Hi,

Am 27.04.2011 um 19:39 schrieb Yuchung Cheng:

Hi Dominik,

On Wed, Apr 27, 2011 at 9:22 AM, Dominik Kaspar [off-list ref] wrote:

quoted

Hi Carsten,

Thanks for your feedback. I made some new tests with the same setup of
packet-based forwarding over two emulated paths (600 KB/s, 10 ms) +
(400 KB/s, 100 ms). In the first experiments, which showed a step-wise
adaptation to reordering, SACK, DSACK, and Timestamps were all
enabled. In the experiments, I individually disabled these three
mechanisms and saw the following:

- Disabling timestamps causes TCP to never adjust to reordering at all.
- Disabling SACK allows TCP to adapt very rapidly ("perfect" aggregation!).

Did you enable tcp_fack when sack is enabled? this may make a (big)
difference. FACK assumes little network reordering and mark packet
losses more aggressively.

It's not necessary to do it manually. Linux will disable FACK as soon as it
will detected reordering

Alex

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// Dipl.-Inform. Alexander Zimmermann
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