This article focuses on the problem of dynamic and distributed shared path protection (SPP) in all-optical GMPLS networks without wavelength conversion capability. In this scenario, both working and backup lightpaths use a single wavelength for all links in their respective paths (i.e., wavelength continuity constraint, WCC). The novelty of this work, from the best of our knowledge, is twofold: presenting and evaluating two routing approaches that besides maximizing resource usage address connection blocking caused by the WCC, and that both schemes are experimentally implemented within a real GMPLS-based network using ADRENALINE testbed. The first approach relies on partial network state information that aims at increasing backup sharing based on aggregated link bandwidth. The second approach relies on full network state information leading to both increase backup sharing based on enhanced link channel information, and reduce connection blocking due to WCC. A detailed description of the two algorithms, along with the required extensions to current GMPLS routing protocols are provided. The experimental performance evaluation and comparison of the two schemes is conducted with regard to two figures of merit: connection blocking probability and restoration overbuild. Whereas the second finer approach does imply an increase of algorithm complexity, higher control overhead and slightly lower scalability, it will be shown that it significantly reduces the blocking probability while maintaining an excellent restoration overbuild usage.
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