Dissertação mest., Engenharia Eléctrica e Telecomunicações, Universidade do Algarve, 2009The concept of Grid networks has recently emerged as an infrastructure able to support, both scientific and commercial applications. The Grid is a dynamic, distributed collection of heterogeneous computational, storage and network resources geographically distributed and shared between organizations.
Optical Burst Switching (OBS) networks have been identified as a technology with potential to support the requirements of the Grids. This approach, known as Grid over Optical Burst Switching (GOBS) is currently the object of intensive research.
This dissertation focus is on GOBS architectures employing Active OBS Routers with centralized control. This approach enables the balance of the overall network traffic potentially minimizing congestion and consequently reducing job blocking. Two different strategies are explored.
The first strategy is a novel signaling scheme applied to a GOBS network employing Active Routers. The Active Router reduces the job blocking probability, because the path used by the Data Burst to reach the Grid Job Resource is selected based on the network actual status. Since the Active Router maintains the network status always updated, the bursts are only dropped when is not possible to connect the source to the end node. Another study associated with this signaling scheme is the reservation time. It is demonstrated that this approach decreases the network blocking probability at the same time that decreases the time delay that a job suffers until it reaches the Grid service provider.
In the second strategy, the Active Router only select the Grid Resource used to resolve the job, the path used to reach it is selected by the Grid client based on the probabilistic model for the link demands. The probabilistic model is used to predict a possible network usage based on the demands from all nodes to all nodes. The results obtained show overall performance improvement
