Multi-Agent Consensus Mechanisms: A Complete Technical Comparison

Introduction Consensus is the process by which a group of distributed agents agree on a single, consistent state or value, despite failures or malicious behavior. The choice of mechanism depends critically on the system's trust model, performance requirements, and scale. This article covers three generations of consensus: classical distributed systems, blockchain-based, and the emerging AI/LLM multi-agent paradigm. 1. Classical Approaches Paxos A two-phase protocol for crash-fault-tolerant consensus: Prepare/Promise — A proposer sends a prepare request with proposal number n . A majority of acceptors respond with a promise. Propose/Accept — The proposer sends an accept request. A majority must accept for consensus to be reached. Fault Tolerance: CFT — tolerates f failures in 2f+1 nodes Weakness: Liveness issues with dueling proposers Raft Leader-based CFT protocol designed for understandability: Leader Election — Randomized timeouts elect a single leader Log Replication — Leader replic