Re: [RFC PATCH RESEND] tcp: avoid F-RTO if SACK and timestamps are disabled

From: Michal Kubecek
Date: Thu Jun 14 2018 - 09:18:09 EST


On Thu, Jun 14, 2018 at 02:51:18PM +0300, Ilpo Järvinen wrote:
> On Thu, 14 Jun 2018, Michal Kubecek wrote:
> > On Thu, Jun 14, 2018 at 11:42:43AM +0300, Ilpo Järvinen wrote:
> > > On Wed, 13 Jun 2018, Yuchung Cheng wrote:
> > > > On Wed, Jun 13, 2018 at 9:55 AM, Michal Kubecek <mkubecek@xxxxxxx> wrote:
> >
> > AFAICS RFC 5682 is not explicit about this and offers multiple options.
> > Anyway, this is not essential and in most of the customer provided
> > captures, it wasn't the case.
>
> Lacking the new segments is essential for hiding the actual bug as the
> trace would look weird otherwise with a burst of new data segments (due
> to the other bug).

The trace wouldn't look so nice but it can be reproduced even with more
data to send. I've copied an example below. I couldn't find a really
nice one quickly so that first few retransmits (17:22:13.865105 through
17:23:05.841105) are without new data but starting at 17:23:58.189150,
you can see that sending new (previously unsent) data may not suffice to
break the loop.

> > Normally, we would have timestamps (and even SACK). Without them, you
> > cannot reliably recognize a dupack with changed window size from
> > a spontaneous window update.
>
> No! The window should not update window on ACKs the receiver intends to
> designate as "duplicate ACKs". That is not without some potential cost
> though as it requires delaying window updates up to the next cumulative
> ACK. In the non-SACK series one of the changes is fixing this for
> non-SACK Linux TCP flows.

That sounds like a reasonable change (at least at the first glance,
I didn't think about it too deeply) but even if we fix Linux stack to
behave like this, we cannot force everyone else to do the same.

Michal Kubecek


17:22:13.660030 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1101588007:1101650727, ack 1871152053, win 28, length 62720
17:22:13.660039 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294151936, win 12146, length 0
17:22:13.660047 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 62720:125440, ack 1, win 28, length 62720
17:22:13.660050 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294178816, win 12146, length 0
17:22:13.660052 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294196736, win 12146, length 0
17:22:13.660131 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 125440:188160, ack 1, win 28, length 62720
17:22:13.660142 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294223616, win 12146, length 0
17:22:13.660164 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 188160:250880, ack 1, win 28, length 62720
17:22:13.660171 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294250496, win 12146, length 0
17:22:13.660177 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294277376, win 12146, length 0
17:22:13.660181 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294304256, win 12146, length 0
17:22:13.660185 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294331136, win 12146, length 0
17:22:13.660196 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294349056, win 12146, length 0
17:22:13.660212 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 250880:313600, ack 1, win 28, length 62720
17:22:13.660224 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 313600:376320, ack 1, win 28, length 62720
17:22:13.660266 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294384896, win 12146, length 0
17:22:13.660292 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294411776, win 12146, length 0
17:22:13.660294 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294438656, win 12146, length 0
17:22:13.660295 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294465536, win 12146, length 0
17:22:13.660353 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 376320:439040, ack 1, win 28, length 62720
17:22:13.660377 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 439040:501760, ack 1, win 28, length 62720
17:22:13.660391 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294501376, win 12146, length 0
17:22:13.660396 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294519296, win 12146, length 0
17:22:13.660400 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 501760:564480, ack 1, win 28, length 62720
17:22:13.660409 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294555136, win 12146, length 0
17:22:13.660420 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294582016, win 12146, length 0
17:22:13.660434 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294608896, win 12146, length 0
17:22:13.660458 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 564480:627200, ack 1, win 28, length 62720
17:22:13.660515 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294644736, win 12146, length 0
17:22:13.660527 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294671616, win 12146, length 0
17:22:13.660540 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294698496, win 12146, length 0
17:22:13.660541 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294725376, win 12146, length 0
17:22:13.660542 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294743296, win 12146, length 0
17:22:13.660580 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 627200:689920, ack 1, win 28, length 62720
17:22:13.660597 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 689920:752640, ack 1, win 28, length 62720 <--- first loss
17:22:13.660642 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294770176, win 12146, length 0
17:22:13.660648 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 752640:815360, ack 1, win 28, length 62720
17:22:13.660655 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294797056, win 12146, length 0
17:22:13.660662 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294823936, win 12146, length 0
17:22:13.660666 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 815360:878080, ack 1, win 28, length 62720
17:22:13.660672 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294850816, win 12146, length 0
17:22:13.660696 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294877696, win 12146, length 0
17:22:13.660704 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 878080:940800, ack 1, win 28, length 62720
17:22:13.660765 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294913536, win 12146, length 0
17:22:13.660779 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 4294940416, win 12146, length 0
17:22:13.660791 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 0, win 12146, length 0
17:22:13.660793 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 26880, win 12146, length 0
17:22:13.660795 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 53760, win 12146, length 0
17:22:13.660821 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 940800:1003520, ack 1, win 28, length 62720
17:22:13.660837 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1003520:1066240, ack 1, win 28, length 62720
17:22:13.660890 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 80640, win 12146, length 0
17:22:13.660897 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1066240:1128960, ack 1, win 28, length 62720
17:22:13.660923 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 107520, win 12146, length 0
17:22:13.660928 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 134400, win 12146, length 0
17:22:13.660932 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 161280, win 12146, length 0
17:22:13.660936 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1128960:1191680, ack 1, win 28, length 62720
17:22:13.660944 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 188160, win 12146, length 0
17:22:13.661015 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 215040, win 12146, length 0
17:22:13.661044 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 241920, win 12146, length 0
17:22:13.661045 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 268800, win 12146, length 0
17:22:13.661047 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 295680, win 12146, length 0
17:22:13.661048 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 322560, win 12135, length 0
17:22:13.661106 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1191680:1254400, ack 1, win 28, length 62720
17:22:13.661139 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1254400:1317120, ack 1, win 28, length 62720
17:22:13.661145 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 349440, win 12146, length 0
17:22:13.661148 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 358400, win 12146, length 0
17:22:13.661149 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 358400, win 12146, length 0
17:22:13.661150 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 358400, win 12146, length 0
17:22:13.661151 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 358400, win 12146, length 0
17:22:13.661153 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 456960, win 12130, length 0
17:22:13.661155 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1317120:1379840, ack 1, win 28, length 62720
17:22:13.661178 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1379840:1442560, ack 1, win 28, length 62720
17:22:13.661192 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1442560:1505280, ack 1, win 28, length 62720
17:22:13.661264 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 483840, win 12146, length 0
17:22:13.661286 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 510720, win 12146, length 0
17:22:13.661292 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1505280:1568000, ack 1, win 28, length 62720
17:22:13.661299 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 537600, win 12146, length 0
17:22:13.661303 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 564480, win 12146, length 0
17:22:13.661308 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1568000:1630720, ack 1, win 28, length 62720
17:22:13.661317 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 582400, win 12140, length 0
17:22:13.661390 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 609280, win 12146, length 0
17:22:13.661411 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 636160, win 12146, length 0
17:22:13.661412 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 663040, win 12146, length 0
17:22:13.661429 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 689920, win 12146, length 0
17:22:13.661430 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 716800, win 12146, length 0
17:22:13.661437 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1630720:1693440, ack 1, win 28, length 62720
17:22:13.661445 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 725760, win 12146, length 0
17:22:13.661447 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661454 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1693440:1756160, ack 1, win 28, length 62720
17:22:13.661508 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0 <--- first dupack
17:22:13.661513 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1756160:1818880, ack 1, win 28, length 62720
17:22:13.661520 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661524 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661527 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661530 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661532 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661635 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661637 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661638 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661640 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661641 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661642 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661653 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1818880:1881600, ack 1, win 28, length 62720
17:22:13.661757 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661761 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661764 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661768 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1881600:1944320, ack 1, win 28, length 62720
17:22:13.661778 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661782 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661886 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661891 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661894 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661897 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661900 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661902 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1944320:2007040, ack 1, win 28, length 62720
17:22:13.661928 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.661931 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662016 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662020 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662023 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662026 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662029 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662032 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 2007040:2069760, ack 1, win 28, length 62720
17:22:13.662039 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662042 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662132 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662136 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662139 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662142 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662145 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662148 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 2069760:2132480, ack 1, win 28, length 62720
17:22:13.662154 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662263 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662267 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662269 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662272 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662275 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662385 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662390 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 2132480:2195200, ack 1, win 28, length 62720
17:22:13.662397 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662400 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662402 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662405 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662408 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662508 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662512 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662515 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 2195200:2257920, ack 1, win 28, length 62720
17:22:13.662522 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662525 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662527 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662530 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662633 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662637 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662640 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662643 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 2257920:2320640, ack 1, win 28, length 62720
17:22:13.662649 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662652 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662759 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662763 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662766 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.662881 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 734720, win 12146, length 0
17:22:13.865105 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 734720:743680, ack 1, win 28, length 8960 <--- first retransmit
17:22:13.865227 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 851200, win 12033, length 0
17:22:14.273092 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 851200:860160, ack 1, win 28, length 8960
17:22:14.273207 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 869120, win 12016, length 0
17:22:15.089125 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 869120:878080, ack 1, win 28, length 8960
17:22:15.089244 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 887040, win 11999, length 0
17:22:16.725135 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 887040:896000, ack 1, win 28, length 8960
17:22:16.725269 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 976640, win 11912, length 0
17:22:19.997144 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 976640:985600, ack 1, win 28, length 8960
17:22:19.997257 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1039360, win 11851, length 0
17:22:26.545096 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1039360:1048320, ack 1, win 28, length 8960
17:22:26.545212 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1057280, win 11834, length 0
17:22:39.629137 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1057280:1066240, ack 1, win 28, length 8960
17:22:39.629268 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1173760, win 11721, length 0
17:23:05.841105 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1173760:1182720, ack 1, win 28, length 8960
17:23:05.841229 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1290240, win 11613, length 0
17:23:58.189150 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1290240:1299200, ack 1, win 28, length 8960
17:23:58.189268 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1344000, win 11670, length 0
17:23:58.189310 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 2320640:2383360, ack 1, win 28, length 62720 <--- new data
17:23:58.189416 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1344000, win 11689, length 0 <--- ack but window update
17:23:58.189424 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1344000, win 11689, length 0
17:23:58.189458 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1344000, win 11689, length 0
17:23:58.189466 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1344000, win 11689, length 0
17:23:58.189475 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 2383360:2446080, ack 1, win 28, length 62720 <--- more new data
17:23:58.189575 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1344000, win 11689, length 0
17:23:58.189620 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1344000, win 11689, length 0
17:23:58.189623 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1344000, win 11689, length 0
17:25:42.769136 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1344000:1352960, ack 1, win 28, length 8960 <--- retransmit only after RTO
17:25:42.769243 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1361920, win 11672, length 0
17:27:43.085128 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1361920:1370880, ack 1, win 28, length 8960
17:27:43.085240 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1469440, win 11631, length 0
17:27:43.085261 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 2446080:2508800, ack 1, win 28, length 62720
17:27:43.085363 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1469440, win 11678, length 0
17:27:43.085425 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1469440, win 11678, length 0
17:27:43.085430 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1469440, win 11678, length 0
17:27:43.085433 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1469440, win 11678, length 0
17:27:43.085437 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 2508800:2571520, ack 1, win 28, length 62720
17:27:43.085458 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1469440, win 11678, length 0
17:27:43.085461 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1469440, win 11678, length 0
17:27:43.085531 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1469440, win 11678, length 0
17:27:43.085578 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1469440, win 11678, length 0
17:27:43.085581 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1469440, win 11678, length 0
17:29:43.405123 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1469440:1478400, ack 1, win 28, length 8960
17:29:43.405249 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1594880, win 11614, length 0
17:29:43.405288 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 2571520:2634240, ack 1, win 28, length 62720
17:29:43.405400 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1594880, win 11671, length 0
17:29:43.405408 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1594880, win 11671, length 0
17:29:43.405446 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1594880, win 11671, length 0
17:29:43.405454 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1594880, win 11671, length 0
17:29:43.405462 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 2634240:2696960, ack 1, win 28, length 62720
17:29:43.405502 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1594880, win 11671, length 0
17:29:43.405579 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1594880, win 11671, length 0
17:29:43.405626 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1594880, win 11671, length 0
17:29:43.405629 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1594880, win 11671, length 0
17:31:43.725113 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1594880:1603840, ack 1, win 28, length 8960
17:31:43.725273 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1657600, win 11610, length 0
17:33:44.045093 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1657600:1666560, ack 1, win 28, length 8960
17:33:44.045248 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1675520, win 11636, length 0
17:35:44.365137 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1675520:1684480, ack 1, win 28, length 8960
17:35:44.365319 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1783040, win 11642, length 0
17:35:44.365345 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 2696960:2759680, ack 1, win 28, length 62720
17:35:44.365370 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 2759680:2822400, ack 1, win 28, length 62720
17:35:44.365463 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1783040, win 11689, length 0
17:35:44.365467 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1783040, win 11689, length 0
17:35:44.365509 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1783040, win 11689, length 0
17:35:44.365513 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1783040, win 11689, length 0
17:35:44.365517 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 2822400:2885120, ack 1, win 28, length 62720
17:35:44.365541 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1783040, win 11689, length 0
17:35:44.365563 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1783040, win 11689, length 0
17:35:44.365567 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1783040, win 11689, length 0
17:35:44.365623 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1783040, win 11689, length 0
17:35:44.365670 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1783040, win 11689, length 0
17:35:44.365674 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1783040, win 11689, length 0
17:35:44.365678 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1783040, win 11689, length 0
17:35:44.365682 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 2885120:2947840, ack 1, win 28, length 62720
17:35:44.365801 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1783040, win 11689, length 0
17:35:44.365850 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1783040, win 11689, length 0
17:35:44.365854 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1783040, win 11689, length 0
17:35:44.365894 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1783040, win 11689, length 0
17:37:44.685086 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1783040:1792000, ack 1, win 28, length 8960
17:37:44.685204 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 1899520, win 11576, length 0
17:39:45.005099 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 1899520:1908480, ack 1, win 28, length 8960
17:39:45.005228 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 2947840, win 11616, length 0
17:39:45.005304 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 2947840:3010560, ack 1, win 28, length 62720
17:39:45.005339 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 3010560:3073280, ack 1, win 28, length 62720
17:39:45.005385 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 3073280:3136000, ack 1, win 28, length 62720
17:39:45.005408 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 3136000:3198720, ack 1, win 28, length 62720
17:39:45.005430 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 3198720:3261440, ack 1, win 28, length 62720
17:39:45.005458 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 3261440:3324160, ack 1, win 28, length 62720
17:39:45.005516 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 3324160:3386880, ack 1, win 28, length 62720
17:39:45.005572 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 3386880:3449600, ack 1, win 28, length 62720
17:39:45.005595 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 3449600:3512320, ack 1, win 28, length 62720
17:39:45.005616 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 3512320:3575040, ack 1, win 28, length 62720
17:39:45.005654 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 3575040:3637760, ack 1, win 28, length 62720
17:39:45.005675 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 3637760:3700480, ack 1, win 28, length 62720
17:39:45.005710 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 3700480:3763200, ack 1, win 28, length 62720
17:39:45.005739 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 2956800, win 11851, length 0
17:39:45.005765 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 3763200:3825920, ack 1, win 28, length 62720
17:39:45.005798 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 3825920:3888640, ack 1, win 28, length 62720
17:39:45.005824 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 2974720, win 11841, length 0
17:39:45.005826 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3001600, win 11827, length 0
17:39:45.005827 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3019520, win 11961, length 0
17:39:45.005829 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3046400, win 11947, length 0
17:39:45.005831 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3073280, win 11932, length 0
17:39:45.005832 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3100160, win 11918, length 0
17:39:45.005834 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3127040, win 11904, length 0
17:39:45.005835 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3136000, win 11898, length 0
17:39:45.005837 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3162880, win 12029, length 0
17:39:45.005838 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3171840, win 12023, length 0
17:39:45.005840 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3198720, win 12009, length 0
17:39:45.005841 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3207680, win 12004, length 0
17:39:45.005842 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3234560, win 11990, length 0
17:39:45.005844 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3252480, win 11980, length 0
17:39:45.005845 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3297280, win 12092, length 0
17:39:45.005859 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 3888640:3951360, ack 1, win 28, length 62720
17:39:45.005892 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 3951360:4014080, ack 1, win 28, length 62720
17:39:45.005899 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3395840, win 12146, length 0
17:39:45.005903 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3422720, win 12146, length 0
17:39:45.005904 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3449600, win 12146, length 0
17:39:45.005906 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3512320, win 12115, length 0
17:39:45.005923 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 4014080:4076800, ack 1, win 28, length 62720
17:39:45.005946 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3539200, win 12146, length 0
17:39:45.005948 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3566080, win 12146, length 0
17:39:45.005996 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3601920, win 12146, length 0
17:39:45.005998 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3628800, win 12146, length 0
17:39:45.005999 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3646720, win 12146, length 0
17:39:45.006002 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 4076800:4139520, ack 1, win 28, length 62720
17:39:45.006040 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3673600, win 12146, length 0
17:39:45.006043 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3700480, win 12146, length 0
17:39:45.006045 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 4139520:4202240, ack 1, win 28, length 62720
17:39:45.006085 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 4202240:4264960, ack 1, win 28, length 62720
17:39:45.006087 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3718400, win 12146, length 0
17:39:45.006111 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 4264960:4327680, ack 1, win 28, length 62720
17:39:45.006135 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3745280, win 12146, length 0
17:39:45.006137 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3772160, win 12146, length 0
17:39:45.006139 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3790080, win 12146, length 0
17:39:45.006168 IP 10.30.59.58.1556 > 10.31.112.14.30284: Flags [.], seq 4327680:4390400, ack 1, win 28, length 62720
17:39:45.006197 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3816960, win 12146, length 0
17:39:45.006200 IP 10.31.112.14.30284 > 10.30.59.58.1556: Flags [.], ack 3843840, win 12146, length 0