MONET: A Multi-Homed Overlay Network

MONET arose from the observation that access links are often the weakest link in Internet availability, particularly for home users, or users in areas without well-established Internet infrastructures. The traditional mechanism for taking advantage of multiple access links — multihoming with the Border Gateway Protocol (BGP) — is not available to many of these people who need redundancy the most. Our implementation of MONET is a Web proxy that uses an application layer approach to harness redundant access links and multiple paths through the Internet to dynamically avoid network failures.

MONET takes advantage of path redundancy from three sources:

(1) Multiple Internet connections
(2) Internet path redundancy accessed via a cooperative overlay network of proxies
(3) Server redundancy and server access link redundancy accessed by simultaneously contacting multiple addresses returned by the Domain Name System.

Given these sources of path redundancy, MONET's waypoint selection algorithm probes a subset of the available paths to quickly find a working path from the proxy to a Web server. Results suggest that MONET can make a large improvement in the end to end availability of Web sites. MONET is a follow-on project to our work on Resilient Overlay Networks (RON). Both MONET and RON take place within the larger context of our research into large-scale, robust distributed systems.

The MONET source code : MONET is implemented as a set of changes to the open-source Squid web proxy and pdnsd parallel DNS resolver. We have released a very beta-quality version of the MONET source code.