[e2e] Question the other way round:

Ted Faber faber at isi.edu
Tue Nov 19 19:14:41 PST 2013

On 11/19/2013 10:15, Joe Touch wrote:
> On 11/19/2013 10:09 AM, Dave Crocker wrote:
>> Given the complete generality of the question that was asked, is there
>> something fundamentally deficient in the answer in:
>>     http://en.wikipedia.org/wiki/Congestion_control#Congestion_control
>> ?
>> In particular, I think it's opening sentence is quite reasonable.
> I agree, but it jumps in assuming packets. Given packets, it's easy to
> assume that oversubscription is the natural consequence of avoiding
> congestion.

Unless someone's edited it, you should read the first sentence again.  I

> Congestion control concerns controlling traffic entry into a telecommunications network, so as to avoid congestive collapse by attempting to avoid oversubscription of any of the processing or link capabilities of the intermediate nodes and networks and taking resource reducing steps, such as reducing the rate of sending packets.

I read the reference to packets as an example.  And I would end the
sentence with "if necessary" to indicate that reducing resource
utilization is done only when needed (which it wouldn't be in a
non-oversubscribed system).  Overall I think it reasonably encompasses
proactive congestion control.

> But it isn't if you have a-priori known traffic patterns - as are
> increasingly common inside data centers, as well as for some past
> circuit use cases.

There's a lot to explore, of course.  When I was in graduate school some
nut was doing congestion control keeping average sending rates constant
and modulating the burstiness of the traffic by adjusting the time over
which the average rate was policed.

It's a fascinating field, in which one can find the trees attractive to
the point of beaching the ship.  The forest is at least as interesting,
especially if one is interested in economics.  Alas, similar to
economics, it's also hard to do a real investigation at any scale anymore.

Ted Faber
http://www.isi.edu/~faber           PGP:
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