NIC Resets seen during ESXi boot up

Products

• VMware vSphere ESXi

Issue/Introduction

During boot, ESXi vmnic adapters are reset as different networking features are enabled on the NICs.

Environment

vSphere ESXi Virtual Networking

Cause

As ESXi boots and features are enabled on the virtual networking stack, VMNICs will be reset.  This will cause the upstream switch to detect a link down event.  At the same time, any vnic or vmk MACs associated with that uplink will move to another active uplink per the vSwitch and portgroup Teaming and Failover policies.

Example events that trigger a NIC reset include but are not limited to:

1) MTU changes on the uplinks

2) NSX configuration being enabled on the uplinks 

This may cause the upstream switch to raise a security alert that MAC addresses are observed moving between multiple switch ports.

Resolution

None needed, this is expected behavior and does not indicate any errors or failures of the vSphere networking stack.