[Iccrg] Heresy recapped
keshav at uwaterloo.ca
Wed Apr 16 20:58:06 BST 2008
On Apr 16, 2008, at 1:03 PM, Lars Eggert wrote:
> I wouldn't go quite so far and call the current status quo of TCP-
> friendliness dogmatic; it's mostly what VJ congestion control left
> us with, and it's sort of a better-than-nothing style of fairness. I
> do encourage folks to revisit that design choice and discuss whether
> this type of fairness is what the current and especially future
> Internet should strive to adhere to, or whether there are
> alternatives or generalizations that offer more flexibility or
> "stronger" notions of fairness.
I think two points are obvious:
1. VJ congestion control, or any end-point congestion control for
that matter, cannot by itself provide fairness of any sort. Fairness
(whatever the definition) must come from inside the network, simply
because the edges are uncontrolled. We can argue all we want what
fairness means, but this fact remains. So the status quo is broken, a
fact that has been known for 20 years.
2. Even if we put into place mechanisms for 'fairness', it is not
clear that anyone cares about fairness in the first place. Two
endpoint owners can compare notes about what service they receive, but
the reason why they get different service could be misconfiguration,
different RTTs, bugs in their software, line noise (or RF noise),
cross traffic or just the phase of the moon. As far as I can observe
since 1988, the need for fairness is always assumed, rarely verified,
and never necessary.
My conclusion: fairness can't be achieved by endpoint control and in
any case is a non-goal :-) Time to move on to something else (I
stopped working in this area in 1991 for exactly this reason).
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