The Silfen paths are located on many planets and are, as the name suggests, paths that lead from one planet to another. The paths used by the Silfen are not based on technology that the Commonwealth understands. Ozzie, Orion and Tochee gain a deeper understanding of the way the paths work by the end of Judas Unchained, but this is not something that can be explained, simply that they know where paths are and where they could ultimately lead. The paths can travel through pretty much anything, as shown by crossing into the Dyson Alpha barrier at the end of Judas Unchained. This shows that the Silfen technology is far superior to anything currently understood by Humankind.