Re: [e2e] opening multiple TCP connections getting popular

Bob Briscoe wrote:
>>
>
> 1/ This isn't just an issue between a user and her local ISP. Shifting
> the focus from your personal DSL use (which is probably to an
> over-provisioned academic campus at the other end), a typical
> filesharing user is just as likely to be hitting a bottleneck in
> another ISP's backhaul (or bottlenecks in both local and remote
> backhauls).
>
> Even if her bottleneck is remote, I'd still like her to be able to
> behave like w TCPs, but we need a simple accountability framework that
> allows her own ISP to choke her if she causes excessive congestion,
> whether the bottleneck is local or remote (which, as you know, is what
> I've proposed).

Isn´t this exactly, what CC does? If congestion causes harm, i.e. dropped packets, these drops will choke the connection.

>
> 2/ If everyone was trying to fill their access link with TCPs (or
> MulTCP) continuously, the bottlenecks would nearly always NOT be their
> own lines, no matter how carefully they spread out the traffic. This
> is in fact close to the current situation - even without everyone
> participating in p2p filesharing, bottlenecks have already moved out
> of the lines into the backhaul.
>

IIRC, this is one of the Todos, Sally Floyd mentions on her open questions list: Where is the bottleneck?

However, stupid me, to my understanding any congestion drop simply throttles the connection. And that´s exactly what we want to do.

To my understanding, your point is mainly the target function, you want to optimize, and the fairness criterion.

And a pure e2e approach is limited here because the individual socket does not see the big picture of your network, neither your prefered fairness criterion or target function.

In some respect, this is similar to the Ethernet capture effect (which was found by Keshav IIRC?).
Without any central- / point- /... coordination function / admission control / ressource control, you will most likely find more or less strange cases which cause "surprising" results.

Detlef

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Detlef Bosau                          Mail:  detlef.bosau@web.de
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