MTU_TO_FRAME_SIZE
hxgep->vmac.maxframesize = HXGE_DEFAULT_MTU + MTU_TO_FRAME_SIZE;
new_framesize = new_mtu + MTU_TO_FRAME_SIZE;
MIN_FRAME_SIZE - MTU_TO_FRAME_SIZE,
MAX_FRAME_SIZE - MTU_TO_FRAME_SIZE);
macp->m_max_sdu = hxgep->vmac.maxframesize - MTU_TO_FRAME_SIZE;