Optimistic synchronization protocols for parallel discrete event simulation employ rollback techniques to ensure causally consistent execution of simulation events. Although event preemptive rollback (i.e. rollback based on timely event execution interruption upon the arrival of a message revealing a causality inconsistency) is recognized as an approach for increasing the performance and tackling run-time anomalies of this type of synchronization, the lack of adequate functionalities at the level of general purpose communication layers typically prevents any effective implementation of event preemptive rollback operations. In this paper we present the design and implementation of a communication layer for Myrinet based clusters, which efficiently supports event preemptive rollback operations. Beyond standard low latency message delivery funcbionalities, this layer also embeds functionalities for allowing the overlying simulation application to efficiently track whether a message will actually produce causality inconsistency of the currently executed simulation event upon its receipt at the application level. Exploiting these functionalities, awareness of the inconsistency precedes the message receipt at the application level, thus allowing timely event execution interruption for activating rollback procedures. We also report experimental results demonstrating the effectiveness of our solution for a Personal Communication System (PCS) simulation application.