Configuring Virtual Switch VLAN Tagging (VST) mode on a vNetwork Distributed Switch

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

This article details the concept and configuration of Virtual Switch Tagging (VST) mode on a dvPortGroup (Distributed Port Group) within a VMware vNetwork Distributed Switch. VST is a common VLAN tagging method where the ESXi host performs the VLAN tagging before sending traffic to the physical switch.

Environment

VMware vSphere ESXi 8.x
VMware vCenter Server 7.x , 8.x

Resolution

• Physical Switch Port Mode: Set the physical port connected to the ESX host to TRUNK mode.
• VLAN Tagging Standard: ESX only supports IEEE 802.1Q (dot1q) trunking.
• VLAN Definition on Physical Switch: Ensure the necessary VLANs are defined and allowed on the physical switch ports connected to the ESXi hosts.
• VLAN Configuration on ESX: VLAN configuration is required on the ESX side, specifically on the dvPortGroup.

Critical Caution: Native VLAN ID

• VST Mode does NOT support Native VLAN ID.
• DO NOT assign a VLAN ID to a dvPortGroup that is the same as the native VLAN ID of the physical switch.
• Reason: Native VLAN packets are not tagged with a VLAN ID when leaving the physical switch towards the ESXi host. If an ESXi host is configured for VST mode, it expects all traffic to be VLAN-tagged. Untagged packets (native VLAN traffic) will be dropped by the ESXi host if it's operating in VST mode.

Step-by-Step VST Configuration on a dvPortGroup:

1. In vCenter, navigate to Home > Inventory > Networking.
2. Right-click on the desired dvPortGroup and select Edit Settings.
3. Within the dvPortGroup > Settings > VLAN > Policies section:
   • Set the VLAN type to VLAN.
   • Select a VLAN ID within the range of 1-4094.
4. Click OK to apply the changes.

 Notes:

• VLAN ID 4095 should not be used. This ID is reserved or has special uses in some environments.
• Configuration Interface: Distributed Switch portgroups can only be configured from the vSphere Client or vSphere Web Client.
• CLI Limitation: It is not possible to configure vDS portgroup VLANs from the ESX/ESXi command-line interface (CLI).

Additional Information

For additional information and physical switch sample configuration, see Sample configuration of virtual switch VLAN tagging (VST Mode).

vNetwork Distributed Switch 上での仮想スイッチ VLAN タギング (VST) モードの構成