A Scalable Wavelength Assignment Approach for Preventive Crosstalk Attack Localization in Optical Networks

The high data rates employed by WDM transparent optical networks make them most suitable for today's growing network traffic demands. However, their transparency makes them highly vulnerable to faults and attacks, potentially leading to tremendous data loss and/or corruption. This makes fault and attack management a crucial factor in maintaining a high quality of service inside the network. In this paper, we consider physical layer attacks, in particular intra-channel crosstalk attacks, which can cause severe service degradation or even service denial. Such attacks have the capability to propagate, i.e. can potentially spread to connections not even traversing the same physical components as the attacking signal. While most approaches focus on network recovery after a fault or an attack has already occurred, we suggest a novel safety strategy, proposing a prevention-oriented method for limiting the propagation of intra-channel crosstalk attacks through careful wavelength assignment. We describe a new objective criterion for the Wavelength Assignment (WA) problem, called the Propagating Crosstalk Attack Radius (P-CAR), as an extension of our work from [1]. Since calculating all direct and indirect crosstalk attacking relations between lightpaths can be computationally prohibitive, considering them in a wavelength assignment approach can significantly increase complexity. Consequently, in this paper we propose bin-packing based heuristics which consider the upper bound on the P-CAR, instead of the P-CAR itself, to obtain good solutions in reasonable time. We implemented the developed heuristics and compared them with the more complex approach of considering the actual P-CAR. The solutions obtained for medium-sized networks show that the proposed heuristics obtain comparable solutions, while dramatically reducing execution time. Furthermore, we compare our algorithms with existing WA approaches which do not consider intra-channel crosstalk propagation, illustrating their benefits with respect to transparent optical networks' security.