Re: Friendliness vs. Performance

Dave Crocker (dcrocker@TWG.COM)
25 Aug 88 10:39:00 PDT

It is quite heartening to have honest-to-goodness customers demanding
robustness features. In a perhaps-overly-cautious attempt to avoid
getting commercial in the discussion, I did not mention in my previous
note that our VMS product was one of the -- maybe even THE -- first to
be shipped to customers with Van & Co.'s congestion/slow-line features
and the next releases of our Streams and DOS products will contain them.
In other words, folks, please don't take my previous comments as suggesting
that the robustness features should not be included.

My concern was that the absolute assumption of its requirement be tempered
somewhat by looking at actual customer requirements; in some percentage of
cases, reasonable robustness and superb performance are more important
than superb robustness and reasonable performance.

Please note that standard implementations of TCP, using old-style congestion
and retransmission algorithms, are significantly robust. In fact, we probably
are missing the boat by using the term to refer to the recent improvements...

The new capabilities do not alter data-loss with respect to the user. They
alter packet-loss on the net, thereby reducing retransmission requirements.
With or without the new features, users will get equivalent data transfer
integrity at the receiving application. With the new code, however, successful
COMPLETION of the transfer may be different. (I.e., if you get the bits, they
will be correct.)

In effect, I was going creating an artificial constraint, much like asking a
person who they would save, if a parent and a spouse were drowning and they
could save only one. On the other hand, there are limited development
resources and prioritizing customer requirements is essential. Just because
all you knowledgeable, demanding networkers have the priorities set one
way -- which I agree with as someone who has suffered with Internet
performance -- does not mean that it is correct for the masses. Long-term,
it IS correct, since they will all be part of a global internet and will
be subject to the phenomena that the new algorithms address. However,
short-term, many of those networkers are isolated.


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