1. This will be followed by a description of the fuzzy nature of the problem and a detailed presentation of how the required membership functions are defined.2. Details on xx and xx are discussed in later sections.3. In the next section, after a statement of the basic problem, various situations involving possibility knowledge are investigated: first, an entirely possibility model is proposed; then the cases of a fuzzy service time with stochastic arrivals and non fuzzy service rule is studied; lastly, fuzzy service rule are considered.