Random Early Detection Parameter

Hi,

I'm trying to use a RED queue with ECN to signal congestion within a
TCP connection. However the parameter setup on the RED queue is very
intransparent. I already tried the hints given by Sally Floyd and the
tc red documentation on setting the parameters but i didn't get the RED
algorithm to mark anything (checked via TCP Dump).
I tried to configure the RED queue in a way to easily mark packet (low
min and max values) but the only real difference in behaviour is
achieved when i cut down the limit value so that the queue has to
really drop packets. I also tried to keep the queue busy with competing
UDP or TCP traffic but that also did not work for me.

Has anyone any experience in dealing with and configuring a RED queue ?

Any hint on how to test the marking of the RED queue are appreciated.

thx in advance
Michael