Migrate ESXi Management Network (vmk) to a VLAN tagged Trunk configuration

Products

• VMware vSphere ESXi

Issue/Introduction

- When migrating an ESXi host's management interface (vmk0) from an access port (untagged) to a trunk port (tagged), a configuration mismatch can occur.

- If the physical switch port is changed to trunk mode before the ESXi Port Group is configured for Virtual Switch Tagging (VST), the host becomes isolated from the network and vCenter Server.

- This article provides a staged procedure to ensure continuous connectivity using dual uplinks.

Environment

VMware ESXi 7.x, 8.x, 9.x

 

Resolution

To perform this migration without downtime, use a "Break-Mirror" approach by migrating one uplink at a time. (scenario with vmnic1 and vmnic2 as active uplinks for management network)

1. Isolate the First Uplink:

   • Navigate to the ESXi host > Configure > Networking > Virtual switches.

   • Select the vSwitch hosting the Management Network.

   • Edit the Management Network Port Group.

   • In Teaming and Failover, move vmnic2 to the Unused adapters section. vmnic1 remains Active.

2. Configure Physical Switch Port:

   • Reconfigure the physical switch port connected to vmnic2 from access mode to Trunk mode.

   • Ensure the management VLAN ID is allowed on this trunk.

3. Create a Tagged Port Group:

   • On the same vSwitch, create a new Port Group named "Management-Tagged".

   • VLAN ID: Set this to the specific ID of your management network.

   • Teaming and Failover: Set vmnic2 as Active and vmnic1 as Unused.

4. Migrate the VMkernel Adapter:

   • Go to VMkernel adapters.

   • Select vmk0 and click Edit.

   • Change the network to the new "Management-Tagged" port group.

   • Note: Connectivity is now flowing through the trunked vmnic2

5. Finalize Trunking on Second Uplink:

   • Reconfigure the physical switch port connected to vmnic1 to Trunk mode.

   • Edit the "Management-Tagged" Port Group settings.

   • Move vmnic1 back to the Active adapters section to restore redundancy.

Additional Information

• Network Rollback: If the connection to vCenter is lost during Step 4, from vSphere version 7.0 onwards, it will automatically roll back the change to the previous working state.

• DCUI: If the host remains isolated, log in via the Direct Console User Interface (DCUI) and use Configure Management Network > VLAN (optional) to manually set the tag.