Setting SplitTX mode on pNIC gives error: "VSISHCmdSet( ):Set failed: Not supported" on ENS enabled environments

Products

• VMware vSphere ESXi

Issue/Introduction

• Environment is configured to utilize the Enhanced Network Stack feature set in NSX-T
• Network I/O Control is enabled on the distributed switch
• Attempts to enable the advanced capability setting on the physical nic results with the following error:

[root@esxi :~ ] vsish
/> set /net/pNics/vmnic0/sched/txMode 1
VSISHCmdSet( ):Set failed: Not supported
Error: Error in command set: Not supported

Environment

6.x
7.x

Resolution

• In a standard non ENS environment, SplitTX mode is only applicable when NIOC (Network I/O Control) is disabled on uplinks, with NIOC disabled the FIFO algorithm is applied to packet processing that is required for SplitTX mode.

 

• In ENS backed environments, the setting will be cosmetic as ENS backed environments bypass the traditional packet processing algorithm thus making it incompatble.

Additional Information

* Enhanced Network Stack (ENS)
https://techdocs.broadcom.com/us/en/storage-and-ethernet-connectivity/ethernet-nic-controllers/bcm957xxx/adapters/introduction/features/enhanced-network-stack--ens-.html

* Enable Network I/O Control on a vSphere Distributed Switch

https://techdocs.broadcom.com/us/en/vmware-cis/vsphere/vsphere/8-0/vsphere-networking/network-io-control/enable-network-i-o-control-on-a-vsphere-distributed-switch.html