Ethereum's Fusaka Upgrade: A Data-Driven Look Under the Hood
Overview of the Fusaka Upgrade
Ethereum's latest upgrade, Fusaka, finalized on December 3rd, 2025, at 21:49 UTC, marking the second major code change for the network this year. Billed as a solution to handle increasing transaction loads from layer-2 networks, Fusaka bundles the Fulu consensus layer update with the Osaka execution changes. But does it live up to the hype? Let's dive into the numbers.
Peer Data Availability Sampling (PeerDAS) Analysis
Peer Data Availability Sampling (PeerDAS), implemented via EIP-7594, is a key component. The promise is reduced bandwidth and storage requirements for nodes by allowing them to randomly sample small chunks from peers to verify data availability. The theory is sound: validators only need to verify a fraction of the data. But what's the real-world impact on node operators, especially smaller ones? How much will this actually lower the barrier to entry, and will the savings be uniform across different hardware configurations? These are questions that need real-world testing.
Blob-Parameter-Only Forks and Complexity
The upgrade also introduces blob-parameter-only forks tied to EIP-7892, intended to allow for adjustments to blob counts and fee curves without requiring a full protocol overhaul. It is essentially a fast-track lane for tweaking blob-related settings. This sounds good on paper, but it also introduces a new level of complexity. Are we simply kicking the can down the road? Will we end up with a patchwork of quick fixes that eventually become unmanageable? (And this is the part of the report that I find genuinely puzzling. Why not address the core issues directly?)
Gas Limit Increase: Benefits and Potential Drawbacks
One of the most significant changes is raising Ethereum’s base gas ceiling to 120-150 million gas per block, up from roughly 30 million pre-Fusaka. That's a 4-5x increase. The network aims to support up to around 50 blobs per block compared to 12 under proto-danksharding, potentially increasing rollup data availability by up to 5x. The stated goal is to handle the increasing transaction batches from layer-2 networks. But this increase comes with a trade-off. While per-transaction gas usage is capped, the overall block size increases. This could lead to concerns about network congestion and increased resource demands on validators, particularly smaller operators. Has the gas limit been increased too much? Or not enough? It's a delicate balancing act. Ethereum Activates Fusaka Upgrade, Aiming to Cut Node Costs, Speed Layer-2 Settlements - CoinDesk
Native Support for Passkey-Style Signatures
Fusaka also adds native support for passkey-style signatures via EIPs in the 79xx range, extending Ethereum’s signature verification to handle WebAuthn and FIDO-like schemes. This is a welcome addition, improving security and user experience by aligning with modern authentication standards.
The Devil's in the EIP Details
The upgrade includes 12 Ethereum Improvement Proposals (EIPs), each addressing specific issues. EIP-7642 removes old, no longer used fields from Ethereum’s networking messages, streamlining the network. EIP-7823 puts a maximum limit on how big certain math operations can be, mitigating potential denial-of-service attacks. EIP-7825 sets an upper cap on how big a single transaction can be, preventing oversized transactions from clogging the network. EIP-7883 makes a specific type of math operation more expensive in gas, disincentivizing inefficient code. EIP-7892 allows future upgrades to change only blob-related settings, as mentioned earlier. EIP-7910 adds a new API method that lets software easily check what configuration or rules a node is using, improving transparency. EIP-7917 makes the process of predicting who will propose the next blocks more transparent and reliable, enhancing consensus security. EIP-7918 makes sure blob data fees stay aligned with the actual cost of processing them, stabilizing the fee market. EIP-7934 adds a strict size limit to certain block data, preventing oversized blocks. EIP-7935 raises the default block gas limit to 60 million (a point I will return to). EIP-7939 adds a simple new instruction for smart contracts, expanding smart contract capabilities. And EIP-7951 adds built-in support for a widely used cryptographic signature type, improving interoperability.
Discrepancy in Gas Limit Values
Fidelity Digital Assets described Fusaka as a decisive step toward a more strategically aligned and economically coherent roadmap for Ethereum. That's quite the endorsement from the TradFi world. However, let’s look at EIP-7935, which raises the default block gas limit to 60 million. Yet, the base gas ceiling has been raised to 120-150 million. This discrepancy (a factor of 2-2.5x) raises questions. Is the default gas limit increase sufficient to handle the increased data availability from layer-2 networks? Or will we see a bottleneck at the 60 million gas mark, negating the benefits of the higher ceiling?
Future Ethereum Upgrades
Ethereum developers moved quickly to ship the upgrade this year, combating a reputation for slow or delayed rollouts. That's a positive sign. The network is responsive and adaptable. The next big upgrade being scoped out is "Glamsterdam," and the Pectra upgrade is also in development, expected to improve financial settlement efficiency.
Conclusion: A Calculated Gamble
Fusaka is a calculated gamble. It addresses immediate concerns about scalability and data availability, but it also introduces new complexities and potential risks. The increased gas limit and PeerDAS are promising, but their real-world impact remains to be seen. The devil, as always, is in the details. Has Ethereum truly taken a decisive step forward, or is this just a temporary fix? My analysis suggests that while Fusaka is a necessary upgrade, it's not a silver bullet. It's a step in the right direction, but Ethereum still has a long road ahead.
