title: ARP in Linux creates FAILED entries
body: <p>Under Linux-4.11 a locally generated ARP request would result in an ARP entry created with state FAILED (as seen by <code>ip neigh show</code>), when there's nobody to respond. Is this normal behaviour?</p>
  
  <p>Also, flushing <code>sudo ip neigh flush dev eth0</code> doesn't flush the entries, they are still there.</p>