rsync & SSL 'for real'
Lawrence D. Dunn
ldunn at cisco.com
Thu Apr 19 16:22:07 GMT 2007
My mistake- read "SSL", immediately started thinking "ssh",
and issues there. No excuse.
So- my comments aren't applicable to the SSL-for-real discussion -
apologies to the list.
(Aside: the issues with ssh are not about modifying TCP buffers.
They are about a fixed-size ssh-windowing behavior,
which happens "on top of" whatever TCP is allowing.
The end result is similar to having too-small TCP buffers.
That's what Chris' patch addresses - he allows the ssh-windowing
behavior to become dynamic, essentially tracking TCP's window size.
Current Linux releases do a good job of auto-tuning TCP buffers,
without need for manual adjustment. )
Again- sorry for the tangent.
At 1:21 PM -0700 4/18/07, Carson Gaspar wrote:
>Lawrence D. Dunn wrote:
>> If you do pursue SSL functionality directly in rsync,
>> please be sure to take a look at Chris Rapier's work
>> to "fix" standard ssh implementations, at:
>> Turns out "-e ssh" using most libraries puts a fixed-window-size
>> behavior on top of TCP - so for large bandwidth*delay product paths,
>> even if you use large TCP buffers (which Wayne added for such paths),
>> an "un-fixed" SSL library can clobber overall performance/throughput,
>> even for a perfectly clean (no errors/loss) path.
>SSL != SSH.
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