VNICs should support a variable MTU
Today a VNIC's MTU is required to be the same as the underlying data link that it's been created at. In other words, once the data link is created the MTU for the vnic is locked in. Instead, the VNIC should have a variable range which ranges from the minimum amount supported by the physical device to the device's current MTU. In addition, the act of doing this will stop the device from being able to go to a lower MTU.