UDP - Iperf Loss ??
Hello IPerf users.
I am trying to test many ethernet switches using IPerf and
found out that I may be doing something wrong, because
I get strange results.
IDEA: to measure if switch can forward the maximum
Ethernet frame/s rate at different frame sizes.
Methodology:
RFC 2544: PC1 ---> switch ---> PC2
Testbed:
PC1: DELL PC with DLink DFE-550TX, Fedora Core 1
PC2: DELL PC with DLink DFE-550TX, Debian
switch: 3COM 3300XM - SNMP management (non-blocking)
Iperf:
PC1: iperf -c IP-PC2 -u -w 200k -l 12 -n 1785708 -b 100m
(which would lead to 148809 frames/s at 100mbps)
PC2: iperf -s -u -w 200k
I know that 100m at UDP is different than 100m at Ethernet,
but I also tested at 90m.
STRANGE:
I check the frame counter on the switch, and the receiving
port does receive 148792 frames from PC1. The switch
outputs (on PC2 port) the amount of 148793 frames. (which
is saying that the switch is non-blocking or did not lose
any frames), but Iperf reports the following in PC2:
time transfer bw jitter loss/total
0.0-2.3s 474 Kbytes 1.71Mbps 0.047ms 108341/148809 (73%)
- This tells me that PC2 did not receive the 148809 frames ??
- then how did it know there were 148809 frames sent to him ??
- WHY did Iperf take 2.3s to send 148809 packets if I told
it to do it at 100mbps ?? (Dlink could not handle it?)
Am I doing something wrong here ?
thanks in advance,
--
Marcelo Maraboli Rosselott
Jefe Area de Redes (Network & UNIX Systems Administrator)
Ingeniero Civil Electronico (Electronic Engineer)
Direccion Central de Servicios Computacionales (DCSC)
Universidad Tecnica Federico Santa Maria, Chile.
phone: +56 32 654237
mailto:marcelo.maraboli --at-- dcsc.utfsm.cl http://elqui.dcsc.utfsm.cl/