VLANInterfaces

VLANInterfaces are logical network interfaces associated with a specific Virtual Local Area Network (VLAN). They provide Layer 3 reachability within the VLAN and frequently serve as gateways for devices in that VLAN, enabling routing to other networks or VLANs. In many devices, a VLANInterface is implemented as a switch virtual interface (SVI) on switches or as a sub-interface on routers connected to a trunk link. In virtualization and cloud environments, VLANInterfaces can also be represented by virtual NICs bound to a VLAN ID.

Key characteristics include the association with a single VLAN ID, the ability to assign an IP address in the VLAN’s subnet, and participation in inter-VLAN routing. Frames destined for the VLAN are tagged with the appropriate 802.1Q VLAN tag on trunk ports, while access ports typically carry untagged frames for the VLAN. The VLANInterface itself handles IP-level processing for traffic entering or leaving the VLAN.

Configuration typically involves creating or enabling the VLAN, creating or selecting the corresponding VLANInterface, assigning an IP address and subnet mask, and configuring any required routing, firewall rules, or DHCP settings. Proper management includes ensuring the VLAN exists on the relevant switch or router, applying consistent tagging on trunk links, and enforcing security policies to limit unnecessary east–west or north–south traffic.

Common use cases involve providing a gateway for hosts in each VLAN, enabling inter-VLAN routing, and offering a manageable management or service interface tied to a dedicated VLAN.