[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

iperf / ftp / http TCP poor performance in one direction (UDP good)

Hi Guys,

I have a 40Mb connection between 2 POPs, and 2 Debian servers connected at each end(L2, same broadcast domain) - I am seeing consistent poor performance with TCP in only one direction.

Latency between the POP's is ~67m/sec

POPA->POPB UDP(IPERF) - consistent 38.5Mb/sec

POPA->POPB TCP(IPERF) - fluctuates ~30Mb/sec -> 32Mb/sec

POPA->POPB TCP(FTP) - fluctuates ~30Mb/sec -> 32Mb/sec

POPA->POPB TCP(WGET) - fluctuates ~30Mb/sec -> 32Mb/sec

POPB->POPA UDP(IPERF) - consistent 38.5Mb/sec

POPB->POPA TCP(IPERF) - fluctuates ~10Mb/sec -> 15Mb/sec

POPB->POPA TCP(FTP) - fluctuates ~10Mb/sec -> 15Mb/sec

POPB->POPA TCP(WGET) - fluctuates ~10Mb/sec -> 15Mb/sec

Both Deb boxes are running the same kernel (2.6.32-5), and I have tried adjusting tcp window without seeing any improvements...all ports are running full duplex, and Im not seeing any errors/drops, nor packet-loss on the link.

Any suggestions are greatly appreciated (Provider of the link is stating it is a tcp window issue) -If that is the case, if someone can provide some suggested tweaks/changes to the Deb servers, It would be fantastic!


Reply to: