[e2e] Question the other way round:

Detlef Bosau detlef.bosau at web.de
Wed Nov 20 09:18:01 PST 2013

Am 20.11.2013 15:21, schrieb Sergey Gorinsky:
>   Dear Detlef,
>   If a sender chooses the D class for all its flows, each of its flows is
> served with small queuing delay at the bottleneck link (but with a smaller
> forwarding rate than the rate given to a throughput-greedy flow of another
> sender that chooses the R class).

Do you really serve the two queues with different rates? Or am I
confused between rate and throughput?
>   The RD design is work-conserving and does not cause underutilization.

Not physically. But the sender delivers the D class from some load by
putting it into the R class.

> The partition of the bottleneck-link capacity between the two classes is
> dynamic and depends on the numbers of R and D flows.
And when the D class alone does not utilize the link you have some kind
of unterutilization ;-)

>   Trying to fit this into your metro-carriage analogy, one can think of
> the D class as quiet (low-delay) carriages and the R class as noisier
> (higher-throughput) carriages.

Yes, I thought so.

>  The point is that some apps naturally
> prefer noisier carriages, i.e., a higher forwarding rate regardless of
> queuing delay. Charging differently for the R and D services would only
> distort the natural preferences of the customers. Thus, the RD service
> differentiation is not an issue of goodness vs. badness (or wealth vs.
> poverty) - it is just that some customers prefer noise and the others like
> quiet.

Hm. I don't think that customers _like_ noise. Nevertheless, they may
distinguish their flows in ones which are more delay sensitive and
others which are less. And you provide an opportunity to reflect this in
your system. Is this correct?

Detlef Bosau
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