实验5：开源控制器实践——POX

一、基础要求

1.h1 ping h2时h2tcpdump抓包结果截图

2.h1 ping h2时h3tcpdump抓包结果截图

3.L2_learning模块代码流程图

二、进阶要求

1.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)

2.所有主机两两互通,查看流表

3.完成ODL实验的硬超时功能

• 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 = 2
        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=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 = 10
        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 = 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=1))  
        msg.actions.append(of.ofp_action_output(port=2)) 
        event.connection.send(msg)

def launch():
    core.registerNew(SendPoxHardTimeOut)

• 先运行SendFlowSingle3，先通再断再恢复
  

• 直接运行SendPoxHardTimeOut，先断后通
  

三、个人总结

本次实验难度适中，主要学习POX控制器。通过验证POX的forwarding.hub和forwarding.l2_learning模块，我初步掌握POX 控制器的使用方法，除此之外，我了解了如何通过编写代码实现硬实时功能，进一步熟悉POX控制器流表下发的方法。本次实验中，我遇到了一个问题，当我关闭hub模块开启L2_Learning模块时出现了错误。通过搜索资料后，我发现是因为使用6633这个端口号的进程还在进行，导致冲突，引起报错。同时，本实验需注意，生成拓扑后，再开启POX。我认为自己还需要进一步学习一些相关知识。