Overview
Overview of multi-party block construction.
Background
In early Ethereum, validators built their own blocks. They would look at the mempool, pick the transactions with the highest fees, order them, and propose the result. This was simple and fair enough when block construction was straightforward. But as on-chain activity grew, block construction became a competitive, technical challenge. The order in which transactions appear inside a block affects the block's value. A validator who could strategically order transactions stood to earn significantly more than one who simply sorted by fee.
The MPBC Upgrade
How multi-party block construction works and its impact.
MPBC Mechanism
MPBC has two stages, a merging stage where operators add transactions from multiple builders to a base block, and a delivery stage where they deliver the highest-paying block to the proposer.
Specifications
MPBC defines four interfaces that allow builders to submit blocks and merging preferences to an operator, operators to share information between themselves, proposers to receive bids, and any stakeholder to query an operator for merging data. MPBC does not prescribe a specific implementation beyond these interfaces, and operators are encouraged to run performant and uncorrelated proprietary implementations.
Node Operators
What MPBC changes for validators, and why most setups already using PBS need no configuration change.
Builders
MPBC compensates builders for flow added to their blocks and for contributions to other builders' blocks. This allows earning revenue without winning the slot outright, and increases the likelihood that a block serving as the base for MPBC wins the auction.
Live Metrics
Multi-party blocks as they are produced: how many, how much value they add, where the surplus goes, and what any address earned.
Roadmap
What is shipped, what is next, and roughly when.
Future Ethereum Upgrades
Two upcoming Ethereum upgrades change the transaction pipeline: ePBS in Glamsterdam, and FOCIL in Hegotá. Both are fully compatible with MPBC.
FAQ
Frequently asked questions about multi-party block construction.