Visualizing the Transfer of ILP Packets

Let’s visualize some of the ILP learning elements from the prior story. ILP specified three kinds of packets, two of them shown here.

stateDiagram
    direction LR
    Sender --> Connector1 : Prepare
    Connector1 --> Connector2 : Prepare
    Connector2  --> Receiver : Prepare
    Receiver --> Connector2 : Fulfill
    Connector2 --> Connector1 : Fulfill
    Connector1 --> Sender : Fulfill

Prepare packets are the initial communications from the sender to the receiver, communicating that some amount of money needs to be transferred.

Fulfill packets confirm that the payment (or IOU) should be completed. As each node in the network gets the Fulfill packet, they adjust their balance and “accept” the IOU. Like in the analogy, each node effectively only deals with its immediate peers, but this can still allow money to go from one node to another node through any number of paths.

The third kind of packet is a Reject packet. If any problems occur at any stage in the process, this packet is sent back to the sender, cancelling the transaction.

This whole process happens in milliseconds. In fact, if it doesn’t happen quickly enough, that will itself trigger a Reject packet.