实验5:开源控制器实践——POX
(一)基本要求
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h1 ping h2、h2和h3的tcpdump抓包结果
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使用 tcpdump 验证Hub模块
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使用 tcpdump 验证Switch模块
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L2_learning模块代码流程图
(二)进阶要求
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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)
- SendFlowInSingle3代码
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基于进阶1的代码,完成ODL实验的硬超时功能。
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先运行SendFlowSingle3,先通再断再恢复
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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)
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个人总结
- 关闭hub模块开启L2_Learning模块时会报错
解决方法- 重启虚拟机
- 找出进程对应的端口号,并且强行杀死进程
lsof -i:[端口号]
找到进程号PID
kill -s 9 [进程号]
强行杀死进程
./pox.py SendFlowSingle3
运行失败
解决方法: 将SendFlowSingle3.py放在pox文件下而非forwarding文件下- Hub:h1 ping h2时h2和h3都能收到报文,说明Hub模块在每个交换机上安装洪泛通配符规则,广播转发数据包。
Switch:h1 ping h2时,只有h2可以收到报文,说明Switch模块让Openflow交换机实现了L2自学习,只有目的主机可以抓取到报文。 - 本次实验难度有所提升,参照pdf理解起来也需要花费很长时间。通过此次实验,理解了POX控制器的工作原理,通过验证了POX的Hub和Switch模块,初步了解掌握了POX控制器的一些使用方法,熟悉了POX控制器流表下发的方法。