Requirements formalization and validation for a telecommunication equipment protection switcher

Using formal methods, namely model checking, we can automatically verify a formal model of the requirements against given properties. This allows us to detect errors early an the design process, thus decreasing development cost and t ime t o market. However to modi fy a well established design process t o introduce formal methods is not easy. W e present a case study exploring the possibility of replacing informal functional specifications with formal ones in the design process of telecommunication Equipment Protection Switchers (EPSs . formal specs f rom informal requirements is comparable with that for writing informal functional specs f rom informal requirements. This suggests that for EPSs replacing informal functional specs in the design process with formal specs can be done without suffering delays due t o the formalization activity.