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Obelia: Scaling DAG-Based Blockchains to Hundreds of Validators

George Danezis, Lefteris Kokoris-Kogias, Alberto Sonnino, Mingwei Tian

TL;DR

It is shown that Obelia does not introduce visible overhead compared to the original protocol, even when scaling to hundreds of validators, or when a large number of auxiliary validators are unreliable.

Abstract

Obelia improves upon structured DAG-based consensus protocols used in proof-of-stake systems, allowing them to effectively scale to accommodate hundreds of validators. Obelia implements a two-tier validator system. A core group of high-stake validators that propose blocks as in current protocols and a larger group of lower-stake auxiliary validators that occasionally author blocks. Obelia incentivizes auxiliary validators to assist recovering core validators and integrates seamlessly with existing protocols. We show that Obelia does not introduce visible overhead compared to the original protocol, even when scaling to hundreds of validators, or when a large number of auxiliary validators are unreliable.

Obelia: Scaling DAG-Based Blockchains to Hundreds of Validators

TL;DR

It is shown that Obelia does not introduce visible overhead compared to the original protocol, even when scaling to hundreds of validators, or when a large number of auxiliary validators are unreliable.

Abstract

Obelia improves upon structured DAG-based consensus protocols used in proof-of-stake systems, allowing them to effectively scale to accommodate hundreds of validators. Obelia implements a two-tier validator system. A core group of high-stake validators that propose blocks as in current protocols and a larger group of lower-stake auxiliary validators that occasionally author blocks. Obelia incentivizes auxiliary validators to assist recovering core validators and integrates seamlessly with existing protocols. We show that Obelia does not introduce visible overhead compared to the original protocol, even when scaling to hundreds of validators, or when a large number of auxiliary validators are unreliable.

Paper Structure

This paper contains 12 sections, 2 figures, 2 algorithms.

Table of Contents

  1. Introduction
  2. System Overview
  3. Validators selection
  4. System and threat model
  5. Design goals and challenges
  6. The Obelia Design
  7. DAG-based consensus protocols
  8. Vertex creation rule and commit rule
  9. Security analysis
  10. Implementation and Evaluation
  11. Discussion and Related Work

Figures (2)

  • Figure 1: Example of Obelia execution with 4 core validators and $t_a = 2$.
  • Figure 2: Comparative evaluation of Mysticeti (10 and 50 validators) and Obelia (10 core + 50 auxiliary validators, 50 core + 200 auxiliary validators). Left: throughput-latency graph. Right: Latency zoom at 50k tx/s.