The upcoming Dencun upgrade marks a pivotal moment in Ethereum’s evolution, introducing EIP-4844—commonly referred to as proto-danksharding. This enhancement is designed to address one of Ethereum’s most pressing challenges: high transaction costs for Layer 2 (L2) networks. By introducing a new type of transaction and a novel data structure called blobs, EIP-4844 lays the groundwork for scalable, cost-effective rollup operations.
In this comprehensive guide, we’ll explore the mechanics of EIP-4844, the role of blob transactions and blob gas, and the transformative impact on L2 networks and the broader Ethereum ecosystem.
The Challenge: High Gas Fees for Layer 2 Networks
Layer 2 solutions such as Optimism, Arbitrum, and Base are essential for Ethereum’s scalability. They process transactions off-chain and periodically submit batched data back to the Ethereum mainnet (Layer 1) for final settlement. Currently, this data is posted using calldata, a part of Ethereum transactions that stores input data permanently on-chain.
While secure, calldata is expensive. Every byte written to Layer 1 incurs gas fees, and with L2s processing thousands of transactions per batch, these costs add up quickly. In December 2023 alone, L2 networks collectively spent over 15,000 ETH (approximately $34 million USD) on data posting—highlighting the urgent need for a more efficient alternative.
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The Solution: Blob Transactions and Proto-Danksharding
EIP-4844 introduces type-3 transactions, which carry blobs—large blocks of temporary data used specifically for L2 settlement. These blobs are not processed by the Ethereum Virtual Machine (EVM), but they are secured by consensus, making them both cheaper and scalable.
Key Features of Blob Transactions
- Each Ethereum block can include up to 6 blobs.
- A single type-3 transaction can carry 1 or 6 blobs.
- Each blob can store up to 128 KB of data.
- Users pay for the full 128 KB even if the space isn’t fully utilized.
- Blobs are stored temporarily—approximately 18 days (4096 epochs)—before being pruned from nodes.
This limited retention period significantly reduces storage burden on validators, allowing blobs to be priced much lower than calldata. Since calldata is stored permanently, it's inherently more expensive. Blobs, by contrast, provide a "just-in-time" data availability layer perfect for rollup security needs.
Technical Enhancements: New Transaction and Block Fields
EIP-4844 introduces new fields to both transactions and block headers to support blob operations.
In Type-3 Transactions:
max_fee_per_blob_gas: The maximum amount a user is willing to pay per unit of blob gas.blob_versioned_hashes: A list of versioned hashes derived from KZG commitments, ensuring cryptographic integrity of the blob data.
In Block Headers:
blob_gas_used: Total blob gas consumed in the block.excess_blob_gas: Tracks cumulative excess blob usage over time, used to dynamically adjust blob base fees.
These additions enable a separate pricing market for blob data—distinct from the traditional EVM gas market.
How Blobs Are Propagated Across the Network
Unlike standard transactions that reside entirely in the mempool, type-3 transactions follow a unique propagation model:
- The transaction itself enters the mempool and contains only a reference (hash) to the blob.
- The actual blob data is transmitted via a blob sidecar, managed by consensus clients.
- Execution clients do not process or store the blob content—only its commitment.
This separation improves network efficiency and reduces bandwidth pressure on execution nodes, aligning with Ethereum’s modular design philosophy.
Understanding Blob Gas Pricing
EIP-4844 introduces an independent blob gas market, inspired by EIP-1559’s dynamic fee mechanism. The system adjusts blob base fees based on demand relative to a target:
- Target: 3 blobs per block.
- If more than 3 blobs are included → blob base fee increases.
- If fewer than 3 blobs are included → blob base fee decreases.
- If exactly 3 → fee remains unchanged.
This elastic pricing ensures that blob space remains affordable during low demand while preventing spam during peak usage.
Additionally, type-3 transactions still include:
max_fee_per_gasmax_priority_fee_per_gas
These cover the standard computational gas used by the transaction (e.g., signature verification), separate from blob costs.
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Frequently Asked Questions (FAQ)
What is EIP-4844?
EIP-4844, or proto-danksharding, is an Ethereum upgrade that introduces blob-carrying transactions to reduce data availability costs for Layer 2 networks.
How do blobs reduce L2 costs?
Blobs provide temporary, low-cost data storage—much cheaper than permanent calldata—allowing L2s to post transaction batches at a fraction of current fees.
Are blobs stored forever like calldata?
No. Blobs are stored for approximately 18 days (4096 epochs), which is sufficient for all network participants to verify and challenge fraud proofs if needed.
What is the difference between blob gas and regular gas?
Blob gas applies only to blob data transmission and storage, while regular gas covers EVM computation. They operate in separate markets with independent pricing mechanisms.
Will all L2s adopt blob transactions immediately?
Adoption will vary. While most major L2s plan to integrate EIP-4844 post-Dencun, operators must evaluate cost trade-offs between type-2 (calldata) and type-3 (blob) transactions under fluctuating network conditions.
What comes after EIP-4844?
EIP-4844 is a stepping stone toward full danksharding, which will further scale Ethereum by enabling distributed data sampling and higher throughput via sharded blob chains.
Implications for Layer 2 Networks
The introduction of blobs is expected to drastically reduce settlement costs for L2s—potentially by 90% or more in many cases. Analysts predict that blob base fees will often hover near their minimum due to underutilized capacity in early stages.
However, this innovation brings new operational complexity:
- L2 operators must now monitor two separate fee markets: EVM gas and blob gas.
- Strategic decisions arise around batching: Should an L2 wait to fill an entire blob? Or share space with another L2?
- Emerging coordination models—such as shared sequencers or blob pooling—could unlock further efficiencies through collective optimization.
These dynamics will shape the next generation of rollup economics and competitive positioning within the L2 landscape.
Future Outlook: Toward Full Danksharding
EIP-4844 is not an end goal—it’s proto-danksharding, a foundational step toward full danksharding. Future upgrades will build on this infrastructure by:
- Increasing the number of blobs per block.
- Enabling proposer-builder separation (PBS) at scale.
- Introducing data availability sampling (DAS), allowing light clients to verify large datasets efficiently.
Together, these advancements will move Ethereum closer to its vision of becoming a highly scalable, globally accessible settlement layer.
As Dencun rolls out, developers, node operators, and L2 teams must adapt to new observability requirements and optimize their systems for hybrid fee environments. The era of affordable rollups has begun—and it starts with blobs.
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