simple, adaptive bandwidth throttling with ipfw/dummynet ?

[Juri Mianovich]

I do simple limiting of bandwidth with dummynet.  Very
simple, in fact - one inbound rule and one outbound
rule.

Easy.

Sometimes people hit the limit I have in place, but if
they only hit it on a short transfer, I don't care -
they can live with being throttled for 30 mins.

BUT, sometimes people have a big massive transfer that
maxes out the limit for a long time.  Not only do they
get throttled too hard, but then other users are
throttled as well - very hard.

So, I am wondering if anybody knows of a simple way to
do something like:

"after 30 minutes of maxed dummynet rule, add X mbps
to the rule for every active TCP session, with a max
ceiling of Y mbps"

and:

"after 30 minutes of less than max usage, subtract X
mbps from the rule every Y minutes, with a minimum
floor of Z"

Make sense ?

Is there an easy way to do this ?

If I wanted to do this myself with a shell script, is
there any way to test a particular dummynet rule for
its current "fill rate" - OR - a simple way to test if
a particular dummynet rule is currently in enforcement
?

Thanks.


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