nanog mailing list archives
Re: TCP and WAN issue
From: Andre Oppermann <nanog-list () nrg4u com>
Date: Wed, 28 Mar 2007 11:12:45 +0200
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 -- 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______________________________________________________________________ ______________Need Mail bonding? Go to the Yahoo! Mail Q&A for great tips from Yahoo! Answers users. http://answers.yahoo.com/dir/?link=list&sid=396546091
Current thread:
- RE: Jumbo frames, (continued)
- RE: Jumbo frames Jim Shankland (Mar 27)
- Re: Jumbo frames Andy Davidson (Mar 29)
- RE: Jumbo frames michael.dillon (Mar 29)
- Re: Jumbo frames Stephen Sprunk (Mar 30)
- RE: Jumbo frames Hank Nussbacher (Mar 27)
- Re: Perry Lorier (Mar 27)
- Re: TCP and WAN issue Steve Meuse (Mar 27)
- Re: TCP and WAN issue Andre Oppermann (Mar 28)
- Re: TCP and WAN issue Marshall Eubanks (Mar 28)
- Re: TCP and WAN issue Simon Leinen (Mar 28)
- Re: TCP and WAN issue Roland Dobbins (Mar 27)
- RE: TCP and WAN issue michael.dillon (Mar 27)
- Re: TCP and WAN issue Roland Dobbins (Mar 27)
- Re: TCP and WAN issue Eric A. Hall (Mar 27)