Written by: Josh Rudolf, Julian Ma, and Josh Stark

Translated by: Chopper, Foresight News

The ultimate goal of the Ethereum Foundation Platform team is to promote Ethereum as a unified cooperative system for scaling, ensuring that all users can use it with confidence. This article aims to share our views on the relationship between L1 and L2, elaborate on the role of each layer, and how we (as an ecosystem) can leverage the advantages of L1 and L2 to create the most appealing platform for all users. Some of these contents are already quite clear, while others need to be verified through ongoing experimentation and iteration with the community and users.

TL;DR:

Objective: All individual and institutional users should have clear pathways to utilize, expand, and benefit from the core attributes provided by Ethereum. The best way to achieve this goal is to fully leverage the unique functionalities of each layer, enhance Ethereum's core attributes, and release meaningful value to end users through these attributes.

As the Ethereum ecosystem develops, the role of each layer evolves accordingly:

• In the past: The primary mission of L2 was to assist Ethereum in scaling, followed by providing differentiated and customized space. Scalability was the key.
• Today: The primary mission of L2 is to achieve scaling capabilities while providing differentiated features, services, custom solutions, marketing strategies, and control areas. Currently, the biggest driving force is differentiation, control, and innovation.
• L1 serves as the truly permissionless global settlement, sharing state, liquidity, and DeFi center with the greatest flexibility. A strong, scalable L1 layer that does not compromise CROPS (Censorship Resistance, Open Source, Privacy, and Security) provides a better foundation for the L2 layer.
• L2 offers valuable new features, customization, and control to develop its own on-chain economy while extending the core attributes of Ethereum to more users. A strong L2 network strengthens the Ethereum ecosystem and its focus.

L2 covers all aspects and establishes differentiated binding relationships with L1 based on its own needs:

• Those L2s seeking the closest integration with L1 should strive for synchronous composability, complete interoperability, shared liquidity, and native Rollup mechanisms.
• L2s with various business models or technical expertise will continue to play an important role in the ecosystem, providing exclusive capabilities that L1 cannot cover.

The Ethereum Foundation (EF) will continue to develop underlying technologies to help L2 seamlessly extend L1 native features, securely enabling cross-layer and cross-chain liquidity and asset interoperability; at the same time, L2s are required to be open and transparent, clearly disclosing their security attributes and validation standards. In short, both sides play important roles, and their words and actions must be consistent.

Introduction

Over the past five years, a vast L2 ecosystem has emerged around Ethereum L1. Various L2s inherit different native characteristics of Ethereum: some completely replicate decentralized architectures (such as Stage 2 Rollup), some inherit partial security features (such as Validium, Prividium), and some are merely compatible with general EVM standards (not L2). Many chains are still under development; they often start as independent chains and gradually integrate deeply into the Ethereum L1 ecosystem.

Now is the time for the Ethereum Foundation (EF) and the broader Ethereum ecosystem to update our understanding of the relationship between L1 and L2 networks. The last update could be said to have been five years ago, when a Rollup-centered roadmap was first proposed as a pathway to scale Ethereum.

Since then, the situation has changed significantly. The technologies that enable L2 layers to share Ethereum's security and liquidity and interact with it have matured; the differentiation competitiveness and user value of L2 have become increasingly prominent; L2 has grown and nurtured independent community ecosystems; and the scaling roadmap for the L1 layer has evolved and become clearer. The Ethereum ecosystem needs to confront these changes and learn from past successes and failures.

In the past few months, the future development direction of the relationship between Ethereum L1 and L2 has gradually become clear:

• A thriving Ethereum ecosystem must be built on a strong L1 foundation.
• Ethereum L1 will achieve orders of magnitude scaling while maintaining the highest levels of security and decentralization, continuing to serve as the core of the on-chain economy and the center of DeFi.
• In the future, an ecosystem composed of independent and interoperable L2 chains will emerge, offering levels of customization, control, and functionality that L1 chains cannot provide. These L2 chains choose to root themselves within the Ethereum ecosystem because it is the best choice for their users, communities, or enterprises.
• L2 chains will both compete and cooperate to provide a diverse array of specialized block spaces, services, and assets.

This article aims to explain in more detail the vision of the symbiosis between L1 and L2 and to establish a path for creating mutually reinforcing relationships between Ethereum L1 and any chains that wish to root themselves and become a part of the ecosystem.

What roles do L1 and L2 play, and how do they work together?

Ethereum L1 is the world's leading programmable blockchain; currently, no other blockchain can compete with it in terms of user adoption, developer ecosystem, decentralization, resistance to risks, and underlying stability. Ethereum L1 is the core of the DeFi ecosystem, gathering the deepest liquidity across the network.

Ethereum L1 now has a clear scaling path while maintaining decentralization and security. Thanks to the collective efforts of numerous teams within the Ethereum ecosystem, the development speed of zero-knowledge proof (ZK) technology has far exceeded expectations. In the coming years, we will be able to enhance Ethereum L1's capacity by several orders of magnitude while adhering to the vision of preserving its core values.

At the same time, no single public chain can accommodate the global diverse on-chain economic demands. Even if Ethereum remains in the lead in the future and scales its capacity by 1000 times, there will still be many different chains because they offer specialization and customization services that L1 cannot provide:

• Specialization for specific applications or use cases
• Non-EVM functionalities
• Additional privacy protection
• Pricing mechanisms or transaction inclusion logic
• Ultra-low latency or other ordering characteristics
• Extreme scalability features unmatched by L1
• Specialized economies, market entry strategies, and growth methods
• Modular designs to meet compliance or other business needs
• Other improvements or innovations that can iterate and deliver faster than L1
• ……

This presents an opportunity to establish a mutually beneficial relationship between L1 and L2, allowing both to focus on complementary roles.

Why are other independent public chains willing to become L2 of Ethereum?

• Low cost. Compared to independent underlying public chains, L2 replicates Ethereum's top-tier security and decentralization at an extremely low threshold; building a global decentralized validation node is costly, time-consuming, and extremely challenging. L2 can shift this responsibility to Ethereum L1, paying as needed without incurring high fixed setup costs.
• Users and developers. Interoperability with the largest L1 and L2 cluster in the network provides access to more users and developers; as zero-knowledge proof technology, real-time proof, faster L1 finality, L2 settlement, and proxy infrastructure mature, interoperability and cross-chain user experiences will accelerate.
• Interoperability. If designed properly, L2 can safely access L1 assets and DeFi liquidity, user accounts on L1, and any services on L1, such as oracles and ENS.
• Marketing: Being part of the Ethereum ecosystem can provide brand and reputation advantages, as the Ethereum ecosystem has the best reputation, security record, and regulatory recognition among all L1s.

What can Ethereum L1 gain from this? Based on our experience and discussions with various stakeholders in the ecosystem, we believe positioning Ethereum L1 at the core of the growing L2 networks can strengthen the unique position of Ethereum and ETH in the on-chain economy:

• Create demand for ETH and provide trust-minimized, secure bridging services between ETH and other assets. ETH plays multiple roles, such as value storage and currency, within the Ethereum network.
• Expand Ethereum's network effects (for example, EVM, developer education, developer tools, user guidance, and interoperability between L2s)
• Consolidate Ethereum's important position as the core of the multi-chain ecosystem and the primary settlement and liquidity layer of the on-chain economy
• Provide wider business expansion, growth, and marketing support for Ethereum.
• L2s help realize the core vision of the Ethereum ecosystem. They serve as distributed engines of Ethereum's core attributes (security, resilience, and stability), maximizing the number of users deriving sustainable value from Ethereum.

The Ethereum ecosystem should not take these advantages for granted. Some of these advantages are still contentious within the community or require long-term theories to be validated through experimentation, measurement, and analysis. Ultimately, the relationship between L1 and L2 must be mutually beneficial to succeed. Over the past five years, this relationship has achieved many accomplishments and laid a crucial foundation for the future.

What does this mean for the future development of L2?

What does this new vision mean for L2-level users, their teams, and their communities?

Here are our recommendations:

• L2 should focus on strategies that complement L1 and achieve platform differentiation. Many L2s have successfully advanced toward this vision. They achieve this by innovating features, targeting specific use cases (e.g., application chains), providing new distribution methods, or adopting novel marketing strategies. This helps them create their unique communities and extend Ethereum's characteristics to millions of new users.
• L2 should have the authority to differentiate in various ways according to their own imaginations. We have already seen differentiation in scalability, trustlessness, privacy protection, enterprise compliance, industry fields, communities, and a range of technological innovations.
• L2 can choose to extend all or some properties of Ethereum according to their own goals. But they should ensure users can easily understand the security attributes they offer and do not offer. L2s dedicated to minimizing trust should at least reach Stage 1 and pass "exit" tests, meaning users can safely exit to L1 even in the presence of malicious operators or security committee failures. L2s that choose to get as close as possible to L1 and fully inherit its attributes should develop in these directions: 1) reach Stage 2; 2) achieve synchronous composability; 3) become native Rollups.
• L2 should continue to commit to building broader interoperability and shared liquidity mechanisms to reinforce the entire Ethereum ecosystem.
• L2 should operate transparently, clearly communicating its respective security attributes and the relationship with the L1 security layer to the ecosystem.

What contributions is the Ethereum Foundation making to build such a world?

To realize the vision of the L1>L2 relationship, the Ethereum Foundation is fully advancing the following tasks:

• We are committed to expanding both L1 and blob without sacrificing decentralization. Currently, the fill rate of the blob is only about 30%, leaving ample scaling space; if necessary, we can confidently further expand the blob.
• Particularly supporting those L2s with or wishing to deepen capabilities in privacy, security, and trustlessness.
• The Platform team led by Josh Rudolf aims to improve the overall performance of the Ethereum platform and serve as an interface between L2 and the core protocol roadmap.
• Improve the liquidity of L1, making it easier for L2s to access liquidity (faster final confirmation, withdrawals, and deposits).
• Work closely with L2 teams to understand their needs and reflect them in protocol priorities while clarifying the relationship between L1 and L2. To ensure this relationship works effectively, we need to understand what is working well and what needs improvement, and collaborate. Our goal is always to clarify and reinforce the value proposition of being part of the Ethereum ecosystem.
• Invest in research and development to achieve "native Rollup" technology, which means L2 chains that L1 can fully and trustlessly verify, thus achieving synchronous composability and secure interoperability.
• We closely collaborate with L2Beat and other organizations to monitor and verify the security characteristics of L2s. We must rigorously and honestly assess the characteristics of L2 and how they relate to L1 security so that users and developers can make informed choices.
• Address the main drawback of the multi-chain ecosystem: fragmentation. We will collaborate with the ecosystem (including various chains, wallets, and infrastructure providers) to build better interoperability solutions to address user experience and developer platform fragmentation issues. Now, with a clearer understanding of the relationship between L1 and L2, we can begin to tackle the issue of Ethereum narrative fragmentation.

We will jointly build a global, permissionless on-chain economy and provide the best platform for all users.