[e2e] Protocols breaking the end-to-end argument

Jon Crowcroft Jon.Crowcroft at cl.cam.ac.uk
Sun Oct 25 02:40:00 PDT 2009

This is exactly right - 

UCL were very much at the
"centre" of this at the turning point
(turning of NCP and on TCP/IP) and relaying from the new
internet world to/from the X.25 (and other) worlds - 

The CLNP/TP4 paer of the ISO thing came to a small
degree from the DEC 
(whose ideas show up again later in 
TCP congestion control and later still in ECN)
which was a computer science approach to networking,
not telco at all.

The "war" was between telco 
(connection oriented, reliable, ordered)
and computer science 
(connectionless, best effort)

on the one hand
1. Sheer complicatedness of X.25 
(both on paper and in reality) 
made it hard to get right,
and the lack of losses on newer links (LANs) +
X.25 interpretations and implmentations' 
failure to mask dynamic routing from transport, 
and therefore from applications, 
meant it was no longer justifiable to build 
such complicated networks 
which were also getting cheaper, albeit slowly.

on the other
2. Increase in end system capability 
(e.g. mini computers like PDPs and LSIs, 
and shortly after that, workstations) 
meant, contrariwise,
the end system effort in TCP was justifiable.

A little too late, some smart switch people build
x.25 systems that did VC on the edge, 
but datagrams within and went fast, 
but missed the curve (e.g. netcom switches).
Some of those people showed up again doing ATM
(e.g. ipsilon), understanding a VC service, but
internal dynamics with pnni etc might work - again
a little too late (and cell switching didn't have the
switch speed up/cost reduction they needed to beat routers)

TP4 (which my colleagues did experiments with)
was a neat piece of design, but has nothing much
to do with any of the main protocol wars ...

The other war story people might be getting confused by
when mentioning CLNP is the IPng NSAP/CLNP fiasco...
again not part of the e2e arguments part of ISO v. DARPA
but its own later skirmish between newer players.

To be strictly fair then, 
while the bogey man in many a tee-shirt slogan was ISO, 
it was the ITU (or CCITT as was) and the
telco mind set that was connection oriented networking 
(with reliable link and network service)
specifically that was the focus of that "war"
or as I prefer to see it, a debate that played out
in markets  and in operations  -

Everyone has their own particular 
turning point tale I'm sure, 
but when we built the "shoestring" 
IP service for UK academics, 
this was a clear point for me that
we were able to make the 
particular end2end choice visible

Around that time too, 
various governments turned off their default
GOSIP (government OSI procurement) policies...

Much has flowed over many bridges since then:-)

A sad recent error has been 
EU statements that everyone doing 
next gen internet research should be
trying to converge on IPv6, but 
that's a whole other rant...

In missive <a06240821c70963885c9b@[]>, John Day typed:

 >>It was not a war between CLNP/TP4 and TCP/IP, but a war between 
 >>(CLNP/TP4; TCP/IP) and X.25.  The argument at the time by the PTTs 
 >>was that a Transport Protocol was unnecessary.  Our argument, of 
 >>course, was that it was absolutely necessary.  This was the big 
 >>argument from about 1976 to 1985.  This is primarily what the 
 >>end-to-end paper discusses and tries to create a "higher moral 
 >>ground" by creating a more general (and hence more fundamental) 
 >>principle to base the debate on.
 >>It was only later that the unwashed in the IETF turned it into a CLNP 
 >>vs IP war.
 >>Take care,



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