The Reliable Server Pooling (RSerPool) architecture is the IETF’s new standard for a lightweight server redundancy and session failover framework to support availability-critical applications. RSerPool combines the ideas from different research areas into a single, resource-efficient and unified architecture. While there have already been a number of research papers on its performance in general, the robustness against intentional attacks has not been intensively addressed yet. In particular, there have not been any analyses for real setups. Therefore, the goal of this paper is to provide a robustness analysis in order to outline the attack bandwidth which is necessary for a significant impact on RSerPool-based services. This analysis is based on lab measurements — using a real RSerPool system setup — as well as on measurements for comparison and validation. Furthermore, we present and evaluate countermeasure approaches to significantly reduce the impact of attacks.