We report on recent developments on stochastic chain modelling of inter-dependent network infrastructures. The problem is approached in the spirit of the Leontief tradition within the framework of the Inoperability Input/Output Modelling  where, instead of dealing with the sector products, inoperabilities are introduced to describe the status of the global system.
A Markov Chain evolution law replaces Leontief equilibrium condition upon external changes, thus allowing to follow the transition from an equilibrium configuration to an other and possibly mimic cascade effects triggered by unwilled disturbances. Moreover, as a variation to the “System of Systems” approach, each network is not treated like an holomorphic entity, but its inner structure is inspected. Multiple implementations of the same scenarios at different level of granularity have been compared providing evidence for intrinsic inconsistency of models disregarding the geographic distribution of networks.