实验5：开源控制器实践——POX

一、实验要求

1.基本要求

（1）使用tcpdump验证Hub模块

h1 ping h2

h1 ping h3

(2) 阅读L2_learning模块代码，画出程序流程图

(3) 使用 tcpdump 验证Switch模块

h1 ping h2

h1 ping h3

2.进阶要求

（1）进阶1

重新搭建拓扑测试连通性

Python程序自定义一个POX模块SendFlowInSingle3

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

class SendFlowInSingle3(object):
    def __init__(self):
        core.openflow.addListeners(self)
    def _handle_ConnectionUp(self, event):
        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)

        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)

        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.registerNew(SendFlowInSingle3)

运行SendFlowSingle3，测试连通性，所有主机两两互通

(2) 基于进阶1的代码，完成ODL实验的硬超时功能

Python程序自定义一个POX模块SendPoxHardTimeOut

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 = 2
        msg.match.in_port = 1 
        msg.hard_timeout = 15
        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=2)) 
        msg.actions.append(of.ofp_action_output(port=3)) 
        event.connection.send(msg)
        
        msg = of.ofp_flow_mod()  
        msg.priority = 2
        msg.match.in_port = 2 
        msg.hard_timeout = 15
        event.connection.send(msg)

        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)
        
        msg = of.ofp_flow_mod()  
        msg.priority = 2
        msg.match.in_port = 3 
        msg.hard_timeout = 15
        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=1))  
        msg.actions.append(of.ofp_action_output(port=2)) 
        event.connection.send(msg)

def launch():
    core.registerNew(SendPoxHardTimeOut)

运行SendPoxHardTimeOut后结果截图

二、个人总结

通过本次实验，学到了POX 控制器的工作原理，在实验中通过验证POX的forwarding.hub和forwarding.l2_learning模块，初步掌握POX控制器的使用方法，在进阶实验中学会运用 POX控制器编写自定义网络应用程序，进一步熟悉POX控制器流表下发的方法。实验过程中遇到了在pox文件夹下无法新建文件的问题，在lab5目录的终端下建立SendFlowInSingle3.py后，用“sudo cp SendFlowInSingle3.py ../pox” 就能成功复制到pox目录下。