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Date:      Tue, 21 Dec 1999 13:23:05 -0800 (PST)
From:      Matthew Dillon <dillon@apollo.backplane.com>
To:        Poul-Henning Kamp <phk@critter.freebsd.dk>
Cc:        Garrett Wollman <wollman@khavrinen.lcs.mit.edu>, jlemon@FreeBSD.ORG, freebsd-current@FreeBSD.ORG
Subject:   Re: Odd TCP glitches in new currents 
Message-ID:  <199912212123.NAA02780@apollo.backplane.com>
References:   <16589.945810831@critter.freebsd.dk>

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:>
:>Hmmm.  I thought we agreed that 200 msec was the minimum reasonable
:>RTO.  That code doesn't seem to have made it in.
:
:I assume you mean 20 msec (= 2 tick @ 100 Hz ) ? 200 msec is enough
:to get halfway around the globe...
:
:--
:Poul-Henning Kamp             FreeBSD coreteam member

    I just rebooted both machines and it didn't fix the problem.  I did a
    packet trace on both boxes and there does indeed appear to be packet loss.

    I may have thrown out a red herring, sorry about that folks!  Something 
    odd is going on, that's for sure.  My packet trace shows that there was 
    packet loss and that the retry did *NOT* occur immediately, so my 
    premise goes out the window.

    I don't understand why my tcp connection has this sort of packet loss when
    all of my ping tests succeed 100%.  I am totally baffled.

						-Matt

    (make window wide to view.  Note: my xntpd's aren't synchronized well
    enough this soon after reboot so the two machine's times do not match
    very well).

machine #1 	(did not receive packet sequence 20400)

13:12:28.730938 216.240.41.6.4006 > 216.240.41.2.22: P 20360:20380(20) ack 36645 win 17520 (DF) [tos 0x10]
13:12:28.756646 216.240.41.2.22 > 216.240.41.6.4006: P 36645:36665(20) ack 20380 win 17520 (DF)
13:12:28.794196 216.240.41.6.4006 > 216.240.41.2.22: P 20380:20400(20) ack 36665 win 17520 (DF) [tos 0x10]
13:12:28.816622 216.240.41.2.22 > 216.240.41.6.4006: P 36665:36685(20) ack 20400 win 17520 (DF)
13:12:28.962999 216.240.41.6.4006 > 216.240.41.2.22: P 20420:20440(20) ack 36685 win 17520 (DF) [tos 0x10]
13:12:28.963059 216.240.41.2.22 > 216.240.41.6.4006: . ack 20400 win 17520 (DF)
13:12:29.027297 216.240.41.6.4006 > 216.240.41.2.22: P 20440:20460(20) ack 36685 win 17520 (DF) [tos 0x10]

machine #2	(sent packet sequence 20400, then timed out later and resent)

13:12:27.743652 216.240.41.6.4006 > 216.240.41.2.22: . ack 36645 win 17520 (DF) [tos 0x10]
13:12:28.176252 216.240.41.6.4006 > 216.240.41.2.22: P 20360:20380(20) ack 36645 win 17520 (DF) [tos 0x10]
13:12:28.202078 216.240.41.2.22 > 216.240.41.6.4006: P 36645:36665(20) ack 20380 win 17520 (DF)
13:12:28.239533 216.240.41.6.4006 > 216.240.41.2.22: P 20380:20400(20) ack 36665 win 17520 (DF) [tos 0x10]
13:12:28.262069 216.240.41.2.22 > 216.240.41.6.4006: P 36665:36685(20) ack 20400 win 17520 (DF)
13:12:28.336525 216.240.41.6.4006 > 216.240.41.2.22: P 20400:20420(20) ack 36685 win 17520 (DF) [tos 0x10]
13:12:28.408355 216.240.41.6.4006 > 216.240.41.2.22: P 20420:20440(20) ack 36685 win 17520 (DF) [tos 0x10]
13:12:28.408512 216.240.41.2.22 > 216.240.41.6.4006: . ack 20400 win 17520 (DF)
13:12:28.472656 216.240.41.6.4006 > 216.240.41.2.22: P 20440:20460(20) ack 36685 win 17520 (DF) [tos 0x10]
13:12:28.472805 216.240.41.2.22 > 216.240.41.6.4006: . ack 20400 win 17520 (DF)
13:12:28.545556 216.240.41.6.4006 > 216.240.41.2.22: P 20460:20480(20) ack 36685 win 17520 (DF) [tos 0x10]
13:12:28.545703 216.240.41.2.22 > 216.240.41.6.4006: . ack 20400 win 17520 (DF)
13:12:28.545770 216.240.41.6.4006 > 216.240.41.2.22: P 20400:20480(80) ack 36685 win 17520 (DF) [tos 0x10]




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