In this paper, we present a new methodology for evaluating fault recovery performance of some existing mechanisms, which considers the establishment of quality of service network paths with protection. In order to evaluate the level of protection of a network, different components, such as protection parameters (packet loss and restoration time), or network parameters and constraints (link failure probability and network load), are analyzed. A formulation to calculate the influence of each component in the establishment of protected paths is discussed in multiprotocol label switching (MPLS) networks. Several experiments are presented to support this formulation. Moreover, an analysis of the relationship between these protection components and different traffic classes is also introduced and justified. q

Abstract-In this paper a novel methodology aimed at minimizing the probability of network failure and the failure impact (in terms of QoS degradation) while optimizing the resource consumption is introduced. A detailed study of MPLS recovery techniques and their GMPLS extensions are also presented. In this scenario, some features for reducing the failure impact and offering minimum failure probabilities at the same time are also analyzed. Novel two-step routing algorithms using this methodology are proposed. Results show that these methods offer high protection levels with optimal resource consumption.

Abstract-IP based networks still do not have the required degree of reliability required by new multimedia services, achieving such reliability will be crucial in the success or failure of the new Internet generation. Most of existing schemes for QoS routing do not take into consideration parameters concerning the quality of the protection, such as packet loss or restoration time.In this paper, we define a new paradigm to develop new protection strategies for building reliable MPLS networks, based on what we have called the Network Protection Degree (NPD). This NPD consists of an a priori evaluation, the Failure Sensibility Degree (FSD), which provides the failure probability and an a posteriori evaluation, the Failure Impact Degree (FID), to determine the impact on the network in case of failure.Having mathematical formulated these components, we point out the most relevant components. Experimental results demonstrate the benefits of the utilization of the NPD, when used to enhance some current QoS routing algorithms to offer a certain degree of protection.

-In this paper, different recovery methods applied at different network layers and time scales are used in order to enhance the network reliability. Each layer deploys its own fault management methods. However, current recovery methods are applied to only a specific layer. New protection schemes, based on the proposed Partial Disjoint Path algorithm, are defined in order to avoid protection duplications in a multi-layer scenario. The new protection schemes also encompass shared segment backup computation and shared risk link group identification. A complete set of experiments proves the efficiency of the proposed methods in relation with previous ones, in terms of resources used to protect the network, the failure recovery time and the request rejection ratio.Index Termns -quality of service, reliability, shared segment protection, GMPLS.

Abstract-This paper focuses on QoS routing with protection in an MPLS network over an optical layer. In this multi-layer scenario each layer deploys its own fault management methods. A partially protected optical layer is proposed and the rest of the network is protected at the MPLS layer. New protection schemes that avoid protection duplications are proposed. Moreover, this paper also introduces a new traffic classification based on the level of reliability. The failure impact is evaluated in terms of recovery time depending on the traffic class. The proposed schemes also include a novel variation of minimum interference routing and shared segment backup computation. A complete set of experiments proves that the proposed schemes are more efficient as compared to the previous ones, in terms of resources used to protect the network, failure impact and the request rejection ratio.