Troubleshooting NIC errors and other network traffic faults in ESXi

Products

• VMware vSphere ESXi

Issue/Introduction

The esxcli network nic stats command may show some counters that are greater than zero, on one or more physical network adapters.

Where vmnic2 is the subject NIC.
$ esxcli network nic stats get -n vmnic2


NIC statistics for vmnic2
   Packets received: 701280499176
   Packets sent: 687061948450
   Bytes received: 664124780523852
   Bytes sent: 676938646792793
   Receive packets dropped: 2452783244
   Transmit packets dropped: 0
   Multicast packets received: 976222150
   Broadcast packets received: 0
   Multicast packets sent: 0
   Broadcast packets sent: 0
   Total receive errors: 0
   Receive length errors: 0
   Receive over errors: 0
   Receive CRC errors: 0
   Receive frame errors: 0
   Receive FIFO errors: 0
   Receive missed errors: 0
   Total transmit errors: 0
   Transmit aborted errors: 0
   Transmit carrier errors: 0
   Transmit FIFO errors: 0
   Transmit heartbeat errors: 0
   Transmit window errors: 0

Notes about esxcli network nic stats ouput:

• Run the uptime command to see over what time frame the counters have been incremented.  
• There is no way to clear network counters. It is possible to unload and reload the NIC device driver. This is not recommended as doing so may produce unpredictable results on the host. 
• To clear the counters, place the host into Maintenance Mode and reboot the host.
• Because the counters are additive, there is no way to determine when or by which event the counters were incremented.
• To monitor the counters, use the "watch" command and monitor for increasing outputs:

$ watch esxcli network nic stats get -n vmnic2

In a healthy environment, "errors" should either be zero, or very small as a percentage of the overall total. If errors are present, the hardware vendor should be consulted.

Environment

VMware vCenter Server 7.x
VMware vCenter Server 8.x

Resolution

If any NICs show errors, consult with the hardware vendor to troubleshoot the physical NIC errors.

1. Check that the driver/firmware of the vmnic is up to date. To check the driver, follow Determining Network/Storage firmware and driver version in ESXi (323110).  For more information on drivers and firmware, see FAQ: Recommendation for Driver/Firmware (318542)
2. It is possible to mitigate FIFO or Missed errors by increasing the Rx buffer ring size on the physical NIC.

Note: These changes impact network adapter performance and must be validated by the hardware vendor prior to implementing the change.

FIFO or Missed errors will increment if the physical NIC is not able to address the peak load of incoming packets with its assigned ring buffer size. Use the following commands to check the maximum (preset) ring buffer size and current ring buffer size.

$ esxcli network nic ring preset get -n vmnicX
$ esxcli network nic ring current get -n vmnicX