Subject: [Tsvwg] Moving NewReno from Experimental to Proposed Standard

From: Sally Floyd <[email-masked]>
Date: Mon, 31 Mar 2003 15:29:35 -0800

At the tsvwg meeting in San Francisco two weeks ago, I gave up
my five-minute slot for discussing "Moving NewReno from Experimental to
Proposed Standard" because of a shortage of time, and said I would
send email to the list instead.  So finally here it is.

(We did take a quick hum at the meeting to verify that people
generally thought that taking NewReno to Proposed was a good idea,
as I recall.)

The viewgraphs for this talk are at:
  http://www.icir.org/floyd/talks/newreno-Mar03.ps
  http://www.icir.org/floyd/talks/newreno-Mar03.pdf

Here is basically what would have been the text part of the talk:

* NewReno was been widely deployed for many years now, and has
been an Experimental RFC since 1999, so it seems time to move
it from Experimental to Proposed. 

* NewReno performs dramatically better than Reno when multiple
packets are dropped from a window of data, and we would recommend
NewReno over Reno, for TCP connections where the other end does not
support SACK.  However, in the interests of full disclosure,
we do know of one scenario where Reno (and Sack) both perform
better than NewReno.  This is when there are reordered packets but
no lost packets, and the sender gets three dup acks from the
reordering alone.  This is illustrated in slides 4, 5, and 6
of the viewgraphs, for Reno, NewReno, and Sack respectively.

* We know of only one change that we want to make to the NewReno RFC.
That RFC describes a Careful and Less Careful variant, and recommends
the Careful variant.  A revision would *require* the Careful instead of 
the Less Careful variant.  The reason for this is illustrated
on slide 8 of the viewgraphs, and has to do with the Less Careful's
quite bad response to a Fast Retransmit that is due to reordering alone.

(The Careful and Less Careful variants are two variants of what is
called "bugfix" in the NS simulator.  The name "bugfix" dates from
the days when Steve McCanne and I were the only users of the NS
simulator, and we had not yet made the simulator publically available,
so I was also less careful in the names that I attached to things...)

* If anyone knows of any other changes that should be made to
the NewReno spec as it goes to Proposed, please let Tom and I 
know.

* For all of the simulations in the viewgraphs, the bottom line
gives the command needed to run that simulation in the NS simulator,
in the directory "tcl/test".

Thanks,
- Sally

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