José-Luis Marzo

Protection performance components in MPLS networks

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.

Adding QoS protection in order to enhance MPLS QoS routing

In this paper, a method for enhancing current QoS routing methods by means of QoS protection is presented. In an MPLS network, the segments (links) to be protected are predefined and an LSP request involves, apart from establishing a working path, creating a specific type of backup path (local, reverse or global). Different QoS parameters, such as network load balancing, resource optimization and minimization of LSP request rejection should be considered. QoS protection is defined as a function of QoS parameters, such as packet loss, restoration time, and resource optimization. A framework to add QoS protection to many of the current QoS routing algorithms is introduced. A backup decision module to select the most suitable protection method is formulated and different case studies are analyzed.

Performance study of wireless sensor and actuator networks in forest fire scenarios

SUMMARY Wireless sensor and actuator networks (WSANs) for environmental disaster scenarios are considered in this paper. A fully independent and autonomous WSAN system that is able to detect and extinguish a fire in a burning wildland area is proposed. Although forest fire detection is a classical application for sensor networks, in this paper, this research area is extended, taking into account actuators and their ability to put out fire in the presence of measurement inaccuracy and network degradation. A system architecture is proposed, modelled and discussed. An extensive set of computer simulations analysing the system performance is reported. The presented results show the efficiency of fire-fighting actions depending on the sensors’ density and the actuators’ mobility. Copyright

Multi-objective optimization scheme for multicast flows: a survey, a model and a MOEA solution

This paper presents a new traffic engineering load balancing taxonomy, classifying several publications and including their objective functions, constraints and proposed heuristics. Using this classification, a novel Generalized Multiobjective Multitree model (GMM-model) is proposed. This model considers for the first time multitree-multicast load balancing with splitting in a multiobjective context, whose mathematical solution is a whole Pareto optimal set that can include several results than it has been possible to find in the publications surveyed. To solve the GMM-model, a multi-objective evolutionary algorithm (MOEA) inspired by the Strength Pareto Evolutionary Algorithm (SPEA) is proposed. Experimental results considering up to 11 different objectives are presented for the well-known NSF network, with two simultaneous data flows.

A Multi-Objective Optimization Scheme for Multicast Routing: A Multitree Approach

In this paper, we propose a multi-objective traffic engineering scheme using different distribution trees to multicast several flows. The aim is to combine into a single aggregated metric, the following weighting objectives: the maximum link utilization, the hop count, the total bandwidth consumption, and the total end-to-end delay. Moreover, our proposal solves the traffic split ratio for multiple trees. We formulate this multi-objective function as one with Non Linear programming with discontinuous derivatives (DNLP). Results obtained using SNOPT solver show that several weighting objectives are decreased and the maximum link utilization is minimized. The problem is NP-hard, therefore, a novel SPT algorithm is proposed for optimizing the different objectives. The behavior we get using this algorithm is similar to what we get with SNOPT solver. The proposed approach can be applied in MPLS networks by allowing the establishment of explicit routes in multicast events. The main contributions of this paper are the optimization model and the formulation of the multi-objective function; and that the algorithm proposed shows polynomial complexity.

Distributed Control Using Cognitive Pilot Channels in a Centralized Cognitive Radio Network

In this paper, a cognitive radio network (CRN) model is presented. In this model, the control of the CRN is distributed among the frequency spectrum considered for transmission using cognitive pilot channels (CPCs). This control is performed by using frequency-division and time-division multiplexing techniques. Frequency-division is used to divide the spectrum into predetermined frequency slots in which cognitive radio users (CRUs) communicate. Then, the frequency slots are divided into sub-frequency slots, some of which are defined as CPC and used by the CRUs to communicate with a central cognitive base station (CCBS) and to determine availability in a frequency slot. Time-division is used to determine if a primary user (PU) has accessed the channel used by CRUs. Using this time-division approach, presence of PUs is detected. We have designed a CRN able to work with today’s available technologies and CRU devices that use different frequency bands of operation. Results of the performance of the network will be presented in terms of the number of CRU and the time these CRUs use the CPCs for control.

Asymmetric tunnels in P2MP LSPs as a label space reduction method

The objective of traffic engineering is to optimize network resource utilization. Although several works have been published about minimizing network resource utilization, few works have focused on LSR (label switched router) label space. This paper proposes an algorithm that takes advantage of the MPLS label stack features in order to reduce the number of labels used in LSPs. Some tunnelling methods and their MPLS implementation drawbacks are also discussed. The described algorithm sets up NHLFE (next hop label forwarding entry) tables in each LSR, creating asymmetric tunnels when possible. Experimental results show that the described algorithm achieves a great reduction factor in the label space. The presented works apply for both types of connections: P2MP (point-to-multipoint) and P2P (point-to-point).

Ant Colony Behaviour as Routing Mechanism to Provide Quality of Service

Quality of Service (QoS) guarantees must be supported in a network that intends to carry real-time and multimedia traffic effectively. The effort of satisfying the QoS different requirements of these applications has resulted in the proposals of several QoS-based frameworks, such as Integrated Services (IntServ) [1], Differentiated Services (DiffServ) [2], and Multi-Protocol Label Switching (MPLS) [6].

Enhancing MPLS QoS routing algorithms by using the network protection degree paradigm

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.

Enhanced multi-layer protection in multi-service GMPLS networks

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.