Updated on May 20, 2022
The Ethereum upgrade known as The Merge will merge the Beacon Chain into Ethereum Mainnet, turning Mainnet into a combination of an execution layer and consensus layer. The Merge will transition Mainnet from proof of work to proof of stake consensus.
Execution and consensus clients
After The Merge, a full Ethereum Mainnet node will be a combination of an execution client (previously called an Ethereum 1.0 client) and a consensus client (previously called an Ethereum 2.0 client).
Execution and consensus clients communicate with each other using the Engine API.
Execution clients, such as Besu, manage the execution layer, including executing transactions and updating the world state. Execution clients serve JSON-RPC API requests and communicate with each other in a peer-to-peer network.
Consensus clients, such as Teku, contain beacon node and validator client implementations. The beacon node is the primary link to the Beacon Chain (consensus layer). The validator client performs validator duties on the consensus layer. Consensus clients serve REST API requests and communicate with each other in a peer-to-peer network.
What happens during The Merge
Teku will periodically request information about the execution client’s configuration to check that they agree on the configuration and can connect. Teku will log warnings if the configuration doesn’t match.
The consensus layer will enable the Merge configuration (Bellatrix) before reaching the TTD. Once the execution layer blocks reach the TTD, the Beacon Chain will merge into Ethereum Mainnet, and Ethereum will move to a proof of stake network.
After The Merge, a Mainnet node operator must run both an execution client and a beacon node at the same time. To become a validator, you must also run a validator client (either in the same process as the beacon node or separately).
You can prepare Teku for The Merge.