VMNICs not using Auto Negotiate

Products

• VMware vSphere ESXi

Issue/Introduction

• You’re trying to enable auto-negotiation on the vmnic, but the NIC does not present any configurable speed/duplex options in the vSphere UI.
• You also attempted to enable auto-negotiation using the command esxcfg-nics vmnicX -a, but it had no effect.

Environment

VMware vSphere ESXi

Cause

Auto Negotiate may or may not be a supported feature on the nic card depending on the make and vendor

Resolution

Please consult your networking equipment vendor or administrator to validate if the nic card supports auto negotiate feature.

Configuring the speed and duplex of an ESXi host network adapter

Note: If the vendor confirms that auto negotiate is a supported feature on the card and the required setting is enabled on the nic, yet you are unable to enable auto negotiate on ESXi, feel free to open a case with Broadcom support team.