Industrial VLAN Trunking is what makes OT network segmentation work across more than one switch. This walkthrough shows engineering managers how managed switches build MAC address tables, route traffic by VLAN tag, and propagate VLANs from one switch to the next. 1Q trunks, the switches maintain one spanning-tree instance for each VLAN allowed on the trunks. It is a fundamental topic of the CCNA exam and the networking field in general. 0 and intelligent manufacturing, industrial Ethernet switches have become the core equipment for building efficient and reliable industrial networks. They achieve logical isolation through VLAN (Virtual Local Area Network) technology and break down isolation barriers. Trunking in networking means combining multiple network links into one logical connection to boost bandwidth and simplify management. It uses protocols like IEEE 802. With repeating hubs, all stations on the network occupy the same collision domain and obey the rules for arbitrating access to the network.