Advanced routing mechanisms in ASON/GMPLS networks

• Autores: Fernando Agraz Buján
• Directores de la Tesis: Salvatore Spadaro (dir. tes.), Jordi Perelló Muntan (dir. tes.)
• Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2012
• Idioma: inglés
• Tribunal Calificador de la Tesis: Josep Solé Pareta (presid.), Eduard Grasa (secret.), Lluís Fàbrega i Soler (voc.)
• Materias:
  • Ciencias tecnológicas
    • Tecnología de las telecomunicaciones
• Enlaces
  • Tesis en acceso abierto en: TDX
• Resumen

  • Current network infrastructures are supported on a layered model whereby heterogeneous data traffic can be seamlessly transported. In this architecture, where client/server relationships are established between adjacent layers, there exists an IP layer on top, two intermediate Asynchronous Transfer Mode (ATM) and Synchronous Digital Hierarchy (SDH) layers, and a Wavelength Division Multiplexing (WDM) layer at the bottom. Despite the benefits provided by the intermediate ATM and SDH layers (i.e., QoS and resilience), the complex interaction between them and the introduced overhead motivate an evolution towards a lighter model, where IP flows are directly sent through the WDM layer. In this new IP/WDM model the functionalities formerly provided by the ATM and SDH layers are moved to the optical domain. From an operational perspective, the static nature of current transport networks, which leads to long service provisioning times (i.e., hours or days), becomes incompatible with the dynamic patterns associated to the prevalent IP traffic. To overcome these limitations, the ITU-T proposed the Automatically Switched Optical Network (ASON) architecture, which utilizes a control plane to provide fast and reliable lightpaths within the optical transport network. In addition, the Generalized Multi-Protocol Label Switching (GMPLS) model defined by the IETF appears as the most promising technology to implement the functionalities of the ASON control plane. Although being a significant advance towards flexible and easy-to-maintain transport network architectures, the ASON/GMPLS paradigm still presents three major open issues that are addressed in this thesis. First, due to the coarse granularity offered by the WDM transport technology, established connections remain underused when sub-wavelength client flows must be transmitted. In light of this, a multi-layer approach, where different higher level data flows are aggregated in the IP layer and transmitted over the same optical path, appears as the most valid solution. Besides, the GMPLS technology is more than indicated to implement the control plane in this multi-layer architecture, since it allows the management of different switching technologies in an integrated way. In this regard, this thesis reports the experimental design and validation of a GMPLS-controlled multi-layer optical transport network. Second, even though pure optical transmission enabled by WDM provides high bandwidth in a cost-effective way, it is also very sensitive to the physical layer impairments that affect to the transmitted optical signal and, thus, to the transported data. Hence, a control plane capable of managing physical layer information to provide feasible lightpaths becomes a must. This thesis introduces and experimentally evaluates different architectural solutions to implement an impairment-aware GMPLS-based control plane. Finally, as transport network infrastructures grow, they are typically segmented into domains due to administrative, technological, or scalability reasons. Furthermore, the interconnection of network infrastructures managed by different operators is mandated by the need to provide long distance connectivity. Here, confidentiality and reliability concerns become of paramount importance. All this justifies the need for multi-domain networks. In GMPLS-controlled multi-domain optical transport networks, this partitioning affects to end-to-end service provisioning, which is hindered by the reduced information exchange between domains resulting from the fulfillment of segmentation criteria. As the third goal of this thesis, different mechanisms for scalable and effective end-to-end service provisioning are proposed in this multi-domain scenario.