Tomé Gomes

Nodes Discovery in the In-Network Management Communication Framework

The main role of a communication framework in distributed autonomic management is to support the dissemination of management information between network nodes. In distributed autonomic management, each network node intelligently self-adapts its behavior through collaboration and cooperation between the several nodes. In this paper, we propose a set of communication mechanisms between self-managed network nodes, comprehending the several stages of communication, including a bootstrapping, discovery and election of entities, and ensure the base of communication of information between nodes to perform the collaborative decisions and to enforce these decisions. We propose a bootstrapping and discovery mechanism that uses the concept of Hide & Seek, where the entities change their role dynamically according to events in the network, with dynamic probing intervals according to the number of Seekers entering or leaving the network. We compare our discovery approach with current solutions, and we show that our mechanism is more efficient both in terms of control messages overhead and convergence time.

A Spanning Tree Protocol over mobile wireless ad hoc networks

This paper proposes mobility-enabled and loop-free extensions to the Spanning Tree Protocol (STP) for wireless ad hoc environments, taking into account requirements such as loop avoidance, root selection, ability to deal with interference, path loss or multipath fading, all without requiring to modify the existing protocol stack. Our approach is compliant with IEEE 802.11 networks and considers that mobile nodes constantly join and leave the range of each other due to their unpredicted movements, often changing the network topology. This implies that coherent information must be forwarded between nodes in order to keep their distributed knowledge synchronized, to allow the spanning tree topology maintenance and avoid or remove undesirable loops in multi-hop paths. The results obtained through simulation show that WSTP ensures a lower distance between the nodes and the root when compared to an approach that performs associations based on the first contact, and therefore, it provides a lower resource consumption and lower delay in the communications.

On the analysis of dissemination management information through an Eyesight perspective

The dissemination of information in wireless networks is a fundamental aspect in several network processes, such as routing, monitoring and management. Nowadays, most of the techniques for dissemination of management information adopt controlled flooding approaches, which usually impairs the network performance. In this sense, the optimization of the dissemination of management information for dense wireless scenarios remains a relevant research challenge. In this paper, it is presented and analyzed the performance of the Neighbors Eyesight Direction (NED) dissemination against to OSPF, uncontrolled flooding and Gossip approaches in wired and large network scenarios. NED is able to work on wired and dense wireless scenarios, showing to be more efficient than the baseline approaches. With lower dissemination cost and lesser recursive cycles, NED proved to be scalable to disseminate management information for scenarios with a large number of devices.

Self-organizing decentralized wireless management through social-based metrics

Autonomic and distributed management requires the cooperation between the network nodes and the periodical exchange of network information between them. To increase scalability of the information exchange, network nodes need to be associated and grouped through an efficient set of rules, to minimize the amount of control messages flowing in the network. This paper proposes a community-based association between nodes, where nodes in a community are connected through social-based metrics. The proposed social-based metrics are able to join the network nodes through their characteristics and probable interactions, reducing the disconnection between nodes and optimizing the information exchange between them. The obtained results show that the social-based metrics increase stability of the links and provide better resource aggregation, decreasing the required number of messages exchanged between nodes in a distributed management approach.

Supporting Unified Distributed Management and Autonomic Decisions: Design, Implementation and Deployment

Nowadays, the prevailing use of networks based on traditional centralized management systems reflects on a fast increase of the management costs. The growth in the number of network equipments and services reinforces the need to distribute the management responsibilities throughout the network devices. In this approach, each device executes common network management functionalities, being part of the overall network management platform. In this paper, we present a Unified Distributed Network Management (UDNM) framework that provides a unified (wired and wireless) management network solution, where further different network services can take part of this infrastructure, e.g., flow monitoring, accurate routing decisions, distributed policies dissemination, etc. This framework is divided in two main components: (A) Situation awareness, which sets up initial information through bootstrapping, discovery, fault-management process and exchange of management information; (B) Autonomic Decision System (ADS) that performs distributed decisions in the network with incomplete information. We deploy the UDNM framework in a testbed which involves two cities (

Improving MAC layer association through social-based metrics in mobile networks

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A genetic algorithm approach to improve network nodes association

≈250 km between), different standards (IEEE 802.3, IEEE 802.11 and IEEE 802.16e) and network technologies, such as, wired virtual grid, wireless ad-hoc gateways, ad-hoc mobile access devices. The UDNM framework integrates management functionalities into the managed devices, proving to be a lightweight and easy-respond framework. The performance analysis shows that the UDNM framework is feasible to unify devices management functionalities and to take accurate decisions on top of a real network.

Socially-Aware Multimedia Dissemination in Personal Mobile Networks

There is a new trend to consider Distributed Mobility Management (DMM) for flat network architectures to cope with the increased distributed nature of the mobile networks. DMM improves the routing optimization and reduces the scalability issues when compared with the centralized mobility management, through the traffic anchoring distribution at the Access Routers (ARs). However, the handover optimization, which also demands for fast and soft handovers to reduce/eliminate the handover latency and the respective packet loss, is not properly addressed in the DMM. Although current seamless handover approaches, already integrated in centralized mobility schemes, could also be adapted to the DMM schemes, they introduce new entities/functionalities, messages and buffering/bicasting mechanisms to reduce the handover latency or the packet loss. In this paper, the seamless IP handover is addressed from a novel make-without-break perspective, which is able to maintain two logical connections in the same physical interface with two Access Points (APs) from distinct IP networks. The outcome of the evaluation shows that make-without-break with a DMM scheme is able to reduce or even eliminate the handover latency and the packet loss from link disconnection, providing seamless IP session continuity in mobile environments.