Mininet 系列实验（六）

• 写在前面

  这次实验遇到了非常多问题，非常非常多，花了很多时间去解决，还是有一些小问题没有解决，但是基本上能完成实验。建议先看完全文再开始做实验。

• 实验内容

  先看一下本次实验的拓扑图：
  
  在该环境下，假设H1 ping H4，初始的路由规则是S1-S2-S5，一秒后，路由转发规则变为S1-S3-S5，再过一秒，规则变为S1-S4-S5，然后再回到最初的转发规则S1-S2-S5。通过这个循环调度的例子动态地改变交换机的转发规则。

• 参考

  Mininet动态改变转发规则实验

• 实验环境

  虚拟机: Oracle VM VirtualBox Ubuntu16.04LTS
  PS：原文中说「本实验需要两台虚拟机，分别安装POX（4G）和支持OpenFlow1.3协议的Mininet。」而我只在自己的一台机子上进行实验，也许这就是出现如此多问题的根源？

• 实验步骤

  1. ~/pox目录下新建文件lab_controller.py

# cd pox
# vim lab_controller.py

脚本内容如下：

from pox.core import core
 
import pox.openflow.libopenflow_01 as of
 
from pox.lib.util import dpidToStr
 
from pox.lib.addresses import IPAddr, EthAddr
 
from pox.lib.packet.arp import arp
 
from pox.lib.packet.ethernet import ethernet, ETHER_BROADCAST
 
from pox.lib.packet.packet_base import packet_base
 
from pox.lib.packet.packet_utils import *
 
import pox.lib.packet as pkt
 
from pox.lib.recoco import Timer
 
import time
 
 
 
log = core.getLogger()
 
 
 
s1_dpid=0
 
s2_dpid=0
 
s3_dpid=0
 
s4_dpid=0
 
s5_dpid=0
 
 
 
s1_p1=0
 
s1_p4=0
 
s1_p5=0
 
s1_p6=0
 
s2_p1=0
 
s3_p1=0
 
s4_p1=0
 
 
 
pre_s1_p1=0
 
pre_s1_p4=0
 
pre_s1_p5=0
 
pre_s1_p6=0
 
pre_s2_p1=0
 
pre_s3_p1=0
 
pre_s4_p1=0
 
 
 
turn=0
 
 
 
def getTheTime():  #fuction to create a timestamp
 
  flock = time.localtime()
 
  then = "[%s-%s-%s" %(str(flock.tm_year),str(flock.tm_mon),str(flock.tm_mday))
 
 
 
  if int(flock.tm_hour)<10:
 
    hrs = "0%s" % (str(flock.tm_hour))
 
  else:
 
    hrs = str(flock.tm_hour)
 
  if int(flock.tm_min)<10:
 
    mins = str(flock.tm_min)
 
    secs = "0%s" % (str(flock.tm_sec))
 
  else:
 
    secs = str(flock.tm_sec)
 
 
 
  then +="]%s.%s.%s" % (hrs,mins,secs)
 
  return then
 
 
 
 
 
def _timer_func ():
 
  global s1_dpid, s2_dpid, s3_dpid, s4_dpid, s5_dpid,turn
 
 
 
 
 
  #print getTheTime(), "sent the port stats request to s1_dpid"
 
 
 
  if turn==0:
 
      msg = of.ofp_flow_mod()
 
      msg.command=of.OFPFC_MODIFY_STRICT
 
      msg.priority =100
 
      msg.idle_timeout = 0
 
      msg.hard_timeout = 0
 
      msg.match.dl_type = 0x0800
 
      msg.match.nw_dst = "10.0.0.4"
 
      msg.actions.append(of.ofp_action_output(port = 5))
 
      core.openflow.getConnection(s1_dpid).send(msg)
 
      turn=1
 
      return
 
 
 
  if turn==1:
 
      msg = of.ofp_flow_mod()
 
      msg.command=of.OFPFC_MODIFY_STRICT
 
      msg.priority =100
 
      msg.idle_timeout = 0
 
      msg.hard_timeout = 0
 
      msg.match.dl_type = 0x0800
 
      msg.match.nw_dst = "10.0.0.4"
 
      msg.actions.append(of.ofp_action_output(port = 6))
 
      core.openflow.getConnection(s1_dpid).send(msg)
 
      turn=2
 
      return
 
 
 
  if turn==2:
 
      msg = of.ofp_flow_mod()
 
      msg.command=of.OFPFC_MODIFY_STRICT
 
      msg.priority =100
 
      msg.idle_timeout = 0
 
      msg.hard_timeout = 0
 
      msg.match.dl_type = 0x0800
 
      msg.match.nw_dst = "10.0.0.4"
 
      msg.actions.append(of.ofp_action_output(port = 4))
 
      turn=0
 
      return
 
 
 
def _handle_portstats_received (event):
 
  global s1_p1,s1_p4, s1_p5, s1_p6, s2_p1, s3_p1, s4_p1
 
  global pre_s1_p1,pre_s1_p4, pre_s1_p5, pre_s1_p6, pre_s2_p1, pre_s3_p1, pre_s4_p1
 
 
 
  if event.connection.dpid==s1_dpid:
 
    for f in event.stats:
 
      if int(f.port_no)<65534:
 
        if f.port_no==1:
 
          pre_s1_p1=s1_p1
 
          s1_p1=f.rx_packets
 
 
        if f.port_no==4:
 
          pre_s1_p4=s1_p4
 
          s1_p4=f.tx_packets
 
          #s1_p4=f.tx_bytes
 
 
        if f.port_no==5:
 
          pre_s1_p5=s1_p5
 
          s1_p5=f.tx_packets
 
        if f.port_no==6:
 
          pre_s1_p6=s1_p6
 
          s1_p6=f.tx_packets
 
 
 
    for f in event.stats:  //非常非常非常坑，原文这一行行首多了一个空格，这里已经是修改好的
 
       if int(f.port_no)<65534:
 
         if f.port_no==1:
 
           pre_s2_p1=s2_p1
 
           s2_p1=f.rx_packets
 
           #s2_p1=f.rx_bytes
 
 
  if event.connection.dpid==s3_dpid:
 
     for f in event.stats:
 
       if int(f.port_no)<65534:
 
         if f.port_no==1:
 
           pre_s3_p1=s3_p1
 
           s3_p1=f.rx_packets
 
 
 
 
  if event.connection.dpid==s4_dpid:
 
     for f in event.stats:
 
       if int(f.port_no)<65534:
 
         if f.port_no==1:
 
           pre_s4_p1=s4_p1
 
           s4_p1=f.rx_packets
 
 
 
 
def _handle_ConnectionUp (event):
 
  global s1_dpid, s2_dpid, s3_dpid, s4_dpid, s5_dpid
 
  print "ConnectionUp: ",dpidToStr(event.connection.dpid)
 
 
 
  #remember the connection dpid for switch
 
  for m in event.connection.features.ports:
 
    if m.name == "s1-eth1":
 
      s1_dpid = event.connection.dpid
 
      print "s1_dpid=", s1_dpid
 
    elif m.name == "s2-eth1":
 
      s2_dpid = event.connection.dpid
 
      print "s2_dpid=", s2_dpid
 
    elif m.name == "s3-eth1":
 
      s3_dpid = event.connection.dpid
 
    elif m.name == "s4-eth1":
 
      s4_dpid = event.connection.dpid
 
      print "s4_dpid=", s4_dpid
 
    elif m.name == "s5-eth1":
 
      s5_dpid = event.connection.dpid
 
      print "s5_dpid=", s5_dpid
 
 
 
  if s1_dpid<>0 and s2_dpid<>0 and s3_dpid<>0 and s4_dpid<>0:
 
    Timer(1, _timer_func, recurring=True)
 
 
 
def _handle_PacketIn(event):
 
  global s1_dpid, s2_dpid, s3_dpid, s4_dpid, s5_dpid
 
 
 
  packet=event.parsed
 
 
 
 
  if event.connection.dpid==s1_dpid:
 
     a=packet.find('arp')
 
     if a and a.protodst=="10.0.0.4":
 
       msg = of.ofp_packet_out(data=event.ofp)
 
       msg.actions.append(of.ofp_action_output(port=4))
 
       event.connection.send(msg)
 
 
 
     if a and a.protodst=="10.0.0.5":
 
       msg = of.ofp_packet_out(data=event.ofp)
 
       msg.actions.append(of.ofp_action_output(port=5))
 
       event.connection.send(msg)
 
 
 
     if a and a.protodst=="10.0.0.6":
 
       msg = of.ofp_packet_out(data=event.ofp)
 
       msg.actions.append(of.ofp_action_output(port=6))
 
       event.connection.send(msg)
 
 
 
     if a and a.protodst=="10.0.0.1":
 
       msg = of.ofp_packet_out(data=event.ofp)
 
       msg.actions.append(of.ofp_action_output(port=1))
 
       event.connection.send(msg)
 
 
 
     if a and a.protodst=="10.0.0.2":
 
       msg = of.ofp_packet_out(data=event.ofp)
 
       msg.actions.append(of.ofp_action_output(port=2))
 
       event.connection.send(msg)
 
 
 
     if a and a.protodst=="10.0.0.3":
 
       msg = of.ofp_packet_out(data=event.ofp)
 
       msg.actions.append(of.ofp_action_output(port=3))
 
       event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =100
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.dl_type = 0x0800
 
     msg.match.nw_dst = "10.0.0.1"
 
     msg.actions.append(of.ofp_action_output(port = 1))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =100
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.dl_type = 0x0800
 
     msg.match.nw_dst = "10.0.0.2"
 
     msg.actions.append(of.ofp_action_output(port = 2))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =100
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.dl_type = 0x0800
 
     msg.match.nw_dst = "10.0.0.3"
 
     msg.actions.append(of.ofp_action_output(port = 3))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =100
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 1
 
     msg.match.dl_type = 0x0800
 
     msg.match.nw_dst = "10.0.0.4"
 
     msg.actions.append(of.ofp_action_output(port = 4))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =100
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.dl_type = 0x0800
 
     msg.match.nw_dst = "10.0.0.5"
 
     msg.actions.append(of.ofp_action_output(port = 5))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =100
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.dl_type = 0x0800
 
     msg.match.nw_dst = "10.0.0.6"
 
     msg.actions.append(of.ofp_action_output(port = 6))
 
     event.connection.send(msg)
 
 
 
  elif event.connection.dpid==s2_dpid:
 
     msg = of.ofp_flow_mod()
 
     msg.priority =10
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.in_port = 1
 
     msg.match.dl_type=0x0806
 
     msg.actions.append(of.ofp_action_output(port = 2))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =10
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.in_port = 1
 
     msg.match.dl_type=0x0800
 
     msg.actions.append(of.ofp_action_output(port = 2))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =10
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.in_port = 2
 
     msg.match.dl_type=0x0806
 
     msg.actions.append(of.ofp_action_output(port = 1))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =10
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.in_port = 2
 
     msg.match.dl_type=0x0800
 
     msg.actions.append(of.ofp_action_output(port = 1))
 
     event.connection.send(msg)
 
 
 
  elif event.connection.dpid==s3_dpid:
 
     msg = of.ofp_flow_mod()
 
     msg.priority =10
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.in_port = 1
 
     msg.match.dl_type=0x0806
 
     msg.actions.append(of.ofp_action_output(port = 2))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =10
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.in_port = 1
 
     msg.match.dl_type=0x0800
 
     msg.actions.append(of.ofp_action_output(port = 2))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =10
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.in_port = 2
 
     msg.match.dl_type=0x0806
 
     msg.actions.append(of.ofp_action_output(port = 1))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =10
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.in_port = 2
 
     msg.match.dl_type=0x0800
 
     msg.actions.append(of.ofp_action_output(port = 1))
 
     event.connection.send(msg)
 
 
 
  elif event.connection.dpid==s4_dpid:
 
     msg = of.ofp_flow_mod()
 
     msg.priority =10
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.in_port = 1
 
     msg.match.dl_type=0x0806
 
     msg.actions.append(of.ofp_action_output(port = 2))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =10
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.in_port = 1
 
     msg.match.dl_type=0x0800
 
     msg.actions.append(of.ofp_action_output(port = 2))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =10
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.in_port = 2
 
     msg.match.dl_type=0x0806
 
     msg.actions.append(of.ofp_action_output(port = 1))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =10
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.in_port = 2
 
     msg.match.dl_type=0x0800
 
     msg.actions.append(of.ofp_action_output(port = 1))
 
     event.connection.send(msg)
 
 
 
  elif event.connection.dpid==s5_dpid:
 
     a=packet.find('arp')
 
     if a and a.protodst=="10.0.0.4":
 
       msg = of.ofp_packet_out(data=event.ofp)
 
       msg.actions.append(of.ofp_action_output(port=4))
 
       event.connection.send(msg)
 
 
 
     if a and a.protodst=="10.0.0.5":
 
       msg = of.ofp_packet_out(data=event.ofp)
 
       msg.actions.append(of.ofp_action_output(port=5))
 
       event.connection.send(msg)
 
 
 
     if a and a.protodst=="10.0.0.6":
 
       msg = of.ofp_packet_out(data=event.ofp)
 
       msg.actions.append(of.ofp_action_output(port=6))
 
       event.connection.send(msg)
 
 
 
     if a and a.protodst=="10.0.0.1":
 
       msg = of.ofp_packet_out(data=event.ofp)
 
       msg.actions.append(of.ofp_action_output(port=1))
 
       event.connection.send(msg)
 
 
 
     if a and a.protodst=="10.0.0.2":
 
       msg = of.ofp_packet_out(data=event.ofp)
 
       msg.actions.append(of.ofp_action_output(port=2))
 
       event.connection.send(msg)
 
 
 
     if a and a.protodst=="10.0.0.3":
 
       msg = of.ofp_packet_out(data=event.ofp)
 
       msg.actions.append(of.ofp_action_output(port=3))
 
       event.connection.send(msg)
 
 
 
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =100
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.dl_type = 0x0800
 
     msg.match.nw_dst = "10.0.0.1"
 
     msg.actions.append(of.ofp_action_output(port = 1))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =100
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.dl_type = 0x0800
 
     msg.match.nw_dst = "10.0.0.2"
 
     msg.actions.append(of.ofp_action_output(port = 2))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =100
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.dl_type = 0x0800
 
     msg.match.nw_dst = "10.0.0.3"
 
     msg.actions.append(of.ofp_action_output(port = 3))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =100
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.dl_type = 0x0800
 
     msg.match.nw_dst = "10.0.0.4"
 
     msg.actions.append(of.ofp_action_output(port = 4))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =100
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.dl_type = 0x0800
 
     msg.match.nw_dst = "10.0.0.5"
 
     msg.actions.append(of.ofp_action_output(port = 5))
 
     event.connection.send(msg)
 
 
 
     msg = of.ofp_flow_mod()
 
     msg.priority =100
 
     msg.idle_timeout = 0
 
     msg.hard_timeout = 0
 
     msg.match.dl_type = 0x0800
 
     msg.match.nw_dst = "10.0.0.6"
 
     msg.actions.append(of.ofp_action_output(port = 6))
 
     event.connection.send(msg)
 
 
 
def launch ():
 
  global start_time
 
  core.openflow.addListenerByName("PortStatsReceived",_handle_portstats_received)
 
  core.openflow.addListenerByName("ConnectionUp", _handle_ConnectionUp)
 
  core.openflow.addListenerByName("PacketIn",_handle_PacketIn)

这段代码原文中是有问题的，如果执行会出现下面的错误：

2. 在~/mininet中创建文件mym.py

# cd mininet
# vim mym.py

脚本内容如下：

#!/usr/bin/python
 
 
 
from mininet.topo import Topo
 
from mininet.net import Mininet
 
from mininet.node import CPULimitedHost
 
from mininet.link import TCLink
 
from mininet.util import dumpNodeConnections
 
from mininet.log import setLogLevel
 
from mininet.node import Controller 
 
from mininet.cli import CLI
 
from functools import partial
 
from mininet.node import RemoteController
 
import os
 
 
 
 
 
class MyTopo(Topo):
 
    "Single switch connected to n hosts."
 
    def __init__(self):
 
        Topo.__init__(self)
 
        s1=self.addSwitch('s1')
 
        s2=self.addSwitch('s2')
 
        s3=self.addSwitch('s3')
 
        s4=self.addSwitch('s4')
 
        s5=self.addSwitch('s5') 
 
        h1=self.addHost('h1')
 
        h2=self.addHost('h2')
 
        h3=self.addHost('h3')
 
        h4=self.addHost('h4')
 
        h5=self.addHost('h5')
 
        h6=self.addHost('h6')
 
         
 
        self.addLink(h1, s1, bw=1, delay='10ms', loss=0, max_queue_size=1000, use_htb=True)
 
        self.addLink(h2, s1, bw=1, delay='10ms', loss=0, max_queue_size=1000, use_htb=True) 
 
        self.addLink(h3, s1, bw=1, delay='10ms', loss=0, max_queue_size=1000, use_htb=True)
 
        self.addLink(s1, s2, bw=1, delay='10ms', loss=0, max_queue_size=1000, use_htb=True) 
 
        self.addLink(s1, s3, bw=1, delay='10ms', loss=0, max_queue_size=1000, use_htb=True) 
 
        self.addLink(s1, s4, bw=1, delay='10ms', loss=0, max_queue_size=1000, use_htb=True) 
 
        self.addLink(s2, s5, bw=1, delay='10ms', loss=0, max_queue_size=1000, use_htb=True) 
 
        self.addLink(s3, s5, bw=1, delay='10ms', loss=0, max_queue_size=1000, use_htb=True)  
 
        self.addLink(s4, s5, bw=1, delay='10ms', loss=0, max_queue_size=1000, use_htb=True) 
 
        self.addLink(s5, h4, bw=1, delay='10ms', loss=0, max_queue_size=1000, use_htb=True) 
 
        self.addLink(s5, h5, bw=1, delay='10ms', loss=0, max_queue_size=1000, use_htb=True) 
 
        self.addLink(s5, h6, bw=1, delay='10ms', loss=0, max_queue_size=1000, use_htb=True) 
 
 
 
def perfTest():
 
    "Create network and run simple performance test"
 
    topo = MyTopo()
 
 
    net = Mininet(topo=topo, host=CPULimitedHost, link=TCLink, controller=partial(RemoteController, ip='10.0.0.13', port=6633))
    //这里的 ip 改为本地 IP 地址，例如我的是 10.0.2.15 否则会连接不上控制器
    net.start()
 
    print "Dumping host connections"
 
    dumpNodeConnections(net.hosts)
 
    h1,h2,h3=net.get('h1','h2','h3')
 
    h4,h5,h6=net.get('h4','h5','h6')
 
    h1.setMAC("0:0:0:0:0:1")
 
    h2.setMAC("0:0:0:0:0:2")
 
    h3.setMAC("0:0:0:0:0:3")
 
    h4.setMAC("0:0:0:0:0:4")
 
    h5.setMAC("0:0:0:0:0:5")
 
    h6.setMAC("0:0:0:0:0:6")
 
    CLI(net)
 
    net.stop()
 
 
 
if __name__ == '__main__':
 
    setLogLevel('info')
 
    perfTest()

这里又是一个坑，参照原文执行会得到以下错误：

因为做实验的时候是在同一台机子上进行，POX 控制器也是部署在本机上，因此在创建拓扑结构时要把控制器的 IP 地址改为本地的 IP 地址
查看 IP 地址：

ifconfig

3. 运行脚本

首先运行 lab_controller.py

# cd pox
# ./pox.py lab_controller

然后运行 mym.py

# cd mininet
# python mym.py

这时观察 pox 控制台，发现出现了一堆 warning 先不理...

在 mininet 中执行 h1 ping -i 0.1 h4，即每秒从 h1 传送 10 个包到 h4

原文中提到「查看虚POX打印出来的结果显示先从 s1_p4 (switch 1, port 4) 发出 10 个包，然后是从 s1_p5 ，接着从 s1_p6 ，
如此循环调度」但是实际过程中在 POX 控制台并没有看到这些信息，重复尝试几次之后，依然看不见。后来在网上看到 POX 是有图形化界面的，也就是 poxdesk，之后利用 pox 的 Web 界面再次进行实验。
poxdesk 安装：

# cd ./pox/ext
# git clone https://github.com/MurphyMc/poxdesk
# cd poxdesk
# wget http://downloads.sourceforge.net/qooxdoo/qooxdoo-2.0.2-sdk.zip
# unzip qooxdoo-2.0.2-sdk.zip
# mv qooxdoo-2.0.2-sdk qx
# cd poxdesk
# ./generate.py
# cd ../../..

参考：SDN常用控制器安装部署之POX篇
到这里 poxdesk 就安装好了。重做实验的流程都不变，只是在执行 pox 脚本时代码改为

./pox.py lab_controller web messenger messenger.log_service messenger.ajax_transport openflow.of_service poxdesk
//通用的命令为：./pox.py 脚本名 web messenger messenger.log_service messenger.ajax_transport openflow.of_service poxdesk

之后再运行 mininet 脚本
然后在浏览器中打开 http://pox-ip:8000/poxdesk 来访问界面，其中pox-ip是本机 IP 地址，例如我的是10.0.2.15
依次点击左下角pox->TableViewer->左上角Switch->第一个交换机00_00_00_00_00_01 观察目的主机 h4 对应的那一行（也就是 nw_dst 为 10.0.0.4/32 的那一行）可以发现 OUTPUT一直在5、6两个端口之间变动


这里还是有一个问题，实验开头说路由规则会在三种情况之间变化，但是这样看来只有两种情况，不知道是什么原因，个人推测应该问题应该出在 POX 脚本上

• 总结

  1. 实验过程中遇到的问题

• 因为之前的实验在关闭 mininet 之后就可以了，开始实验前我都没有执行
  「sudo mn -c」
  然而这次实验在运行 mininet 脚本之后，想要再次进行实验必须先输入 「sudo mn -c」，否则会报错
• 在运行 pox 时会出现这样的错误 「error: [Errno 98] Address already in ues」这是因为在上一次实验结束的时候没有关闭 pox 控制器。解决方法：重启...
• 在 h1 ping h4 一段时间后会出现错误，具体是为什么还没有弄清

• 其他的问题在实验步骤中都有提到了

  2. 收获

• 熟悉Mininet自定义拓扑脚本的编写
• 熟悉编写POX脚本动态改变转发规则

• 这是 Mininet 系列实验做到现在遇到最多问题的一次，主要是原文中代码的错误本身就比较多。解决问题的过程远比实验本身重要的多，收获也更多。

来源：https://www.cnblogs.com/multhree/p/9389430.html