Acknowledgments

We are grateful for the help of our shepherd, Robert Morris, whose suggestions have greatly improved the final draft of this paper. We would also like to thank Brian Bershad, David Wetherall, Neil Spring, Tom Anderson, John Zahorjan, and Hank Levy for their valuable feedback. This work also benefitted greatly from many discussions with the Systems and Networking group at Microsoft Research, particularly Bill Bolosky, Marvin Theimer, Mike Jones, and John Douceur. This work was supported in part by NSF Career award ANI-0132817, funding from Intel Corporation, and a gift from Nortel Networks.