etherstubs confuse min mtu with min sdu
6824511 check the MTU value that can be set on an etherstub, introduced changes to the vnic driver to set the range for the MTU of an etherstub. While it established a lower bound for the MTU, the code also set that as the minimum size SDU. This is used by dlpi in the DL_INFO_ACK with the member dl_max_sdu and dl_min_sdu. These are meant to describe the minimum sized frame that can be transmitted on these devices which is honored by vnd. The problem is that the dl_min_sdu was set to the minimum size MTU. The minimum size MTU is definitely not the value of the minimum size frame that can be set.