Unable to communicate with VMs directly attached to T0 Gateway

Products

• VMware NSX

Issue/Introduction

An overlay segment is configured and directly connected to the Tier-0 (T0) gateway.

VMs on that overlay segment directly attached to the T0 cannot communicate on the network.

VMs can communicate on an overlay segment using the Tier-1 (T1) gateway, even if that T1 is connected to the same overlay transport zone.

Changing the impacted segment to use the T1 rather than the T0 allows connectivity.

Environment

VMware NSX 4.x

Cause

The Tier-0 is not pushing traffic from the segment because route re-distribution has not been configured to allow the T0 to do so for directly-connected segments/interfaces.

Resolution

Enable "Connected Interfaces & Segments" in the Tier-0 Route Re-distribution settings and save the configuration completely:

The above menu can be found by:

1. Log into the NSX UI as "admin"
2. Navigate to Networking -> Tier-0 Gateways and edit the T0 gateway by selecting the vertical ellipses next to the gateway
3. Expand the "Route Re-distribution" field
4. Select the number next to the "Route Re-Distribution" item in the view
5. Select the number under the "Route Re-distribution" column header
6. Click "Edit" in the popup

Ensure the changes are saved in the pop-ups as well as the Tier-0 Gateway editing page (once "Close Editing" is visible, all changed settings have been saved).

Additional Information

See Enable Route Redistribution on the Tier-0 Logical Router in Manager Mode for more information on this configuration.