Date: Fri, 13 Jun 2008 12:40:48 -0400 From: Robert Boyle <robert@tellurian.com>
At 12:01 PM 6/13/2008, Kevin Oberman wrote:
Clearly you have failed to try very hard or to check into what others have done. We routinely move data at MUCH higher rates over TCP at latencies over 50 ms. one way (>100 ms. RTT). We find it fairly easy to move data at over 4 Gbps continuously.
That's impressive.
If you can't fill a GE to 80% (800 Mbps) at 30 ms, you really are not tying very hard. Note: I am talking about a single TCP stream running for over 5 minutes at a time on tuned systems. Tuning for most modern network stacks is pretty trivial. Some older stacks (e.g. FreeBSD V6) are hopeless. I can't speak to how Windows does as I make no use of it for high-speed bulk transfers.
Let me refine my post then... In our experience, you can't get to line speed with over 20-30ms of latency using TCP on _Windows_ regardless of how much you tweak it. >99% of the servers in our facilities are Windows based. I should have been more specific.
Sorry, but I don't do Windows, but my friends who do claim that this is not true. -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: oberman@es.net Phone: +1 510 486-8634 Key fingerprint:059B 2DDF 031C 9BA3 14A4 EADA 927D EBB3 987B 3751