This proposal introduces a protocol-level cap on the maximum RLP-encoded execution block size to 10 megabytes (MiB), which includes a margin of 2 MiB to account for beacon block sizes.
Currently, Ethereum does not enforce a strict upper limit on the encoded size of blocks. This lack of constraint can result in:
Additionally, blocks exceeding 10 MiB are not propagated by the consensus layer's (CL) gossip protocol, potentially causing network fragmentation or denial-of-service (DoS) conditions.
By imposing a protocol-level limit on the RLP-encoded block size, Ethereum can ensure enhanced resilience against targeted attacks on block validation times. Adding an additional margin of 2MiB explicitly accommodates beacon block sizes, ensuring compatibility across network components.
MAX_BLOCK_SIZE set to 10 MiB (10,485,760 bytes)SAFETY_MARGIN set to 2MiB (2,097,152 bytes)MAX_RLP_BLOCK_SIZE calculated as MAX_BLOCK_SIZE - MARGINMAX_RLP_BLOCK_SIZE must be considered invalid.Thus add the following check to the Ethereum protocol:
MAX_RLP_BLOCK_SIZE.MAX_RLP_BLOCK_SIZE.A cap of 10 MiB aligns with the gossip protocol constraint in Ethereum's consensus layer (CL). An additional 2MiB margin explicitly accounts for beacon block sizes, ensuring compatibility and consistent block propagation across the network. Blocks significantly larger than 10 MiB will not be broadcast by the CL, potentially leading to network fragmentation or denial-of-service scenarios.
This change is not backward-compatible with any blocks larger than the newly specified size limit. Validators and miners will need to ensure their block construction logic strictly respects this limit.
Restricting maximum block size provides inherent protection against deliberate oversized-block attacks.
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