Recovering guaranteed performance service connections from single and multiple faults
Fault recovery techniques must be reexamined in the light of the new guaranteed performance services that high-speed packet/cell switched networks will support. We investigate the rerouting of guaranteed performance service connections on the occurrence of link faults, focussing on the aspects of route selection and establishment in the network. In a previous investigation, we explored some components of rerouting in the presence of single link faults in the network. In this paper we study the behavior of our techniques in the presence of multiple link faults in the network. We also examine the technique of retries to improve the success of rerouting. Our schemes are simulated on a cross-section of network workloads, and compared using several performance criteria. We use our results to develop a new delayed retry technique, which performs well for all our performance criteria.
Abstract A layer of random defects in the simple cubic Ising model with nearest neighbor ferromagnetic interactions of strength J is considered. Using the real space renormalization group method we calculate defect free energy in the whole temperature range. Specifically, we analyze: the layer of diluted defects, the layer of spin-glass type defects, and the layer of mixed defects. The free energy is strongly dependent on the value of couplings between the defect and the bulk.