A New Server Selection Strategy for Reliable Server Pooling in Widely Distributed Environments

In order to provide a generic, application- independent and resource-efficient framework for server redundancy and session failover, the IETF RSerPool WG is currently standardizing the reliable server pooling (RSerPool) framework. Server redundancy has to take load distribution and load balancing into consideration since these issues are crucial for the system performance. There has already been some research on the server selection strategies of RSerPool for different application scenarios. In particular, it has been shown that the adaptive least used selection usually provides the best performance. This strategy requires up-to-date load information of the services, which has to be propagated among distributed pool management components. But network delay (which is realistic for systems being widely distributed to achieve availability in case of regional servers failures) as well as caching of information may both lead to obsolete load information. Therefore, the purpose of this paper is to analyse and evaluate the performance of a new server selection rule to cope with update latencies. Especially, we will also analyse the impact of different workload parameters on the performance of the new server selection strategy.