+ * @brief Probe the routing path between two points
+ *
+ * The networking model uses this function when creating a communication
+ * to retrieve both the list of links that the create communication will use,
+ * and the summed latency that these links represent.
+ *
+ * The network could recompute the latency by itself from the list, but it would
+ * require an additional link set traversal. This operation being on the critical
+ * path of SimGrid, the routing computes the latency in behalf of the network.
+ *
+ * Things are rather complex here because we have to find the path from ASes to ASes, and within each.
+ * In addition, the different ASes may use differing routing models.
+ * Some ASes may be routed in full, others may have only some connection information and use a shortest path on top of that, and so on.
+ * Some ASes may even not have any predefined links and use only coordinate informations to compute the latency.
+ *
+ * So, the path is constructed recursively, with each traversed AS adding its information to the set.
+ * The algorithm for that is explained in http://hal.inria.fr/hal-00650233/