实验5：开源控制器实践——POX

1、基础要求
h1 ping h2

h2 ping h3

L2_learning模块代码流程图

2、进阶要求为选做
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。

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()  # 下发流表
        msg.priority = 1
        msg.match.in_port = 1  # 使数据包进入端口1
        msg.actions.append(of.ofp_action_output(port=2)) # 从端口2转发出去
        msg.actions.append(of.ofp_action_output(port=3)) # 从端口3转发出去
        event.connection.send(msg)
        msg = of.ofp_flow_mod()  
        msg.priority = 1
        msg.match.in_port = 2  # 使数据包进入端口2
        msg.actions.append(of.ofp_action_output(port=1)) # 从端口1转发出去
        msg.actions.append(of.ofp_action_output(port=3)) # 从端口3转发出去
        event.connection.send(msg)
        msg = of.ofp_flow_mod()  
        msg.priority = 1
        msg.match.in_port = 3  # 使数据包进入端口3
        msg.actions.append(of.ofp_action_output(port=1)) # 从端口1转发出去
        msg.actions.append(of.ofp_action_output(port=2)) # 从端口2转发出去
        event.connection.send(msg)
def launch():
    core.registerNew(SendFlowInSingle3)

基于进阶1的代码，完成ODL实验的硬超时功能。

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  #硬超时10秒
        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 = 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 = 1)) 
        msg.actions.append(of.ofp_action_output(port = 2)) 
        event.connection.send(msg)

def launch():
    core.registerNew(SendPoxHardTimeOut)

ovs-ofctl交换机流表项

3、个人总结
本次实验，我对 POX 控制器的工作原理；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；能够运用 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。本次实训，是对我本事的进一步锻炼，也是一种考验。这次的实验的基础部分虽然参照文档也能完成，但由于我对一些命令的不熟悉，所以这次实验过程也是磕磕碰碰的。