VLANStruktur

VLANStruktur refers to the logical segmentation of a computer network into multiple broadcast domains using virtual local area networks (VLANs). This structure allows groups of devices to communicate within their own segment while reducing unnecessary broadcast traffic and increasing security and manageability. Each VLAN is identified by a VLAN ID (IEEE 802.1Q allows IDs from 1 to 4094; 0 and 4095 have special meanings).

VLAN tagging and port types form the technical basis of a VLAN structure. Switches connect devices via access ports, which carry untagged frames belonging to a single VLAN. Trunk ports interconnect switches and carry frames for multiple VLANs, with frames tagged to indicate their VLAN. The native VLAN is a special VLAN on trunks where untagged frames are associated.

Membership to VLANs can be configured statically on switch ports (port-based VLAN) or dynamically through policies or MAC addresses. For consistency across the network, VLAN IDs and their purpose should be standardized so that devices in the same VLAN can communicate when connected to different switches.

Inter-VLAN routing is required for devices in different VLANs to communicate. This can be provided by a Layer 3 switch or a router using subinterfaces on a trunk (router-on-a-stick) or by a dedicated routing device in the network core.

Common VLAN types include data VLANs for user traffic, voice VLANs for IP phones, and management VLANs for network administration. Best practices involve limiting the number of untagged VLANs on trunks, using a dedicated native VLAN, securing unused ports, and applying VLAN pruning and proper Spanning Tree configurations to prevent loops. A well-designed VLAN structure supports scalable, secure, and efficient network operation.