ABE (was Re: [e2e] QoS vs Bandwidth Overprovisioning)

Paul Hurley paul.hurley at epfl.ch
Mon Apr 30 08:25:16 PDT 2001

> > In this vein, has anyone tried to deploy the "Alternative Best Effort"
> > proposal of Jean-Yves Le Boudec?
> > (http://ica1www.epfl.ch/PS_files/abe.htm). His basic idea is
> > that there
> > is a simple way to prevent cheating, i.e. provide a trade-off: you may
> > get a lower latency if you mark the packets for "alternate
> > best effort",
> > but you will also get a lower bandwidth. Indeed, the whole
> > thing can be
> > combined with ECN marking, to trigger adequate bandwidth adaptation by
> > the VoIP application, e.g. choice of the right codec and parameters.
> >
> I saw a presentation of Jean-Yves Le Boudec at the QoS Summit '99 (
> http://www.upperside.fr/baqos.htm ) and have been wondering why I never
> heard of it since. Maybe he just did not discuss it in the IETF?

ABE is alive and well, and has been improved considerably since the early
incarnation you saw presented at QoS Summit '99.

A description of the service, the latest paper, to appear in IEEE Network
Magazine May/June, and an Internet Draft is available at the home page,

If anyone has any questions, I will be more than willing to help.

> > In fact, if we observed a real problem with latency of VoIP, we could
> > even implement ABE without requiring any particular marking. Just
> > profile the packets that fit the VoIP profile, i.e. short UDP packets,
> > or maybe just short packets, and fit them into the ABE queue. If I
> > remember correctly, Sandy Fraser had implemented something
> > like that to
> > provide adequate latency for interactive traffic in the Datakit, and
> > reported that it was satisfactory. So, if there is a need, an
> > ISP could
> > just turn on the service at some choke point, without any particular
> > coordination with other networks, or any change in the end systems.
This indeed is one possible use of ABE (using profile of the traffic instead
of marking), and one we haven't yet investigated.


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