In enterprise networks, idle desktop machines rarely sleep, because users (and
IT departments) want them to be always accessible. While a number of solutions
have been proposed, few have been evaluated via real deployments. We have built
and deployed a sleep proxy system at Microsoft Research. Our system has been
operational for six months, and has over 50 active users. To the best of our
knowledge, this paper is the first to report on lessons learned from building,
deploying and running a sleep proxy system on a real network. Overall, we find
that our system allowed user machines to sleep quite well (most sleeping over
50% of the time), but much potential sleep time was missed due to IT management
tasks that play havoc with machine sleep. We suggest a number of ways to fix
this problem. We also discover and address a number of issues overlooked by
prior work, including complications caused by IPsec. We found certain popular
cloud-based applications did not work well with our design, and we deployed an
ad-hoc fix to the problem. We believe our experience and insights will prove
useful in guiding the design of future sleep solutions for enterprise networks.