Impact of node switching capabilities on the performance of wavelength routed networks

Abstract

SUMMARYPerformance of wavelength routed optical networks (WRONs), which consist of circuit switched all-optical connections, namely lightpaths, heavily depends on network node capabilities. Advanced network node switching capabilities might improve WRON performance but they often imply an increase in node cost. In this paper, we evaluate the performance benefits brought by the introduction of selected capabilities in the WRON node architecture. In particular, we consider the WRON performance dependence on the (i) wavelength selection and (ii) wavelength conversion capabilities and (iii) on the number of available transponders at the tributary side. For this purpose, we propose and utilise a modified version of the shortest path algorithm for the wavelength graph (SPAWG). The modified SPAWG utilises a graph in which 'virtual hops' are added for modelling the utilisation and the cost of specific node capabilities. Numerical results show the performance advantages in utilising wavelength selection instead of wavelength conversion, when only one of the two capabilities can be implemented in each network node. When wavelength conversion and wavelength selection utilisation is limited to a subset of network nodes to reduce the overall network cost, results indicate that sparse wavelength selection is not as beneficial as sparse wavelength conversion. In addition, a limitation on the number of transponders at the tributary side slightly affects network performance.

Encompassing ROADM add/drop constraints in GMPLS‐based WSONs

“…This impacts two main aspects: the node cost and the constraints imposed during routing and wavelength assignment (RWA) . For example, the simplest ROADM architecture adopting no WSS in add/drop guarantees the lowest cost but imposes coloured (C) and direction‐bound (D) add/drop , that is tributaries at fixed wavelengths and fixed direction. More expensive ROADM architectures adopting one or two WSS per add/drop (either shared or dedicated per direction) are then able to guarantee some colourless (CL) and/or directionless (DL) add/drop, that is tributaries at tunable wavelength and/or configurable direction.…”