Interledger Protocol (ILP) Architecture

ILP Payment Lifecycle

Hover over steps to highlight the protocol layer routing and underlying ledger settlements.

Setup & Addressing

The Receiver generates a cryptographic condition (hash) and shares it, along with their ILP Address, with the Sender (usually out-of-band via SPSP).

ILP Prepare Packets

The Sender constructs an ILP Prepare packet containing the condition and amount. Connectors route this packet hop-by-hop toward the Receiver.

Conditional Holds (Ledgers)

Simultaneously, peers execute conditional transfers on the underlying Ledgers. Funds are locked (held) pending the release of the cryptographic preimage.

ILP Fulfill (The Preimage)

The Receiver validates the packet and replies with an ILP Fulfill packet containing the fulfillment (preimage). This packet travels back exactly the way it came.

Ledger Settlement

As the Fulfill packet is routed back, Connectors use the revealed preimage to execute/claim the conditional holds on their respective underlying ledgers, settling the funds.

ILP Protocol Layer (Data)

Underlying Ledger Layer (Value)

Sender

alice.bank.acc

Connector Alpha

ILP Router

Connector Beta

ILP Router

Receiver

bob.crypto.wallet

Ledger A (Fiat Bank)

Sender Acct Conn Alpha Acct

Ledger B (Blockchain)

Conn Alpha Conn Beta

Ledger C (Mobile Money)

Conn Beta Acct Receiver Acct