Anna Urra - Academia.edu (original) (raw)

Papers by Anna Urra

In the next generation backbone networks, IP/MPLS over optical networks, the ability to maintain ... more In the next generation backbone networks, IP/MPLS over optical networks, the ability to maintain an acceptable level of reliability has become crucial since a failure can result in a loss of several terabits of data per second. Although routing schemes with protection exist, they generally relate to a single switching layer: either wavelength or packet switching oriented. This paper presents a new dynamic and multi-layer routing scheme with protection that considers cooperation between IP/MPLS and optical switching domains. A complete set of experiments proves that the proposed scheme is more efficient when compared to routing algorithms with full optical protection or full IP/MPLS protection.

This paper presents the difficulty in routing and managing protected paths in inter-domain fault-... more This paper presents the difficulty in routing and managing protected paths in inter-domain fault-protection. This is caused by the lack of trust be- tween such domains. A multi-agent system is proposed for managing this spe- cific problem. This approach takes advantage of intrinsic distributed agents' benefits and explodes the high level communication capacities through the definition of a common ontology that can solve the limitations imposed by the reluctance between the involved domains.

Fourth International Workshop on Design of Reliable Communication Networks, 2003. (DRCN 2003). Proceedings., 2003

In this paper, we define a new scheme to develop and evaluate protection strategies for building ... more In this paper, we define a new scheme to develop and evaluate protection strategies for building reliable GMPLS networks. This is based on what we have called the network protection degree (NPD). The 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),

Proceedings ITCC 2003. International Conference on Information Technology: Coding and Computing, 2003

This paper presents a tool, for the analysis and regeneration of web contents, implemented throug... more This paper presents a tool, for the analysis and regeneration of web contents, implemented through XML and Java. At the moment, the web content delivery from server to clients is carried out without taking into account clients' characteristics. Heterogeneous and diverse characteristics, such as user's preferences, different capacities of the client's devices, different types of access, state of the network and current load on the server, directly affect the behavior of web services. On the other hand, the growing use of multimedia objects in the design of web contents is made without taking into account this diversity and heterogeneity. It affects, even more, the appropriate contents delivery. Thus, the objective of the presented tool is the treatment of web pages taking into account the mentioned heterogeneity and adapting contents in order to improve the performance on the web.

2004 IEEE International Workshop on IP Operations and Management, 2004

A recent study defines a new network plane: the knowledge plane. The incorporation of the knowled... more A recent study defines a new network plane: the knowledge plane. The incorporation of the knowledge plane over the network allows having more accurate information of the current and future network states. In this paper, the introduction and management of the network reliability information in the knowledge plane is proposed in order to improve the quality of service with protection routing algorithms in GMPLS over WDM networks. Different experiments prove the efficiency and scalability of the proposed scheme in terms of the percentage of resources used to protect the network.

GLOBECOM '05. IEEE Global Telecommunications Conference, 2005., 2005

This paper focuses on QoS routing with protection in an MPLS network over an optical layer. In th... more 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.

Lecture Notes in Computer Science, 2006

The next generation backbone networks, optical IP/MPLS networks, enable increasingly higher volum... more The next generation backbone networks, optical IP/MPLS networks, enable increasingly higher volumes of information to be transported. In this network architecture, a fiber failure can result in a loss of several terabits of data per second and leads to multiple failures in the upper network layer. Thus, the ability of the network to maintain an acceptable level of reliability has become crucial. In this paper, a dynamic cooperation between packet and wavelength switching domain is considered in order to provide protected paths cost effectively. A new multi-layer routing scheme that incorporates recovery mechanisms in order to guarantee connectivity against any single fiber failure is presented.

Journal of Optical Networking, 2006

We define new quality-of-service (QoS) routing schemes with protection in Internet Protocol (IP)/... more We define new quality-of-service (QoS) routing schemes with protection in Internet Protocol (IP)/Multiprotocol Label Switching (MPLS) over optical networks. The novelty of the proposed routing schemes is the use of the knowledge of the logical links already protected by the optical layer. The logical topology defined by the optical layer is given and fixed, and we assume that it is partially protected. Thereby, at the IP/MPLS layer, spare capacity is reserved to protect only those links that are unprotected. Moreover, we also characterize the traffic services based on their level of reliability and QoS requirements. In order to guarantee fast protection, segment protection and shared backups are combined, resulting in suitable fault recovery time and resource consumption. A complete set of experiments proves that the proposed schemes are more efficient than the previous ones in terms of resources used to protect the network, failure impact, and blocking probability.

International Symposium on Computers and Communications, 2005

In networks with small buffers, such as optical packet switching based networks, the convolution ... more In networks with small buffers, such as optical packet switching based networks, the convolution approach is presented as one of the most accurate method used for the connection admission control. Admission control and resource management have been addressed in other works oriented to bursty traffic and ATM. This paper focuses on heterogeneous traffic in OPS based networks. Using heterogeneous traffic

Lecture Notes in Computer Science, 2003

In this paper we present an implementation using XML and Java (X-SHAAD) based on a modular archit... more In this paper we present an implementation using XML and Java (X-SHAAD) based on a modular architecture of SHAAD to support a web-based Adaptive Hypermedia System. This architecture considers the hypermedia adaptation along three different "adaptivity dimensions": user characteristics, technology (the network and the user's terminal), and user interaction. At present, web content delivery from server to clients is carried out without taking into account such heterogeneous and diverse characteristics as user preferences, the different capacities of the clients' devices, the different types of access, the state of the network and the current load on the server, all of which directly affect the behavior of web services. The growing use of multimedia objects in the design of web contents further complicates the issue, greatly affecting appropriate contents delivery. Thus, the objective of the system we present here is a treatment of web pages that takes into account such heterogeneity and adapts content with the aim of improving web performance.

2007 IEEE International Conference on Communications, 2007

In the next generation optical internet, GMPLS- based IP-over-optical networks, ISPs will be requ... more In the next generation optical internet, GMPLS- based IP-over-optical networks, ISPs will be required to support a wide variety of applications each having their own requirements. These requirements are contracted by means of the SLA. This paper describes a recovery framework that may be included in the SLA contract between ISP and customers in order to provide the required level of survivability. A key concern with such a recovery framework is how to present the different survivability alternatives including recovery techniques, failure scenario and layered integration into a transparent manner for customers. In this paper, two issues are investigated. First, the performance of the recovery framework when applying a proposed mapping procedure as an admission control mechanism in the edge router considering a smart-edge simple-core GMPLS-based IP/WDM network is considered. The second issue pertains to the performance of a pre-allocated restoration and its ability to provide protected connections under different failure scenarios. application/customer by means of the Service Level Agreement (SLA) (3). With the SLA, customers define and contract the service that ISPs should provide. The survivability parameters that customers contract are the accepted/expected recovery time and availability. No particular resilience scheme (restoration, protection, 1+1, etc.) is indicated by the customer; this decision pertains to the operator and should be transparent to the client. Based on client requirements, ISPs determine an appropriate recovery mechanism according to the contracted availability and recovery time coupled with the considerations of low network cost (in terms of spare capacity), scalability, and simplicity. In this paper, a service level agreement framework, focusing upon the trade-off between the various aspects of survivability performance parameters and the customer/application requirements is presented. The proposed framework, by providing a range of possibilities for customer survivability parameters (availability and recovery time), allows ISPs to embed survivability within the SLA. Different aspects pertinent to survivability such as survivability techniques, layer integration and different failure scenarios are considered.

Lecture Notes in Computer Science, 2007

Journal of Communications and Networks, 2000

This paper presents a new enhanced dynamic and multilayer protection (DMP) routing scheme that co... more This paper presents a new enhanced dynamic and multilayer protection (DMP) routing scheme that considers cooperation between packet and wavelength switching domain in order to minimize the resource consumption. The paper describes the architecture of the multilayer network scenario and compares the proposed algorithm with other routing mechanisms applying protection at the IP/MPLS layer or at the Optical layer. Simulation results show that DMP reduces the number of o-e-o operations and makes an efficient use of the network resources compared to non-multilayer proposals.

IEEE Communications Magazine, 2000

Computer Communications, 2004

In this paper a new methodology to evaluate the protection performance of some existing mechanism... more In this paper a new methodology to evaluate the protection performance of some existing mechanisms for establishing quality of service network paths with protection is presented. In order to evaluate the protection degree 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 relate the influence of each component in the creation of protected paths is discussed over different network scenarios. Several experiments and analytical cases are presented to support these formulations. Moreover, an analysis of the relationship between these components and different traffic classes are also introduced and experimented. MPLS has been selected as a suitable technology for evaluating these mechanisms. However, the results can be easily applied in those network technologies that implement the concept of virtual paths.

Computer Communications, 2007

Minimum interference routing schemes are good options for achieving fewer working-path request re... more Minimum interference routing schemes are good options for achieving fewer working-path request rejections. They improve the vast majority of the current QoS routing proposals. However, when backup paths are added there is no guarantee of achieving a similar performance. In this paper, we analyze the suitability of these routing schemes in protected network scenarios. The main objective was to define the network scenarios in which the required performance can be achieved using only minimum interference. Some simulation results are presented to consider different network topologies and different routing schemes and to show the main drawbacks and advantages of using minimum interference schemes in protected network scenarios.

… , 2003. GLOBECOM'03. …, 2003

IP based networks still do not have the required degree of reliability required by new multimedia... more 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.

10th IEEE Symposium on Computers and Communications (ISCC'05), 2005

The paper presents a novel protection methodology for setting protected paths in a multiservice G... more The paper presents a novel protection methodology for setting protected paths in a multiservice GMPLSbased network scenario. By applying the proposed methods, label switched paths can be protected to obtain small failure probabilities and fast failure recovery time. The presented methodology allows classifying the required protection level depending on the traffic class. Another important development is the fact that considers protection at a WDM level by not overprotecting paths, which are already protected at this level. The proposed routing algorithms strictly restrict the backup path computation to one shared segment per path, optimizing the resource consumption and simplifying the failure management. A complete set of experiments proves the efficiency of the proposed method in relation with previous ones, in terms of the percentage of resources used to protect the network and the request rejection ratio.