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Thanks for the reply. POPB MEM - 2Gb POPA MEM - 4Gb Wireshark: (During a wget) #tcp window size in the "bad" direction: starts at win=6912 and grows to 165504 (This is where I start to see a heap of TCP Dup ACK and TCP segment of a reassembled PDU)), then increases to 353408 (Again, more TCP Dup ACK's), and looks to max out at 669056. #tcp window size in the "good" direction: starts at win=6912 and looks to max out at 1995392 and has very few TCP Dup ACK and TCP segment of a reassembled PDU > Hi > > >Provider of the link is stating it is a tcp window issue > I think that would be a bit weird, TCP is a very robust protocol > capable to adapt pretty much any bandwidth / latency situations. > What are the specifications on the hosts? Maybe POPA has too little > RAM and can't allocate a big enough TCP window? > Can you use wireshark or some other tool to capture the TCP segments > and look at the advertised window? > > Greetings, Guido. > > On Fri, Apr 12, 2013 at 12:37 AM, John Elliot <johnelliot67@hotmail.com> wrote: > > 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! > > > > Cheers. > > > > > > > > |