[Fwd: Re: [Click] generating artificial delay]

[Eddie Kohler]

Simon Schuetz wrote:
> Hi,
> I think I have to revise my recent postings.
> It seems, that the click router is not the absolute bottleneck,
> neither by using 
> FromDevice(eth0) -> Queue -> DelayUnqueue(0.05) -> ToHost(eth0)
> nor
> FromDevice(eth0) -> Queue -> DelayShaper(0.05) -> ToDevice(eth2)
> 
> Tested with several TCP streams at a time, and found out that the total
> troughput of those streams is far higher than with one stream. So the
> limiting factor is probably the TCP configuration.
> 
> Sorry about that
> Simon

Ah!!!  Of course.  Somehow I thought you were testing throughput with UDP. 
Adding 100 milliseconds to a TCP flow's RTT will *seriously* impact its 
throughput (throughput is inversely proportional to RTT).  I'd be interested if 
your throughput went down a lot when measured with UDP.

Eddie