[altq 1478] Re: RED implementation

[Nguyen-Tuong Long Le <le@cs.unc.edu>]

It's been a long time and I've put this on the back burner
but now it all comes back to me.

On Sun, 27 May 2001, Kenjiro Cho wrote:

> 
> Nguyen-Tuong Long Le wrote:
> > I am wondering why the drop_early function has a different drop
> > probability than in the original RED paper ( prob/(2 - count*prob)
> > instead of prob/(1 - count*prob) ). Does it mean that we have to
> > provide redd with a value of inv_pmax/2 instead of inv_pmax?
> 
> ALTQ/RED does compute (prob/(2 - count*prob)).
> The code is a bit cryptic since the constants are precomputed.
> See the comments in the source code.

I can follow and understand the code but my question is
why does ALTQ/RED compute (prob/(2 - count*prob)) instead
of (prob/(1 - count*prob)) as in the Floyd and Jacobson paper.

I'm not saying that this is wrong since one can always scale inv_pmax
but I'm interested in why it was done this way.

Thanks,
-- long