The Wackamole approach to fault tolerant networks

We present Wackamole, a high availability tool for clusters of servers. Wackamole ensures that a server handles the requests that arrive on any of the service's public IP addresses. Wackamole is a completely distributed software solution based on a provably correct algorithm that negotiates the assignment of IP addresses among the available servers upon detection of faults and recoveries, and provides N-way fail-over, so that any one of a number of servers can cover for any other. Using a simple algorithm that utilizes strong group communication semantics, Wackamole demonstrates the application of group communication to address a critical availability problem at the core of the system, even in the presence of cascading network or server faults and recoveries. The same architecture is extended to provide a similar service for highly available routers.