Re: [j-nsp] Speed
On (2013-04-08 03:46 +0200), Johan Borch wrote: of a single session with a RTT of only 8ms? The performance is the same if I use 2 switches and the clients directly connected as if i use routers between. Any idea what it could be? bw * delay = window so window / delay = bw 64k*8 / 0.008 = 64000kbps = 64Mbps To achieve 40Mbps, you'd need 40M*1000/8 * 0.008 = 48kB window make sure with tshark what your actual window size is, don't trust iperf. Best thing is to configure OS TCP stack to window scaling and dont touch iperf window settings, I don't know why, but they just seem to break stuff. Also never measure network with TCP, measure network with UDP, measure TCP stack of hosts with TCP. -- ++ytti ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
Re: [j-nsp] Speed
Use TCP Optimizer to increase WSCALE/RWIN on Windows hosts to achieve better TCP perf http://www.speedguide.net/downloads.php Thanks Alex - Original Message - From: Saku Ytti s...@ytti.fi To: juniper-nsp@puck.nether.net Sent: Monday, April 08, 2013 8:13 AM Subject: Re: [j-nsp] Speed On (2013-04-08 03:46 +0200), Johan Borch wrote: of a single session with a RTT of only 8ms? The performance is the same if I use 2 switches and the clients directly connected as if i use routers between. Any idea what it could be? bw * delay = window so window / delay = bw 64k*8 / 0.008 = 64000kbps = 64Mbps To achieve 40Mbps, you'd need 40M*1000/8 * 0.008 = 48kB window make sure with tshark what your actual window size is, don't trust iperf. Best thing is to configure OS TCP stack to window scaling and dont touch iperf window settings, I don't know why, but they just seem to break stuff. Also never measure network with TCP, measure network with UDP, measure TCP stack of hosts with TCP. -- ++ytti ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
Re: [j-nsp] Speed
Saku Ytti s...@ytti.fi writes: make sure with tshark what your actual window size is, don't trust iperf. Best thing is to configure OS TCP stack to window scaling and dont touch iperf window settings, I don't know why, but they just seem to break stuff. In my experience, you cannot trust iperf to not override the OS window size. Explicit -w seems to be the only reliable solution. /Benny ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
Re: [j-nsp] Speed
On (2013-04-08 13:44 +0200), Benny Amorsen wrote: In my experience, you cannot trust iperf to not override the OS window size. Explicit -w seems to be the only reliable solution. I remember one test I had, not long ago, where any -w value fared worse than no -w value. I never tsharked it, I just presumed iperf doing something stupid with static window size and OS doing something smart. This highlights the fact that you should not test network with TCP, always UDP, with TCP there are so many things to go wrong which are not network related, UDP is much more reliable indication that problem actually may be in the network. -- ++ytti ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
Re: [j-nsp] Speed
Saku Ytti s...@ytti.fi writes: This highlights the fact that you should not test network with TCP, always UDP, with TCP there are so many things to go wrong which are not network related, UDP is much more reliable indication that problem actually may be in the network. UDP tests can be too generous on the network. A stream of perfectly spaced UDP packets will not show problems with microbursts. Almost all bulk transfer protocols are TCP, so it is important to test with TCP. /Benny ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
