[e2e] Switched Ethernet is Not an End-to-End System; was Protocols breaking the end-to-end argument

Jon Crowcroft Jon.Crowcroft at cl.cam.ac.uk
Mon Nov 2 01:37:22 PST 2009

In missive <4AEDCCF6.3090600 at isi.edu>, Bob Braden typed:

 >>It does not really matter, of course, but your quick summary is not 
 >>quite accurate.

 >>It depends upon what you consider to be "Day 1".  E.g., RFC 793 did NOT 

absolutely - sorry - i was talkin about first cut at design - the RSRE
discussion predates the RFC and the result made it in to the spec..

 >>have a
 >>fixed retransmit time.  And if you want to give RSRE credit for 
 >>exponentially smoothed
 >>RTT measurements (a fact I had forgotten, assuming you are correct), you 

see  IEN160 for the discussion and credit - was a couple of years
before i was doin this sort of thing so you prob. know more about this
than me...

but the smarter smoothing happened in 87 
(using smoothed mean + mean squre difference
for retransmit rather than just EWMA)
and the late 80s stuff had input from Karn&Partridge

 >>ought to
 >>give Van credit for finally figuring out how to do real congestion 
 >>control, in 1987.

of course!
but that work is so heavily cited I just thought everyone would know
it anyhow :)
one should also cite Raj Jain and KK Ramakrishnan for the DECNET work
from which some of it came, and Frank Kelly for packet conservation

but the purpose of my comment wasnt to go down memory lane and build a
perfect family tree of ideas (that would be a good thing to do 
e.g. based o na code audit:)
but to point out that the original designers 
did NOT get everything right in one go...
indeed some of donald davies' (and others)
original ideas about resource pooling and
congestion control which were integral in his vision 
of packet switching, were actually lost from between 
early 70s and late 80s...


suppose those who teach history 
are doomed to repeat themselves:)
 >>> early TCPs had fixed retransmit until the RSRE algorithm
 >>> and then it was still some time before the Karn/Partridge
 >>> improvements kicked in
 >>> plus 
 >>> early TCPs had no congestion control at all 
 >>> until '87



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