（一）基本要求
搭建下图所示SDN拓扑，协议使用Open Flow 1.0，控制器使用部署于本地的POX（默认监听6633端口）
sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow10
阅读Hub模块代码，使用 tcpdump 验证Hub模块；
阅读L2_learning模块代码，画出程序流程图，使用 tcpdump 验证Switch模块。
h1 ping h2
h1 ping h3
程序流程图:
（二）进阶要求
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。
代码如下：
点击查看代码
from pox.core import core
import pox.openflow.libopenflow_01 as of
from pox.lib.util import dpid_to_str, str_to_dpid
from pox.lib.util import str_to_bool
import time
from pox.openflow.of_json import *
def _handle_ConnectionUp(event):
# 发往10.0.0.1的数据流将会从交换机的端口1转发出去
msg = of.ofp_flow_mod()
msg.priority = 1
msg.match.in_port = 1
msg.actions.append(of.ofp_action_output(port = 1))
msg.actions.append(of.ofp_action_output(port = 2))
msg.actions.append(of.ofp_action_output(port = 3))
event.connection.send(msg)
# 发往10.0.0.2的数据流将会从交换机的端口2转发出去
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 = 2))
msg.actions.append(of.ofp_action_output(port = 3))
event.connection.send(msg)
# 发往10.0.0.3的数据流将会从交换机的端口3转发出去
msg = of.ofp_flow_mod()
msg.priority = 1
msg.match.in_port = 3
msg.actions.append(of.ofp_action_output(port = 3))
msg.actions.append(of.ofp_action_output(port = 2))
msg.actions.append(of.ofp_action_output(port = 1))
event.connection.send(msg)
def launch():
core.openflow.addListenerByName("ConnectionUp", _handle_ConnectionUp)
基于进阶1的代码，完成ODL实验的硬超时功能。
代码如下：
点击查看代码
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 #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 = of.OFPP_ALL))
event.connection.send(msg)
msg = of.ofp_flow_mod()
msg.priority = 3
msg.match.in_port = 3
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 = 3
msg.actions.append(of.ofp_action_output(port = of.OFPP_ALL))
event.connection.send(msg)
def launch():
core.registerNew(SendPoxHardTimeOut)