Acknowledgments

This work was partly supported by the EU SCAMPI project IST-2001-32404, while Intel provided the IXP1200 network cards. A massive thanks is owed to the following people for commenting on earlier versions of this paper: Luca Deri (Netikos), Kobus van der Merwe (AT&T Labs), Andrew Moore (Cambridge University, UK), Sean Rooney (IBM Research, Zurich), and Jeffrey Mogul (HP Labs).