Distributed Sharing of Functionalities and Resources in Survivable GMPLS-controlled WSONs

Sharing of functionalities and sharing of network resources are effective solutions for improving the cost-effectiveness of wavelength-switched optical networks (WSONs). Such cost-effectiveness should be pursued together with the objective of ensuring the requested level of performance at the physical layer (i.e., quality of transmission, QoT) and at the upper layer also in the case of a failure (i.e., survivability). This paper aims to apply the sharing concept to a WSON with QoT and survivability requirements (against single-link failures). QoT is guaranteed by resorting to regeneration of the optical signal in intermediate nodes. Survivability is guaranteed by resorting to path protection. To exploit the sharing benefits, the scarce regenerators are used for both regeneration and wavelength conversion (WC) leading to a sharing of functionalities. Also, the shared path protection mechanism is exploited to ensure survivability against single-link failures and make the sharing of network resources (regenerators and wavelengths) possible. The paper presents a novel distributed scheme (DISTR) for reservation of regenerators and wavelengths in generalized multi-protocol label switching controlled WSONs, in order to ensure the required level of QoT and survivability. Novel objects and selection strategies for the resource reservation protocol with traffic engineering extensions are proposed and evaluated. The DISTR scheme effectively combines regeneration and WC points, leading to a noticeable reduction of the regeneration usage with respect to the existing schemes. Moreover, a significant reduction of the blocking probability is achieved, independently of the wavelength selection strategy used.