Combine XL with mesh networks, and unusual radio propogation and you have something interesting and suddenly usable. One problem with large (10's of thousands of nodes) mesh networks has always been how to contain the routing information, and where to draw "edge" boundaries. Just when you thought you'd had a clearly defined problems you have monkey wrenches tossed into your problem such as transient propogation conditions or mobile (possibly rapidly moving) nodes, unusual antenna patterns and other such problems. There was always a tradeoff between limiting connectivity and maximizing network efficiency. Consider the case of an airborn node flying through a mesh, both needing connectivity and providing it. Typical algorhythms would be unusably slow at converging and provide a route that is unusable by the time it is stable.