Re: new feature: UDP packet rate ?
Marc
Interesting feature...!!
I would like to add something similar..... "number_of_packets_to_send".
when I used iperf to send a numero of UDP packets of a certain
size I had to calculate the total size in octets (bytes)...like:
iperf -c IP -u -l 100 -n 1000
this would send 10 UDP packets (since there is no fragmentation)
I would like something like:
iperf -c IP -u -l 100 -N 10
to send 10 UDP packets of 100 bytes each...
regards,
Marc Herbert wrote:
> On Thu, 5 Aug 2004, Kevin Gibbs wrote:
>
>
>>>Jim Mozley wrote:
>>>
>>>>So I need to script a wrapper to set the correct -b option given a -l
>>>>value so I allow for the overhead, assuming I want a constant wire rate.
>>>
>
>>Actually you are quoting my post ever so slightly out of context. It is
>>true that there is no _programatical_ way to before hand compute the
>>amount of headers, i.e. Iperf will never be able to do it. However a
>>user (or more likely network admin) can "easily" compute this
>>information before hand. The caveat being if you are sending data over the
>>Internet in general then you will not be able to calculate it. If you know
>>exactly the path that every packet will take and what those network types
>>are then you can calculate the header size. For instance if I have 2 GigE
>>(or 10 or 100 Mb/s ethernet link) cards connected over a crossover cable
>>then I know that the headers (and footers) are ethernet, IP, UDP. Even if
>>I threw in a ethernet switch I would still get the same headers. However
>>if I connected two machines directly through a ATM link I would get a
>>different set of headers. Since Iperf can not detect these link types or
>>any along a multi-hop path it can not provide the functionality you are
>>looking for. You should be able to provide it yourself given you know your
>>setup.
>
>
> Granted, a "wire-rate" command line option for iperf is probably not a
> Good Thing. However, I thought there is something good that iperf
> could do to help a lot: a new "packet-rate" option, which would
> directly pace the sendmsg() system calls in UDP mode.
>
> Today, Jim's wrapper script (see above) would have to compute this
> packet rate more or less directly, then convert it to UDP bitrate,
> feed it to iperf, which converts it back to a packet rate (because
> iperf obviously sends UDP packets, and not UDP bits). A packet rate
> command line option would skip those two steps, making the whole thing
> easier and less error-prone (especially for the wrapper script ;-)
> Morever, I suspect there wouldn't be much to implement. As opposed to
> some wire bitrate option, this one would be simple and clean, needing
> no fuzzy logic (like: "mmmm, let's say we have IP+Ethernet headers").
> And finally, I am sure some people are sometimes actually more
> interested in the packet rate itself than in the wire bitrate or UDP
> bitrate, so they would be pleased too.
>
> What do you guys think about this ? Should I start coding ?
>
> Cheers,
>
>
--
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/