OSPF/BGP Route Advertisement Failure from TGW to Physical Infrastructure

Products

• VMware NSX

Issue/Introduction

• In an NSX environment, routes from a Transit Gateway (TGW) are not being advertised to upstream physical routers.
• While the TGW routes are present within the NSX environment, they are not successfully redistributed via OSPF or BGP to the physical layer, resulting in a lack of reachability between virtual and physical workloads.

Environment

VMware NSX

Cause

The primary cause was an incomplete Route Redistribution configuration on the Tier-0 Gateway. Specifically, the option for Transit Gateway Static (TGWS) was not enabled in the redistribution rules. Because this specific route source was not selected, the Tier-0 Gateway did not include TGW-learned static routes in the OSPF/BGP updates sent to physical neighbors.

Resolution

To resolve this issue, the Transit Gateway Static routes must be explicitly included in the redistribution criteria on the Tier-0 Gateway.

Step-by-Step Instructions:

1. Log in to the NSX Manager UI.
2. Navigate to Networking > Tier-0 Gateways.
3. Select the relevant Tier-0 Gateway and click Edit.
4. Expand the Route Redistribution section.
5. Click on the number next to Route Redistribution Table (or click 'Set' on the redistribution rule).
6. In the Tier-0 Subnets list, locate and check the box for Transit Gateway Static.
7. Click Apply and then Save the configuration.