Abstract
An approximation is introduced for the mean value analysis of queueing networks with transfer blocking. The blocking occurs when a job, after completing service at a station, wants to join a station which is full. The job resides in the server of the source station until a place becomes available in the destination station. The approximation is based on the modification of mean residence times, due to the blocking events that occur in the network. Several examples are executed that validate the approximate results.