In the first post of our Rollups 2.0 series, we covered based rollups, where the based sequencing is one of the most decentralized, and Ethereum-compatible method for managing a rollup. By handing over the task of transaction sequencing to Ethereum’s Layer 1, based rollups leverage the decentralization, simplicity, and liveness of L1, along with other advantages.

In today’s post, we delve into the next evolution of rollups: Booster rollups. Booster rollups not only build upon the foundation laid by based rollups but also push the boundaries of Ethereum’s composability. But how exactly do we expand this composability?

What are the problems within the L2 Space right now?

To ensure that L2 networks function as expected, additional checks are often needed. However, the main settlement and execution processes still take place directly on L1. This means that while L2s extend functionality with off-chain EVM execution, they also add extra complexity. Although this extra logic is not ideal, the ultimate goal is to standardize operations and rely entirely on the standard EVM.
Standardization is essential for enabling smooth transaction exchanges between different L2s. To achieve this, a new type of transaction might be necessary—one that can operate across multiple chains. In this system, a single transaction could create smaller subtransactions. Each subtransaction would include details like the source chain ID, the destination chain ID, input data (such as caller, address, and call data), and the resulting output from the destination chain.
This transaction data serves two important roles:

1. It acts as input on the source chain, letting participants see the output without involving the destination chain directly.

2. It is used on the destination chain to confirm that the given inputs produce the expected outputs.

   By using this approach, each chain can independently verify its own transactions while following a shared standard for transaction formats and inputs. As a result, block verification remains straightforward, using the familiar L1 verifier contract to ensure blocks are valid.

How are booster rollups different?

Booster rollups process transactions as if on L1, with access to L1’s state but with separate storage, scaling both execution and storage to L2. Each L2 extends L1’s blockspace, distributing transaction processing and data storage.

Envision deploying your decentralized application (dapp) just once, and it automatically scales across all Layer 2 (L2) networks. If you need more blockspace, simply add more booster rollups without any further configuration. In other words, developers face no extra workload, no redeployment expenses, and no additional complications.

In layman’s terms, booster rollups are like adding extra CPUs or SSDs to your laptop: They enhance performance, allowing applications to run more efficiently and expand easily.

Or for readers with a technical mindset, booster rollups can be also described as “distribute the execution of transactions and storage across multiple shards.”

How do booster rollups work?

Any rollup, whether optimistic or ZK, can adopt booster functionality. However, full boosting isn’t mandatory for all rollups, as some might benefit from L2-specific optimizations.

The optimal scenario for boosting is with a based rollup if the goal is to achieve native Ethereum scaling. By enabling L1 validators to propose blocks for the entire boosted network, you’re effectively scaling Ethereum seamlessly.

Boosted rollups also tackle the fragmentation issue prevalent in current rollup ecosystems. By leveraging based sequencing, they maintain L1 sequencing’s benefits while introducing atomic cross-rollup transactions across all L2s within the booster network. This setup allows for the kind of Ethereum scaling envisioned from the start—integrated yet expansive, offering a unified solution to Ethereum’s growth challenges.

A description of how booster rollup architecture

Since booster rollups support synchronous composability by their nature, this rollup model eliminates the hassle of dealing with fragmentation or switching between L2s. All preferred dapps will be available across every L2, providing a seamless Ethereum experience.

With boosted rollups, developers can scale their dapps without the need for multiple redeployments across L2s. Deploy your dapp on L1 just once, and it automatically scales to all existing and future boosted L2s, simplifying the overall process of development and deployment.

Which teams are building booster rollups?

One of the few teams that are building booster rollups right now is@gwyneth_taiko""> @gwyneth_taiko which is also a based rollup synchronously composable with Ethereum. Gwyneth leverages the foundation of Ethereum, where transaction sequencing is handled by L1 validators, and blocks are assembled by compatible L1 builders.

Gwyneth embodies synchronous composability by enhancing and extending L1 capabilities. With native sequencing, it allows for fluid integration between rollups and L1 states. As demand for block space escalates, deploying additional booster rollups is straightforward, akin to upgrading a laptop with more CPUs or SSDs to boost computational power and enable broader application scope. Gwyneth envisions a seamlessly integrated Ethereum, devoid of fragmentation.

Gwyneth introduces a preconfirmation mechanism, where L1 validators can commit to L2 states ahead of time, providing users with rapid transaction confirmations and ensuring congestion and contention fees are equitably shared among base layer participants. Following the pioneering based preconfirmed transaction on Taiko’s testnet, this innovation continues to be pushed forward.

From its inception, Gwyneth is designed with finality in mind. Powered by Taiko’s in-house multi-prover, Raiko, it’s built to achieve synchronous composability. At present, Trusted Execution Environments (TEEs) serve as a minimal safeguard for execution, but the future holds the promise of leveraging optimized zero-knowledge Virtual Machines (zkVMs) such as SP1, Risc0, and potentially many others.

The case for booster rollups

Booster rollups enhance scalability transparently, like adding servers to a farm. This design allows applications to utilize additional resources seamlessly, ensuring that developers can scale their solutions without requiring extra steps, such as deploying complex L2 infrastructures.

They address the fragmentation problem by providing a uniform experience across L1 and L2. With smart contracts sharing the same address, users benefit from consistency and simplicity, regardless of whether they interact with an L1 or L2 environment.

They solve deployment inefficiencies by allowing developers to deploy once on L1, making dapps multi-rollup by default, with updates managed centrally. Users enjoy a single address across networks, whether using an EOA or smart wallet, facilitating seamless transactions across L1 and L2.

They address the challenge rollup operators face in persuading developers to deploy on their network, as dapps are automatically available. The concept is stackable, combining booster with based rollups for significant scaling. Not all L2s need to be booster rollups, allowing for mixed networks.

They solve sovereignty and security concerns by eliminating the need for specific wrapper contracts, as smart contracts work the same on L1 and L2, keeping control with developers. Security is enhanced by addressing single points of failure, with security now applied per dapp, rather than relying on bridges or specific implementations.

On the limitations of booster rollups

To ensure L2 mirrors L1, contract deployments should be restricted to L1 only, ensuring uniform access across L2s. This isn’t a major limitation since smart contracts can still behave differently via data-driven methods, like storing contract addresses in storage which can vary between chains.

While L1 holds the shared data, this doesn’t directly increase scalability, an inherent challenge in scalable systems. Developers must optimize to minimize this impact. Like traditional software, not all dapps can leverage parallel processing fully. However, these dapps still benefit from interoperability; even though they operate on individual L2s, they remain universally accessible.

Booster rollups essentially act as an extension of the L1 chain but with unique transaction execution and storage. To interpret Booster Rollup transactions, L1 and L2 nodes have to run in sync. Yet, one approach could involve running both L1 and L2 on the same node, switching between shared L1 storage and L2-specific storage during transaction execution.

Conclusion

Booster rollups offer a transformative solution to Ethereum’s scalability challenges by seamlessly integrating with L1 to enhance transaction throughput and storage efficiency. They tackle issues like fragmentation and deployment inefficiencies, allowing developers to scale dapps across multiple L2s effortlessly while maintaining security and sovereignty. By streamlining scalability and fostering interoperability, booster rollups pave the way for a more cohesive and user-friendly Ethereum ecosystem.

In our next series, we will delve into the intriguing worlds of native rollups and gigagas rollups, exploring how these technologies could further revolutionize the Ethereum scaling landscape.

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