[e2e] Open the floodgate

Jonathan M. Smith jms at central.cis.upenn.edu
Wed Apr 28 19:13:20 PDT 2004


Hi Bob, not clear. I think the issues are two: where you maintain state
(i.e., reachability information) and how out of date this information becomes 
by the time it needs to be used, something which is at least partially
a function of propagation delay, partly a function of how rapidly the 
information
changes, and partly a function of how often it needs to be used. It seems
to me not at all outrageous to think of discovering, maintaining and using
routes entirely at the end points. It's perhaps an interesting coincidence
that I have recently been reading Waldrop's "Dream Machine", which whether
accurate or not (it seems so to me) argues that the real reason for IMPs
rather than pure E2E (as we know it today) was that the operating system 
folks at the time (working on GENIE, MULTICS, etc.) would have been 
overwhelmed,
and thus Wesley Clark of Wash U. suggested outboard packet switches. I wasn't
there, but it is interesting to speculate how things might have evolved 
differently.

Thanks,
-JMS

> 
>   *> 
>   *> so the one thing you could "add" in the network is somethign that we
>   *> discussed on this list before (i think it was JMS who put it that the
>   *> real purist end2end thing would be to take routing decisions out of the
>   *> net and put them in the end systems too along with error recovery) -
>   *> 
> 
> If putting routing entirely in end systems were a consequence of strict
> application of the E2E arguments, then I would say that the E2E
> arguments must be wrong or at least incomplete.  But I don't believe
> that is a correct deduction.  Datagram routing cannot be done
> effectively by end systems alone (you encounter problems of robustness
> and scalability), so it is not really a candidate for movement up the
> stack and towards the edges.
> 
> Bob Braden
 



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