Improving Web Availability for Clients with MONET

Despite the increasing degree of multi-homing, path and data redundancy, and capacity available in the Internet, today's clients experience outage rates of a few percent when accessing Web sites. MONET ("Multi-homed Overlay NETwork), is a new system that improves client availability to Web sites using a combination of link multi-homing and a cooperative overlay network of peer proxies to obtain a diverse collection of paths between clients and Web sites. This approach creates many potential paths between clients and Web sites, requiring a scalable way to selecting a good path. MONET solves this problem using a waypoint selection algorithm, which picks a good small subset of all available paths to actively probe. MONET runs on FreeBSD, Linux, and Mac OS X, and is deployed at six different sites. These installations have been running MONET for over one year, serving about fifty users on a daily basis. Our analysis of proxy traces shows that the proxy network avoids between 60% and 94% of observed failures, including access link failures, Internet routing problems, persistent path congestion, and DNS failures. The proxy avoids nearly 100% of failures due to client and wide-area network failures, with negligible overhead.