Virtual LAN

A Virtual Local Area Network (VLAN) uses IEEE 802.1Q tagging — a 4-byte header inserted into Ethernet frames — to logically separate traffic on shared switch infrastructure into independent broadcast domains. Each VLAN has a 12-bit ID (1–4094) and behaves as if devices share a separate physical network, even when they share cables, ports, and switches.

In datacentre environments, VLANs provide the foundational layer of network segmentation: separating IPMI/management traffic from production workloads; isolating multi-tenant customer networks in colocation facilities; dividing storage (iSCSI, NFS) from general IP traffic; and enforcing security boundaries between network zones. VLAN-aware switches enforce isolation at hardware speed. VLANs are frequently paired with VXLAN overlays for larger-scale or multi-site deployments and are a fundamental component of any DCIM network topology.