Strange things on GBit / 1000->100 / net.inet.tcp.inflight.*

Raphael H. Becker rabe at
Fri Sep 17 16:39:31 PDT 2004

On Sat, Sep 18, 2004 at 01:11:13AM +0200, Andre Oppermann wrote:
> I'm unable to reproduce your problem.
> Usually in these cases there is an ethernet duplex mismatch somewhere.
> Can set the network cards and the switches to fixed 1000 or 100 full-duplex?

Yes, one of my first tests. Both machines fixed to their nominal
transfer rate. Tested different ports, different irons (source and
target), different cables. Always same result.

All channels are able to do their maximum speed.

Changing target and source (100 -> 1000) resulted in >10MBytes/sec, same
machines, same cables, same everything 1000 -> 100 resulted in what we
discuss here (300kBytes).

100->100 (between the two PE350) is working fine, too.

The problematic case (1000 -> 100) was tested with 3 machines 5.x and 2
machines 4.x, all cases the same.

I'm not sure this is a "physical" problem. 

I will try something else next days:
* New cables
* FreesBIE with 4.10 on the 5.3-Boxes, ftp'in /dev/zero directly to /dev/null ...
* throtteling 1000MBit ... maybe

* another GBit-Switch (if available)

* Buy 1000MBit-Cards for the both "Router"-boxes

Raphael Becker

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