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Message-ID: <00EBC850E752CC46B8509DAB4D0D2CB910692D@xch-nw-29.nw.nos.boeing.com>
From: "Henderson, Thomas R" <thomas.r.henderson@boeing.com>
To: "'Mike Silbersack'" <silby@silby.com>
Cc: "'freebsd-net@freebsd.org'" <freebsd-net@freebsd.org>
Subject: RE: [patch] Possible newreno fix, please test
Date: Thu, 8 Aug 2002 17:40:35 -0700 
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> Personally, I don't believe that the code in question was 
> correct in the
> first place.  Isn't the congestion window supposed to be increased for
> every dupack received, not just every third?
> 

I agree-- but it seems to me that the problem line in there is 
     t_dupacks = 0;
which causes two possible problems
i) cwnd incremented for every third dupack
ii) (more serious) you never do the window deflation in
certain loss scenarios, because your dupack counter doesn't
indicate that you were previously in fast retransmission. 

I wonder if the patch should be instead:

 +++ tcp_input.c Wed Aug  7 23:03:38 2002
@@ -1662,9 +1662,7 @@
                                                /* False retransmit, should
not
                                                 * cut window
                                                 */
                                                tp->snd_cwnd +=
tp->t_maxseg;
-                                               tp->t_dupacks = 0;
                                                (void) tcp_output(tp);
                                                goto drop;
                                        }
                                        if (win < 2)

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