NSX-T VTEP vmk10 and vmk11 points to fallback on team-pnic instead of an actual physical nic during time of failover.

Products

• VMware NSX

Issue/Introduction

In an NSX-T environment, Nic Teaming configured for an ESXi host transport node fails to properly fail over traffic. When an active physical NIC goes down, esxtop shows the new active NIC as a "fallback" to team-pnic instead of an actual physical NIC. This leads to VTEP traffic (vmk10 and vmk11) being blackholed.

Environment

VMware NSX
VMware NSX-T Datacenter

Cause

The root cause is an inconsistency in the mapping between the Uplinks of the Virtual Distributed Switch (VDS) on vCenter and their association within the Transport Node Profile (TNP) in NSX-T. Specifically, there's a mismatch between the VDS uplink-to-physical NIC mapping on vCenter and what is configured in the TNP.

Resolution

To resolve this issue, you need to verify and correct the uplink mappings:

1. Identify VDS Uplink-to-vmnic Mapping on vCenter:

   • Log in to vCenter Server UI.
   • Navigate to the affected ESXi host > Configure > Virtual Switches (under Networking).
   • Expand the NSX Switch and note down the association between the VDS Uplinks and the physical vmnics.
     

2. Validate/Correct Uplink Mapping on NSX-T Transport Node Profile:

   • Log in to the NSX-T Manager UI.
   • Go to System > Fabric > Transport Node Profile.
   • Examine the Teaming Policy Uplink Mapping associated with Uplinks and VDS Uplinks.
   • If any inconsistencies are found (e.g., blank Uplinks where physical NICs should be mapped), re-map the correct VDS Uplinks to their associated physical vmnics.
     
     
   • The resolution for the above screenshot is to change uplink-2 to map to Uplink 2 instead of Uplink 3 as there is no physical uplink association on the vCenter.