In-depth Analysis of the Advantages and Challenges of Decentralized Metis Sorter
What is Metis, the Layer2 network that has seen a rapid increase in on-chain funds recently? By focusing on the centralization issue of Rollups sequencers, Metis has attracted market attention by creating a peer-to-peer network and a staking consensus mechanism to become the first decentralized sequencer.
Metis is a general-purpose Layer2 network in the Ethereum ecosystem. The project was launched in May 2021 and the mainnet, Andromeda, was launched in November of the same year.
Metis Andromeda’s features include its Metis Virtual Machine (MVM) achieving EVM equivalence, early completion of decentralized sequencer, and other unique highlights among mainstream Layer2 solutions. Initially, Metis was developed as a hard fork network of Optimism. However, after Optimism gained control over the centralization of sequencer power, Metis embarked on its own path, striving for a decentralized sequencer from the beginning.
Recently, Metis has experienced rapid growth in on-chain funds (TVL). Since the 20th of this month, it has rapidly grown from $100 million to a historical high of $720 million, currently ranking as the third-largest Layer2 ecosystem in Ethereum.
The token of the project is called METIS, which is used to pay for on-chain fuel and staking for the operation of the Metis Andromeda sequencer. The METIS token has seen a price increase of approximately 350% this month and currently has a price of around $84 and a circulating market capitalization of about $340 million.
When researching blockchain technology architecture, it can be approached from three aspects: distributed ledger, consensus mechanism, and virtual machine. Rollups usually also need to consider the verification mechanism of transaction proofs, namely optimistic proofs or zero-knowledge proofs.
Metis inherits the Optimistic Rollups architecture, and its database mainly consists of two parts of smart contracts: the Canonical Transaction Chain (CTC) for storing complete transaction information and distinguishing the order of transactions, and the State Commitment Chain (SCT) for recording the computed transaction states. However, in order to reduce the technical feasibility of decentralized sequencers and the cost of on-chain transaction data, Metis stores complete transaction information on the IPFS system outside the Ethereum mainnet.
Metis Andromeda’s consensus layer is different from Optimistic Rollups. It incorporates a peer-to-peer network transmission structure and uses Proof of Stake (PoS) to ensure the normal operation of sequencers, allowing the network to accommodate multiple sequencers simultaneously for decentralization. The consensus technology stack of Metis mainly consists of three roles: sequencers, proposers, and verifiers. Any transaction information on the Metis network will be sorted and executed by sequencers, and proposers will upload the results to the Ethereum mainnet. To ensure the normal operation of sequencers, there are also verifiers responsible for monitoring the correctness of transaction results. If any abnormalities are found, sequencers will be penalized, strengthening the existing fraud proof.
Currently, the two mainstream proof mechanisms for Rollups, fraud proofs, and zero-knowledge proofs (ZKP), each have their own drawbacks. Fraud proofs require a locking period, usually taking a week to ensure transaction finality, which is unfriendly to user experience. Although zero-knowledge proofs can provide fast finality, the computational requirements for generating proofs are large, requiring hardware upgrades for Layer2 nodes (sequencers), which is not conducive to decentralization. Additionally, the development difficulty of zkEVM is currently high, making it difficult to achieve EVM equivalence.
Metis integrates the advantages of both proof mechanisms and introduced the Hybrid Rollup Zero Knowledge Fraud-Proof (ZKFP) in March of this year. By assuming that all transactions are valid to improve transaction processing speed and verifying transaction finality through zero-knowledge proofs, if any abnormalities occur, fraud proofs are provided. This combines the Optimistic Rollups architecture to improve transaction speed and uses Zero-Knowledge Rollups to enhance transaction finality and security. The integration of both brings the following benefits: EVM equivalence by leveraging the Optimistic architecture, enhanced security through zero-knowledge proof verification, and faster finality by reducing the locking period of fraud proofs from seven days to four hours.
Metis inherits the design of Optimistic Rollup and builds the specialized EVM-equivalent virtual machine, Metis Virtual Machine (MVM). MVM’s design is almost the same as EVM and can use existing tools and services in the Ethereum ecosystem. However, due to the network design requirements mentioned above, there are two differences: providing native IPFS invocation functions and an anti-fraud contract called MVM_Verifier, which manages the verification process of fraud proofs. In the case of verification by the anti-fraud contract, specific states can be deleted from SCT (usually abnormal transactions).
In addition, MVM also establishes a more versatile execution environment using WASM and MIPS, providing a more practical execution environment for zero-knowledge proofs. By building a solid foundation with programs written in low-level languages, it can be used across different networks and systems with minimal modifications.
To achieve a decentralized sequencer system, Metis Andromeda brings many interesting innovations besides utilizing the well-established proof of stake. These include integrating IPFS functionality for off-chain storage of transaction information to overcome the limitations of multi-sequencer technology, or introducing verifiers and ZKFP proof mechanisms to enhance the fraud-proof security of decentralized sequencers. Compared to existing Rollups, Metis promotes network decentralization and has indeed achieved it.
In the current atmosphere where Layer2 projects are receiving widespread market attention, although they also face the market issue of the lack of substantial ecosystems, the narrative of “decentralization” is fundamental in the Web3 ecosystem. Unlike Arbitrum or Optimistic’s control over sequencers, Metis offers a unique perspective with its “truly decentralized sequencer,” which indeed sparks market imagination.
Metis should also consider the advantages beyond decentralized sequencers. However, we should not forget the existing mainstream Rollups. If they open up sequencer decentralization, whether Metis’ advantages can be sustained remains to be seen by the market.
(This article is not investment advice.)
(Metis, Optimistic Rollups, Rollups, Sequencer)
