Failed to Validate Reachability of Application Virtual Networks with Gateway IPs in NSX

Products

• VMware NSX

Issue/Introduction

When adding Application Virtual Networks (AVNs) for VMware Aria Suite from SDDC Manager, the following error may occur:

Failed to validate reachability of Application Virtual Networks with gateway IPs

The AVN segments are successfully created, but gateway IP validation fails. This prevents the completion of the AVN setup process.

The error message appears in the SDDC Manager interface as a task status "Failed" with a detailed error referencing gateway IPs validation failure.

Steps to verify this issue:

1. Observe the "Validate Application Virtual Network (AVN) Connectivity" task shows Failed status
2. Review the error details which show "Failed to validate reachability of Application Virtual Networks with gateway IPs"
3. Confirm that the AVN segments were created but are not working correctly

Environment

• SDDC Manager
• NSX-T Data Center
• VMware Aria Suite

Cause

The issue occurs when BGP (Border Gateway Protocol) in NSX is incorrectly configured for the subnet containing the AVN gateway IPs. The BGP route advertisements don't match the actual network implementation, creating a subnet mask mismatch.

This mismatch prevents proper routing to the gateway IPs, causing the validation check to fail.

Resolution

To resolve this issue:

1. Log in to NSX Manager.
2. Navigate to Networking > Tier-0 Gateways.
3. Select the relevant Tier-0 Gateway.
4. Go to the BGP routing configuration section.
5. Modify the BGP advertisement to correctly specify the subnet masks for the AVN gateway IPs.
   • If there are multiple subnets, ensure each subnet is properly defined.
   • Verify that the BGP route advertisements match the actual implemented network configuration.
6. Save the configuration changes.
7. Return to SDDC Manager and retry the AVN validation.

If the error persists after following these steps, contact Broadcom Support for further assistance.

Please provide the following information when opening a support request with Broadcom for this issue:

• Complete error messages from SDDC Manager
• NSX Manager version
• Detailed BGP configuration information
• Log files from SDDC Manager and NSX