Network

The network layer of the Cardano protocol handles two aspects of communication:

• Node-to-node (N2N) - transmission of data between network nodes
• Node-to-client (N2C) - integration of application clients to a single node

graph LR
    A(Node)
    B(Node)
    C(Node)
    X[Client]
    Y[Client]
    A <-->|N2N| C
    A <-->|N2N| B
    B <-->|N2N| C
    X <-->|N2C| A
    C <-->|N2C| Y

The network protocols consist of a multiplexing layer which carries one or more mini-protocols, according to the type of connection - for example:

graph TB
    HS(Handshake)
    CS(ChainSync)
    BF(BlockFetch)
    Mux[Multiplexing]
    Con([Raw Connection])

    HS <--> Mux
    CS <--> Mux
    BF <--> Mux
    Mux <--> Con

Shared mini-protocols

These protocols are used in both N2N and N2C modes:

• Handshake - for connection and version negotiation
• Chain Synchronization - for synchronization of changes to the Cardano chain¹

Node-to-node mini-protocols

These protocols are only used for node-to-node communication:

• Block Fetch - for transferring chain blocks between nodes
• Transaction Submission - for propagating transactions between nodes
• Keep Alive - for maintaining and measuring timing of the connection
• Peer Sharing - for exchanging peer information to create the peer-to-peer (P2P) network

Node-to-client mini-protocols

These protocols are only used for node-to-client communication:

• Local State Query - for querying ledger state
• Local Tx Submission - for submitting transactions locally
• Local Tx Monitor - for monitoring transactions

Dummy mini-protocols

These protocols are only used for testing and experimentation:

• Ping-Pong - a simple presence test
• Request-Response - a generic mechanism for exchanging data