Browsing by Author "Veiga, Pedro"
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- An Investigation of Inter-Domain Control Aggregation ProceduresPublication . Sofia, Rute; Guérin, Roch; Veiga, PedroCurrent Quality of Service models such as those embodied in the Differentiated Services proposals, rely on data path aggregation to achieve scalability. Data path aggregation bundles into a single aggregate multiple individual flows with the same quality requirements, hence decreasing the amount of state that needs to be kept along a path. A similar scalability concern exists on the control path, where the state required to account for individual reservations needs to be minimized. There have been a number of proposals aimed at control path aggregation, and the goal of this report is to expand on these works in an attempt to gain a better understanding of the various parameters that influence the efficiency of different approaches. In particular, we focus on inter-domain control aggregation, and compare an Autonomous System (AS) sink-tree based approach with several examples of a shared AS segment based approach. The comparison is done in terms of the amount of state that is kept, both within a given AS, as well as at edge routers. The comparison is carried out primarily through simulations, but we also develop a simple analytical model for a basic AS configuration, which provides additional insight into the impact of different parameters on the efficiency of each approach. Our main contributions are in providing a greater understanding into the design of efficient control path aggregation methods.
- An Investigation of Inter-Domain Control Aggregation ProceduresPublication . Sofia, Rute; Guérin, Roch; Veiga, PedroCurrent Quality of Service models such as those embodied in the Differentiated Services proposals, rely on data path aggregation to achieve scalability. Data path aggregation bundles into a single aggregate multiple individual flows with the same quality requirements, hence decreasing the amount of state that needs to be kept along a path. A similar scalability concern exists on the control path, where the state required to account for individual reservations needs to be minimized. There have been a number of proposals aimed at control path aggregation, and the goal of this report is to expand on these works in an attempt to gain a better understanding of the various parameters that influence the efficiency of different approaches. In particular, we focus on inter-domain control aggregation, and compare an Autonomous System (AS) sink-tree based approach with several examples of a shared AS segment based approach. The comparison is done in terms of the amount of state that is kept, both within a given AS, as well as at edge routers. The comparison is carried out primarily through simulations, but we also develop a simple analytical model for a basic AS configuration, which provides additional insight into the impact of different parameters on the efficiency of each approach. Our main contributions are in providing a greater understanding into the design of efficient control path aggregation methods
- Small-scale coastal fisheries in European Seas are not what they were: Ecological, social and economic changesPublication . Lloret, Josep; Cowx, Ian G.; Cabral, Henrique; Castro, Margarida; Font, Toni; Gonçalves, Jorge M.S.; Gordoa, Ana; Hoefnagel, Ellen; Matić-Skoko, Sanja; Mikkelsen, Eirik; Morales-Nin, Beatriz; Moutopoulos, Dimitrios K.; Muñoz, Marta; dos Santos, Miguel Neves; Pintassilgo, Pedro; Pita, Cristina; Stergiou, Konstantinos I.; Ünal, Vahdet; Veiga, Pedro; Erzini, KarimCoastal, small-scale fisheries (SSF), whether artisanal (professional) or recreational, represent important socioeconomic activities across Europe that are currently undergoing a number of changes. This paper reviews and analyses the drivers of these changes, and makes recommendations for the future management of SSF. From the biological standpoint, the use of fishing gears that actively select certain species, sizes and sexes, the deployment of fishing gears on certain fragile habitats, the loss of fishing gears and the use of non-native species as bait are examples of how SSFs can threaten the sustainability of vulnerable coastal species and habitats. From a socioeconomic perspective, several factors are altering the traditional characteristics of coastal SSF. Among the most important is the growth of recreational fisheries in coastal waters and the disappearance of traditional low technology fisheries or their substitution by more mechanised, technical fisheries, which is leading to a loss of the traditional ecological knowledge held by artisanal fishers. On the other hand, the increasing competition between artisanal and recreational fisheries, and between them and commercial fishing operations, are also altering the classical features of coastal fisheries in some European countries. SSFs must adapt to the requirements of the new Common Fisheries Policy (CFP), namely management based on Maximum Sustainable Yield (MSY), multi-annual management plans and ecosystem based principles. It is concluded that it is necessary to integrate different assessment approaches (biological, social and economic), with active participation from stakeholders, governments and relevant research institutions, to better evaluate and manage coastal fisheries.