(一)基本要求

1.h1 ping h2、h2和h3的tcpdump抓包结果

使用 tcpdump 验证Hub模块

使用 tcpdump 验证Switch模块

2.L2_learning模块代码流程图

(二)进阶要求

1.重新搭建（一）的拓扑，此时交换机内无流表规则，拓扑内主机互不相通；编写Python程序自定义一个POX模块SendFlowInSingle3，并且将拓扑连接至SendFlowInSingle3（默认端口6633），实现向s1发送流表规则使得所有主机两两互通

SendFlowInSingle3代码

from pox.core import core
import pox.openflow.libopenflow_01 as of
from pox.openflow.of_json import *

def _handle_ConnectionUp(event):

# h1 -> h2 h1 -> h3
msg = of.ofp_flow_mod()
msg.priority = 1
msg.match.in_port = 1
msg.actions.append(of.ofp_action_output(port=2))
msg.actions.append(of.ofp_action_output(port=3))
event.connection.send(msg)

# h2 -> h1 h2 -> h3
msg = of.ofp_flow_mod()
msg.priority = 1
msg.match.in_port = 2
msg.actions.append(of.ofp_action_output(port=1))
msg.actions.append(of.ofp_action_output(port=3))
event.connection.send(msg)

# h3 -> h1 h3 -> h2 
msg = of.ofp_flow_mod()
msg.priority = 1
msg.match.in_port = 3
msg.actions.append(of.ofp_action_output(port=1))
msg.actions.append(of.ofp_action_output(port=2))
event.connection.send(msg)

def launch():
core.openflow.addListenerByName("ConnectionUp", _handle_ConnectionUp)

2.基于进阶1的代码，完成ODL实验的硬超时功能。

1.先运行SendFlowSingle3，先通再断再恢复

2.直接运行SendPoxHardTimeOut，先断后通，能验证流表项生效即可

SendPoxHardTimeOut代码

from pox.core import core
import pox.openflow.libopenflow_01 as of

class SendPoxHardTimeOut(object):
def init(self):
core.openflow.addListeners(self)
def _handle_ConnectionUp(self, event):

   msg = of.ofp_flow_mod()  
   msg.priority = 3
   msg.match.in_port = 1 
   msg.hard_timeout = 10  
   event.connection.send(msg)
   
   msg = of.ofp_flow_mod()  
   msg.priority = 1
   msg.match.in_port = 1 
   msg.actions.append(of.ofp_action_output(port = of.OFPP_ALL)) 
   event.connection.send(msg)

   msg = of.ofp_flow_mod()  
   msg.priority = 3
   msg.match.in_port = 3 
   msg.hard_timeout = 10 
   event.connection.send(msg)
   
   msg = of.ofp_flow_mod() 
   msg.priority = 1
   msg.match.in_port = 3  
   msg.actions.append(of.ofp_action_output(port = of.OFPP_ALL))
   event.connection.send(msg)

def launch():
core.registerNew(SendPoxHardTimeOut)

个人心得

通过本次实验能够理解pox控制器的工作原理，学习pox控制器的使用方法。基本要求难度较小，都是进阶要求难度较大（代码太多）。