Stanford Security Lunch

Abstract: Replicated state machines (RSMs) cannot communicate effectively today as there is no formal framework or efficient protocol to do so. To address this issue, we introduce a new primitive, Cross-Cluster Consistent Broadcast (C3B) and present Picsou, a practical C3B implementation. Picsou draws inspiration from networking and TCP to allow two RSMs to communicate with constant metadata overhead in the failure-free case and a minimal number of message resends in the case of failures. Picsou is flexible and allows both crash fault tolerant and Byzantine fault tolerant protocols to communicate. At the heart of Picsou's good performance and generality is the concept of Quacks (quorum acknowledgments). Quacks allow nodes in each RSM to precisely determine when messages have definitely been received, or likely lost. Our results are promising: we obtain up to 24× better performance than prior solutions on microbenchmarks and applications, ranging from disaster recovery to data reconciliation.

Bio: Micah Murray is a 4th Year PhD student at UC Berkeley advised by Prof. Natacha Crooks and Prof. Scott Shenker. His research centers on distributed systems and networking. His most recent research interests center around using programmable networking hardware to build high performance distributed protocols. You can see more about him at his website: https://micahmurray.codeberg.page/