Full & Light Nodes

Full Nodes

Full nodes can be thought of as the backbone of the Bullet network. Similar to Solana validators, they receive and execute transaction data to sync with the tip of the rollup network. Unlike Solana validators, however, they receive their data from the DA layer (rather than from gossip) and don't participate in consensus voting, only execution.

Since transactions have to first be ordered, batched and written to DA before they can be read by full nodes, they lag the sequencer state by several seconds (this is essentially the difference between sequencer "soft" and full node "hard" finality). But for the sake of a typical user interacting via an application, soft finality is all they should need.

Full nodes as we say above have to download full blocks from DA and execute every transaction in them, requiring their hardware specs to be non-negligible in order to keep up with the breakneck pace of Bullet. To trustlessly read the state of the network you can run your own full node (more expensive), else you can choose to trust a 3rd party RPC provider to run one as is common on Solana.

Prover Nodes

Prover nodes are basically identical to full nodes, except that they run their computation in a zero-knowledge Virtual Machine (zkVM) instead of native Rust. This allows them to either create validity proofs of entire blocks (zk-mode), or simply create fraud proofs (optimistic mode) which can be posted to the DA layer where any disputes can be publicly verified and settled. If a prover is successful in challenging the integrity of a sequencer's work, the prover can earn the bond that has been slashed from the dishonest sequencer.

Light Nodes

Light nodes, also known as lightweight clients, require only block headers—containing the zero-knowledge (zk) proofs, rather than the full block data—to be downloaded and verified. This approach eliminates the need for heavy transaction execution, resulting in much lower hardware requirements. Light nodes are excellent for decentralization since they allow frontends, mobile devices, and other client-side hardware to trustlessly determine the state of the rollup.