On Tue, 2010-02-09 at 14:32 -0200, Christiano F. Haesbaert wrote: > When you use UDP, you're seeing the results on the client or in the server ? > > iperf uses busy-waiting to implement flow-control in UDP, so basically > if you specify an absurd rate transfer, the client will try to deliver > at that rate and packets will be dropped. > > If you do specify a rate consistent with your network bandwith, the > resuts will be more accurate. > > Nevertheless check what the server reports when measuring UDP.
I'm specifying a consistent bandwidth (about 35 Mbit/s) and the dropping rate is very low (2 - 3%): specifying a lower bw (30 Mbit/s) would led to no dropping dataframes. Anyway I see results on both server and client (unfortunately I haven't attached the UDP iperf log and I'm not in the lab anymore). I also specified the option "-d" so to have a bidirectional test, and the rate of 35 Mbit/s is reached in both directions. Problems seem to regard TCP transfer, my OpenBSD box and the Cisco router (I point out again that, on local subnet, TCP performances are really high). As a consequence (I think) of this slowness, httpd and ftp performances are really bad.
