P2P Network

1. Steps

When a node connects to the blockchain network for the first time, it follows a series of steps to establish a connection, synchronize with the network, and become a fully participating node. Here is an overview of these steps along with the messages typically exchanged:

1. Network Discovery:
   • The node initiates a connection to one or more seed nodes, which are well-known nodes in the network.
   • The node sends a version message to the seed node, containing its protocol version, network services, and a nonce.
2. Handshaking:
   • The seed node responds with a version message, containing its own protocol version, services, and nonce.
   • The node verifies the seed node's identity and checks protocol compatibility.
   • The node may send a verack message to acknowledge the successful connection.
3. Synchronization:
   • The node sends a getheaders message to request block headers from the seed node.
   • The seed node responds with headers in a headers message, containing a sequence of block headers.
   • The node verifies the headers, checks their validity and links to the existing blockchain, and requests missing headers if needed.
   • The node may send a getdata message to request full blocks for the missing headers.
   • The seed node responds with the requested blocks in a block message.
4. Validation and Consensus:
   • The node verifies each received block, checking its validity and adherence to the consensus rules.
   • The node may send getdata messages to request missing transactions referenced in the blocks.
   • The seed node or other connected nodes respond with the requested transactions in a tx message.
   • The node validates and verifies each transaction.
5. Peer-to-Peer Networking:
   • Once the node has synchronized with the blockchain and validated the data, it becomes a fully participating peer.
   • The node can connect to additional nodes in the network and exchange messages such as version, verack, ping, pong, inv, getdata, etc.
   • The node actively participates in the decentralized peer-to-peer network, receiving new transactions and blocks, propagating its own transactions and blocks, and contributing to the network's security and consensus.

1.1. Connection Path

send version message → receive version message → check protocol compatibility → send verack message → getheaders message → receive headers message

→ check their validity and links to the existing blockchain

→ getdata message

→ receives block message

→ verifies each block