No traffic past Tier-0 gateway. Error: "Dropped for no route found"

Products

• VMware NSX

Issue/Introduction

• Traffic can not get out of the environment past the Tier-0 gateway.
• Traceflow from a test VM through the Tier-0 shows the traffic was dropped.  The identified cause is "Dropped for no route found".
• Affected Tier-0 Gateway is in HA Mode "Active Active"
• Environment had been upgraded to 4.2.1.0 at some point.  To identify if an applicable upgrade took place, confirm via the API - GET https://<NSX-Manager-IP>/api/v1/upgrade/history
  • An upgrade to the affected release will include a result like:
    • {
   "initial_version": "4.1.1.0.0.22224312",
   "target_version": "4.2.1.0.0.24304122",
   "timestamp": 1734058496961,
   "upgrade_status": "SUCCESS"
},

Environment

VMware NSX 4.2.1.0+

Cause

• The 4.2.1.0 upgrade did not retain the stateful mode of the Tier-0 router.  This resulted in an invalid re-configuration where the Tier-0 router was converted from active-active stateful to active-active stateless.
• This invalid conversion left stale service router information in the database.
• This stale information cannot be properly realized on the transport nodes, resulting in the routing problems.

Resolution

It is required to remove the invalid Tier-0 configuration so the stale information can be removed.

• Use the configuration from the affected Tier-0 router to re-create it as a new Tier-0 router and migrate to the new instance.
• Remove the improperly converted Tier-0 router so the stale information will be cleaned up.

Additional Information

This problem only occurs on Tier-0 routers in Active-Active configuration that were present during an upgrade to 4.2.1.0.  Upgrades to other versions are not affected.