Multi-domain crankback operation for IP/MPLS & DWDM networks

Network carriers and operators have built and deployed a very wide range of networking technologies to meet their customers needs. These include ultra scalable fibre-optic backbone networks based upon dense wavelength division multiplexing (DWDM) solutions as well as advanced layer 2/3 IP multiprotocol label switching (MPLS) and Ethernet technologies as well. A range of networking control protocols has also been developed to implement service provisioning and management across these networks. As these infrastructures have been deployed, a range of new challenges have started to emerge. In particular, a major issue is that of provisioning connection services between networks running across different domain boundaries, e.g., administrative geographic, commercial, etc. As a result, many carriers are keenly interested in the design of multi-domain provisioning solutions and algorithms. Nevertheless, to date most such efforts have only looked at pre-configured, i.e., static, inter-domain route computation or more complex solutions based upon hierarchical routing. As such there is significant scope in developing more scalable and simplified multi-domain provisioning solutions. Moreover, it is here that crankback signaling offers much promise. Crankback makes use of active messaging techniques to compute routes in an iterative manner and avoid problematic resource-deficient links. However very few multi-domain crankback schemes have been proposed, leaving much room for further investigation. Along these lines, this thesis proposes crankback signaling solution for multi-domain IP/MPLS and DWDM network operation. The scheme uses a joint intra/inter-domain signaling strategy and is fully-compatible with the standardized resource reservation (RSVP-TE) protocol. Furthermore, the proposed solution also implements and advanced next-hop domain selection strategy to drive the overall crankback process. Finally the whole framework assumes realistic settings in which individual domains have full internal visibility via link-state routing protocols, e.g., open shortest path first traffic engineering (OSPF-TE), but limited \u27next-hop\u27 inter-domain visibility, e.g., as provided by inter-area or inter-autonomous system (AS) routing protocols. The performance of the proposed crankback solution is studied using software-based discrete event simulation. First, a range of multi-domain topologies are built and tested. Next, detailed simulation runs are conducted for a range of scenarios. Overall, the findings show that the proposed crankback solution is very competitive with hierarchical routing, in many cases even outperforming full mesh abstraction. Moreover the scheme maintains acceptable signaling overheads (owing to it dual inter/intra domain crankback design) and also outperforms existing multi-domain crankback algorithms.\u2

End-to-end provisioning in multi-domain/multi-layer networks

The last decade has seen many advances in high-speed networking technologies. At the Layer 1 fiber-optic level, dense wavelength division multiplexing (DWDM) has seen fast growth in long-haul backbone/metro sectors. At the Layer 1.5 level, revamped next-generation SONET/SDH (NGS) has gained strong traction in the metro space, as a highly flexible sub-rate\u27 aggregation and grooming solution. Meanwhile, ubiquitous Ethernet (Layer 2) and IP (Layer 3) technologies have also seen the introduction of new quality of service (QoS) paradigms via the differentiated services (Diff-Serv) and integrated services (Intserv) frameworks. In recent years, various control provisioning standards have also been developed to provision these new networks, e.g., via efforts within the IETF, ITU-T, and OIF organizations. As these networks technologies gain traction, there is an increasing need to internetwork multiple domains operating at different technology layers, e.g., IP, Ethernet, SONET, DWDM. However, most existing studies have only looked at single domain networks or multiple domains operating at the same technology layer. As a result, there is now a growing level of interest in developing expanded control solutions for multi-domain/multi-layer networks, i.e., IP-SONET-DWDM. Now given the increase in the number of inter-connected domains, it is difficult for a single entity to maintain complete \u27global\u27 information across all domains. Hence, related solutions must pursue a distributed approach to handling multi-domain/multi-layer problem. Namely, key provisions are needed in the area of inter- domain routing, path computation, and signaling. The work in this thesis addresses these very challenges. Namely, a hierarchical routing framework is first developed to incorporate the multiple link types/granularities encountered in different network domains. Commensurate topology abstraction algorithms and update strategies are then introduced to help condense domain level state and propagate global views. Finally, distributed path computation and signaling setup schemes are developed to leverage the condensed global state information and make intelligent connection routing decisions. The work leverages heavily from graph theory concepts and also addresses the inherent distributed grooming dimension of multi-layer networks. The performance of the proposed framework and algorithms is studied using discrete event simulation techniques. Specifically, a range of multi-domain/multi-layer network topologies are designed and tested. Findings show that the propagation of inter-domain tunneled link state has a huge impact on connection blocking performance, lowering inter-domain connection blocking rates by a notable amount. More importantly, these gains are achieved without any notable increase in inter-domain routing loads. Furthermore, the results also show that topology abstraction is most beneficial at lower network load settings, and when used in conjunction with load-balancing routing.\u2

Inter-Domain Path Computation using Improved Crankback Signaling in Label Switched Networks

The paper deals with the problem of finding suboptimal routing paths in multi-domain Internet environment. The proposed solution can be used in traffic enginering with MPLS

ATM PNNI Interfacing Issues with MPLS Networking

School of Electrical and Computer Engineerin

A Survey on the Path Computation Element (PCE) Architecture

Quality of Service-enabled applications and services rely on Traffic Engineering-based (TE) Label Switched Paths (LSP) established in core networks and controlled by the GMPLS control plane. Path computation process is crucial to achieve the desired TE objective. Its actual effectiveness depends on a number of factors. Mechanisms utilized to update topology and TE information, as well as the latency between path computation and resource reservation, which is typically distributed, may affect path computation efficiency. Moreover, TE visibility is limited in many network scenarios, such as multi-layer, multi-domain and multi-carrier networks, and it may negatively impact resource utilization. The Internet Engineering Task Force (IETF) has promoted the Path Computation Element (PCE) architecture, proposing a dedicated network entity devoted to path computation process. The PCE represents a flexible instrument to overcome visibility and distributed provisioning inefficiencies. Communications between path computation clients (PCC) and PCEs, realized through the PCE Protocol (PCEP), also enable inter-PCE communications offering an attractive way to perform TE-based path computation among cooperating PCEs in multi-layer/domain scenarios, while preserving scalability and confidentiality. This survey presents the state-of-the-art on the PCE architecture for GMPLS-controlled networks carried out by research and standardization community. In this work, packet (i.e., MPLS-TE and MPLS-TP) and wavelength/spectrum (i.e., WSON and SSON) switching capabilities are the considered technological platforms, in which the PCE is shown to achieve a number of evident benefits

Some open issues in multi-domain/multi-operator/multi-granular ASON/GMPLS networks

Large optical backbone networks may be composed of several domains, each one controlled by different administrators/operators. Besides, the bandwidth granularity of these domains may be different. Label Switched Paths (LSPs) provisioning in multi-domain/multi-operators/multi-layer network scenarios is a challenging problem actually, which has to be properly faced. In this paper, some open issues related to end-to-end bandwidth provisioning are discussed. Among others, the grooming problem in multi-layer/multi-domain optical networks and the performance degradation of recovery mechanisms due to limited inter-domain knowledge are analyzed.Postprint (published version

On the challenges of establishing disjoint QoS IP/MPLS paths across multiple domains

MPLS is being actively adopted as the core switching infrastructure at the intradomain level. This trend is mainly attributable to the undeniable potential of MPLS in terms of virtual private networks (VPNs) management, traffic engineering (TE), QoS delivery, path protection, and fast recovery from network failures. However, little progress has been made to attain the expected extension of MPLS label-switched paths (LSPs) across domain boundaries. Among the problems that remain unsolved is how to efficiently find and establish primary and protection interdomain LSPs for mission-critical services subject to QoS constraints. This article explores the major limitations hindering the deployment of these kinds of LSPs across multiple domains, in the context of the current interdomain network model. We describe the critical problems faced by the research community, and present our vision on how to rationally overcome some of the problems exposed. Our perspective is that we should be prepared for rather coarse-grained solutions as long as we need to coexist with the current interdomain network modelPostprint (published version

Mecanismos de protección en escenarios IP-MPLS multidominio

Una de las aplicaciones de ingeniería de tráfico más utilizadas en redes IP-MPLS es la protección de enlaces y nodos de la red mediante LSPs de modo que pueda llevarse a cabo una recuperación rápida del tráfico en casos de fallo. Las ventajas de utilizar MPLS en estos esquemas de protección frente a utilizar el reencaminamiento IP es bien conocida y documentada en la comunidad científica, fundamentalmente, rapidez de reacción, lo que conlleva una menor pérdida de tráfico. Uno de los requisitos para poder proteger recursos en una red es ser capaz de encontrar un camino alternativo (o disjunto) al principal que no utilice los recursos protegidos. En los últimos años ha habido un esfuerzo por llevar estos esquemas de protección al interdominio. El principal problema para aplicar los esquemas intradominio a la protección de tráfico interdominio es el desconocimiento topológico de la red que impide obtener de manera sencilla los caminos de protección, disjuntos a los caminos principales. Parte de este desconocimiento viene dado por el modelo de encaminamiento interdominio por agregación utilizado en Internet basado en el protocolo BGP-4. Existen en la literatura algunos esquemas distribuidos propuestos para solucionar este problema, pero todos ellos requieren compartir información topológica entre los dominios y la posibilidad de caer en topologías trampa, que sumen a estos mecanismos en un “prueba y error” retardando el establecimiento de los caminos. En la actualidad existe otra opción que está adquiriendo fuerza, la utilización de PCEs, entidades especializadas en computar caminos. La utilización de estos PCEs permite utilizar esquemas centralizados/distribuidos para la obtención de caminos disjuntos que sean utilizables en la protección de flujos de datos interdominio. Si bien no es una opción viable actualmente puesto que se está definiendo su arquitectura y protocolos básicos en el IETF en estos momentos. En la presente Tesis Doctoral se proponen diversas soluciones que permiten obtener y señalizar dos caminos MPLS disjuntos (principal y de protección) interdominio. Se propone una modificación al protocolo BGP-4 de forma que a los dominios les sea posible tener información de dos AS_PATHs disjuntos que lleven a otro dominio. Si cada uno de los caminos sigue un AS_PATH distinto los caminos serán intrínsecamente disjuntos. Utilizando el modelo de encaminamiento actual se proponen, además, dos esquemas distribuidos de cómputo y señalización de los caminos principal y de respaldo. El primero de ellos, evita las topologías trampa, tiene en cuenta la posible división en áreas de los diferentes dominios y respeta la privacidad entre los dominios, siendo un esquema especialmente rápido en el establecimiento de los caminos. El segundo de ellos, utiliza la protección interna de cada dominio para facilitar el cómputo de los caminos y reutilizar LSPs de respaldo. Finalmente, se realiza un estudio sobre cómo podrían utilizarse los p-ciclos propuestos por Stamatelakis y Grover para proteger los enlaces interdominio

Improving resource management in multi-protocol label switched traffic engineered networks

Over the years, the Internet has emerged as an indispensable platform for information exchange. As availability increases, development of new applications generate enormous volumes of tra c. Such growth continually taxes service provider resources. A common and e ective resource management option deployed by several service providers is Multi-Protocol Label Switched (MPLS) based Tra c Engineering (TE).This dissertation proposes new MPLS based TE mechanisms capable of dealing with tra c changes, such as growth and shifts. Speci cally, new techniques for dynamic bandwidth allocation and routing are proposed and developed through simulations under failure and non-failure scenarios. Issues related to inter-domain deployment are also studied and nally, an experimental testbed setup is proposed and implemented for realistic small scale testing.A new tra c engineering technique involving the coupling of dynamic bandwidth allocation with rerouting to nd the best path for the current tra c is proposed. Realistic topologies and tra c pro les are used for detailed analysis and comparisons with existing techniques. Performance analysis is also undertaken in an International network scenario carrying a mix of voice and data tra c across several timezones. Several key issues are highlighted after studying underlying network dynamics such as signaling overhead, router load, tra c path quality, etc. Keeping these issues in mind, a new trend-based bandwidth reservation mechanism is proposed. The problem of inter-domain TE is analyzed next. Existing inter-domain path computation approaches, signaling and path setup issues are studied, quanti ed and compared. Lastly, the functional prototype of a testbed architecture consisting of Cisco routers and Linux boxes is presented. A new Java based API that has been developed to con gure the testbed and deploy new mechanisms is also discussed.Ph.D., Computer Engineering -- Drexel University, 200