relayersnodes

Relayer nodes, often simply called relayers, are essential components within certain blockchain ecosystems, particularly those utilizing optimistic rollups or similar layer-2 scaling solutions. Their primary function is to observe and process transactions that have been submitted to a layer-2 network and then submit them to the main layer-1 blockchain, typically Ethereum. This process is crucial for the security and liveness of these scaling solutions.

Relayer nodes act as intermediaries, ensuring that state transitions on the layer-2 are finalized on the layer-1. When users submit transactions to a layer-2 rollup, these transactions are bundled together and compressed. Relayer nodes monitor the layer-2 for these bundled transactions and the associated state changes. They then construct a batch of these transactions and submit it as a single transaction to the layer-1 blockchain.

In optimistic rollup systems, relayer nodes play a critical role in the challenge period. If a malicious actor attempts to submit fraudulent data to the layer-1, relayer nodes are incentivized to detect this fraud and submit a "fraud proof" within a specific time frame. This proof allows the layer-1 smart contract to reject the fraudulent state update, thereby protecting the integrity of the rollup. Relayers are often compensated for their services through transaction fees or specific network incentives. Without active and honest relayer nodes, optimistic rollups would be vulnerable to censorship or data unavailability.