We would like to thank Anurag Acharya, Erik Riedel, Yasushi Saito, John Bent, Nathan Burnett, Timothy Denehy, Brian Forney, Florentina Popovici, and Lakshmi Bairavasundaram for their insightful comments on earlier drafts of the paper. We also would like to thank Richard Golding for his excellent shepherding, and the anonymous reviewers for their thoughtful suggestions, many of which have greatly improved the content of this paper. Finally, we thank the Computer Systems Lab for providing a terrific environment for computer science research.
This work is sponsored by NSF CCR-0092840, CCR-0133456, CCR-0098274, NGS-0103670, ITR-0086044, ITR-0325267, IBM, EMC, and the Wisconsin Alumni Research Foundation.