NetScaler VPX Loses Network Connectivity Intermittently on VMware ESXi After Upgrading to Version 12.0

NetScaler VPX loses network connectivity intermittently on VMware ESXi after upgrading to version 12.0.

The following are the symptoms of this issue:

• Interface will start flapping followed by the network connectivity being lost
• Interfaces on VPX will NOT show DOWN or HANG or STALL
• RESET interface or reboot of the NetScaler will bring the connectivity back for few minutes
• Adapter type on VMware is E1000

This is a known issue and will be fixed in the following NetScaler releases:
12.0 Build 51.x
11.1 Build 55.x
11.0 Build 71.x

Workaround

Complete the following steps to workaround this issue:

1. Remove all the E1000 interfaces.
   Note: Not just disconnect interfaces but all the E1000 interfaces.
2. Change the adapter type from E1000 to VMXNET3 VMware ESXi.
3. Ensure to use the same MAC address as mentioned in the license to avoid license re-allocation. If using the same MAC address does not help with license, then re-allocation of license is required.
   

Rx ring was cleaned completely as a part of every reset which is not in sync with backends expectation.