An unreliable open queueing network with Poisson arrivals is considered. For each queueing system the service and failures times are exponentially distributed random variables. The failures of systems lead to changes in the structure of the network and corresponding changes in the performance measures of the queueing network. https://www.ngetikin.com/limited-save-Apple-iPhone-14-Pro-Clear-Case-with-MagSafe-save-big/