Closed Finite Queuing Networks with Time Lags and with Several Classes of Units

The authors have previously investigated a broad class of closed, finite queuing networks with time lags, in which all units were considered to be identical. In this paper, that work is extended to the treatment of systems having several classes of units in which units belonging to different classes may have different sets of service parameters at the stations, different sets of travel-time distributions between stations, and different routing procedures through the system.