[e2e] "congestion" avoidance...

[Joerg Widmer]

<snip>

> lets assume we now design networks for datagram, with TCP "friendly"
> adaption being the NORM, and that we look at the people that need
> predictable throughput on the session timescale as the odd ones
> out...(predictable price or predictable throughput are natural
> duals of each other in this formulation)
> 
> now if we have _enough_ of these non-adaptive flows, actually, enough
> rate of change of them, they can collectively be made to look like a
> bunch of TCP-like flows quite easily - by varying the admission
> probabiliyu (could do this by increasing the loss or ECN markign
> probability for SYN or RTP equivalent packet - but thats an
> implementation detail, - it could also just be done by varying the
> price differently for these type flows as yo usay - e.g. the ECN to
> price mapping for EF diffserve class might specifiy a different
> fucntion than that for BE and AF, for example:-)
> 
> so then we can cause the aggregate of a set of CBR flows
> to behave exactly like the aggergate of a set of TCP flows just by
> varying the number of flows
> 
> what say we do some analysis...?

We have actually done some work in this direction (Jon you've seen this
already), where an aggregate on non-adaptive flows is made to look like
TCP-friendly flows by suspending them at appropriate times using sort of
a binary end-to-end congestion control mechanism. The technical report
about the PCC protocol can be found at
http://www.informatik.uni-mannheim.de/informatik/pi4/projects/CongCtrl/pcc/pcc-tr.pdf
or
http://www.informatik.uni-mannheim.de/informatik/pi4/projects/CongCtrl/pcc/pcc-tr.ps.gz

Since this is work in progress we're very interested in any comments.

Cheers,
  Joerg and Martin


-- 
Joerg Widmer
Praktische Informatik IV, University of Mannheim