实验参考：

实验步骤：

1. 在装有mininet的虚拟机中新建文件mymininet.py并编辑以下内容，这里要注意一点，文中的dp0与dp1须填POX安装的虚拟机的地址，由于本次实验是在同一台虚拟机中安装，因此地址为127.0.0.1：

 

#!/usr/bin/python from mininet.net import Mininetfrom mininet.node import Nodefrom mininet.link import TCLinkfrom mininet.log import  setLogLevel, infofrom threading import Timerfrom mininet.util import quietRunfrom time import sleep def myNet(cname='controller', cargs='-v ptcp:'):    "Create network from scratch using Open vSwitch."    info( "*** Creating nodes\n" )    controller = Node( 'c0', inNamespace=False )    switch = Node( 's0', inNamespace=False )    switch1 = Node( 's1', inNamespace=False )    h0 = Node( 'h0' )    h1 = Node( 'h1' )        info( "*** Creating links\n" )    linkopts0=dict(bw=100, delay='1ms', loss=0)    linkopts1=dict(bw=100, delay='1ms', loss=10)    link0=TCLink( h0, switch, **linkopts0)    link1 = TCLink( switch, switch1, **linkopts1)         link2 = TCLink( h1, switch1, **linkopts0)    #print link0.intf1, link0.intf2    link0.intf2.setMAC("0:0:0:0:0:1")    link1.intf1.setMAC("0:0:0:0:0:2")    link1.intf2.setMAC("0:1:0:0:0:1")     link2.intf2.setMAC("0:1:0:0:0:2")     info( "*** Configuring hosts\n" )    h0.setIP( '192.168.123.1/24' )    h1.setIP( '192.168.123.2/24' )           info( "*** Starting network using Open vSwitch\n" )    switch.cmd( 'ovs-vsctl del-br dp0' )    switch.cmd( 'ovs-vsctl add-br dp0' )    switch1.cmd( 'ovs-vsctl del-br dp1' )    switch1.cmd( 'ovs-vsctl add-br dp1' )     controller.cmd( cname + ' ' + cargs + '&' )         for intf in switch.intfs.values():        print intf        print switch.cmd( 'ovs-vsctl add-port dp0 %s' % intf )    for intf in switch1.intfs.values():        print intf        print switch1.cmd( 'ovs-vsctl add-port dp1 %s' % intf )       # Note: controller and switch are in root namespace, and we    # can connect via loopback interface    switch.cmd( 'ovs-vsctl set-controller dp0 tcp:127.0.0.1:6633' )    switch1.cmd( 'ovs-vsctl set-controller dp1 tcp:127.0.0.1:6633' )      info( '*** Waiting for switch to connect to controller' )    while 'is_connected' not in quietRun( 'ovs-vsctl show' ):        sleep( 1 )        info( '.' )    info( '\n' )     #info( "*** Running test\n" )    h0.cmdPrint( 'ping -Q 0x64 -c 20 ' + h1.IP() )        sleep( 1 )     info( "*** Stopping network\n" )    controller.cmd( 'kill %' + cname )    switch.cmd( 'ovs-vsctl del-br dp0' )    switch.deleteIntfs()    switch1.cmd( 'ovs-vsctl del-br dp1' )    switch1.deleteIntfs()    info( '\n' ) if __name__ == '__main__':    setLogLevel( 'info' )    info( '*** Scratch network demo (kernel datapath)\n' )    Mininet.init()    myNet()

 

2. 在装有POX的虚拟机（本次实验与mininet安装在同一台虚拟机）里新建文件flow_stats.py并编辑以下内容：

#!/usr/bin/python# Copyright 2012 William Yu# wyu@ateneo.edu## This file is part of POX.## POX is free software: you can redistribute it and/or modify# it under the terms of the GNU General Public License as published by# the Free Software Foundation, either version 3 of the License, or# (at your option) any later version.## POX is distributed in the hope that it will be useful,# but WITHOUT ANY WARRANTY; without even the implied warranty of# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the# GNU General Public License for more details.## You should have received a copy of the GNU General Public License# along with POX. If not, see 
     .# """This is a demonstration file created to show how to obtain flow and port statistics from OpenFlow 1.0-enabled switches. The flowstatistics handler contains a summary of web-only traffic.""" # standard includesfrom pox.core import corefrom pox.lib.util import dpidToStrimport pox.openflow.libopenflow_01 as offrom pox.lib.addresses import IPAddr, EthAddr # include as part of the betta branchfrom pox.openflow.of_json import *from pox.lib.recoco import Timerimport time log = core.getLogger() src_dpid = 0dst_dpid = 0input_pkts = 0output_pkts = 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 = "0%s" % (str(flock.tm_min))  else:    mins = str(flock.tm_min)  if int(flock.tm_sec)<10:    secs = "0%s" % (str(flock.tm_sec))  else:    secs = str(flock.tm_sec)  then +="]%s.%s.%s" % (hrs,mins,secs)  return then # handler for timer function that sends the requests to all the# switches connected to the controller.def _timer_func ():  for connection in core.openflow._connections.values():    connection.send(of.ofp_stats_request(body=of.ofp_flow_stats_request()))    connection.send(of.ofp_stats_request(body=of.ofp_port_stats_request()))  log.debug("Sent %i flow/port stats request(s)", len(core.openflow._connections)) # handler to display flow statistics received in JSON format# structure of event.stats is defined by ofp_flow_stats()def _handle_flowstats_received (event):   #stats = flow_stats_to_list(event.stats)   #log.debug("FlowStatsReceived from %s: %s", dpidToStr(event.connection.dpid), stats)   global src_dpid, dst_dpid, input_pkts, output_pkts   #print "src_dpid=", dpidToStr(src_dpid), "dst_dpid=", dpidToStr(dst_dpid)   for f in event.stats:     if f.match.dl_type==0x0800 and f.match.nw_dst==IPAddr("192.168.123.2") and f.match.nw_tos==0x64 and event.connection.dpid==src_dpid:        #print "input: ", f.byte_count, f.packet_count       input_pkts = f.packet_count     if f.match.dl_type==0x0800 and f.match.nw_dst==IPAddr("192.168.123.2") and f.match.nw_tos==0x64 and event.connection.dpid==dst_dpid:       #print "output: ", f.byte_count, f.packet_count         output_pkts = f.packet_count       if input_pkts !=0:         print getTheTime(), "Path Loss Rate =", (input_pkts-output_pkts)*1.0/input_pkts*100, "%" # handler to display port statistics received in JSON formatdef _handle_portstats_received (event):   #print "\n<<

 

3. 运行脚本flow_stats.py。

4. 运行脚本mymininet.py：

 

 

5. 查看POX控制台信息：

 

实验结论：

基于Mininet的脚本设计拓扑，主要是对交换机间传输数据包的路径损耗速率进行设置，并且通过控制器POX进行测量。