There are challenges for both IP and ATM if either is to succeed on a global scale. For ATM, the main obstacle is likely to be the huge installed base of non-ATM technology. It is hard to believe that all those users will want to discard their existing network adaptors, hubs, routers, wiring, and so on. For IP, one of the biggest challenges will be to provide quality of service guarantees that are suitable for high quality voice and video, something that is likely to be available in ATM networks from the outset. In a sense, ATM does not deal well with heterogeneous technologies: it works best when everyone uses ATM. IP, at present, does not deal well with a wide range of applications: it is best suited to those without real-time constraints.
