Availability and Cost Analysis of Network-Attack-Resilient Byzantine Fault Tolerant Systems

Byzantine Fault Tolerant (BFT) system designs have evolved to withstand increasingly challenging threat scenarios. In particular, network-attack-resilient BFT systems have developed frameworks for distributing replicas among multiple geographical sites to withstand sophisticated network denial of service attacks that can isolate an entire site. To make such systems economically feasible, data centers can be used in addition to on-premises sites to reduce the overall cost. Prior work focuses on developing system designs that tolerate a fixed number of replica failures and site disconnections. However, it has not considered the trade-offs between these designs in terms of their availability and cost. In this paper, we develop a framework to assess network-attack-resilient BFT systems in terms of their cost and availability, while accounting for differences between on-premises and data center sites. We compare five system designs proposed in the literature and identify the most cost-effective designs for a given availability target.