Re: bandwidth option ( -b ) in udp


On Wed, 22 Jan 2003 Steve.Brenne --at-- radisys.com wrote:

> Is the bandwidth option in udp intended to represent the actual bit rate on
> the line, or is it intended to only measure the rate of data transfer?
> Would there be any value in an option that allows for the bandwidth to
> represent either data rate or line rate.  For my application I only care
> about the line rate not about the data transfer rate.
> 

I am not exactly sure what you are getting at here. The -b option 
specifies at what speed the client sends data to the server. As such I 
believe you would call that data rate. There is no way to measure the 
exact line rate. The best you can do is determine the highest data rate 
which will be close to the line rate. For example we have had TCP tests 
get 9.97 Mb/s on a 10Mb/s link so the 9.97 is approximately (and more 
importantly it is effectively) the line rate. I am not sure what you think 
iperf would do differently with a line rate option vs a data rate option. 
If you want to use UDP to determine line rate then send larger amounts of 
data than the line rate and look at the results seen by the server.

Kevin



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