We propose a novel survivable algorithm, called backup-shared with trap avoidance (BSTA), to protect against single failure with shared-risk link groups (SRLGs) in wavelength-division multiplexing optical networks. In BSTA, each connection request will be assigned one primary path and one SRLG-disjoint backup, or one primary path and two SRLG-disjoint segment-backup paths. In contrast with previous algorithms, BSTA not only can effectively avoid the trap problem, but also can obtain better resource utilization ratio and lower blocking probability. Simulation results are shown to be promising.
In wavelength-division-multiplexing optical networks, the fiber links may share some common physical resources (e.g., cables, conduits), and the consequence is that they have a correlated link failure probability (CLFP), which means that the probability that link l will fail depends on whether link f has failed. Based on CLFP, we propose a new heuristic survivable algorithm, called differentiated path-shared protection (DPSP), to protect against double-link failures in WDM optical networks. In DPSP, each connection request can be assigned one working path and additional backup paths according to the differentiated reliability requirements of users. Compared to previous work, DPSP can obtain better performances in resource utilization ratio and blocking probability.
The preconfiguration cycle (p-cycle) is an excellent protection scheme that benefits both the fast recovery time and the efficient resource utilization in wavelength-division-multiplexing (WDM) mesh networks. Before providing protection for any link whose end nodes are both on the p-cycle, the spare capacity assignment for the p-cycles is a very important step for p-cycle design in WDM networks. We present a heuristic scheme, called the p-Cycle Capacity Assignment Algorithm (CCAA), to achieve an optimal capacity assignment of p-cycles in WDM networks without using Integer Linear Programming (ILP). CCAA can configure the p-cycles with good actual efficiency because it first consumes the spare capacity of the links where more spare capacity exists. This scheme is more suitable for the design of maximum p-cycle restorability with a given spare capacity distribution. When allocating the spare capacity for the p-cycles in WDM mesh networks, this scheme considers the actual distribution of the working capacity and the spare capacity of a certain traffic pattern. The performance of CCAA is evaluated by computer simulations on the real-world network topology.
The survivable design is a key issue in reliable WDM optical networks to assure the service guarantee to customers. In this paper we propose a novel heuristic dynamic Sub-Path Protection with Hop Constraint routing algorithm (SPP-HC) to provide a more flexible way to compute the sub-paths and the backup paths. Compared with the conventional equal-length sub-path protection metrics, SPP-HC can further improve the resource utilization ratio and reduce the blocking probability. We evaluate the effectiveness of the SPP-HC and the results are found to be promising.