If you are planning an NSX upgrade in a Cisco UCS environment, pay close attention to your ‘nenic’ driver version before you begin. The nenic driver is the new native driver replacement for the older vmklinux enic driver. It’s used exclusively for the Cisco VIC adapters found in UCS systems and is now the default in vSphere 6.5 and 6.7.
We’ve seen several instances now where Cisco VIC adapters can go link-down in an error state during NSX VIB upgrades. It doesn’t appear to matter what version of NSX is being upgraded from/to, but the common denominator is an older nenic driver version. This seems to be reproducible with nenic driver version 126.96.36.199 and possibly others. Version 188.8.131.52 and later appear to correct this problem. At the time of writing, 184.108.40.206 is the latest version available.
You can obtain your current nenic driver and firmware version using the following command:
# esxcli network nic get -n vmnicX
Before you upgrade your drivers, be sure to reach out to Cisco to ensure your firmware is also at the recommended release version. Quite often vendors have a recommended driver/firmware combination for maximum stability and performance.
I expect a KB article and an update to the NSX release notes to be made public soon but wanted to ensure this information got out there as soon as possible.