Interledger Protocol Stack Architecture

Protocol Layers

Hover over the layers to view their specific role and interface in the Interledger network.

Application: SPSP

Simple Payment Setup Protocol. Exchanged over HTTPS. The Client queries the Server's endpoint to retrieve the destination_account (ILP Address) and a cryptographically secure shared_secret prior to payment.

Transport: STREAM

End-to-End communication. Uses the shared_secret to encrypt data, generate conditions/fulfillments, and multiplex money/data streams. Connectors are completely blind to this layer.

Interledger: ILPv4

Core Network Layer. Hop-by-hop packet routing (Prepare, Fulfill, Reject). Connectors read the destination address, apply exchange rates, adjust timeouts, and forward packets to the next hop.

Link: BTP / HTTP

Bilateral Transfer Protocol. Establishes secure, authenticated peer-to-peer WebSocket connections between adjacent nodes. It wraps ILP packets, adding a necessary request/response layer for state tracking.

Sender / Client

Payment Originator

SPSP (HTTPS Client)

STREAM Module

ILPv4

BTP / Link

Connector

Intermediary Router

(Blind to STREAM/SPSP)

ILPv4 Router

BTP (In)

BTP (Out)

Receiver / Server

Payment Destination

SPSP Endpoint (HTTPS)

STREAM Module

ILPv4

BTP / Link

Underlying Ledger / Settlement Layer