Ethereum’s Fusaka upgrade is more than just PeerDAS as it introduces Blob Parameter Only (BPO) forks, a lightweight yet powerful mechanism that allows Ethereum to scale blob throughput gradually without overwhelming validators. By tweaking only blob target & blob maximum values, BPO forks ensure Ethereum’s rollup ecosystem can keep growing sustainably.

What Are BPO Forks?

BPO forks (Blob Parameter Only) are a new type of Ethereum upgrade designed to make incremental changes to blob capacity. Unlike traditional hard forks that include many EIPs at once, BPO forks only adjust two values:

  • Blob target (the expected number of blobs per block)
  • Blob maximum (the hard cap per block)

This makes them fast, safe, and easy to deploy, acting as pressure valves against congestion. For Fusaka, two BPO forks are planned:

  • BPO1: Raises blob target & max to 10 & 15
  • BPO2: Raises blob target & max further to 14 & 21
    Each step helps Ethereum handle increasing rollup demand without risking network instability.

Why BPO Forks Matter

Since the Dencun upgrade, demand for blobs has skyrocketed. Ethereum frequently hits the 9 blobs per block limit, pushing rollup fees higher. Left unchecked, this could drive rollups to alternative data availability layers like Celestia.

BPO forks prevent this by providing a timely scaling solution. Instead of waiting for a full hard fork cycle, developers can introduce targeted adjustments to keep Ethereum’s blob supply aligned with demand.

This approach also strengthens Ethereum’s position as the primary settlement layer for rollups by keeping costs competitive.

The Balancing Act

Scaling blobs isn’t just about raising limits—it’s about safeguarding decentralization. According to EIP-7892, blob growth must account for bandwidth constraints faced by solo stakers running validators at home.

Ethereum researchers have identified ~50 Mbps as a safe baseline for node operators. Every BPO fork undergoes congestion testing & safety validation to ensure blocks still propagate reliably across the network.

By balancing scalability with inclusivity, BPO forks protect Ethereum’s ethos: a network that anyone can validate.

Fusaka’s use of BPO forks represents a measured path forward in Ethereum’s scaling roadmap. PeerDAS enables blob sampling, while BPO forks ensure capacity grows steadily without compromising decentralization. Together, they mark a turning point: Ethereum scaling not just bigger, but smarter.

BPO forks may be small in scope, but their impact is massive—they’re Ethereum’s secret weapon against blob congestion, ensuring rollups remain cheap, secure, & firmly anchored to Ethereum L1.

If you find any issues in this blog or notice any missing information, please feel free to reach out at yash@etherworld.co for clarifications or updates.

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