A Detailed Study of Asynchronous Transfer Mode Techniques

TELECOMMUNICATIONS STANDARDS have usually followed sometime after the development of products for a particular need. This has led to subtle, or sometimes gross, incompatibilities between two functionally similar products, making interworking both inefficient and expensive. When telecommunication networks were largely considered as a local, or national, resource then the incompatibilities were not particularly significant; but, in many respects, the public network now needs more and more to be regarded as an international resource and such matters as interworking cannot be 'put on one side' until the local network is functioning. The cost of designing and installing the equipment is now so great that to justify replacing the current network with a new one requires that significant benefit be obtained by doing so and, further, that a similar need must not occur again for a long time (if ever). This paper describes in detail the background and functionality of a B.I.S.D.N., showing how both new and old, error-sensitive and delay-sensitive, services can co-exist on a single network. The prospects of implementing such a network are still a few years in the future, and it will not appear 'overnight': in the interim it will be necessary for the new and old networks to interoperate. At present, the plain old telephone service (POTS) is still, by far, the largest revenue earner for the network operators and such a service must continue to be provided with an equivalent, or higher, grade of service (GOS, or quality of service, QOS) in any new system that is installed.