How do Layer 2 protocols achieve consensus?
Layer 2 protocols are designed to enhance scalability and throughput of blockchain networks by processing transactions off the main chain (Layer 1). They achieve consensus through various mechanisms that differ from those utilized in Layer 1 protocols.
1. Rollups
Rollups bundle multiple transactions together and submit them to the main chain as a single transaction. They maintain their own consensus algorithm, either optimistic or zero-knowledge (zk-rollups). Optimistic rollups assume transactions are valid and only check for fraud when challenged, while zk-rollups use cryptographic proofs to validate transactions before submission.
2. State Channels
State channels allow participants to conduct multiple off-chain transactions without broadcasting each one to the blockchain. Consensus is reached off-chain, and only the final state is recorded on the Layer 1 chain when the channel closes, ensuring efficiency and reduced costs.
3. Sidechains
Sidechains operate independently but are pegged to the main blockchain. They utilize their own consensus mechanisms, which may differ from the parent chain, enabling different rules and faster transaction finality while still allowing cross-chain asset transfers.
4. Plasma
Plasma uses a hierarchical structure of child chains that can execute transactions independently. It leverages the main chain for security and periodic commitment of state changes, combining elements of off-chain processing with Layer 1 security.
In summary, Layer 2 protocols use diverse approaches to consensus to improve blockchain scalability while maintaining security and decentralization.