[e2e] TCP in outer space

Cannara cannara at attglobal.net
Thu Apr 12 21:31:43 PDT 2001


I'm glad you agree, since I certainly did not say today's result is "due to
lack of smarts back then".  The issue as, you say, is it's hard to get a
parochial group, like the IETF, to think more broadly, even critically, about
their prior work.  This and "complex reasons", whether you have time or not,
is an essential feature of bureaucracies, in all human domains in all

Indications of parochialism were clear years ago, when Xerox had a wordwide,
functioning, XNS network, followed by 3Com's worldwide XNS-like network,
paralleled by the Marine Corps worldwide Banyan Vines network, various Netware
networks, etc., etc.  These were indeed largely datagram networks.  There has
been ample opportunity for cross-fertilization of networking ideas, over many
years.  Apparently, however, the IETF has been another way of abbreviating

On the plus side, this situation lends itself to teaching networking students
how to think for themselves, graps important network concepts, and evaluate
bureaucratic definitions and techniques in networking, in order to improve the
prospects for a better fit between future protocols and advancing techniques
and demands.


It would be amusing to speculate 

"J. Noel Chiappa" wrote:
>     > From: Ted Faber <faber at ISI.EDU>
>     >> since 1978, there has been no mystery that, for instance, TCP's
>     >> retransmission algorithm has been given no means to distinguish among
>     >> even the two most important causes of loss -- physical or queue drop.
>     > Mechanisms based on internal network state were considered and
>     > discarded because they conflicted with the well-defined and
>     > well-prioritized list of design goals for the nascent Internet.
>     > Specifically, depending on such internal information made the net less
>     > robust to gateway failures .. so such mechanisms weren't included.
> Actually, neither of these positions is right. The early Internet *did* try
> and *explicitly* signal drops due to congestion, separately from drops due to
> damage - that's what the ICMP "Source Quench" message was all about.
> It turned out that SQ probably wasn't the right way to go about it - but I
> seem to recall a very recent, very lengthy debate about the utility of SQ, as
> compared to ECN, so I think those who made that particular mistake back when
> can't be castigated too hard.
> In fact, the thing is that we just didn't understand a lot about the dynamics
> of very large pure datagram networks, back in the late 70's when the initial
> TCP work was being done. (And I'm not talking about only congestion, etc
> here.) To start with, nobody had ever built one (the ARPAnet was *not* a pure
> datagram network, for reasons I'm not going to explain here). With the *very*
> limited amount of brain/programming power available in the early days of the
> project (most of which was focussed on down-to-earth tasks like getting
> packets in and out of interfaces), it's not too surprising that there were
> lots of poorly-examined regions of the design space.
> But to get back to the topic, even ECN is at best a probabilistic mechanism
> for letting the source know which drops are due to congestion, and which to
> packet damage. The only "more reliable" (not that *any* low-level mechanism
> in a pure datagram network is wholly reliable) method is SQ - and as I
> mentioned, we just got through a long disquisition about how SQ is not the
> right thing either.
>     >> nothing in 2001 is new with respect to Internet design criteria, that
>     >> was not evident to network engineers in and out of the Internet
>     >> community over a decade ago
> Perhaps - but the basic Internet framework was done in the mid-70's, when
> this stuff was *not* "evident" to all and sundry.
> And if you think it's due to lack of smarts back then, I think there are a
> lot of things you only learn via experience. I'll point to Sorcerer's
> Apprentice Syndrome, which was apparently independently re-invented by people
> at Xerox PARC *and* MIT - neither of whom is known for being below-average
> clever.
>     >> If the old tunes were spur-of-the-moment (ad hoc), as we know some
>     >> significant ones were, then why be so resistant to new ideas for a new
>     >> networking realm? Bureaucracies are resistant. Productive, competent
>     >> research cannot be.
> As someone who's spent a lot of time trying to get the IETF community to take
> on some novel ideas, let me tell you that it's one heck of a lot harder than
> it looks.
> And it's not "bureacracy", but a much more complex set of reasons - ones I
> don't have the time/energy to expand on right now.
>         Noel

More information about the end2end-interest mailing list