<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<div class="moz-cite-prefix">On 5/21/2014 12:00 PM,
<a class="moz-txt-link-abbreviated" href="mailto:internet-history-request@postel.org">internet-history-request@postel.org</a> wrote:<br>
</div>
<blockquote
cite="mid:mailman.1.1400698801.16398.internet-history@postel.org"
type="cite">
<pre wrap="">Send internet-history mailing list submissions to
<a class="moz-txt-link-abbreviated" href="mailto:internet-history@postel.org">internet-history@postel.org</a>
To subscribe or unsubscribe via the World Wide Web, visit
<a class="moz-txt-link-freetext" href="http://mailman.postel.org/mailman/listinfo/internet-history">http://mailman.postel.org/mailman/listinfo/internet-history</a>
or, via email, send a message with subject or body 'help' to
<a class="moz-txt-link-abbreviated" href="mailto:internet-history-request@postel.org">internet-history-request@postel.org</a>
You can reach the person managing the list at
<a class="moz-txt-link-abbreviated" href="mailto:internet-history-owner@postel.org">internet-history-owner@postel.org</a>
When replying, please edit your Subject line so it is more specific
than "Re: Contents of internet-history digest..."
----------------------------------------------------------------------
Message: 1
Date: Wed, 21 May 2014 10:31:31 -0400 (EDT)
From: <a class="moz-txt-link-abbreviated" href="mailto:jnc@mercury.lcs.mit.edu">jnc@mercury.lcs.mit.edu</a> (Noel Chiappa)
Subject: Re: [ih] internet-history Digest, Vol 84, Issue 4
To: <a class="moz-txt-link-abbreviated" href="mailto:internet-history@postel.org">internet-history@postel.org</a>
Cc: <a class="moz-txt-link-abbreviated" href="mailto:jnc@mercury.lcs.mit.edu">jnc@mercury.lcs.mit.edu</a>
Message-ID: <a class="moz-txt-link-rfc2396E" href="mailto:20140521143131.5577A18C0E0@mercury.lcs.mit.edu"><20140521143131.5577A18C0E0@mercury.lcs.mit.edu></a>
> From: Guy Almes <a class="moz-txt-link-rfc2396E" href="mailto:galmes@tamu.edu"><galmes@tamu.edu></a>
> Clarity on the degree to which the authors of the early TCP RFCs did
> not recognize the importance of developing very good congestion control
> algorithms.
I think it was as much (if not more) an issue of 'we didn't have the
capability to do one as good as Van's' as "recogniz[ing] the importance of
developing [a] very good" one.</pre>
</blockquote>
<br>
Very definitely the latter. Van brought an entirely new perspective
to the problem, from his experience designing digital control
systems for LBL.<br>
<br>
<blockquote
cite="mid:mailman.1.1400698801.16398.internet-history@postel.org"
type="cite">
<pre wrap="">
To what degree that was the lack of a good understanding of the problem, and
to what degree simply that Van was better at control theory and analysis of
the system than the rest of us, is a good question, and one I don't have a
ready answer too. But if you look at something like "Why TCP Timers Don't
Work Well", it's clear we all just didn't understand what could be done.</pre>
</blockquote>
<br>
It is not a "good question", there is no doubt.<br>
<blockquote
cite="mid:mailman.1.1400698801.16398.internet-history@postel.org"
type="cite">
<pre wrap="">
We did understand that congestion control was important (although my
recollection is that I don't think we clearly foresaw the severe congestive
collapse which the ARPANET-based section of the Internet suffered not too
long before Van started working on the problem). Hence, we did put a certain
amount of thought into congestion control (Source Quench, the Nagle
algorithm, etc).
</pre>
</blockquote>
<br>
Nagle and Partridge had only recently made us clearly aware of the
congestion collapse problem; Mills had already produced the
disasterous consequences in NSFnet ;-)<br>
<br>
<br>
<blockquote
cite="mid:mailman.1.1400698801.16398.internet-history@postel.org"
type="cite">
<pre wrap="">
My vague recollection is that in the very early days we were more focused on
flow control in the hosts, rather than congestion control in the network, but</pre>
</blockquote>
<br>
Yes, and to the extent we did recognize the problem, we had no clue
about how to cure it. Van worked out, and taught the rest of us,
the fundamentals of "packet physics". Once he explained about ack
clocking, slow start, etc., it made sense, but that does not mean we
figured it out ourselves. <br>
<br>
<big> I think we did understand that congestion in the network was
also aan issue
(hence SQ, </big><br>
<br>
Yes, and Source Quench was a perfect example of our pre-VJ
cluelesssness. Wwhat seemed a plausible congestion control mechanism
was in fact completely broken. <br>
<br>
<big>etc).
The thing is that we understand all this so much better now - the
importance
of congestion control, source algorithms to control it, etc - and
we were
really groping in the dark back then.
The ARPANET (because of its effective VC nature, with flow and
thus
congestion control built into the network itself) hadn't given us
much in the
way of advance experience in this particular area. So, as with
many things,
what is crystal clear in<br>
</big><br>
Quite true.<br>
<br>
<br>
Also, in fairness, we were being stressed by the complexity of
making the entire system work at all in the face of exponential
growth. We struggled to make routing actually work despite
repeated routing table overflows, and we had to solve the network
management problem. Until we began to experience congestion collapse
in NSFnet, congestion control seemed more an academic problem. The
early Internet was a continuing "success disaster".<br>
<br>
Bob Braden<br>
<br>
<br>
<big>to solve hindsight was rather obscured without the mental
frameworks, etc that we have</big> <big>now (e.g. F=ma). >
Clarity on how/when it began to become evident that the naive >
algorithms documented in the TCP RFCs and used in early testing
would > themselves become the source of trouble.
Not just testing, but early service! (Q.v. the ARPANET-local
congestive
collapse.)
But your wording makes it sound like they were positively
incorrect. Well,
not really (to my eyes); they mostly simply were not _always
effective_ at
controlling congestion (although they did generate some useless,
duplicate
packets). But they were not positively defective, the way TFTP
was, with
Sorcerer's Apprentice Syndrome:
<a class="moz-txt-link-freetext" href="http://en.wikipedia.org/wiki/Sorcerer's_Apprentice_Syndrome">http://en.wikipedia.org/wiki/Sorcerer's_Apprentice_Syndrome</a> Noel
------------------------------
------------------------------
<br>
<br>
<br>
<br>
</big>
</body>
</html>