Performance evaluation for optical networks with OTDM Add-Drop functionality

The solution of routing and wavelength assignment (RWA) problem allows to overlay a logical topology, comprising logical connections and routers, on a physical topology, comprising optical fibers and optical crossconnects, using either lightpaths or super-lightpaths which use a simple bit level time division multiplexing. In this paper we introduce an add-drop function which allow to reuse the super-lightpath sub-channels. Being the mathematical problem computationally intractable we have used heuristic methods which show that the number of wavelengths required to overlay the same logical topology on the same physical topology is reduced up to 27% using the add-drop function.