实验3:Mininet 实验——测量路径的损耗率

实验3:Mininet 实验——测量路径的损耗率

一、实验 目的

实验 2 的基础上进一步熟悉 Mininet 自定义拓扑脚本,以及与损耗率相关的设定;初步了解 Mininet 安装时自带的 POX 控制器脚本编写,测试路径损耗率。

二 、实验 任务

h0 向 h1 发送数据包,由于在 Mininet 脚本中设置了连接损耗率,在传输过程中会丢失一些包,本次实验的目的是展示如何通过控制器计算路径损耗速率(h0-s0-s1-h1)。这里假设控制器预先知道网络拓扑。控制器将向 s0 和 s1 发送flow_stats_request,当控制器接收到来自 s0 的 response 时,将特定流的数据包数保存在 input_pkts 中,当控制器接收到来自 s1 的 response 时,将接收到特定流的数据包数保存在 output_pkts 中,差值就是丢失的数据包数量。

基于上述拓扑,编写 Mininet 脚本,设置特定的交换机间的路径损耗速率,然后编写 POX 控制器脚本,实现对路径的损耗率的测量。

三 、实验步骤

1. 实验环境

安装了 Ubuntu 18.04.5 Desktop amd64 的虚拟机

2. 实验过程

(1)新建并编辑 pox 脚本 flowstat.py:

  • __步骤一:__在 pox 安装目录下(Mininet 完整安装包含了 pox),执行一下指令,在装有POX的虚拟机里新建文件flow_stats.py

    $cd pox
    $touch flow_stats.py
    
  • __步骤二:__编辑文件flow_stats.py,内容如下:

    #!/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 <http://www.gnu.org/licenses/>.
    #
     
    """
    This is a demonstration file created to show how to obtain flow 
    and port statistics from OpenFlow 1.0-enabled switches. The flow
    statistics handler contains a summary of web-only traffic.
    """
     
    # standard includes
    from pox.core import core
    from pox.lib.util import dpidToStr
    import pox.openflow.libopenflow_01 as of
    from pox.lib.addresses import IPAddr, EthAddr
     
    # include as part of the betta branch
    from pox.openflow.of_json import *
    from pox.lib.recoco import Timer
    import time
     
    log = core.getLogger()
     
    src_dpid = 0
    dst_dpid = 0
    input_pkts = 0
    output_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 format
    def _handle_portstats_received (event):
       #print "\n<<<STATS-REPLY: Return PORT stats for Switch", event.connection.dpid,"at ",getTheTime()
       #for f in event.stats:
          #if int(f.port_no)<65534:
            #print "   PortNo:", f.port_no, " Fwd's Pkts:", f.tx_packets, " Fwd's Bytes:", f.tx_bytes, " Rc'd Pkts:", f.rx_packets, " Rc's Bytes:", f.rx_bytes
            #print "   PortNo:", f.port_no,  " TxDrop:", f.tx_dropped, " RxDrop:", f.rx_dropped, " TxErr:", f.tx_errors, " RxErr:", f.rx_errors, " CRC:", f.rx_crc_err, " Coll:", f.collisions 
      stats = flow_stats_to_list(event.stats)
      log.debug("PortStatsReceived from %s: %s", dpidToStr(event.connection.dpid), stats)
     
    def _handle_ConnectionUp (event):
      global src_dpid, dst_dpid
      print "ConnectionUp: ", dpidToStr(event.connection.dpid)
      for m in event.connection.features.ports:
        if m.name == "s0-eth0":
          src_dpid = event.connection.dpid
        elif m.name == "s1-eth0":
          dst_dpid = event.connection.dpid
     
      msg = of.ofp_flow_mod()
      msg.priority =1
      msg.idle_timeout = 0
      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 =1
      msg.idle_timeout = 0
      msg.match.in_port =2
      msg.actions.append(of.ofp_action_output(port = of.OFPP_ALL))
      event.connection.send(msg)
     
      msg = of.ofp_flow_mod()
      msg.priority =10
      msg.idle_timeout = 0
      msg.hard_timeout = 0
      msg.match.dl_type = 0x0800
      msg.match.nw_tos = 0x64
      msg.match.in_port=1
      msg.match.nw_dst = "192.168.123.2"
      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.dl_type = 0x0800
      msg.match.nw_tos = 0x64
      msg.match.nw_dst = "192.168.123.1"
      msg.actions.append(of.ofp_action_output(port = 1))
      event.connection.send(msg)
        
    # main functiont to launch the module
    def launch ():
      # attach handsers to listners
      core.openflow.addListenerByName("FlowStatsReceived", 
        _handle_flowstats_received) 
      core.openflow.addListenerByName("PortStatsReceived", 
        _handle_portstats_received) 
      core.openflow.addListenerByName("ConnectionUp", _handle_ConnectionUp)
     
      # timer set to execute every five seconds
      Timer(1, _timer_func, recurring=True)
    
  • __步骤3:__运行脚本flow_stats.py。

    $./pox.py flow_stats
    
  • 运行结果

(2)新建脚本 mymininet3.py:

  • __步骤一:__在装有Mininet的虚拟机里新建文件mymininet3.py

    $touch mymininet.py
    
  • __步骤二:__编辑文件mymininet3.py,内容如下:

    #!/usr/bin/python
     
    from mininet.net import Mininet
    from mininet.node import Node
    from mininet.link import TCLink
    from mininet.log import  setLogLevel, info
    from threading import Timer
    from mininet.util import quietRun
    from 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:10.0.0.13:6633' )
        switch1.cmd( 'ovs-vsctl set-controller dp1 tcp:10.0.0.13:6633' )
      
        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)编辑脚本 mymininet3.py:

  • 参照拓扑图,新建并编辑 Mininet 脚本 mymininet3.py,控制器因为安装在本机,
    所以需修改参考资料代码中的控制器地址为 127.0.0.1:6633。
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' )
  • 设置 s0 和 s1 之间链路的丢包率为 0
info( "*** Creating links\n" )
linkopts0=dict(bw=100, delay='1ms', loss=0)
linkopts1=dict(bw=100, delay='1ms', loss=0)
link0=TCLink( h0, switch, **linkopts0)
link1 = TCLink( switch, switch1, **linkopts1)
link2 = TCLink( h1, switch1, **linkopts0)
  • 再执行命令运行 Mininet 脚本 mymininet3.py
$ sudo python mymininet3.py
  • POX端的结果
  • 如果修改代码中 s0 和 s1 之间链路的丢包率为 10。
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)
  • POX 端重新测试,会发现出现丢包现象,但是实际测量出的丢包率会有浮动,链
    路的性能总体受到了限制。

四、总结

当丢包率设置为0的时候,实际上测试数据中还是会有一定程度的丢包的。

posted @ 2020-09-22 21:54  小野狗  阅读(237)  评论(0编辑  收藏  举报