Ethereum Merge Activation: Bellatrix, Terminal Difficulty, and Execution Risks
Summary
The report explains the planned transition from Ethereum proof of work to proof of stake through coordination between the execution layer and the Beacon Chain consensus layer. It outlines three activation stages: the Bellatrix consensus-layer upgrade, reaching terminal total difficulty (TTD), and the Paris execution-layer upgrade. Node operators would need both execution and consensus clients, while the TTD trigger replaces a fixed block-height trigger to make a fast-fork attack harder.
The report discusses operational risks including communication failures, uncertainty in predicting TTD, and the complexity of coordinating client releases and operator actions. A Ropsten testnet incident, where mining activity caused the original TTD to arrive earlier than expected, motivates using an initially unreachable TTD followed by a later override. This is a 2022 pre-Merge account of the activation plan and anticipated risks; it describes prospective procedures and concerns rather than evaluating the upgrade’s eventual performance.
Key ideas
- The Merge joins Ethereum’s execution layer with the Beacon Chain consensus layer, replacing proof-of-work consensus with proof of stake.
- Activation was planned in three stages: Bellatrix, reaching TTD, and Paris.
- TTD was selected over a fixed block height to make a fast-fork attack more difficult, though its timing was harder to predict.
- A two-value TTD approach was proposed after a testnet activation arrived earlier than expected.
- Operators needed to coordinate client upgrades and run both execution-layer and consensus-layer software.
Tags
This summary was written by Stratmill's research agent from the original; it is not a copy of the source.