You didn't adjust the TCP window size of the stack.
Wish I could remember the exact syntax, but if you do a google search you should find the systl commands to make the necessary changes for the protocol stack. — Laurent On Mon, Apr 1, 2013 at 7:08 PM, CiscoNSP List <[email protected]> wrote: > Thanks for the reply - I am testing from two Linux servers, and as mentioned, > I adjusted the tcp window size in IPERF (-w), but it actually made the > performance worse? > Date: Mon, 1 Apr 2013 16:04:37 -0700 > From: [email protected] > To: [email protected] > CC: [email protected] > Subject: Re: [c-nsp] Performance issue on link > Bandwidth delay product (BDP). > You'll find a bunch of articles out there searching for those terms. > Adjusting the TCP windows size to compensate for the delay should help you > achieve close to CIR. > You mention a Linux server (most distributions have TCP window scaling > enabled), but I'll venture to say you're testing from a Windows client. > Windows systems are notoriously poor at dealing with BDP without some fine > tuning. > BDP would certainly explain the discrepancy between UDP and TCP throughput.— > Laurent > On Mon, Apr 1, 2013 at 6:56 PM, CiscoNSP List <[email protected]> > wrote: > Hi, > We have a 40Mb link between 2 POPs - Latency ~65m/sec (No packet-loss) > POP A Is a 7301 and 2960POP B is a 7200 and 4948 > 40Mb link is connected to the two switches (L2), and then a trunk link to > both routers for all L3. > Have a Linux server connected to both switches, and achieve the following > performance: > IPERF (UDP) > POP A -> POP B - 38.5Mb/secPOP B -> POP A - 38.5Mb/sec > IPERF (TCP) > POP A -> POP B - ~20Mb/secPOP B -> POP A - ~12Mb/sec > FTP > POP A -> POP B - ~38Mb/secPOP B -> POP A - ~16Mb/sec > WGET > POP A -> POP B - ~30Mb/sec POP B -> POP A - ~16Mb/sec > Any suggestions on why I am seeing poor performance with TCP transfers? > (Especially POP B -> POP A direction) - I've tried adjusting the window size > in IPERF but it actually made the results worse? > Thanks in advance. > _______________________________________________ > cisco-nsp mailing list [email protected] > https://puck.nether.net/mailman/listinfo/cisco-nsp > archive at http://puck.nether.net/pipermail/cisco-nsp/ > _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
