This paper deals with the problem of controllers/filters implementation over networked control systems (NCS). The implementation of a given controller/filter over NCS is not unique, depending on its realization and how it is distributed over several CPU. The point here is to consider a dedicated descriptor model, allowing the essential features of the implementation to be represented. This macroscopic model accounts for the inherent delays or packet losses occurring during communication between subsystems. It makes possible to consider in the same framework, deteriorations induced by implementation of whatever nature: i) computation using a Finite Word Length arithmetic and ii) communication delays over the network. Focusing on the last point, the paper shows how to evaluate the resilience of a given realization against internal delays. Finally, a filtering problem is considered to show the importance on how the filter is implemented, by using the modeling and analyzing tools proposed.