On Sun, Apr 29, 2012 at 4:39 PM, Łukasz Bromirski <[email protected]> wrote: > 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).
We checked all the usual stuff and haven't found anything wrong anywhere in the path despite looking at this from a number of different angles for days. However, Drew emailed me off-list and suggested that we look to see if apf is running on the linux servers. This has a known "feature" that disables TCP window scaling, which would certainly cause what we're seeing. I'm going to have a server guy check it tomorrow. _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
