Recently, the MIP-4 proposal of the Metis community was passed. This is the first among all L2s to start decentralized sequencer testing. This also means that Metis has begun a special operation to remove the Rollup training wheels.
The concept of Rollup training wheels comes from Vitalik. In November 2022, Vitalik posted a post on the Ethereum community forum to discuss the milestones in the development of Rollup L2. He proposed setting three milestones, which are:
-- Stage 0: Full training wheels stage
Rollup L2, which is in Phase 0, allows a centralized sequencer to package and submit all L2 state data to L1 (Ethereum mainnet), and at the same time deploy a set of verification smart contracts on L1 (such as Optimism Gateway deployed by Optimism on the Ethereum mainnet) to ensure data availability and ensure that users can freely transfer assets without permission.
-- Phase 1: Limited training wheels
In Rollup L2, which is in Phase 1, OP-Rollup needs to deploy fraud proofs on L1, and ZK-Rollup needs to deploy validity proofs on L1.
A multi-signature “security committee” is needed with the authority to overwrite fraud proofs and validity proofs of erroneous outputs
An upgrade mechanism is allowed, but the time lock has a minimum 7-day delay.
--Stage 2: No training wheels
There must be two independent fraud proof contracts or validity proof contracts that back up each other. When a state data conflict occurs, the "Security Committee" will adjust according to the situation.
An upgrade mechanism is allowed, but the time lock has a delay of at least 30 days.
After publishing this post, Vitalik Bullish Rollup’s three milestones. He was optimistic at the time that L2 would reach at least the Phase 1 milestone after the Cancun upgrade.
However, since the Cancun upgrade was separated from the Shanghai upgrade into an independent major upgrade and the deployment time has been repeatedly postponed, all Rollup L2s are currently still in phase 0.
There are two reasons for this phenomenon:
--The smart contract structure for implementing the fraud proof mechanism is complex, requiring a large amount of on-chain computing and verification resources, and the operating cost is very high. The probability of an event requiring a fraud challenge is very low. At least so far, no state conflict event has occurred in many OP-Rollup L2s.
It is not economical to invest high costs for a low-probability event. Even if economic factors are not taken into consideration and only for the purpose of enhancing safety, the L2 development team hopes to deploy it after the Cancun upgrade has significantly reduced the operating costs of L2.
--Some L2s are the vested interests of Phase 0. Relying on the L2 hair-pulling craze and centralized sequencers, they can earn more than 10 million US dollars in MEV from users every month. They lack the motivation to enter Phase 1 or Phase 2.
Faced with L2's stagnant and stuck in stage 0, the patience of the market and users has gradually run out.
There have been more and more criticisms of L2 recently, focusing on the delay in conducting fraud proof testnet verification, sequencer centralization, and endless task MEV user gas fees.
Faced with these criticisms, some L2s use Ethereum Maxi’s ideology as a shield, believing that decentralized sequencers establishing independent/semi-independent consensus are decoupling from Ethereum.
Some L2 believe that there is a fractal relationship between L2 and Ethereum. The decentralized sequencer, to some extent, is a fractal of the Ethereum PoS consensus mechanism at the L2 level.
The L2s that hold this attitude include Starknet and Metis. In order to achieve balance, Starknet chooses to pay 1/3 of the Gas fee protocol token STRK, which can be regarded as 1/3 of the sovereign Rollup. Metis, as "Vitalik's fucking L2", is more determined in choosing the path of sovereign Rollup and decisively started the decentralized sequencer test this month.
Centralized sequencer or decentralized sequencer, this is a huge question for every L2.
Here we will put aside the political correctness of Ethereum's orthodoxy and only analyze the methodology of L2 construction.
At present, the methodology of L2 construction is vaguely divided into two camps. One camp insists on the supremacy of Ethereum orthodoxy and developers, and uses fraud proof/validity proof technical solutions to achieve minimum trust and decentralization of L2. The other camp believes that the community is the largest and users are king, and uses the decentralized sequencer + sovereign Rollup architecture to achieve decentralization of L2.
We have no intention of getting involved in this dispute, but only want to state a basic fact: the web3 protocol is not a web2 product. The process of building the web3 protocol is more like building a biosphere ecosystem, rather than building an industrial product like a web2 product.
This is why the Metis community emphasizes the principles of diversity, inclusion, and sharing. This is also why Metis continues to promote the decentralization of the sequencer despite the doubts of some Ethereum Maxi.
Economic decentralization and community co-governance may be the passcode for L2 decentralization.
Finally, as the Bitcoin ecosystem and modular public chains rise and compete with the Ethereum ecosystem for the right to define the future Web3 paradigm, the Ethereum ecosystem needs to restrain its e/acc impulse and listen more to the voice of the community than ever before.
