TY - CHAP A1 - Berger, Christian A1 - Reiser, Hans P. A1 - Sousa, João A1 - Bessani, Alysson T1 - Resilient Wide-Area Byzantine Consensus Using Adaptive Weighted Replication T2 - 38th IEEE International Symposium on Reliable Distributed Systems (SRDS 2019) N2 - In geo-replicated systems, the heterogeneous latencies of connections between replicas limit the system’s ability to achieve fast consensus. State machine replication (SMR) protocols can be refined for their deployment in wide-area networks by using a weighting scheme for active replication that employs additional replicas and assigns higher voting power to faster replicas. Utilizing more variability in quorum formation allows replicas to swifter proceed to subsequent protocol stages, thus decreasing consensus latency. However, if network conditions vary during the system’s lifespan or faults occur, the system needs a solution to autonomously adjust to new conditions. We incorporate the idea of self-optimization into geographically distributed, weighted replication by introducing AWARE, an automated and dynamic voting weight tuning and leader positioning scheme. AWARE measures replica-replica latencies and uses a prediction model, thriving to minimize the system’s consensus latency. In experiments using different Amazon EC2 regions, AWARE dynamically optimizes consensus latency by self-reliantly finding a fast weight configuration yielding latency gains observed by clients located across the globe. KW - adaptivness, weighted replication, consensus, geo-replication, Byzantine fault tolerance, self-optimization Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-7537 PB - IEEE Xplore ER - TY - CHAP A1 - Berger, Christian A1 - Reiser, Hans P. T1 - Scaling Byzantine Consensus: A Broad Analysis T2 - SERIAL'18 Proceedings of the 2nd Workshop on Scalable and Resilient Infrastructures for Distributed Ledgers N2 - Blockchains and distributed ledger technology (DLT) that rely on Proof-of-Work (PoW) typically show limited performance. Several recent approaches incorporate Byzantine fault-tolerant (BFT) consensus protocols in their DLT design as Byzantine consensus allows for increased performance and energy efficiency, as well as it offers proven liveness and safety properties. While there has been a broad variety of research on BFT consensus protocols over the last decades, those protocols were originally not intended to scale for a large number of nodes. Thus, the quest for scalable BFT consensus was initiated with the emerging research interest in DLT. In this paper, we first provide a broad analysis of various optimization techniques and approaches used in recent protocols to scale Byzantine consensus for large environments such as BFT blockchain infrastructures. We then present an overview of both efforts and assumptions made by existing protocols and compare their solutions. KW - Distributed Ledgers KW - Blockchain KW - Byzantine Fault-Tolerant Consensus Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-7526 SN - 978-1-4503-6110-1 PB - ACM CY - New York, NY, USA ER -