The main purpose of the thesis work is to conduct a critical and in-depth study of the routing algorithms adopted by LEO satellite constellations. In particular, the focus is on finding conventional standards or approaches that are applied in real constellations and that govern the flow of data exchanged by satellites through Inter Satellite Link(ISL). The work not only clarifies these aspects, but also aims to offer a methodology and a set of tools useful for recreating a LEO constellation in an emulated environment in order to conduct test experiments and analysis.