rollup chains batch the transactions data of its blocks/transactions, and submit it to mainnet(layer 2 e.g. ethereum ).

But i doubt if rollup chain submit all data of all transactions in batch form, or just submit the transactions data which take place between two chains. e.g. transfer like ethereum to optimism's etherum.

what data of layer 2 rollup chains are submitted to main blockchain (layer1) ?

1 Answer 1


Rollups submit all their transactions to L1.

It's necessary in order to have the same security assumptions as the L1. Other nodes can use the list of L2's transactions to reconstruct its state and validate the chain themselves.

In optimistic rollups this is needed to catch the sequencer if it submits fraudulent transactions.

In zk rollups it's needed so that other nodes are able to produce validity proofs and the sequencer can't stall the chain.

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