[c-nsp] Network performance question - TCP Window issue?

[Łukasz Bromirski]

On 2012-04-29 19:57, John Neiberger wrote:
> The timing of this is coincidental. I've been helping to troubleshoot
> a similar problem at work for days. Let's say we have three servers,
> A, B and C. We transfer files between them and here is what we see:
>
> A to B: Fast (around 18 MB/s)
> B to A: Slow (around 1 MB/s)
> A to C: Slow (around 1MB/s)
> C to A: Fast (around 18MB/s)
>
> In our case, Server A is fast when sending to B but not when sending
> to C. C can send at a high speed when sending back to A, though.

Typical problems with the different speed depending on the direction
are caused either by duplex mismatch at access port (test, don't
trust what one side tells you!) or problems with negotiating the
TCP windows size (depending on the TCP/IP stack, application and tool
you may get a number of different results).

-- 
"There's no sense in being precise when |               Łukasz Bromirski
  you don't know what you're talking     |      jid:lbromirski at jabber.org
  about."               John von Neumann |    http://lukasz.bromirski.net