In this paper, a semi-dynamic protection path configuration method is proposed for WDM optical networks. In the method, the protection path is established by connecting several sub-lightpaths from the source node to the destination node of the original working lightpath, as opposed to conventional path restoration method where a single protection lightpath between the source-destination pair performs restoration. The proposed method provides enhanced flexibility in protection path configuration and relieves the cost of spare capacity reservation. This paper also studies the effects of wavelength conversion capability of intermediate optical cross-connect nodes on protection path routing and spare capacity utilization. In terms of spare capacity utilization, the proposed method shows substantial reduction of spare capacity overhead compared with dedicated path restoration in all optical networks without wavelength conversion, and shows similar capacity efficiency compared with shared path restoration in opaque networks with full wavelength conversion capability. In terms of robustness, the proposed method shows nearly the same restoration ratio for double-link failure as that of dynamic restoration method.

In this paper, a cycle-based network recovery method for optical mesh networks is studied. The study in this paper concentrates on improving two performance requirements on network recovery: efficient spare resource utilization, and robustness for multiple failures. The proposed method uses multiple ring-covers and performs distributed link restoration using preplanned logical cycles embedded in physical mesh topologies. This method provides fast and simple recovery operation by exploiting the characteristics of ring topology and also provides efficient resource utilization by using multiple backup paths per link to improve the sharability of overall spare resources in the networks. With this method, layered reliability can be provided to network services by enabling priority-based robustness against multiple failures. The performance results reveal the trade-off between the resource efficiency for single failure and the robustness for multiple failures, and show the preconfiguration of a few logical cycles per link can provide enhanced resource efficiency and priority-based hierarchical robustness.

In this paper, we address the survivable routing problem with and without wavelength-continuity constraints by proposing a new Integer Linear Programming (ILP) algorithm, which is based on a simplified necessary and sufficient condition. Numerical results are given and discussed to show the efficiency of our algorithm and the impact of wavelength-continuity constraints.

Optical switching networks to transport vast amounts of information are important for B-ISDN services. The wavelength division multiplexing (WDM) is emerging as the dominant technology for future optical networks. This paper proposes a large capacity photonic ATM switch architecture using WDM technology. The switch consists of two stages. The first stage is a space switch and the second stage is a wavelength switch. The proposed switch is suitable for WDM optical ATM networks, that is, an input and an output of the switch are wavelength-division-multiplexed. The switch can provide very large ATM cell switching capacity, for instance, 10Tbit/s, with reasonable complexity. The main switch module of the proposed switch has a simple architecture, and reduces the amount of a buffer hardware by introducing the WDM concept.

Optical switching networks to transport vast amounts of information are important for B-ISDN services. Wavelength division multiplexing (WDM) is emerging as the dominant technology for future optical networks. A large capacity photonic ATM switch architecture using WDM technology is proposed in this paper. The proposed switch is suitable for WDM optical ATM networks, that is, an input and an output of the switch are wavelength division multiplexed. The basic switch module of the proposed switch has a simple architecture, and reduces the amount of a buffer hardware by introducing the WDM concept.