Avalanche Overview and Consensus

Who am I?

Gyuho Lee (이규호)
Protocol Engineer, Ava Labs
github.com/gyuho
twitter.com/gyuhox
t.me/leegyuho (Telegram)
linkedin.com/in/gyuho

Agenda

What is Avalanche?
Avalanche Consensus ☃️
Avalanche Platform

Slides talk.gyuho.dev/avalanche-hacks-2022.html

What is Avalanche?

Overview

Avalanche ($AVAX)

Mainnet launched in Sep 2020
Supports EVM
Novel Consensus Algorithm: Snowman
Proof-of-Stake
Fast and Scalable L1 (>2K EVM TPS)
Reliable (no downtime, no reorg)
Platform for deploying "Subnets"

Ava Labs

Founded in 2020 by Emin Gün Sirer, ex-Cornell professor, the creator of the first p2p cryptocurrency system in 2003, and Cornell PhDs

Ava Labs builds products and infrastructure that streamline the user experience for web3.

Avalanche Today

>3.6B requests (a day, July 2022) with ~80ms latency

Avalanche Today

Subnet effect -- scales without congestion

subnets.avax.network/stats

Horizontal Scale with Subnets

Consensus with sub-second finality (Fast)
Decentralized with >1,300 validators (Secure)
Subnets for application specific chains (Isolation)

Avalanche Consensus ☃️

Snowman Protocol

Consensus

"Assume a collection of processes that can propose values. A consensus algorithm ensures that a single one among the proposed values is chosen." Leslie Lamport, Paxos Made Simple (2001)

Should this transaction be placed in a block or not?

PoW or PoS is NOT a consensus mechanism!

Consensus Until Now

Classical (Lamport 1998, Paxos/Raft/etcd)

Quick finality but does not scale
Quadratic message complexity
Permissioned, requires precise membership

Consensus Until Now

Nakamoto (Bitcoin 2008)

Robust, no need for precise membership
High latency, low throughput
Wastes energy, not green, not sustainable

Consensus Until Now

PBFT (1999)

Powers many PoS networks (Tendermint, Casper)
Committee/leader-based

Can't scale easily ("leader/coordinator" dilemma)
Quorum-based: must know all participants
Fast when membership is small

Deterministic safety (100% safe)

Hard limit on the Byzantine adversaries

Many are very complicated

Avalanche Consensus Family

Published in 2020
Instant finality, low latency (~1 sec)
High throughput (>1,500 TPS on EVM, 5K on X-chain)
Scales >10-million nodes
Robust, no need for precise membership
Leaderless
Quiescent, green, sustainable
Inspired by epidemic protocols and gossip networks
New idea: deliberately metastable

Avalanche Sustainability

Binary Consensus

Pick one red/blue -- no correct answer
Adopt the majority color by repeated sub-sampling
Consensus results in the entire network agreeing on either red or blue
Even with 50/50 split, random perturbation in the sampling results in a single value being selected