From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm1-x335.google.com (mail-wm1-x335.google.com [IPv6:2a00:1450:4864:20::335]) (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 C6D673CB35 for ; Sat, 11 Dec 2021 22:15:19 -0500 (EST) Received: by mail-wm1-x335.google.com with SMTP id g191-20020a1c9dc8000000b0032fbf912885so9403997wme.4 for ; Sat, 11 Dec 2021 19:15:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=h3HVH3GrscZmmK8KAEYxeK8n51ils7Ug8CNLnXSr09k=; b=Lg57f5qb0ijpWhv1BGk80csNViF6A8UuYEKEAYu4+3P2PPbuTeveYRRtbrJ56aGeHr W+ZqfUrd9KmJSF5zNNPjtODwdFak4zUMbjqFMx39A5lMxhLdfG3fq/OLTD9ISTF7Gy5o +ls99/4uH4jHP2p1/YZD7FrVpJP+x9ewFRxt3gyv9YlCNaIXKYrPEkyxtVXgj354cdY+ DxauWmSl5GAaTRV65HOPB9ktzj724JAx63F9TLBSiM6w+o0xE7x0Psp7oKF/ElMJLxXK 6RfCSOG6k8GER3nB3yVRFWGQTX3DZILniNXwvglqjhwmVFQ/eLkUvnk9XVOnEdzrZkic 8nPA== 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; bh=h3HVH3GrscZmmK8KAEYxeK8n51ils7Ug8CNLnXSr09k=; b=w5mxrWJByI4Z+LwkRER8KM2ASoKYetN39JqFIM6KgoMlx93mGpJMKIdhXfs+IOR4/Y VRUGeqkqpyvDdSC4NQgYnqz4BpS9uD2RI7REZWv2E4/jdmnqVf6Wm4blBawYvVGIvjD4 xwgUWL0JGt85iVif7TAJ2wV1B3sFCOQtu1T3GDkkPc9KIqmDbrpIwE8qnyh4WqW4+XnG 0u/nFjz4deBQVNDSMS9JytGCaRc8CxHlmhgrhnNK3H58x0LFflPktdKghXcFPJ3exdh9 KKuZ4mHBV816Q3WCn0oZLU4fEqi6PmeRE5Uty1zt0wUAHyFn5ULVJhlVvpDIIE4Ukrlv HLhw== X-Gm-Message-State: AOAM530fgXMloBRrEa6SxtRUuTLlQKjxKDtNO9aXdcDpXFxP+VEk+1f8 UBkOCLLnvowwiQJGAN40AQNS2iKngsIuvpqcGas5yFyGsvo= X-Google-Smtp-Source: ABdhPJztC2cValAWJe53obAnhDeYaJ1TSnXuaT8ZZZBGIjvh3pHc8QgoAlDV2tcG9urebHzgYTNyOnMo/jVcni+mVIM= X-Received: by 2002:a1c:9842:: with SMTP id a63mr28051312wme.102.1639278918468; Sat, 11 Dec 2021 19:15:18 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Vint Cerf Date: Sat, 11 Dec 2021 22:15:05 -0500 Message-ID: To: Dave Taht Cc: starlink@lists.bufferbloat.net Content-Type: multipart/alternative; boundary="000000000000a03b5b05d2ea5d05" 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: Sun, 12 Dec 2021 03:15:19 -0000 --000000000000a03b5b05d2ea5d05 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable 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 might derive measurements to compare with actual data and modeled (queueing theoretic) data. 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 > --=20 Please send any postal/overnight deliveries to: Vint Cerf 1435 Woodhurst Blvd McLean, VA 22102 703-448-0965 until further notice --000000000000a03b5b05d2ea5d05 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
I haven't pushed to much further until we get some rea= l data from running implementations. I also hope we can develop a simulator= from which we might derive measurements=C2=A0to compare with actual data a= nd modeled (queueing theoretic) data.=C2=A0

v
=

On Sat, Dec 11, 2021 at 9:58 PM Dave Taht <dave.taht@gmail.com> wrote:
A good deep dive into DTN with vint = cerf is here:
https://www.datac= enterdynamics.com/en/analysis/vint-cerfs-interplanetary-ambitions/

=C2=A0I went looking for existing source code for it, some here:
https://projet.liris.cnrs.fr/riot/d= tn_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?= 9;
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 thi= s
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/?sit= e=3Dhttps%3A%2F%2Fwww.icei.org

Dave T=C3=A4ht CEO, TekLibre, LLC
_______________________________________________
Starlink mailing list
Starlin= k@lists.bufferbloat.net
https://lists.bufferbloat.net/listinfo/starlink


--
Please send any postal/ove= rnight deliveries to:
Vint Cerf
1435 Woodhurst Blvd=C2= =A0
McLean, VA 22102
703-448-0965

<= div>until further notice



=
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