我的mininet拓扑图片：

Mininet拓扑

任何人都可以帮助我在循环拓扑中ping主机 . 静态痘控制器如下 . 我的拓扑有4个交换机和3个主机 . 左边有一个主机，右边有两个主机 . 显然，我必须为每个主机实现路由路由，以便数据包可以到达目的地，而不是在无限循环中漫游网络 . 但是我无法让它发挥作用

任何帮助将不胜感激，并提前感谢您

from pox.core import core
import pox.openflow.libopenflow_01 as of
from pox.lib.util import dpidToStr
log = core.getLogger()
s1_dpid=0

s2_dpid=0
s3_dpid=0
s4_dpid=0

def _handle_ConnectionUp (event):
 global s1_dpid, s2_dpid, s3_dpid, s4_dpid
 print "ConnectionUp: ", dpidToStr(event.connection.dpid)
#remember the connection dpid for switch
 for m in event.connection.features.ports:
  if m.name == "s1-eth1":
     s1_dpid = event.connection.dpid
     print "s1_dpid=", s1_dpid
  elif m.name == "s2-eth3":
    s2_dpid = event.connection.dpid
    print "s2_dpid=", s2_dpid
  elif m.name == "s3-eth3":
    s3_dpid = event.connection.dpid
    print "s3_dpid=", s3_dpid
  elif m.name == "s4-eth4":
    s4_dpid = event.connection.dpid
    print "s4_dpid=", s4_dpid
def _handle_PacketIn (event):
   global s1_dpid, s2_dpid, s3_dpid, s4_dpid
   print "PacketIn: ", dpidToStr(event.connection.dpid)
   if event.connection.dpid==s1_dpid:
     msg = of.ofp_flow_mod()
     msg.priority =1
     msg.idle_timeout = 0
     msg.hard_timeout = 0
     msg.match.dl_type = 0x0806
     msg.actions.append(of.ofp_action_output(port = of.OFPP_ALL))
     event.connection.send(msg)
     msg = of.ofp_flow_mod()
     msg.priority =10
     msg.idle_timeout = 0
     msg.hard_timeout = 0
     msg.match.dl_type = 0x0800
     msg.match.nw_dst = "10.0.0.1"
     msg.actions.append(of.ofp_action_output(port = 1))
     event.connection.send(msg)
     msg = of.ofp_flow_mod()
     msg.priority =10
     msg.idle_timeout = 0
     msg.hard_timeout = 0
     msg.match.dl_type = 0x0800
     msg.match.nw_dst = "10.0.0.6"
     msg.actions.append(of.ofp_action_output(port = 3))
     event.connection.send(msg)
     msg = of.ofp_flow_mod()
     msg.priority =10
     msg.idle_timeout = 0
     msg.hard_timeout = 0
     msg.match.dl_type = 0x0800
     msg.match.nw_dst = "10.0.0.2"
     msg.actions.append(of.ofp_action_output(port = 2))
     event.connection.send(msg)


   elif event.connection.dpid==s2_dpid:
     msg = of.ofp_flow_mod()
     msg.priority =1
     msg.idle_timeout = 0
     msg.hard_timeout = 0
     msg.match.in_port =3
     msg.actions.append(of.ofp_action_output(port =4))
     event.connection.send(msg)
     msg = of.ofp_flow_mod()
     msg.priority =1
     msg.idle_timeout = 0
     msg.hard_timeout = 0
     msg.match.in_port =4
     msg.actions.append(of.ofp_action_output(port =3))
     event.connection.send(msg)

   elif event.connection.dpid==s4_dpid:
     msg = of.ofp_flow_mod()
     msg.priority =1
     msg.idle_timeout = 0
     msg.hard_timeout = 0
     msg.match.in_port =3
     msg.actions.append(of.ofp_action_output(port = 4))
     event.connection.send(msg)
     msg = of.ofp_flow_mod()
     msg.priority =1
     msg.idle_timeout = 0
     msg.hard_timeout = 0
     msg.match.in_port =4
     msg.actions.append(of.ofp_action_output(port = 3))
     event.connection.send(msg)
     elif event.connection.dpid==s3_dpid:
     msg = of.ofp_flow_mod()
     msg.priority =1
     msg.idle_timeout = 0
     msg.hard_timeout = 0
     msg.match.dl_type = 0x0806
     msg.actions.append(of.ofp_action_output(port = of.OFPP_ALL))
     event.connection.send(msg)
     msg = of.ofp_flow_mod()
     msg.priority =10
     msg.idle_timeout = 0
     msg.hard_timeout = 0
     msg.match.dl_type = 0x0800
     msg.match.nw_dst = "10.0.0.6"
     msg.actions.append(of.ofp_action_output(port = 2))
     event.connection.send(msg)

     msg = of.ofp_flow_mod()
     msg.priority =10
     msg.idle_timeout = 0
     msg.hard_timeout = 0
     msg.match.dl_type = 0x0800
     msg.match.nw_src="10.0.0.6"
     msg.match.nw_dst = "10.0.0.1"
     msg.actions.append(of.ofp_action_output(port = 4))
     event.connection.send(msg)
     # msg = of.ofp_flow_mod()
     # msg.priority =10
     #msg.idle_timeout = 0
     #msg.hard_timeout = 0
     #msg.match.dl_type = 0x0800
     #msg.match.nw_src="10.0.0.5"
     #msg.match.nw_dst = "10.0.0.1"
     #msg.actions.append(of.ofp_action_output(port = 4))
     #event.connection.send(msg)
     def launch ():
     core.openflow.addListenerByName("ConnectionUp",_handle_ConnectionUp)
     core.openflow.addListenerByName("PacketIn",_handle_PacketIn)