anchor.diff:        [{table_id, 0},
          Priority,
          {cookie, unique_cookie()}]},
  +    IpBroadcastThere = {
  +      [FromPort1,
  +       {ipv4_dst, <<255, 255, 255, 255>>}],
  +      %% XXX: In principle, we should broadcast this packet.
  +      [ToPort2],
  +      [{table_id, 0},
  +       {cookie, unique_cookie()}]},
       ArpPacketsThere = {
         [FromPort1,
          {eth_type,<<16#806:16>>}] ++
  
positive.code:       [{table_id, 0},
         Priority,
         {cookie, unique_cookie()}]},
      ArpPacketsBack = {
        [FromPort2,
         {eth_type,<<16#806:16>>}] ++
  
negative.code:       [{table_id, 0},
         Priority,
         {cookie, unique_cookie()}]},
      NewRules = [IpTrafficThere, IpBroadcastThere, ArpPacketsThere,
                  IpTrafficBack, IpBroadcastBack, ArpPacketsBack],
      NewFlowRules = [{SwitchId, ?OF_VERSION, NewRule} || NewRule <- NewRules] ++ FlowRules,
      flow_rules(Tail, Graph, NewFlowRules, Endpoint1, Endpoint2).
  
  