是否可以使用 OpenFlow 的 Pox 控制器删除与某个 cookie 编号匹配的流？我试过类似的东西：

def delete_flow(dpid,cookie):
   msg = of.ofp_flow_mod()
   msg.match=of.ofp_match()

   msg.match.cookie=cookie
   msg.match.cookie_mask=0xffffffff

   msg.command=of.OFPFC_DELETE
   msg.flags = of.OFPFF_SEND_FLOW_REM    

   sw = switches[dpid]
   if sw.connection is None: return
   sw.connection.send(msg)
   log.info("Flow %i deleted from sw %i" %(cookie,dpid))

但看起来所有流量都从所有交换机中删除。