Re: wire rate vs UDP throughput
On Fri, 30 Jul 2004, Marcelo Maraboli wrote:
> Marc:
>
> how do you figure/calculate the number 22 Mbps from
> what I am sending ??
>
> 12/54 ?? this is the efficiency of USER-DATA v/s DATA-ON-WIRE
Something like that...
> I think that would mean 22Mbps at the UDP level, but If I use
> Iperf with -b 100m (UDP level desired byte rate),
> then Iperf is not obeying me ?? ;)
Since you are sending packets with approximately 80% headers and 20%
data on a 100Mb/s Ethernet link (-l 12), iperf can obviously not
achieve 100Mb/s throughput at the data-UDP level.
- If packets can be dropped _inside_ the networking stack of the
sender where throughputs are much higher than 100Mb/s (this is
system dependent, read my previous message concerning linux for
instance), then iperf will obey you and send 100Mb/s, but 80% of
them in the void inside the sender, and only 20% on the Ethernet
link. Is that what you want ?
- If no packets can be dropped inside the sender, it means iperf will
block waiting for the network interface and will be throttled down
to about 20%, not obeying you.
> I use: iperf -c IP_PC2 -u -w 200k -l 12 -n 1785708 -b 100m
> are some of these options mutually excluyent ??
No, it's fine.
> (which would lead to 148809 frames/s at 100mbps)
No.
"-l 12" means you send 12*8 = 96 bits of UDP data/frame.
"-b 100M" means you send 100M bits of UDP data/second
So this would be about 1 million of frames per second.
But 100Mb/s of UDP data is not possible anyway on a 100Mb/s link (see
above and before). You could try that on a 1Gb/s interface.
> thanks for your input...
You are welcome.