Ethereum Fusaka Upgrade Guide: Making L2s Even Better

Ethereum Fusaka is a blend of two upgrades: Fulu and Osaka, for consensus and execution layers, respectively. 

It’s going to optimize the interactions with L2s and improve Ethereum scaling, while also introducing several new instruments for validators and developers. 

As always, we monitor such developments closely, so let’s dive into the thorough guide of the upgrade.

Fusaka upgrade highlights: PeerDAS, blob optimization, L1 scaling, UX, and more

Fusaka consists of a range of Ethereum Improvement Proposals (EIPs) related to scaling and user experience enhancements. 

Most notably, they include optimization of L2s communication with the Ethereum mainnet via blobs (binary large objects), but aren’t limited to it. 

On October 14, these EIPs were deployed on the Ethereum Sepolia testnet, and the upgrade proceeded smoothly so far.

Did you know you can connect to GetBlock via our contact form to order a node or propose a partnership? If you have something to offer—go ahead and reach out!

Here is a quick summary of the EIPs that are planned to be included in Fusaka:

With GetBlock, let’s go forward and explore each of these in detail.

Solving L2s data transmission inefficiencies

Ethereum layer-2 (L2) blockchains need to deal with the essential parameter: data availability, which means that all data required to verify the blockchain transactions is available to network participants. The primary role of Ethereum Fusaka is to optimize L2 data availability for Ethereum validators, improving the network throughput.

You can also read our 2024 overview of the Pectra upgrade, which was deployed in May 2025, and compare it with the upcoming upgrade.

That’s how most L2s work, in short:

Thus, each Ethereum node must receive and store every blob (binary large object) from the L2, which creates a huge bottleneck and reduces the transaction speed. For the Ethereum ecosystem to become faster, it must be optimized.

That’s why the PeerDAS approach was designed.

PeerDAS: Peer data availability sampling

DAS stands for Data Availability Sampling, an approach that ensures block data availability without overloading individual nodes. PeerDAS was introduced in EIP-7594 in early 2024, on the basis of blob sharding offered in EIP-4844 two years earlier. It divides blob data and distributes it among validators, reducing the load for each of them.

Here is how PeerDAS works:

As a result, each node must proceed only with one-eighth of the original data load, while still being able to recover the original data via peer connections. It reduces bandwidth usage and computational expenses greatly without compromising security.

Blob parameter settings for seamless node updating

To ensure that the updating process runs smoothly, Ethereum Fusaka also introduces the parameter-only fork mechanics via EIP-7892. It allows each node client to deploy small hardforks with the custom adjustment of blob parameters, such as the expected and maximum number of blocks in a blob.

Source: Dune Analytics

As seen on the graph, these parameters increased after the Pectra upgrade, contributing to the increased Ethereum throughput. 

Blob fee auto-adjustment

The final element is adjusting the L2 gas fee, which is paid by L2 operators for each blob sent and consists of:

In case the execution fee is much larger than the blob fee, the latter can repeatedly decrease to the minimum value of 1 wei, which is highly inefficient and doesn’t represent the actual computational expenses. To prevent it, EIP-7918 introduces the blob base fee, bound to the current execution fee, ensuring that it remains relevant and contributes to the network.

Ethereum L1 scaling improvements

Along with ensuring smooth data transition between L2s and the Ethereum mainnet, Fusaka introduces several enhancements to the mainnet itself.

Modifications of the modexp EVM precompile

Ethereum precompiles are, basically, low-level smart contracts. Instead of being written on Solidity, they are integrated directly into the Ethereum Virtual Machine using its bytecode. Thus, they can be accessed and executed much faster compared to high-level Solidity programs, which must be compiled first.

The modexp precompile was introduced in 2017 via EIP-198 and represents the modular exponentiation procedure, used in various forms of cryptography. Being essential for various applications, it has several known vulnerabilities, which are addressed in the update.

Due to these changes, modexp is going to become more optimized and efficient.

New transaction limits for better stability 

To prevent costly mistakes or potentially malicious operations, Fusaka is going to introduce gas limits for transactions. Currently, a transaction can potentially burn all block gas, leading to unwanted consequences:

EIP-7825 introduces an upper limit for transactions: 16,777,216 (or 2^24) gas. If the transaction is going to consume more, it will be rejected with an error message.

Block size limits and history expiry for accessibility

Keeping the Ethereum node hardware requirements accessible for the wider population is essential for ensuring its decentralization. For that, Fusaka introduces improved history expiry and block size limits for its full nodes. Let’s explore further.

History expiry isn’t new for Ethereum and other chains. For example, the Solana archive node is larger than 400 TB, while the ordinary full node usually requires less than 4 TB. For Ethereum, the full ledger data takes about 15 TB, while full nodes currently require less than 2 TB. With these two upgrades, requirements may fall even further, making Ethereum nodes much more accessible.

Increasing the default gas limit to boost data throughput

In addition, as the Fusaka upgrade increases the data throughput of Ethereum, the default gas unit limit is going to be increased from 36 million units to 60 million, as proposed in EIP-7935. As it can potentially increase the network load, it’s also proposed to test this limit thoroughly before fully implementing it.

Note: Don’t confuse gas units with gas fees. The former is the basic computational unit that shows the amount of computational effort required to execute an Ethereum operation. The latter is measured in Gwei and corresponds to the cost needed for that. Therefore, increasing the gas unit limit increases the maximum amount of computations allowed onchain.

Other essential details: UX improvements

Fusaka mostly focuses on improving the Ethereum ecosystem's scalability, but it also touches the user experience part, making network participation more convenient. Let’s explore them in detail, too.

With these developments and new methods, it’ll be much easier for participants to manage their privacy and check the current state of the network.

Summary of Ethereum Fusaka planned upgrades

If everything runs as planned, L2 chains will scale Ethereum even more efficiently, while mainnet validators and EVM developers will obtain new instruments for their activities.

Closing thoughts

To wrap it up, Fusaka focuses on L2 economics and scaling the Ethereum ecosystem, adapting it to the growing number of users and projects. It also introduces new functionalities for network participants and improves the existing ones. As a result, the ecosystem will become more convenient, resilient, and faster.

GetBlock monitors the crypto landscape developments closely to keep its nodes up-to-date and provide the most relevant information for Web3 users. Our primary focus is to ensure the steady functioning of Web3 projects and support the emergence and development of new ones, and our Ethereum nodes are available for all user categories—from small projects to international enterprises. Sign up now and select the plan that ensures your growth.