4. SUMMARY
A feature of the development of the Internet has been the
gradual erosion of the end-to-end principle. In a world of
mobile gateways, NATs and other middlebox impositions, it
is less clear what it means for the ends" to connect. Sign-
posts is a system which allows us to evolve past this current,
rather unsatisfactory, state of aairs. It provides a control
plane that enables edge-to-edge connectivity, between the
many heterogeneous and often mobile edge networks that
have now sprung up around the Internet.