This work addresses the impact of best-effort traffic on network-dependent real-time functions in distributed control systems. Motivated by the increased Ethernet use in real-time dependent domains, such as the automation industry, a growth driven by Industry 4.0, interconnectivity desires, and data thirst. Ethernet allows different network-based functions to converge on one physical network infrastructure. In the automation domain, converged networks imply that functions with different criticality and real-time requirements coexist and share the same physical resources. The IEEE 60802 Time-Sensitive Networking profile for Industrial Automation targets the automation industry and addresses Ethernet network determinism on converged networks. However, the profile is still in the draft stage at the time of writing this paper. Meanwhile, Ethernet already provides attributes utilized by network equipment to prioritize time-critical communication. This paper shows that Ethernet Controller filtering with prioritized processing is a prominent solution for preserving real-time guarantees while supporting best-effort traffic. A solution capable of eliminating all best-effort traffic interference in the real-time application is exemplified and evaluated on a VxWorks system.