How to Choose a Timing Model

When employing a consensus algorithm for state machine replication, should one optimize for the case that all communication links are usually timely, or for fewer timely links? Does optimizing a protocol for better message complexity hamper the time complexity? In this paper, we investigate these types of questions using mathematical analysis as well as experiments over PlanetLab (WAN) and a LAN. We present a new and efficient leader-based consensus protocol that has O(n) stablestate message complexity (in a system with n processes) and requires only O(n) links to be timely at stable times. We compare this protocol with several previously suggested protocols. Our results show that a protocol that requires fewer timely links can achieve better performance, even if it sends fewer messages.

• Type: Journal
• Year: 2008
• Where: TPDS
• Authors: Idit Keidar, Alexander Shraer
• Keywords: Fewer Timely Links, Message Complexity, Timely, TPDS 2008