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Future Ethereum Upgrades

Two upcoming Ethereum upgrades change the transaction pipeline: ePBS in Glamsterdam, and FOCIL in Hegotá. Both are fully compatible with MPBC.

ePBS​

Enshrined Proposer-Builder Separation (ePBS) moves the handoff between proposer and builder into the Ethereum protocol. It is specified as EIP-7732 and planned for the Glamsterdam upgrade.

In PBS, proposers sign bids without seeing the blocks behind them because knowledge of the block allows them to propose it as their own, withholding compensation for the builder that has constructed it. Blind commitments therefore need a guarantee that a valid block exists and will be released. This is addressed by the relay, which escrows the builder's block, showing the proposer only the bid, and releasing the payload after the proposer commits to the block.

ePBS removes the need for escrow by enshrining the commit and the reveal in the protocol. For that exchange to be trustless the proposer has to be paid even when the builder never reveals the block, so builders register with the protocol as staked entities and lock stake. The proposer is paid out of that stake whether or not the payload arrives, which makes the payment unconditional. A staked builder can bid over a direct connection or the public P2P network, or improve the value of its blocks through MPBC by connecting through a MPBC operator.

ePBS and MPBC​

ePBS moves escrow into the protocol which removes the need for a trusted hand-off between builders and the proposer. This complements MPBC as operators can register as staked entities and offer unconditional payments on the same terms as builders. Operators can also connect to the proposer outside of the protocol and provide particularly competitive bids that can exceed the stake any builder has locked, keeping the auction competitive for the most valuable blocks.

FOCIL​

Fork-Choice enforced Inclusion Lists (FOCIL) gives a committee of validators the power to force transactions into blocks. It is specified as EIP-7805 and planned as the consensus-layer headliner of Hegotá, the upgrade after Glamsterdam.

Every slot, sixteen validators each build an inclusion list from their own view of the public mempool. The next block must include the union of those lists. A block may omit transactions contained within the combined inclusion list only if it has insufficient space, or when a specific transaction would be invalid at the end of the block. Inclusion lists are constructed from transactions visible in the public mempool, therefore transactions sent directly to builders are not considered.

Inclusion lists and MPBC​

FOCIL guarantees inclusion for transactions the protocol is aware of, i.e., the public mempool. MPBC increases the probability of inclusion for transactions any builder is aware of, including private order flow and searcher bundles. Additionally, base blocks that fail to satisfy an inclusion list no longer need to be discarded as operators can add the required transactions through MPBC.