[e2e] Why do we need congestion control?
Alex C. Snoeren
snoeren at cs.ucsd.edu
Wed Apr 3 11:40:24 PDT 2013
I've remained deliberately quiet here, but will point out that the mere fact that one has to pay for a service does not mean there is actually a marginal cost. Take, for example, 10G Ethernet---it is constantly sending bits to keep the link locked. Only some of those bits are currently used to send actual packets, however.
On Apr 3, 2013, at 8:43 AM, Detlef Bosau <detlef.bosau at web.de> wrote:
> I've just had a first look at the Snoeren paper.
> Remembers me of typical parliament debates.
> Let the people babble as much as they can - afterwards make a "fair bullshit removal" (so, no party is advantaged while others are disadvantaged) and the rest is the reasonable content of the debate.
> Perhaps, my knowledge is a bit outdated here, but I well remember times where people had to pay for network resources.
> The idea is interesting anyway, however we should carefully discuss who eventually does the clean up work and which are the consequences of congestion.
> I agree with Dave, that erasure codes do not obviate the need for congestion control. Actually, at the moment we shift around the responsibilities, what does not necessarily clarify the situation.
> The idea of the paper is appealing: When we have 10 flows, let each flow send as fast as he can - the network imposes fair drop on each flow and hence the experienced goodput is a consequence of the drop rate. A single flow may experience no drop and hence yields high good put, if the network is fully overcrowded, each flow experiences high packet drop and the goodput is hence low.
> The first immediate objection is the same as with VJCC: How is fairness defined and what is the common resource for two flows? Particularly, we meet the same difficulty here as I have seen it in some papers by Frank Kelly: Implicitly, the common resource is always sending time.
> What about wireless networks? Where the shared resource is not always time but power? And when I may elaborate on this one: In UMTS like networks, the approach would only lead to maximum interference in a cell - which most likely simply would render the cell unusable.
> Detlef Bosau
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