From: Rick Jones <rick.jones2@hp.com>
To: John Heffner <johnwheffner@gmail.com>
Cc: Netdev <netdev@vger.kernel.org>
Subject: Re: TCP being hoodwinked into spurious retransmissions by lack of timestamps?
Date: Tue, 04 Mar 2014 11:33:02 -0800 [thread overview]
Message-ID: <53162A6E.2010907@hp.com> (raw)
In-Reply-To: <CABrhC0k5-x=qJgH4izXtRR=9+cLJh_emAy9Yt=+xrY6K5982Fg@mail.gmail.com>
>>> There is some other strangeness just before that, where the SACK
>>> block shrinks then grows again.
>>
>>
>> That would be this yes?
>>
>> 15:20:46.798816 IP 91.216.86.7.56064 > 75.236.145.7.443: Flags [.], seq
>> 3660468:3661928, ack 4262, win 297, length 1460
>> 15:20:46.799027 IP 75.236.145.7.443 > 91.216.86.7.56064: Flags [.], ack
>> 3168256, win 32081, options [nop,nop,sack 1 {3171368:3172828}], length 0
>> 15:20:46.799042 IP 91.216.86.7.56064 > 75.236.145.7.443: Flags [.], seq
>> 3661928:3664848, ack 4262, win 297, length 2920
>> 15:20:46.799465 IP 75.236.145.7.443 > 91.216.86.7.56064: Flags [.], ack
>> 3169716, win 32241, options [nop,nop,sack 1 {3171368:3172828}], length 0
>> 15:20:46.799479 IP 91.216.86.7.56064 > 75.236.145.7.443: Flags [.], seq
>> 3664848:3666308, ack 4262, win 297, length 1460
>> 15:20:46.799497 IP 75.236.145.7.443 > 91.216.86.7.56064: Flags [.], ack
>> 3169716, win 32241, options [nop,nop,sack 1 {3171368:3174288}], length 0
>> 15:20:46.799504 IP 75.236.145.7.443 > 91.216.86.7.56064: Flags [.], ack
>> 3169716, win 32241, options [nop,nop,sack 1 {3171368:3175748}], length 0
>> 15:20:46.799509 IP 91.216.86.7.56064 > 75.236.145.7.443: Flags [.], seq
>> 3666308:3667768, ack 4262, win 297, length 1460
>> 15:20:46.799773 IP 75.236.145.7.443 > 91.216.86.7.56064: Flags [.], ack
>> 3171176, win 32491, options [nop,nop,sack 1 {3171368:3172828}], length 0
>> 15:20:46.799787 IP 91.216.86.7.56064 > 75.236.145.7.443: Flags [.], seq
>> 3667768:3669228, ack 4262, win 297, length 1460
>> 15:20:46.800063 IP 75.236.145.7.443 > 91.216.86.7.56064: Flags [.], ack
>> 3171368, win 32716, options [nop,nop,sack 1 {3171368:3177208}], length 0
>> 15:20:46.800081 IP 91.216.86.7.56064 > 75.236.145.7.443: Flags [.], seq
>> 3171368:3172828, ack 4262, win 297, length 1460
>>
>> Might that be packet-reordering in the other direction? Sadly, I don't have
>> good "both sides" traces as the receiving system doesn't seem to capture
>> traffic terribly well. I suppose TCP timestamps might have helped answer
>> that question.
>
> Regardless of any possible reordering, in this case we know something
> odd is going on in the receiver because ACK advances at the same time
> the SACK block shrinks.
Ah yes, I'd not picked-up on that.
thanks,
rick jones
next prev parent reply other threads:[~2014-03-04 19:33 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-04 0:29 TCP being hoodwinked into spurious retransmissions by lack of timestamps? Rick Jones
2014-03-04 3:22 ` John Heffner
2014-03-04 18:50 ` Rick Jones
2014-03-04 19:14 ` John Heffner
2014-03-04 19:33 ` Rick Jones [this message]
2014-03-04 20:35 ` Neal Cardwell
2014-03-04 21:56 ` Rick Jones
2014-03-04 22:23 ` Yuchung Cheng
2014-03-04 23:14 ` Rick Jones
2014-03-21 21:53 ` Rick Jones
2014-03-25 17:39 ` Rick Jones
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