How does Ripple find payment paths?
Ripple allows each node to identify itself with keywords, preferably those shared by many of the node’s neighbours, such as city/province/country, but also possibly with unique keywords, such as the node’s URI. Ideally, each node would store the shortest distance in every direction to a node with any given keyword, but that would involve developing an potentially complicated protocol for keeping such tables up-to-date. And since ever-shifting account balances mean that payment paths cannot be counted on long-term, it might not be worth the effort. Instead, as search messages are sent out with source and destination keywords appended, each node that sees the message keeps track of where those keywords came from, and whether their guess where to route the search message was successful. This information can be used to help route future queries on those same keywords. More about searching.
