Pedro Gonçalves

Evaluation of latex from five Hevea clones grown in São Paulo State, Brazil

Abstract Membranes of latex extracted from five clones of rubber tree (Hevea brasiliensis (Willd. ex Adr. de Juss) Muell.-Arg.) improved by selection and statistics methods have been prepared by air drying a 10% suspension in ammonia solution. TG–DTG and DSC, were used to characterize the membranes. The results obtained show no differences among latex from different clones.

An evaluation of network management protocols

During the last decade several network management solutions have been proposed or extended to cope with the growing complexity of networks, systems and services. Architectures, protocols, and information models have been proposed as a way to better respond to the new and different demands of global networks. However this offer also leads to a growing complexity of management solutions and to an increase in systems requirements. The current management landscape is populated with a multiplicity of protocols, initially developed as an answer to different requirements. This paper presents a comparative study of currently common management protocols in All-IP networks: SNMP, COPS, Diameter, CIM/XML over HTTP and CIM/XML over SOAP. This assessment was focused on wireless aspect issues, and as such includes measures of bandwidth, packets, round-trip delays, and agents requirements. We also analyzed the advantages of compression in these protocols.

Adapting SDN datacenters to support Cloud IIoT applications

IIoT (Industrial Internet of Things) cloud applications require reliable, fault-tolerant networks, supporting real-time guarantees and allowing interaction with other applications already existing in the datacenter. The Software Defined Networks (SDN) paradigm is especially suited for the management of the network cloud because of its fine grained admission control and the management flexibility provided by the centralized resource management. This paper presents a SDN management approach for IIoT datacenters, which provides an efficient fault-tolerant network, enabled with deterministic QoS guarantees. By taking advantage of a centralized resource management mechanism, the proposed solution integrates topology definition with resource allocation, allowing to efficiently distribute available network resources for admitted packet flows.

A WBEM based solution for a 4G network integrated management

Next generation networks will put a new set of challenges related to operation and management, due to the increased complexity arising by the seamless integration of different kinds of technologies, services and terminals, and with the expected offered bandwidth. In this paper we present a policy-based management system that is being developed inside the Daidalos IST project for such environments. This system uses policy based management concepts associated with Web-based enterprise management to control QoS aspects in this complex network

Enabling IIoT IP backbones with real-time guarantees

Industrial Internet and Industrial Internet of Things are emerging concepts that concern the use of Internet technologies on industrial environments. The main objective of such architectural visions is allowing a tight and seamless integration between all the functional units and layers that compose industrial processes, from the lowest levels (e.g. field-level devices such as sensors and actuators) to the higher layers, including management, logistics and maintenance. This kind of architecture promises, among other advantages, improving efficiency and flexibility, reduce installation and maintenance costs and reduce unplanned downtime. However, industrial processes often encompass functionalities like closed-loop control of physical processes that are highly critical and have strict timeliness requirements. These requirements are not satisfied by normal Ethernet-based systems. Standards such as IEEE AVB and TSN are addressing this problem, enhancing the real-time properties of Ethernet. However, considering the information presently available, such standards still present some limitations and inefficiencies. This paper reports the extension of HaRTES, an Ethernet-based real-time architecture originally developed for use at the lower layers of industrial scenarios, with MAC Bridge standard functionalities, to make it capable of being integrated on Industrial Internet of Things frameworks. The paper also presents preliminary results obtained with a prototype realization of the extended HaRTES switch.

A fail-safe SDN bridging platform for cloud networks

Redundancy in Ethernet networks has always been an unresolved problem, with associated solutions continuously failing in providing proper support for available network resources management, as well as in the fault tolerance of such networks. However, with the introduction of novel configurable and dynamic mechanisms, such as Software Defined Networking (SDN) and their programmable nature, a unique opportunity for finally solving such issues presents itself. This paper presents a solution based on SDN, which improves network resources management and the fault tolerance of the network elements, applied to a data center management scenario. Results show that the proposed solution achieves minimum packet loss when network links fail, as well as an acceptable topology adaptation time for data center operation.

NETCONF agent for link state monitoring

Fault detection mechanisms have a major importance for network managers, allowing them to respond to system failures by resolving or mitigating their effects. Network and system management technologies should include fault detection mechanisms. NETCONF is a new technology that includes monitoring capabilities and defines a fault-detection mechanism based on sending notifications. This paper documents the development of a NETCONF agent for link-state monitoring and analyzes/evaluates the most important features and capabilities of this management protocol. Additionally, it also analyzes the encoding of the monitoring messages that is performed by NETCONF and evaluates the amount of overhead introduced by the gSOAP API.

A transsignaling strategy for QoS support in heterogeneous networks

The increasing usage of multiple signalling mechanisms, with associated QoS extensions, creates several problems to commercial data networks. New and scalable approaches are required for the network operator to support this diversity. This paper discusses a highly flexible, scalable architecture for processing QoS Admission Control in public networks. The architecture relies on the cooperation of two different entities, an agent and a manager, with fully distributed implementation, and able to perform the required signalling, authorization, and admission control decisions. If required, the agent is capable of interfacing with different signalling mechanisms. Early implementation conclusions are also presented. This architecture is capable of operating with multiple QoS frameworks, with minimal added overhead.

An IDE for NETCONF management applications

The development of network and system management software typically requires data models definition, the creation of specific applications respecting the data model, and yet the implementation of communication interfaces. Skilled professionals usually perform such tasks in a predefined sequence and using different development solutions, but any error or lacks in the data model frequently force to repeat several time-consuming tasks. In this paper we present an integrated development framework that simplifies the construction of NETCONF management applications, from data model specification to deployment and evaluation. The framework is available at http://atnog.av.it.pt/∼ptavares/ yangplugin.

Evaluation of policy-based admission control mechanisms in NGN

The 3GPP consortium proposed in the release 7 of the IP Multimedia Subsystem (IMS) a Diameter interface for the resource admission communication process replacing the previous COPS solution. Although both academic and industry communities have deeply debate the advantages and disadvantages of each protocol, its impact in NGN may have not been thoroughly quantified. This paper compares both protocols in terms of messages exchanged between network entities, and of bandwidth requirements during the admission control process. Based on general network operator environment characteristics, we present several exploitation scenarios where it is analyzed the scalability and adequacy of each protocol.