# Nexus: Settlement on ETH L2s

A zkLink Nexus L3 rollup settles the transactions and transition of states on Ethereum's L2s, and the L2s settle on Ethereum. The smart contract on Ethereum plays the key role to check if sync hashes from different rollups are consistent.

<figure><img src="https://3769499472-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F6MmO5lFN4McSMz0tzyOs%2Fuploads%2Fgit-blob-d6b3830e865517033b7a5e245ba07a1c99ee9e95%2Ffigure3.png?alt=media" alt=""><figcaption><p>Security inheritance of zkLink Nexus</p></figcaption></figure>

The settlement process of a Nexus L3 rollup is shown above. Nexus rollup posts data and ZKP to the connected L2s, where the correctness of the states and transactions is verified via the verifier contract.

Since the correctness of the states and transactions of L2s will be finalized on Ethereum via validity proof (for ZK-Rollup L2s) & fraud proof (for Optimistic-Rollup L2s), and multi-chain state synchronization is finalized via Ethereum, it could be stated that a zkLink Nexus L3 rollup inherits the security of Ethereum.


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