The Compaan compiler automatically derives a Process Network (PN) description from an application written in Matlab. The basic element of a PN is a Producer/Consumer (P/C) pair. Four different communication patterns for a P/C pair have been identified and the complexity of communication structure differs depending on the communication pattern involved. Therefore, in order to obtain cost-efficient process networks our compiler automatically identifies the communication pattern of each P/C pair. This problem is equivalent to integer linear programming and thus in general can not be solved efficiently. In this paper we present simpler techniques that allow to classify the interprocess communication in a PN. However, in some cases those techniques do not allow to find an answer and therefore, an ILP test has still to be applied. Thus, we introduce a hierarchical classification scheme that correctly classifies the interprocess communication, but uses dramatically less integer linear programming. In only 5% of the cases to classify, we still rely on integer linear programming; in the remaining 95%, the techniques presented in this paper are able to classify a case correctly.