ESXi hosts shows as degraded in NSX-T ui

Products

• VMware NSX

Issue/Introduction

• ESXi host's status shows as 'Degraded' in NSX-T ui.
  • Path: NSX UI --> System--> Fabric--> Hosts.
• 
• In the view details of ESXi hosts , the manager and controller connectivity was showing as 'Up':-
  • Path: NSX UI --> System--> Fabric--> Host --> Click on "View Details" on the problematic Host .
    
• The vmnic's link status was down which was connected to vSwitch0 for affected ESXi hosts:-
  • Path: Login to vCenter UI--> select the problematic host --> Configure--> Virtual Switches --> expand physical adapters.
• 
• From the NSX manager log bundle, "desired_state_manager.json" file reports following entries:-

  • "node_uuid": "######-f###-4###-a##7-5###########",
            "pnic_status": {
              "degraded_count": 0,
              "down_count": 1,
              "down_pnics": [
                {
                  "name": "vmnic0",
                  "nsx_type": "NONNSX",
                  "status": "DOWN",
                  "type": "PNIC"
                }
              ],
              "last_status_changed_time": 1756459833053, ===> 
    Friday, August 29, 2025 9:30:33.053 AM
    
    
              "status": "DEGRADED",
              "up_count": 2
            },
    
     "status": "DEGRADED",
            "status_description": "Status DEGRADED caused by [pnic], please check sub-status fields.",

• In /var/run/log/nsx-syslog.log on ESXi host, the following entries of link down vmnic getting assigned to DVS used by NSX were seen:-

  • 2025-09-01T09:31:17.596Z  INFO TransportNodeStatusMessageListener-1-1 TransportNodeStatusMessageHandler 2353544 MONITOR
    ING [nsx@6876 comp="nsx-manager" level="INFO" subcomp="manager"] Received message for PnicBonds : 'rolled_up_status':DE
    GRADED, 'num_up':2, 'num_down':1, 'num_down':0, 'pnic_bonds':[{'name':DVSwitch, 'status':UP, 'type':BOND}, {'n
    ame':DVSwitch, 'status':UP, 'type':BOND}, {'name':vmnic0, 'status':DOWN, 'type':PNIC}, ] : ########-f###-4###
    -a###-5###########

• In the /var/run/log/nsxdavim.log on ESXi host , the "assign" operation reported for vmnic0 :-

  • 025-09-01T10:07:54Z nsxdavim: nnectionCookie Operation=assign Value=1673507733 Name=config.network.nics.vnic.vmk50 Operation=assign Value=Changed Name=config.network.nics.vnic.vmk50.LportAttachmentId Operation=assign Value=empty Name=config.network.nics.vnic.vmk50.BackingType Operation=assign Value=DVS Name=config.network.nics.vnic.vmk50.BackingPortSwitchUuid Operation=assign Value=## ## ## ## ## ## ## ## ## ## Name=config.network.nics.vnic.vmk50.BackingPortPortgroupKey Operation=assign Value=empty Name=config.network.nics.vnic.vmk50.BackingPortPortKey Operation=assign Value=##### #### ##### #######
    Name=config.network.nics.vnic.vmk50.BackingPortConnectionCookie Operation=assign Value=1673507734 Name=config.network.nics.vnic.vmk2 Operation=assign Value=Changed Name=config.network.nics.vnic.vmk2.LportAttachmentId Operation=assign Value=empty Name=config.network.nics.vnic.vmk2.BackingType Operation=assign Value=DVS Name=config.network.nics.vnic.vmk2.BackingPortSwitchUuid Operation=assign Value=## ## ## ## ## ## ## ## ## ## ## ## Name=config.network.nics.vnic.vmk2.BackingPortPortgroupKey Operation=assign Value=dvportgroup-2179604 Name=config.network.nics.vnic.vmk2.BackingPortPortKey Operation=assign Value=484 Name=config.network.nics.vnic.vmk2.BackingPortConnectionCookie Operation=assign Value=867424528 Name=config.network.switches Operation=assign Value=Changed Name=config.network.switches.vmnic0 Operation=assign Value=vSwitch0 Name=config.network.switches.vmnic0.BackingType Operation=assign Value=Standard ChangeDataEnd done]

   

Environment

VMware NSX

Cause

NSX by default checks the PNIC status of all the virtual switches on the host transport node. If a PNIC is down on any of the virtual switches, the host will be marked as 'Degraded'.

Resolution

Remove the unused/down uplink mapping from the virtual switch configuration. If the uplink is required, perform troubleshooting to bring the physical link back online.

Note: When utilizing Mellanox InfiniBand adapters, NSX may report a 'Degraded' status as a false positive. This occurs because the hypervisor requires an active uplink mapping to facilitate Virtual Functions (VFs). However, in non-RoCE environments, the backend switch fabric does not provide a standard Ethernet 'link-up' signal. Consequently, the interface reports as 'Down' at the Ethernet layer, triggering an NSX alert that does not accurately reflect the health of the Data Plane. This can be ignored safely.

Refer KB NSX Host Status Degraded due to Mellanox InfiniBand pNIC Down State