VMkernel fails to set MTU on vNetwork Distributed Switch

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

Summary

When VMkernel sets a Maximum Transmission Unit (MTU) value for a vNetwork Distributed Switch (vDS) in the vSphere Client, it might fail to set this value on certain uplinks.

Example

If the MTU value is set to higher than 1500, the NIC might not support jumbo frames.

Impact

The MTU of the NIC remains unchanged.

Environment

VMware ESXi 4.1.x Installable
VMware ESXi 4.1.x Embedded
VMware vCenter Server 4.1.x
VMware ESX 4.1.x

Resolution

Verify that the MTU value meets the following conditions:

• The MTU value is valid. If it is invalid (for example, less than 60), reset the value.
• The MTU value is compatible with the NICs connected as uplinks on the vDS. If it is not compatible, reset the MTU value or change the NICs.