mininet实验 动态改变转发规则实验

写在前面

---

本实验参考

• POX脚本设置好控制器的转发策略，所以只要理解脚本。
• mininet脚本设置好拓扑和相关信息，所以也只要理解脚本。
• POX脚本目前基本看不懂。
• 本实验我学会了：POX控制器Web界面，第一次真正的看到了流表项。

实验拓扑

---

• 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。

实验步骤

---

1.搭建环境

• 安装了mininet的虚拟机。
• 安装了pox的虚拟机。

2.创建脚本

• /pox目录下新建文件lab_controller.py，编辑其内容：

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:

       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)

• 该脚本实现了动态转发策略。
• 我猜测基本思想应该是，基于时间来给交换机s1下发流表项。
• 在Mininet中创建文件mymininet.py。编辑其内容为：

#!/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))

    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()

• 该脚本设置了拓扑。基本可以理解。

3.运行脚本

• /pox目录下运行脚本lab_controller.py

./pox.py lab_controller

• 在Mininet下运行脚本mymininet.py

chmod +x mymininet.py
./mymininet.py

• mininet终端信息

• POX控制器终端信息

• 现在我们通过h1向h4发包，来检测动态转发功能。
• 在mininet终端输入：

h1 ping -i 0.1 h4 #h1每秒向h4发10个包

• 这时在POX界面并没有出现有用的信息，反而是一些warning信息。

4.解决方案

• 既然在终端中没法看到发送的细节，我想到了Web界面。别的控制器都有UI界面POX也应该有吧？
• 我在一篇博客中找到了POX UI界面的实现方式：Poxdesk。

参考博客

• 运行POX脚本时要想使用poxdesk必须多加一些参数，对于本实验运行lab_controller.py时，命令如下：

./pox.py lab_controller web messenger messenger.log_service messenger.ajax_transport openflow.of_service poxdesk

• 通用命令：

./pox.py 要运行的脚本 web messenger messenger.log_service messenger.ajax_transport openflow.of_service poxdesk

• 浏览器中输入：http://pox-ip:8000/poxdesk 来访问界面，其中pox-ip是本机IP地址。
• 进入Web界面后，我们打开s1的flowtable窗口。可以发现：对于目的是10.0.0.4（主机h4）的流表项在周期性变化，action中output端口在5，6之间切换。但是没有4（交换机s2），这个问题没有解决，可能是脚本本身的问题。

5.具体的连接图

• 通过mininet中的net命令可以得拓扑的详细信息，我简单的画了个示意图便于理解：

存在问题

---

• 端口切换时，为什么不能切换到s2？