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: Fri, 21 Mar 2014 14:53:20 -0700 [thread overview]
Message-ID: <532CB4D0.50403@hp.com> (raw)
In-Reply-To: <CABrhC0=hHpZSdE5-dLqysuFn_d_VK7r1jKb0kGZF9hn1+UHjDw@mail.gmail.com>
On 03/03/2014 07:22 PM, John Heffner wrote:
> Running with such a large window scale and no timestamps (PAWS
> protection) is generally not a great idea, but I don't think is part
> of the issue here.
>
> If you look where things really go wrong, the receiver is sending
> anomalous SACK blocks that will trigger the SACK renege handling path.
> Reneging triggers go-back-n behavior, so we see the spurious
> retransmits from there on.
What triggers go-back-n when SACK is not in use? I ask because at least
once I have seen the same sort of thing without SACK enabled on the
connection. The total quantity of retransmissions is roughly the same,
but spread-out - looks like cwnd shrinks considerably and re-grows in
the no-SACK case. Not sure I still have that trace though :(
rick jones
next prev parent reply other threads:[~2014-03-21 21:53 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
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 [this message]
2014-03-25 17:39 ` Rick Jones
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