > --=20 I tried to build a better future, a few times: https://wayforward.archive.org/?site=3Dhttps%3A%2F%2Fwww.icei.org Dave T=C3=A4ht CEO, TekLibre, LLC