From theory to practice: Can Based Rollup implement L1 sort-driven Rollup solution?

Author: YBB Capital Researcher Ac-Core

Foreword:

The working principle of Ethereum is that each node will store and execute every transaction submitted by the user, in order to expand the entire network, Ethereum adopts the Rollup solution. Simply put, it moves most of the transaction processing off-chain (L2), thereby reducing the burden on the Ethereum main network (L1) and reducing transaction fees, that is, Rollup = a set of smart contracts of L1 + network nodes of L2, that is, on-chain Smart contracts and off-chain aggregators, which rely on Ethereum itself for its own settlement, consensus and data availability, are only responsible for executing transactions. The L2 network node consists of multiple parts, the most important of which is the sequencer, but currently Rollup's sequencers are facing centralization problems.

Rollup and Sequencer

Rollup is a scaling solution for Ethereum (L1) that executes transactions off-chain, packaging transactions in blocks. For each block, Rollup publishes the data needed to reconstruct the chain state (as a source of data availability) to the data availability layer, and publishes proof of the correctness of the off-chain execution to the settlement layer (there are two types of Rollup, in In the case of ZK-rollup, zero-knowledge proofs are issued for each block; in the case of Optimistic rollup, fraud proofs are only issued when a dispute occurs). After EIP-4844, when data publishing switches to blobs, This layer might be called the "data publishing layer". Among them, Rollup's smart contract verifies the issued proof on L1, and each Rollup will have one or more bridges to realize data transmission between chains as well as deposits and withdrawals.

In the implementation logic of Rollup, the sequencer is a key component. It is mainly responsible for receiving transaction requests on L2, determining their execution order, and packaging the transactions into batches (Batch) for final transmission to L1. The Rollup smart contract on the Internet plays an important role in improving transaction processing efficiency and reducing costs.

The function and working principle of the sorter mainly include four parts.

1. Receive transactions: The sequencer receives transaction requests from users or applications. These transactions are first processed on L2 instead of directly on the Ethereum mainnet;

2 Sorting Transactions: The sequencer is responsible for sorting the received transactions and determining their execution order. This process is similar to what Ethereum miners do before packaging transactions into blocks;

3 Packing Transactions: The sorter packs the sorted transactions into batches that contain multiple transactions Summary information of transactions;

4 Submit to L1: Finally, the sequencer submits the packaged transaction batch to the Ethereum mainnet (L1), where settlement and data storage are performed. This way, L1 can verify and store state updates on L2.

Although Rollup technology provides an effective scaling solution, there are still some problems in the design and implementation of sorters. The first one is the centralization problem. Most Rollup projects currently rely on centralized sorters, usually by The intuitive risks brought by the control of a single entity or a few entities are a lack of transparency and single points of failure.

Putting aside the above rigid explanation, the discussion on the L2 decentralized sorter solution, mentioned in YBB Capital’s previous articles, is whether it is the L2 solution of sorting pool node staking that Metis directly opens to the market. , or an independent project Espresso plan started from scratch, its essence is to sort the distribution of the "profit cake" and the space expectation for future market speculation, so the correctness of interests and legitimacy is the key that is difficult to avoid. The historical background and design of Based Rollup A "Total Anarchy" state to allow unlimited trading expansion by anyone. Combined with the above-mentioned problems with the current sorter, in 2023

Justin Drake proposed

solution

Based Rollups to be managed by Ethereum L1 itself, the content of which is as follows (See extended link 1 for the source)

:

Definition:

“When the ordering of a rollup is driven by the base layer (L1), we call it L1-based or L1-ordered rollup. Specifically, L1-based rollup refers to the next L1 proposer Can work with L1 searchers and builders to include the next Rollup block in the next L1 block without permission.

Pros:

• Liveness: Based Rollup enjoys. Same liveness guarantee as L1. Please note that the activity of non-Based Rollup with Escape Hatches will be reduced (Escape Hatches is a safety mechanism in Rollup that allows users to safely extract assets from L2 back to the L1 master when there is a problem with the Rollup system. chain. It is similar to an emergency exit);

Weaker settlement guarantee: Escape pod transactions must wait for a timeout period before settlement is guaranteed;

Censorship-based MEV : Rollups with escape pods are vulnerable to adverse MEV effects from short-term sequencer censorship during timeouts;

Network effects at risk: Mass rollouts triggered by sequencer liveness failures (e.g. to 51% attack on the centralized PoS sorting mechanism) will destroy the network effect of Rollup. Note that unlike L1, Rollup cannot use social consensus to recover gracefully from sequencer liveness failures. In all known non-Based Rollup designs, mass exit is the Sword of Damocles;

Gas Penalty: Transactions settled via escape pods often incur Gas penalties for their users (e.g. due to Sub-optimal data compression without batch packing).

• Decentralization: Based Rollup inherits the decentralization of L1 and naturally reuses the L1 searcher-builder-proposer infrastructure. L1 seekers and builders are incentivized to include rollup blocks in their L1 blocks to extract the rollup's MEV. This then incentivizes L1 block proposers to package rollup blocks on L1.

• Simplicity: Based Rollup sorting is the simplest, even much simpler than centralized sorting. Based Rollup requires no orderer signature verification, no escape hatches, and no external PoS consensus.

Historical Notes: In January 2021, Vitalik called the solution based on L1 sorting "complete anarchy", which has the risk of submitting multiple rollup blocks at the same time, resulting in a decrease in Gas and workload waste. The current block proposer-builder separation (PBS) scheme can strictly control L1 ordering, with at most one rollup block per L1 block, and no gas waste. This avoids wasting the proof work of a ZK-rollup when block n+1 of the rollup (or n+k for k >= 1) contains a SNARK proof of block n.

• Cost: Based Rollup has zero gas overhead – there is no need to even verify signatures from decentralized or centralized orderers. The simplicity of Based Rollup reduces development costs, shortens release time, and reduces the exposure area for code vulnerabilities. Based Rollup sorting is also token-free, avoiding the regulatory burden of token-based sorters.

• Consistent with L1 economic alignment (L1 economic alignment): The MEV originating from Based Rollup naturally flows to the L1 it is based on. This flow strengthens L1 economic security and, in the event of MEV destruction, increases the economic scarcity of L1’s native tokens. This strong economic integration with L1 may help build the legitimacy of Based Rollup. Importantly, despite sacrificing MEV revenue, Based Rollup retains the option to generate revenue from L2 congestion charges (such as L2 base charges in the form of EIP-1559).

• Sovereignty: Despite delegating ordering to L1, Based Rollup retains sovereignty. Based Rollup can have a governance token, charge base fees, and the proceeds from these base fees can be used when appropriate (e.g. Optimism funds public goods).

Disadvantages:

• No MEV income: Based Rollup hands off MEV to L1, limiting its income to base fees. Counter-intuitively, this may increase the total revenue of Based Rollup. The reason is that the rollup landscape appears to be winner-take-all, with the winning rollup likely to leverage the security, decentralization, simplicity, and consistency of Based Rollup to achieve dominance and ultimately maximize revenue.

• Constrained sorting: Delegating sorting to L1 reduces sorting flexibility. This makes certain ordering services more difficult and possibly impossible to implement:

• Pre-confirmation: Fast pre-confirmation is not a problem for centralized ordering and can be achieved through external PoS consensus. Fast prevalidation using L1 sorting is an open problem with many promising research directions, including EigenL, Inclusion Lists, and Builder Bonds.

• First come first served (FCFS): It is not sure whether Arbitrum-style FCFS sorting can be implemented on Based Rollup. EigenL may provide an overlay of FCFS for L1 sorted Based Rollup.

Naming:

"Based Rollup" The name comes from the affinity with the base chain (Base L1). This conflicts with Coinbase’s recently announced Base chain, which is a wonderful coincidence. In fact, Coinbase shared two design goals in their Base announcement:

• Tokenlessness: "We have no plans to issue new network tokens."

• Decentralization: " We [...] plan to gradually decentralize the blockchain over time."

Base can achieve tokenless decentralization by becoming a Based Rollup.

Source: @jchaskin22

To sum up the theory, Based Rollup allows anyone to expand to the Rollup block and put the sorted transaction status Publishing changes to L1 extracts MEV from L2, allowing all ordering and security to be provided by Ethereum L1. This can circumvent the external proof-of-stake consensus and specific Rollup Token requirements. At the same time, compared with other Rollups' "emergency escape cabin" functions that are essential to keep assets safe, they can be removed in the vision of Based Rollup, and the process only requires Transactions on Rollup must be completed successfully while maintaining the safe operation of Ethereum.

Taiko Labs on Based Rollup

Source: Taiko official website

Taiko Labs is the main team that develops and promotes Based Rollup ed Rollup is Taiko Labs Projects on Ethereum Layer 2 scaling solutions. Its vision is to solve the scalability problem of the Ethereum main network through innovative technologies such as Based Rollup. It has three main features:

1. Completely equivalent to Ethereum’s EVM (Type 1) ZK-EVM: The (Type1) zkEVM used has complete Ethereum compatibility, and developers can seamlessly Migrate decentralized applications (dApps) between Ethereum and Taiko without worrying about the risk of smart contract execution failure;

2. Open source: All source code of Taiko is open to anyone on GitHub All can be viewed, built or modified. This open source model ensures that the development of blockchain technology is not limited to the efforts of a small team, but also encompasses communities and developers worldwide;

3.Full decentralization: In addition to ensuring high compatibility with EVM, Taiko is also committed to achieving complete decentralization of the protocol. Taiko plans to submit blocks and generate zkPs through decentralized proposers and validators to ensure the decentralized nature of the system.

Taiko is committed to building type 1 ZK-EVM that is fully equivalent to Ethereum (fully Ethereum-equivalent)

, that is, Vitalik Buterin in "The different types of ZK-EVMs" (see extended link 2), The pursuit mentioned in is completely and without compromise equivalent to Ethereum. Its purpose is to be fully compatible with Ethereum to verify Ethereum blocks (at least the verifiable execution layer, excluding the beacon chain consensus but including all transactions, smart contracts and account logic, and does not replace hashes, state/transaction trees and other consensus logic), so compared to other types, Type 1 is the most complex and challenging one to be close to a native solution.

Picture source: Vitalik Buterin: "The different types of ZK-EVMs"

Other core structures:

Competitive Rollup (BCR - Base Competitive Rollup)

Yes An innovative blockchain scaling solution developed by Taiko Labs. BCR aims to improve the efficiency and security of Rollup through a competition mechanism, allowing different participants to compete freely to submit blocks and generate proofs, thereby improving the performance and decentralization of the entire network. A comprehensive summary is as follows.

• Features

Open competition: Allows any qualified participant to compete to submit blocks and generate proofs. This open mechanism reduces centralized control and improves the decentralization of the network degree. Competitors win rewards and transaction fees by providing better services;

Efficient expansion: can effectively improve the efficiency of block generation and verification. Multiple competitors can work in parallel, avoiding single-point bottlenecks and improving transaction processing speed and network expansion capabilities;

Security: Through the competition mechanism involving multiple parties, the system's anti-attack ability is improved. The blocks and certificates generated by multi-party competition increase the transparency and security of the system and are difficult to be controlled or attacked by a single entity.

• Advantages

EVM Compatible: BCR is fully compatible with the Ethereum Virtual Machine (EVM), allowing existing Ethereum smart contracts and decentralized applications (DApps) to be easily migrated to Run on BCR without major modifications;

High throughput: Since BCR can process transactions and generate blocks in parallel, the throughput of the network is significantly improved, able to handle higher transaction volumes and reduce transaction costs Cost and delay;

Decentralization: Through the decentralized block generation and certification mechanism, the decentralized nature of the network is ensured and the risk of being controlled by centralized entities is reduced.

• Disadvantages

Increased complexity: System complexity requires complex algorithms and protocols to coordinate block generation and verification among multiple competitors. Smart contract complexity makes smart contracts Additional logic may be needed to handle competition results;

Potential issues: Under BCR’s competition mechanism, when multiple competitors calculate and submit blocks at the same time, it may lead to an increase in fees, and users are using BCR for transactions You may face higher transaction fees, especially if the network is busy or competition is fierce. At the same time, large nodes with rich resources may have an advantage in competition, resulting in centralization.

Booster-based Rollup (BBR-Based Booster Rollup)

Booster is a special participant in BBR, which is responsible for optimizing transaction batches, The actual function of compressing transaction data and processing multiple transaction batches in parallel is to separate execution and storage, maintain L2 execution while L1 remains decentralized, and keep the addresses of smart contracts on L1 and all BBRs. consistent.

At the same time, it also faces challenges such as increased system complexity, resource consumption, and potential centralization. In the future, BBR still needs to be further optimized and expanded to meet the needs of the continuous development of blockchain technology.

Source: Taiko Labs

Conclusion:

Based Rollup can be regarded as a huge change in the second-layer expansion method of Ethereum, and the sorting of Rollup is directly delegated In one layer of proposers, we use the separation design of proposers and builders to let one layer perform all sequencer roles for Rollup. It also allows MEV to be extended so that L2 searchers can send transaction bundles to L2 builders, who are also L1 searchers, and these complete L2 blocks then become part of L1 blocks, which are ultimately used by L1 builders and Ethereum mainnet processing.

Whether Based Rollup can be assumed to be the final solution of Rollup remains to be verified, but it is undeniable that it is a major innovation in the second-layer expansion of Ethereum at this stage, providing more security and decentralization for expansion. solution. If the same thinking is brought into the Bitcoin ecosystem, compared with the strong scalability of Ethereum to implement a native and decentralized VM, its implementation is understandably difficult. Therefore, the entire industry is currently solving the problem of truly decentralized expansion. There is still a long way to go. ： Extension link: 展 [1]

Https: //Ethresear.ch/t/based-rollpowers-from -l1-sequencing/15016/1

】The different types of ZK-EVMs https://vitalik.eth.limo/general/2022/08/04/zkevm.html

Reference article:
【1】The game of credit: Rollups controlled by multi-signing and committeeshttps://mp.weixin.qq.com/s?__biz=Mzk0OTYwMDM1Mg==&mid=2247486544&idx = 1 & SN = 7A0EE8EB1D32E6EF0BD08354986C0A1F & Source = 41#WeChat_redirect

[2] TAIKO Research: Etherewer 2 solution for seamless expansion Https: //www.pane wslab.com/zh /articledetails/id09jfto.html

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