实验5：开源控制器实践——POX

基本要求

1.使用 tcpdump 验证Hub模块的抓包结果截图

• h1 ping h2,h3主机同样收到icmp报文
  

• h1 ping h3,h2主机同样收到icmp报文
  

2、L2_learning程序流程图

3、使用 tcpdump 验证Switch模块的抓包结果截图

• h1 ping h2，只有h2能收到icmp报文
  

• h1 ping h3，只有h3能收到icmp报文
  

进阶要求

• 编写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)

• 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
  

• 完成ODL实验的硬超时功能

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()  # 使用ofp_flow_mod()方法向交换机下发流表
        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)

个人总结

本次实验验证了POX的hub和switch模块，初步掌握了POX控制器的使用方法，并且进一步熟悉POX控制器流表下发的方法。基本要求中的实验操作还是比较简单的，但进阶要求就进行的比较困难。比如在lab5目录下创建SendFlowInSingle3.py后无法将SendFlowInSingle3.py放入pox目录下或直接在pox目录下创建，这时需要在在lab5目录下打开终端，输入“sudo cp SendFlowInSingle3.py ../pox”将py文件复制到pox目录下。还有在完成ODL实验的硬超时功能时，需要先运行SendFlowInSingle3，再运行SendPoxHardTimeOut，再运行SendFlowInSingle3。总之我对于POX控制器的原理仍然有不太懂的地方需要进一步去了解。