[e2e] Re: [pilc] Bidirectionnal traffic over assymetric link

Dr G Fairhurst gorry at erg.abdn.ac.uk
Tue Jul 23 08:41:09 PDT 2002

One thing you may like to look at is the internet draft developed
by the PILC WG on this topic.


The draft is at:


and has been recommended to the IESG for publication as a RFC.

The draft talks of many of the issues you mention (plus a few more).

If you'd like to know more, or have further questions, you are welcome
to email me directly, and I'll try to help.

best wishes,

Gorry Fairhurst

Fatma Louati wrote:
>   Hi,
> I have made some simulations of bidirectionnal TCP traffic passing
> through an assymmetric link, evolving several simultaneous connections
> in both direction. It seems that the combination of using AckFiltering
> and Ack Reconstruction, AckFirst scheduling and an Active Queue
> Management like RED gives the best results in term of global throughput.
> In fact the asymmetry that forward connections encounter necessitate the
> use of AF/AR, however the presence of traffic in the other direction
> implies the use of an AckFirst scheduling to protect ACKs against Data
> packets. But limited buffer size will result in a ACK packets
> monopolization. That's why I thought about using a AQM mechanisms in the
> router. This solution gives also an acceptable fairness among the
> different flows.
> Before I go further in this direction I would like to know what do you
> think about it.
> Could you please tell me if you are aware of recent work on this domain.
> Thanx
> Fatma Louati -
> PhD Student - INRIA Sophia Antipolis
> http://www.inria.fr/planete/flouati <http://www.inria.fr/planete/dabbous>
> ps: Simulations topology is accessible in
> http://www-sop.inria.fr/planete/louati/topo2Way.eps
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