[Iccrg] Proposal for ICCRG operations

[Tim Shepard]

> > > > > A better congestion control scheme would control the queue length,
> > > > > with a target of zero (or very few) packets, thereby minimizing the
> > > > > impact on delay.
> > > 
> > > by targetting a queue level of few packets we  have that each flow gets
> > > a constant fraction of the buffer space. In a FIFO queue this translates
> > > in the same fraction of used bandwdith.
> > 
> > Why is that?
> > 
> > I don't think that is necessarily true.  It may be true for some kinds
> > of control schemes, but it is not necessarily true for all kinds of
> > control schemes.
>
> let assume  that you have a buffer of 10 packets and two connections: A
> and B. Let assume that target queue is 6 packets for flow A and  4 for
> flow  B. Then flow A would get 6/10-th of the bandwdith and B 4/10-th.
> 

I think you are assuming that the queue occupancy for each flow is
constant over time.  If you relax that assumption, then you no longer
have the implication.

There may exist viable control schemes which control the flows (and
have whatever other desirables properties) while keeping the average
queue occupancy small.

Do you agree?

> i have read somewhere, maybe on s. floud homepage, a note on "why
> control queue length should not be a target". i am not sure, but i think
> she had  similar arguments.

I looked on her web pages at http://www.icir.org/floyd/papers.html
and  http://www.icir.org/floyd/notes.html  and did not manage to
identify which note you would be refering to.

> in other words, if you control queue at fixed value you would prevent
> other flows to join.

I think there must be assumptions in your reasoning that I did not
mean to imply.

			-Tim Shepard
			 shep at alum.mit.edu