For demanding Grid applications that use resources at different cluster sites a reservation mechanism can ensure the availability of resources to guarantee a certain level of QoS. Besides computational and storage resources, we see the network as a reservable resource as well. Our approach to QoS is to schedule resources in the network for exclusive usage in advance. For this purpose, a flexible reservation mechanism is needed to meet the requirements of Grid applications and schedulers. In this paper we introduce a wider notion of network service than previous work. Special focus is on a file transfer service that guarantees the timely availability of data at the different Grid sites. To cope with these requirements, strategies and algorithms for a flexible network reservation service are introduced and evaluated systematically. Here, algorithms using a single path strategy are compared to algorithms using multiple paths. Our simulation results show that data transport via multiple paths leads to a higher user and network provider satisfaction than single path transfers.
['Christoph Barz', 'Peter Martini', 'Markus Pilz', 'Florian Purnhagen']
Experiments on Network Services for the Grid