Overlay Network failed to extended with the error "Network used as backing for overlay network cannot be extended"

Products

• VMware HCX
• VMware NSX

Issue/Introduction

• Network extension has many restrictions and limitations. When extending NSX overlay, it is supported when the connector side uses NSX and NSX Manager is registered on HCX Manager via port 9443.
• NSX-T Overlay and NSX-T VLAN networks can be extended. These extensions are always created as NSX Overlay networks at the destination. HCX Network Extension is always to NSX Overlay networks. Pre-created segments in the vSphere Distributed Switch, CVDS, or VLAN transport zone, cannot be used as a destination.
• When trying to extend the overlay network, the task failed with the error "Network used as backing for overlay network cannot be extended". 

Environment

VMware HCX
VMware NSX 

Cause

This issue occurs when the Overlay transport zone is not selected while configuring the Compute Profile.

Resolution

• When extending logical segments, make sure the Compute Profile is configured to use the overlay transport zone.
• Login to the HCX Hybridity page --> https://<hcx-manager/
• Go to Interconnect --> Compute Profiles --> Edit Compute Profile --> Select Network Containers Eligible for Network Extension
• Ensure you have the overlay network selected as shown below.

• Additionally, ensure that you re-sync the specific Service Mesh to update the changes done in the compute profile.
• Login to the on-prem HCX manager hybridity page --> https://hcx-manager/
• Go to --> Interconnect --> Service Mesh --> Choose the specific service mesh --> Resync

Additional Information

For other restrictions and limitations, please review the "Restrictions and Limitations for Network Extension" section in the VMware HCX Product Documentation.