Enhanced Backwards Recursive Path Computation for Multi-area Wavelength Switched Optical Networks Under Wavelength Continuity Constraint

In the context of the future Internet, all-optical wavelength switched optical networks will play an important role in either evolutionary or revolutionary design paradigms. In any paradigm, dense wavelength domain multiplexing (DWDM) is the most cost-effective technology to increase bandwidth capacity. DWDM provides the basis for a core optical transport infrastructure supporting a wide range of heterogeneous services. However, such all-optical networks raise well-known challenges such as the wavelength continuity constraint (WCC). The WCC is hard to address in a multiarea scenario when provisioning an end-to-end lightpath owing to network topology hiding requirements and the limited exchange of information between areas. The Internet Engineering Task Force (IETF) is currently standardizing the path computation element (PCE) architecture, a good candidate to perform multidomain path computation. In such an architecture, the approach named backwards recursive path computation (BRPC), also under standardization at the IETF, aims at overcoming the limitations of the per-domain mechanism. However, although BRPC does provide end-to-end shortest paths, it fails to take into account the WCC, which is the main motivation for this work. We extend the BRPC algorithm and the companion PCE protocol in order to address the end-to-end WCC efficiently. We perform a quantitative comparative analysis of the different approaches, experimentally showing the improvements of the conceived solution, which has been evaluated in a GMPLS-controlled network of the ADRENALINE testbed.