On Mar 28, 2007, at 5:12 AM, Andre Oppermann wrote:
Marshall Eubanks wrote:
You might want to look at this classic by Stanislav Shalunov http://shlang.com/writing/tcp-perf.html
The description on this website is very good.
Disclaimer: I'm a FreeBSD TCP/IP network stack kernel hacker.
To quickly sum up the facts and to dispell some misinformation:
- TCP is limited the delay bandwidth product and the socket buffer sizes. - for a T3 with 70ms your socket buffer on both endss should be 450-512KB. - TCP is also limited by the round trip time (RTT). - if your application is working in a request/reply model no amount of bandwidth will make a difference. The performance is then entirely dominated by the RTT. The only solution would be to run multiple sessions in parallel to fill the available bandwidth. - Jumbo Frames have definately zero impact on your case as they don't change any of the limiting parameters and don't make TCP go faster. There are certain very high-speed and LAN (<5ms) case where it may make a difference but not here. - Your problem is not machine or network speed, only tuning.
Change these settings on both ends and reboot once to get better throughput:
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip \Parameters] "SackOpts"=dword:0x1 (enable SACK) "TcpWindowSize"=dword:0x7D000 (512000 Bytes) "Tcp1323Opts"=dword:0x3 (enable window scaling and timestamps) "GlobalMaxTcpWindowSize"=dword:0x7D000 (512000 Bytes)
http://www.microsoft.com/technet/network/deploy/depovg/tcpip2k.mspx
And, of course, if you have Ethernet duplex or other mismatch issues anywhere along the path, performance will be bad. Regards Marshall
-- Andre
Marshall On Mar 27, 2007, at 4:26 PM, Philip Lavine wrote:
To all,
I have an east coast and west coast data center connected with a DS3. I am running into issues with streaming data via TCP and was wondering besides hardware acceleration, is there any options at increasing throughput and maximizing the bandwidth? How can I overcome the TCP stack limitations inherent in Windows (registry tweaks seem to not functions too well)?
Philip
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