Decrease in vmnic and vmhba throughput after rebooting the interconnect fabric

Products

• VMware vSphere ESXi

Issue/Introduction

The speed reported in ESXi for the server vmnics is half of the expected speed after a flap of the adapter links, such as during a reboot of a Fabric Interconnect.

• Run command: esxcli network nic list
  • For example: VMNICs went from 20 to 10 Gbps and VMHBAS from 16 to 8 Gbps

 

Environment

VMware vSphere ESXi

Cause

This behavior corresponds to Cisco Bug ID: CSCwc19789, which describes ESXi inaccurately reporting half the expected vmnic link speed after an adapter link flap (e.g., due to a Fabric Interconnect reboot).

Refer to CISCO bug ID: https://bst.cisco.com/quickview/bug/CSCwc19789 

Resolution

Engage CISCO team for further assistance