VLAN Segmentation & 802.1Q Protocol in Enterprise Networks

Virtual LANs (VLANs) divide physical broadcast domains into logical segments, improving network security and bandwidth utilization.

IEEE 802.1Q Tagging: When frames cross a switch trunk line, an 802.1Q header inserts a 4-byte tag into the Ethernet frame header: - TPID (0x8100): Tag Protocol Identifier - VLAN ID (12 bits): Supports up to 4094 distinct VLANs

By enforcing strict PVST+ or MSTP topologies alongside AAA-based 802.1X dynamic VLAN assignments, campus networks maintain defense-in-depth security.