Modularity requirements for optical cross-connects in transport networks

The introduction of an optical path layer in the transport network allows the improving of the transport nodes processing capability, through wavelength routing , besides increase in point-to-point transmission capacity granted by wavelength division multiplexing (WDM) technique. A generic node of a transport network could be designed as an optical crossconnect (OXC) interfacing a digital cross-connect (DXC). In this paper we distinguish between low, medium and high degree of modularity, and discuss the modularity for some relevant OXC architectures. Moreover a new highly modular OXC architecture is proposed.