The eth1_data field and execution_payload in a beacon chain block serve different purposes, even though they may seem related due to their connection to the Ethereum execution layer.
eth1_data
pub struct Eth1Data {
pub deposit_root: Hash256,
#[serde(with = "serde_utils::quoted_u64")]
pub deposit_count: u64,
pub block_hash: Hash256,
}
eth1_data specifically exists to help with the deposit contract and the initial staking mechanism that allowed the Beacon Chain to track validators registering on Ethereum 1.0 (the proof-of-work chain) before the merge. It tracks the root of the Eth1 deposit logs and includes the following fields:
deposit_root: The Merkle root of the deposit contract's logs.deposit_count: The total number of deposits processed.block_hash: The block hash of the corresponding Ethereum PoW chain
block (before the merge).
These fields help ensure that deposits made to the deposit contract on the execution layer are reflected and synchronized on the Beacon Chain, which was crucial before the merge when Eth1 and Eth2 were distinct. This was necessary for the registration of validators since the Beacon Chain needs to keep track of validator deposits made on the execution layer (Eth1).
execution_payload
pub fn execution_payload(&self) -> Result<Payload::Ref<'a>, Error> {
match self {
Self::Base(_) | Self::Altair(_) => Err(Error::IncorrectStateVariant),
Self::Bellatrix(body) => Ok(Payload::Ref::from(&body.execution_payload)),
Self::Capella(body) => Ok(Payload::Ref::from(&body.execution_payload)),
Self::Deneb(body) => Ok(Payload::Ref::from(&body.execution_payload)),
Self::Electra(body) => Ok(Payload::Ref::from(&body.execution_payload)),
}
}
After the merge, the execution_payload is the link between the execution layer (formerly Ethereum 1.0, now part of the proof-of-stake chain) and the consensus layer (Beacon Chain). It contains all the transactions of an execution block, effectively representing the transaction execution on the Ethereum network. It includes:
- Transactions and block data that directly relate to the Ethereum
execution layer.
- The core component that ensures Ethereum's execution layer functions properly after the merge.
Why eth1_data Still Exists and Why It's Behind the execution_payload
Purpose: eth1_data continues to exist post-merge for backward compatibility and to maintain validator information related to deposits. It does not track regular Ethereum transactions but only the specific deposit contract logs, which are used for validator onboarding.
Deposit Tracking: While the deposit transactions technically appear in the execution_payload as regular transactions, eth1_data ensures the consensus layer knows the cumulative state of the deposit contract, which is critical for managing validators in the proof-of-stake system. The eth1_data is updated periodically, not in real-time, which explains why it lags behind the execution_payload by a few thousand blocks.
Lag: The lag between eth1_data and the execution_payload is due to how often the consensus layer fetches and processes deposit data. It is designed to be asynchronous to avoid real-time coupling with the execution layer, which minimizes dependencies between the two layers. This allows the beacon chain to focus on consensus while periodically synchronizing validator deposits from the execution layer.
Different Treatment by Beacon Nodes
Execution Payload: Used directly to finalize the state of the execution layer, including all transactions.
Eth1 Data: Primarily used for managing validator deposits and onboarding. It’s part of the historical process to onboard new validators and will likely diminish in importance as validator onboarding stabilizes.
In summary
While both fields are linked to the execution layer, they serve distinct roles: eth1_data is for tracking validator deposits, and execution_payload handles the execution of all transactions. The lag is due to the asynchronous design in syncing validator deposits from the execution layer.
