Recent years witnessed a fast-growing demand, in the context of industrial use-cases, for the so-called Deterministic Networks (DetNet). IEEE 802.1 TSN architecture provides link-layer services and IETF DetNet provides network-layer services for deterministic and reliable forwarding. In such a context, in the first part of this paper, we tackle the problem of misbehaving flows and propose a novel queuing and scheduling mechanism, based on Push-In-First-Out (PIFO) queues. Differently from the original DetNet/TSN specifications, our solution is able to guarantee performance of priority flows in spite of misbehaving flows. In the second part of this paper, we present our simulator DeNS: DetNet Simulator, based on OMNET++ and NeSTiNG, providing building blocks for link-layer TSN and network-layer DetNet. Existing simulators have important limitations that do not allow simulating the full DetNet/TSN protocol stack. We overcome these limitations, making easy DetNet/TSN evaluations possible. Our simulations clearly show that our solution is able to satisfy constraints of deterministic networks, namely, guarantee zero packet loss and low latency, while at the same time allowing best-effort flows to co-exist. Furthermore, we show how our newly-proposed queuing and scheduling solution successfully limits the impact of misbehaving flows.