Recovery mechanisms in ason/gmpls networks
- Autores: Luis Velasco Esteban
- Directores de la Tesis: Jaume Comellas Colome (dir. tes.), Salvatore Spadaro (codir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2009
- Idioma: español
- Tribunal Calificador de la Tesis: Gabriel Junyent Giralt (presid.), Davide Careglio (secret.), Albert Rafel Portí (voc.), Eusebi Calle Ortega (voc.), Ricardo Víctor Martínez Rivera (voc.)
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- Resumen
This thesis is devoted to the study and physical implementation of different recovery mechanisms in GMPLS-controlled ASON networks. Under the standardization of the legacy SONET/SDH technology, several protection schemes were defined providing recovery times within 50ms. However, with the advent of optical networks providing automatic switching, the 50ms figure has been questioned; in our opinion due to the fact that this figure is so difficult to reach in transparent optical networks with the commercially available technology.
Three main objectives are undertaken in this thesis. First, we rely on the GMPLS control plane to bring protection schemes to the optical layer providing shorter recovery times. Therefore, we assume the 50ms figure as the recovery time objective. Moreover, flexibility is an important issue for network operators. It is important to provide different protection mechanisms allowing network planning to choose among several protection schemes, to implement the most appropriated to a particular network case. In this regard, the second objective of this thesis is to provide several protection mechanisms covering different requirements. Nevertheless, choosing a protection scheme at the planning phase may not be enough, being desirable some mechanism to choose the protection scheme in real time as a function of the current state of the network. That is thus our third objective.
Physical implementation of recovery mechanisms has been carried on building optical nodes, and the functional and physical designs of the nodes are described. Stringent performance requirements imposed notably optimization in its software and hardware architecture. Experimental results proved the efficiency of the node. Moreover, several advances have been done within the framework of the ASON/GMPLS CARISMA network test-bed. The new architecture of different modules at the three planes of the test-bed is described including some algorithms and mechanisms implemented. Experimental tests are carried on to obtain its performance. Firstly, a proposal to implement shared-path protection on rings is presented in detail. Then, an algorithm to compute disjoint routes under the wavelength continuity constraint is presented. Its performance is experimentally compared with a generally accepted RWA algorithm. Moreover, the fundamental configuration time is experimentally obtained. Besides, two strategies for fault localization are presented and experimentally compared.
Two different recovery schemes are proposed and implemented Availability for every protection scheme is computed, and algebraic equations are derived. At the link layer, two complete solutions to build ring-based dynamic optical networks with link protection capabilities are proposed and evaluated. They consist of: 1) a novel GMPLS-based mechanism which coordinates the protection actions after failures, and 2) a new node design to support link protection. At the path layer, the shared path protection with extra-traffic scheme is implemented in ASON rings provided with a GMPLS control plane. The protection time provided by this scheme is analyzed as a function of physical optical components. We demonstrate that the switching time of the components prevents from protecting the complete set of affected connections within 50 ms after fault detection. This limitation can be solved by traffic differentiation. Finally, a mechanism to provide protection times under 50 ms to the complete set of connections is presented. It chooses the layer (link or path) in which the protection is performed as a function of the number of paths to protect.
