This is a multi-server Ripple with person-to-person consensus only. It is built on a penalty system that applies a force on the multi-hop payment coordination (see multihop.xyz for an interactive simulation). The penalty system advances on Ryan Fugger's original idea of a penalty as an enforcement mechanism. This implementation also solves the Two Generals' Problem, something Ryan Fugger never did in his original Ripple Inter Server Protocol design ideas as far as I am aware (Ryan did address user-to-user consensus as early as 2006 here, that state changes had to be agreed on, but never mentioned how to do so as far as I know).
Whitepaper: ripple_inter_server_protocol.pdf (and for an article with some images, see multi_hop_payment_game_theory.pdf
Repository: bitbucket.org/bipedaljoe/ripple (also on ripple.archi/code)
Simulation: 8_users_payment_scenario.json
Simulation output: output.txt
Illustration of the web-of-trust and payments in the simulation above (full size)
Contact: johan@ripple.archi
Ripple papers by Ryan Fugger: 2003, 2004, 2006
Resilience swarm redistribution on ripple.archi: My system "Resilience" (swarm redistribution) is added in full in the code at bitbucket.org/bipedaljoe/resilience/. Formal website for it is on resilience.me.