Aaron,
That may well be the case - but FWIW, when I was testing DVTS with the
University of São Paulo last year, we consistently got huge packet loss
reported by iperf depending on the settings and which Iperf version we used.
Linux iperf versions did not give the same results. I compiled a newer version
of Iperf for use with Windows which "behaved" better, but only after adjusting
the -w settings. It consistently reported out-of-order packets which Wireshark
and other sniffers didn't "see" - and no artifact was seen on DVTS. I believe
we communicated about this then, but no clear explanation could be found for
that behavior - at least not that I recollect. There are, of course, a number
of parameters that could affect iperf but we did try to have both computers
network details matched - and tried several network cards.
All best,
José
From: Aaron Brown [mailto:aa...@internet2.edu]
Sent: Tuesday, February 16, 2010 7:56 AM
To: Wichai Komentrakarn
Cc: iperf-us...@dast.nlanr.net
Subject: Re: [Iperf-users] Iperf UDP Packet Loss
On Feb 14, 2010, at 8:51 PM, Wichai Komentrakarn wrote:
I am trying to use the Iperf to analyze UDP packet loss on a network. I saw
Iperf reported several % packet loss but when I used Wireshark to capture the
sent and received packets and compared them. I couldn't see any packets loss on
the received side. Can you explain how Iperf reported percentage of packet loss
or what is the condision that Iperf decided it didn't recieve a UDP packet.
Since UDP is a lossy protocol, the kernel does not guarantee that it will send
data its been handed, and will sometimes drop the packets if, for example, the
send or receive buffer are filled. It could also be that the packets got
corrupted on the wire, didn't checksum properly and were tossed out.
Cheers,
Aaron
Internet2 Spring Member Meeting
April 26-28, 2010 - Arlington, Virginia
http://events.internet2.edu/2010/spring-mm/
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