The authors are grateful to the many people that have helped our work. Ahmed Amer, Randal Burns, Scott Brandt and the other members of the Computer Systems Lab provided useful comments and support. The Usenix Association, National Science Foundation and the Office of Naval Research have provided funding that supported this work. The Linux community was helpful in working with the Linux kernel. Rod Van Meter and Melanie Fulgham provided helpful comments on early drafts of this work. Nokia's Clustered IP Solutions supported Dr. Kroeger's efforts in bringing this work to publication.