The Simple Ordered Update Protocol (SOUP) and the Link-Ordered Update Protocol (LOUP) are loop-free alternatives to iBGP. They are clean-slate dissemination protocols for external routes that do not create transient loops, make stable route choices in the presence of failures, and achieve policy-compliant routing without any configuration. SOUP is provably loop-free, whereas LOUP converges faster, but can exhibit transients in the presence of very high churn rates. If you are interested take a look at the publications.
On this page you will find the simulator that was used during the development of the protocol, as well as resources on how to use it, how to repeat the experiments from the papers and how to extend it. The topologies and the BGP dumps used are also available for download.
If you are interested you can take a look at the publications and the list of protocols currently implemented.
N.Gvozdiev, B.Karp and M.Handley. LOUP: Who's Afraid of the Big Bad Loop? In HotNets-XI, 2012. pdf
N.Gvozdiev, B.Karp and M.Handley. LOUP: The Principles and Practice of Intra-Domain Route Dissemination. In NSDI, 2013. pdf