Thread by @mt_1466

Ethereum just moved to #PoS but #Avalanche and its C-Chain have been PoS for ~2 years. So, what's the big deal?

How does $AVAX PoS work?
How does its consensus algo differ from what ETH just implemented?
And can #Avalanche truly have a million+ validators one day??

The Avalanche network doesn’t use just one consensus mechanism but rather a collection of consensus protocols.

What is the Primary Network?

A three-chain (X, P, and C) system that segregates the work done by the overall network.

This enables more efficient use of network resources & the ability to process more txs simultaneously.

Avalanche’s primary network consists of three governing blockchains with diff consensus algos:

Platform (P)-Chain
Exchange (X)-Chain
Contract (C)-Chain

image @hansolar21

Avalanche uses (delegated) PoS consisting of validators and delegators.

Validators are responsible for securing the network, approving txs, and reaching consensus.

The four consensus mechanisms under the Avalanche family are Slush, Snowflake, Snowball, and Avalanche.

Ultimately, Avalanche’s consensus performs repeated sub-sampling among its validator set, needing only a subset of nodes to communicate with one another rather than all-to-all.

This results in low messaging complexity in the network, leading to faster finality.

Because of this approach, the bandwidth and processing power requirements per node stay constant even as the network grows to many thousands of validators.

Node overhead does not (materially) increase with additional nodes, same sub-sampling set no matter the total

At a practical level, this is the process of random sub-sampled voting:

1. Txs are submitted by network users and validators must then decide to either accept or reject the transaction based on the rules set by the Virtual Machine (VM) for that subnet.

2. Once a specific validator has made their decision (valid or invalid), the validator then begins polling a random portion of other nodes in the network on their decisions. Other validators do exactly the same thing simultaneously.

Roughly speaking, this is what’s known as a “gossip protocol.” A validator’s probability of being randomly polled by a peer is weighted based on the amount of AVAX stake it controls.

3. Each polled node must answer: valid or invalid...

If >50% of the randomly polled nodes agree with the initial decision, it adds to the confidence of the polling node. If the supermajority supports a diff value, the validator will switch its initial position to reflect the majority.

Because simply polling a small, random group of validators once won’t always be an accurate representation of the actual “truth,” validators will run through this process multiple times, each time sampling at random.

All nodes are working in parallel to check other validators’ tx confirmations randomly.

After enough rounds of polling, a majority position begins to proliferate and each subsequent round builds on the momentum of the previous round.

eventually becoming probabilistically true

5. This polling process will continue until a confidence threshold is met (set by the individual subnet).

Validators collect enough data via sampling that the probability of being incorrect is less than the odds of Bitcoin’s SHA-256 hashing algorithm being broken!

Once met, the txs are finalized when all validators settle on one side of the decision.

At this point, txs achieve true finality (known as “0-conf”) and no reorganization of the blockchain is possible.

In terms of validator participation, this makes Avalanche more inclusive than classical BFT systems like #Polkadot or #Cosmos because of unbounded participation per chain.

The number of chains a validator can work on depends on the chain runtime and virtual machine design.

The primary consensus mechanism used by the default asset chain is Avalanche Consensus, which builds upon Slush, Snowflake, and Snowball.

Avalanche's primary network is an UTXO-based Directed Acyclic Graphs (DAG).

A DAG is an alternative distributed ledger technology that has a tree-like architecture with roots & branches rather than a linear, sequential chain of blocks.

Connections between nodes are called ‘edges’ in network theory, and these edges are directional in DAGs.

DAGs enable the partial ordering of decisions by linking transactions together, thereby allowing for multiple transactions to be validated simultaneously rather than one after the other as in many sequential blockchains.

AKA scalability!

Avalanche consensus could work with either PoW or PoS, but Ava Labs chose PoS as its Sybil-resistant mechanism of choice.

In short, Avalanche validators must stake some capital before being allowed to vote on transactions simply to deter spam/bot/DDoS attacks.

And now we've finally reached the C-Chain (EVM-compatible) and its consensus (whew!)

Snowman Consensus
The Avalanche consensus protocol can be applied to traditional “linear chains,” as opposed to DAGs, in what @avalabsofficial calls Snowman Consensus.

Snowman enables the network’s validators to reach consensus much quicker than previous consensus mechanisms, like Classical or #Nakamoto consensus.

Snowman Consensus =Avalanche consensus, except that its architecture is linearized to make it EVM-compatible.
@el33th4xor

Linear chains follow the “longest” chain rule in which nodes on the network select the chain with the most work done as the valid chain.

#AVAX consensus prioritizes safety over liveness, meaning network will halt rather than submit anything invalid.

@TrustNodes

Up to 50% of the nodes can be malicious and try to imbalance the vote, however, they’ll be unable to do this in a way that causes two nodes to push through invalid data.

Snowman Consensus is account-based rather than UTXO-based (diverging from Avalanche consensus) to be more compatible with #Ethereum and other account-based smart contracts and dapps.
@HorizenLabs

That's all the space I have for now.

If you want to read the full AVAX report, including tokenomics, vulnerabilities, and more, check it out here

cryptoeq.io/corereports/av…

That's a wrap!

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