VDI Horizon Infrastructure Migration and Connectivity Triage for New VLAN Schemes

Products

• VMware vSAN

Issue/Introduction

Network isolated when transitioning Virtual Desktop Infrastructure (VDI) to updated network segments.
This guide addresses connectivity failures—such as the inability to reach default gateways—that occur during Horizon desktop migration within a VMware vSphere environment.
By synchronizing Distributed Virtual Switch (DVS) port group tags with physical switch trunking and Horizon pool settings, administrators can ensure a non-disruptive transition.

• Virtual machines reassigned to new Distributed Virtual Switch (DVS) port groups cannot ping the default gateway (e.g., ####.####.6.1).
• The physical switch MAC address table does not learn the MAC addresses of migrated VMs.
• Active desktop sessions disconnect immediately upon network reassignment.
• Horizon Desktop Pools fail to provision new clones or map them to the incorrect network.

 

Environment

VMware vSAN 8.x

VMware Horizon VDI

 

Cause

1. Physical Network Gaps: The migration VLAN is missing from the global switch database or is excluded from the "allowed trunk" list on ESXi host ports and core uplinks.
2. Configuration Mismatch: Desktop pool settings in the Horizon management layer have not been updated to match the new vCenter port group configuration.

Resolution

1. Validate Physical Switch Readiness

   • Confirm the new VLAN is globally defined in the switch database.
   • Ensure the physical ports connected to the ESXi hosts are configured to permit the new VLAN ID in their trunk allowed lists.
   • Verify that core uplinks connecting the access switches to the Layer 3 gateway also permit the migration VLAN.

2. Staged vCenter Network Migration

   • Create a new Distributed Port Group in vCenter and assign the updated VLAN tag. 
   • Use the "Migrate VMs to Another Network" wizard to move active VM network adapters to the new port group.   
   • Test connectivity from a guest VM to the gateway before proceeding with bulk migrations.

3. Update Horizon Management Layer

   • Log in to the Horizon Console and navigate to the Desktop Pool settings.
   • Modify the network provisioning configuration to point to the newly created vCenter Port Group.
   • Provision a test clone to verify the new network is being applied to automated tasks.

Additional Information

Broadcom supports the underlying vSphere infrastructure. For issues restricted to Horizon Console logic or Desktop Pool provisioning, please engage Omnissa support.

Configure VLAN Tagging on a Distributed Port Group or Distributed Port