PHOTON: a software system for SONET interoperability analysis

SONET is a standard for fiber-optics equipment. One of the main reasons for developing SONET was interoperability: the ability of network elements from different suppliers to work with each other. In the past, however, compliance of equipment to standards has not always guaranteed interoperability. Thus, it is important to determine whether there are conditions under which interoperability cannot be achieved in SONET. An obvious approach to identifying these conditions is building SONET networks and testing them. While this “hardware” approach yields valuable empirical information, it tends to be limited in scope. The scope can be substantially expanded with a “software” approach, based upon modeling and simulating SONET networks. The paper reports on an exploration of this approach. The paper outlines PHOTON, a research prototype software system, which models and allows simulation of a subset of SONET´s alarm-surveillance procedures. Based upon experience with PHOTON, the software approach appears feasible for interoperability analysis of SONET. In particular, it appears feasible to model the scale and complexity of other parts of SONET in a timely, accurate and computationally efficient manner