Catálogo de publicaciones - libros

The Internet is composed by different domains, each of them managed by different ISPs (Internet Service Providers). These Domains have different access networks and capabilities, users and policies that rule their behavior. Policies control QoS and other service parameters like security, and automate network management. Each ISP has an SLA (Service Level Agreement) established between its users, which defines what kind of resources and prices was agreed to be offered to each user. However there is no SLA between a visited domain and a mobile user. Thus there is a need to integrate mobility and QoS management envisaging seamless services and users’ satisfaction. We propose POlicy Based Unified access Control System (POBUCS) Framework providing mobility and QoS management, in an integrated way, for IP Multimedia Systems and Next Generation Mobile Networks. The architecture presents the Domain Policy Manager (DPM) as the Decision-making and controller of a domain. The proposed architecture uses policies for inter-domain negotiation.

The specification of a policy is performed in a policy language, usually following a textual representation. However, humans process images faster than text and they are prepared to process information presented in two or more dimensions: sometimes it is easier to explain things using figures and their graphical relations than writing textual representations.

This paper describes a visual language, in the form of graphics that are executed in a networking environment, to define a network management policy. This approach allows to map visual tokens and corresponding arrangements into other languages to which a mapping is defined.

Management is an essential task for the correct behavior of networks. In this field, several aspects should be taken into account. Among them, network topology is one of the most important elements to control. This paper proposes an approach to the topology discovery based on a hybrid methodology. We propose a tool, called (Hybrid Network-Topology Discovery), that effectively combines active and passive measurements to discover network topologies at router level. Architectural choices are presented and discussed and some preliminary experimental results, carried out over a controlled test-bed, are given.

The Internet consists of many self-administered and inter-connected Autonomous Systems (ASms). ASms exchange inter-AS routing information with each other via the Border Gateway Protocol (BGP). Neighboring BGP routers located in different ASms share their inter-AS routing information via external BGP (eBGP), whereas two routers in the same AS share their inter-AS routing information via internal BGP (iBGP).

From the paths received from its peers, each BGP router chooses the best path based on routing policies chosen locally at its own AS. Conflicting policies between different ASms may cause divergence problems in eBGP, i.e., permanent oscillations in the chosen path to the destination. On the other hand, divergence problems may also occur in iBGP. This is caused by the interaction of route-reflection clustering, which is a technique to improve the scalability of iBGP, and other factors, such as intra-AS link costs, among others. In this paper, we provide a comprehensive solution that avoids all the known anomalies with both eBGP and iBGP. In our solution, each AS can locally choose its routing policies, while still ensuring anomaly-free behavior.

Network robustness is something all providers are striving for without being able to know all the aspects it encompasses. A key aspect of network design is the sensitivity of the network to internal failures. In this paper we present an open-source tool implementing the sensitivity model of [1], allowing network operators to study the sensitivity of their network to internal failures. We apply our methodology on the GEANT network, and we show that some of the routers and links of GEANT are sensitive to internal failures. Our results indicate that improvements can be made to the network design so as to reduce the risk of disruptions due to internal failures. Furthermore, we show great consistency between the results of the control plane and the data plane, indicating that applying the analysis on the control plane might be sufficient to provide insight into how to improve the resilience of the network to internal failures.

This paper presents a full NetConf-based network management suite. The described management suite allows to assess the potential of XML based management in complex configuration scenarios, validate NetConf operational characteristics, compare with existing models, verify the admitted ideas about XML and experiment the interoperability with CLI. We share here our implementation and deployment experience and discuss through illustrations the advantages and drawbacks of NetConf.

Routing changes of the interior gateway protocol (IGP), especially unexpected ones, can significantly affect the connectivity of a network. Although such changes can occur quite frequently in a network, most operators have hardly noticed them because of a lack of effective tools. In this paper, we introduce Rtanaly, a system to (i) detect IGP routing changes in real-time and instantly alert operators of the detected changes, (ii) quantify routing changes over the long term to provide operators with a general view on the routing stability of a network, (iii) estimate the impact of routing changes, and (iv) help operators troubleshoot in response to unexpected changes. Rtanaly has the following features: (i) it supports all three widely deployed IGPs – OSPFv2, OSPFv3, and IS-IS, (ii) it uses a completely passive approach, (iii) it visually displays the measurement results, and (iv) it is accessible through the web. We present the results of measurements that we have performed with Rtanaly as well as some observed pathological behavior to show its effectiveness. We have released the first version of Rtanaly as free software and its distribution is based on a BSD-style license.

This paper presents a network management framework for an auto-configuration of dynamic networks using Web Services. The example of VPN configuration is used as a proof of concept, and the Active XML technology provides the underlying Web Services technology with a Peer2Peer infrastructure. We present those technologies applied to network management as well as our prototype implementation, and we discuss the pros and cons of our solution and our future work.

Fast Handovers is an enhancement to the Mobile IPv6 protocol, currently specified in an IETF draft, which reduces the handover latency. This can be beneficial to real-time applications. This paper presents a novel implementation of Fast Handovers and an analysis of the handover. Using a real testbed we study the handover latency and the provided QoS: analyzing the OWD, IPDV and Packet Loss before and after the handover. Finally we present a comparison between the Mobile IPv6 and the Fast Handovers handover.

This article presents a component-based, distributed management system for Multiprotocol Label Switched (MPLS) multiservice networks. Delivery of “triple play” multimedia services to the broadband residential user is a demanding challenge. The complexity is increased by the requirement of preserving Quality of Service (QoS) assurance for legacy connectivity services to the enterprise segment over the same infrastructure. New technologies are being introduced in the access, aggregation and core networks. Management applications must be aware of these advances and shall evolve accordingly. The proposed management architecture benefits from the capabilities of the MPLS Control Plane, in conjunction with a traditional management approach to provision QoS-aware services. This hybrid solution pursues short connectivity setup times by means of Control Plane signalling, with Traffic Engineering capabilities provided by the management framework. The system is being prototyped on a trial metropolitan testbed. Simulation results show that an advantageous trade-off between speed and resource optimisation is feasible.