Proceedings Second IEEE Symposium on Computer and Communications (1997)
July 1, 1997 to July 3, 1997
D.R. Jeske , Lucent Technol., Bell Labs., Holmdel, NJ, USA
M.A. Qureshi , Lucent Technol., Bell Labs., Holmdel, NJ, USA
R. Nagarajan , Lucent Technol., Bell Labs., Holmdel, NJ, USA
Consider m offices with each operating a duplexed unit. Suppose a centrally located warehouse is to be provisioned with k spares to be used when offices experience failures. Assume that failed units are instantaneously replaced with spare units, provided a spare is available at the warehouse and the failed units are repaired and used to replenish the spare inventory. We consider two approaches for determining a suitable value for k. In the first approach, a network emergency is declared whenever the number of failed units in the network exceeds k. A simple expression for the mean time to a network emergency (MTNE) is obtained using a birth and death process model. The value of k is selected to make MTNE satisfactorily large. In this approach, it is conservatively assumed every network emergency will be service affecting. However, only when the number of failures exceeds k AND at least one office has two failures is the incident service affecting. Our second approach accounts for this distinction by evaluating the mean time to a service affecting incident (MTSI). The two approaches are compared by contrasting the different valves of k each requires to achieve a specified objective for MTNE and MTSI, respectively.
warehouse automation; duplexed units; offices; centrally located warehouse; failures; spare units; repair; spare inventory; network emergency; failed units; mean time to network emergency; sparing rules; birth and death process model; mean time to service affecting incident
M. Qureshi, R. Nagarajan and D. Jeske, "Sparing rules for duplexed units," Proceedings Second IEEE Symposium on Computer and Communications(ISCC), vol. 00, no. , pp. 449, 1997.