Intermittent Connectivity Issue in Overlay Network Due to Invalid Replication Mode in NSX

Products

• VMware NSX

Issue/Introduction

• VMs connected to an overlay network segment are intermittently unable to communicate with each other via ping.
• Replication mode on the NSX UI (Manager view) is set INVALID.
  
• API call PUT /api/v1/logical-switches/{lswitch-id} may have been used to update the Logical Switch.

Environment

VMware NSX-T Data Center
VMware NSX

Cause

VMware NSX supports two different replication modes:

• Hierarchical two-tier (sometimes called MTEP)
• Head (sometimes called source)

The Replication mode will be incorrectly set as INVALID when the body of the API to update the logical switch doesn't specify the replication_mode attribute.

Resolution

This is a known issue impacting VMware NSX.

To workaround this issue perform the following steps:

1. In the NSX UI, toggle the view to Manager.
2. Select the impacted Logical Switch.
3. Edit the selected Logical Switch by clicking Edit on the UI.
4. Perform a dummy change by updating the Description and click Save.
5. (Optional) This change can be reverted once the UI shows the correct Replication mode for the Logical Switch.

Alternatively you can use the PUT /api/v1/logical-switches/{lswitch-id} API to set the correct Replication mode.