mininet实验 脚本实现控制交换机行为

写在前面

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本文参考

• 通过这个实验，我学习到了另一种下流表的方式。
• 下流表有两种方式（我目前了解）：
  • 通过controller下发。
  • 通过OvS提供的API直接向OvS交换机下流表。
• 本实验脚本已经把相关过程写好，读一下脚本熟悉API是关键。

实验简介

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在SDN环境中，控制器可以通过对交换机下发流表操作来控制交换机的转发行为。在本实验中，使用Mininet基于python的脚本，调用“ovs-vsctl”命令直接控制Open vSwitch。

本实验在基于Mininet脚本的不同拓扑环境下使用OpenDaylight控制交换机行为。

• 任务一：一台交换机两台主机，从1端口进入的数据流转发到2端口，从2端口进入的数据流转发到1端口；
• 任务二：两台交换机两台主机，主机0连接交换机0，主机1连接交换机1，交换机0连接交换机1，数据转发端口同任务一；
• 任务三：与任务二类似，但是在创建link的时候，设置带宽、延迟以及丢包率。

实验步骤

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1.搭建环境

• mininet虚拟机
• OpenDaylight虚拟机

2.任务一

一台交换机两台主机，实现从1端口进入的数据流转发到2端口，从2端口进入的数据流转发到1端口。

• 在Mininet里新建文件mymininet1.py。
• 查看ODL控制器所在主机IP。
• 编辑myminnet1脚本内容如下：

#!/usr/bin/python
from mininet.net import Mininet
from mininet.node import Node
from mininet.link import Link
from mininet.log import setLogLevel, info
from mininet.util import quietRun

from time import sleep

def scratchNet( cname='controller', cargs='-v ptcp:' ):
    "Create network from scratch using Open vSwitch."

    info( "*** Creating nodes\n" )
    controller = Node( 'c0', inNamespace=False )
    switch0 = Node( 's0', inNamespace=False )
    h0 = Node( 'h0' )
    h1 = Node( 'h1' )

    info( "*** Creating links\n" )
    Link( h0, switch0 )
    Link( h1, switch0 )

    info( "*** Configuring hosts\n" )
    h0.setIP( '192.168.123.1/24' )
    h1.setIP( '192.168.123.2/24' )
    info( str( h0 ) + '\n' )
    info( str( h1 ) + '\n' )

    info( "*** Starting network using Open vSwitch\n" )
    controller.cmd( cname + ' ' + cargs + '&' )
    switch0.cmd( 'ovs-vsctl del-br dp0' )
    switch0.cmd( 'ovs-vsctl add-br dp0' )

    for intf in switch0.intfs.values():
        print intf
        print switch0.cmd( 'ovs-vsctl add-port dp0 %s' % intf )
    switch0.cmd( 'ovs-vsctl set-controller dp0 tcp:10.0.0.8:6633' )
    switch0.cmd( 'ovs-ofctl add-flow dp0 \"in_port=1 actions=output:2\"' )
    switch0.cmd( 'ovs-ofctl add-flow dp0 \"in_port=2 actions=output:1\"' )

    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 -c6 ' + h1.IP() )
    h1.cmdPrint( 'ping -c6 ' + h0.IP() )

    info( "*** Stopping network\n" )
    controller.cmd( 'kill %' + cname )
    switch0.cmd( 'ovs-vsctl del-br dp0' )
    switch0.deleteIntfs()
    info( '\n' )

if __name__ == '__main__':
    setLogLevel( 'info' )
    info( '*** Scratch network demo (kernel datapath)\n' )
    Mininet.init()
    scratchNet()

• 修改其为可执行文件并运行：

chmod +x mymininet1.py
./mymininet1.py

• mn -c命令清理进程。

3.任务二

两台交换机两台主机，主机0连接交换机0，主机1连接交换机1，交换机0连接交换机1，数据转发端口要求同任务一。

• 在Mininet里新建文件mymininet2.py。
• 查看ODL控制器所在主机IP。
• 编辑myminnet2脚本内容如下：

#!/usr/bin/python
from mininet.net import Mininet
from mininet.node import Node
from mininet.link import Link
from mininet.log import setLogLevel, info
from mininet.util import quietRun

from time import sleep

def scratchNet( cname='controller', cargs='-v ptcp:' ):
    "Create network from scratch using Open vSwitch."

    info( "*** Creating nodes\n" )
    controller = Node( 'c0', inNamespace=False )
    switch0 = Node( 's0', inNamespace=False )
    switch1 = Node( 's1', inNamespace=False )
    h0 = Node( 'h0' )
    h1 = Node( 'h1' )

    info( "*** Creating links\n" )
    Link( h0, switch0 )
    Link( h1, switch1 )
    Link( switch0, switch1 )

    info( "*** Configuring hosts\n" )
    h0.setIP( '192.168.123.1/24' )
    h1.setIP( '192.168.123.2/24' )
    info( str( h0 ) + '\n' )
    info( str( h1 ) + '\n' )

    info( "*** Starting network using Open vSwitch\n" )
    controller.cmd( cname + ' ' + cargs + '&' )
    switch0.cmd( 'ovs-vsctl del-br dp0' )
    switch0.cmd( 'ovs-vsctl add-br dp0' )
    switch1.cmd( 'ovs-vsctl del-br dp1' )
    switch1.cmd( 'ovs-vsctl add-br dp1' )

    for intf in switch0.intfs.values():
        print intf
        print switch0.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 )

    switch0.cmd( 'ovs-vsctl set-controller dp0 tcp:10.0.0.8:6633' )
    switch1.cmd( 'ovs-vsctl set-controller dp1 tcp: 10.0.0.8:6633' )
    switch0.cmd( 'ovs-ofctl add-flow dp0 \"in_port=1 actions=output:2\"' )
    switch0.cmd( 'ovs-ofctl add-flow dp0 \"in_port=2 actions=output:1\"' )
    switch1.cmd( 'ovs-ofctl add-flow dp1 \"in_port=1 actions=output:2\"' )
    switch1.cmd( 'ovs-ofctl add-flow dp1 \"in_port=2 actions=output:1\"' )

    info( '*** Waiting for switch to connect to controller' )
    while 'is_connected' not in quietRun( 'ovs-vsctl show' ):
        sleep( 1 )
        info( '.' )
    info( '\n' )
    print switch0.cmd( 'ovs-ofctl show dp0' )
    print switch1.cmd( 'ovs-ofctl show dp1' )

    info( "*** Running test\n" )
    h0.cmdPrint( 'ping -c3 ' + h1.IP() )
    h1.cmdPrint( 'ping -c3 ' + h0.IP() )

    info( "*** Stopping network\n" )
    controller.cmd( 'kill %' + cname )
    switch0.cmd( 'ovs-vsctl del-br dp0' )
    switch0.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()
    scratchNet()

• 修改其为可执行文件并运行：

chmod +x mymininet2.py
./mymininet2.py

• mn -c命令清理进程。

4.任务三

与任务二类似，但是在创建link的时候，设置带宽、延迟以及丢包率。

• 在Mininet里新建文件mymininet3.py。
• 查看ODL控制器所在主机IP。
• 编辑myminnet3脚本内容如下:

#!/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 mininet.util import quietRun

from time import sleep

def scratchNet( cname='controller', cargs='-v ptcp:' ):
    "Create network from scratch using Open vSwitch."

    info( "*** Creating nodes\n" )
    controller = Node( 'c0', inNamespace=False )
    switch0 = Node( 's0', inNamespace=False )
    switch1 = Node( 's1', inNamespace=False )
    h0 = Node( 'h0' )
    h1 = Node( 'h1' )

    info( "*** Creating links\n" )

    linkopts0=dict(bw=10)
    linkopts1=dict(bw=10, delay='5ms', loss=10)
    TCLink( h0, switch0,**linkopts0)
    TCLink( h1, switch1,**linkopts0)
    TCLink( switch0, switch1,**linkopts1)

    info( "*** Configuring hosts\n" )
    h0.setIP( '192.168.123.1/24' )
    h1.setIP( '192.168.123.2/24' )
    info( str( h0 ) + '\n' )
    info( str( h1 ) + '\n' )

    info( "*** Starting network using Open vSwitch\n" )
    controller.cmd( cname + ' ' + cargs + '&' )
    switch0.cmd( 'ovs-vsctl del-br dp0' )
    switch0.cmd( 'ovs-vsctl add-br dp0' )
    switch1.cmd( 'ovs-vsctl del-br dp1' )
    switch1.cmd( 'ovs-vsctl add-br dp1' )

    for intf in switch0.intfs.values():
        print intf
        print switch0.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 )

    switch0.cmd( 'ovs-vsctl set-controller dp0 tcp:10.0.0.8:6633' )
    switch1.cmd( 'ovs-vsctl set-controller dp1 tcp: 10.0.0.8:6633' )
    switch0.cmd( 'ovs-ofctl add-flow dp0 \"in_port=1 actions=output:2\"' )
    switch0.cmd( 'ovs-ofctl add-flow dp0 \"in_port=2 actions=output:1\"' )
    switch1.cmd( 'ovs-ofctl add-flow dp1 \"in_port=1 actions=output:2\"' )
    switch1.cmd( 'ovs-ofctl add-flow dp1 \"in_port=2 actions=output:1\"' )

    info( '*** Waiting for switch to connect to controller' )
    while 'is_connected' not in quietRun( 'ovs-vsctl show' ):
        sleep( 1 )
        info( '.' )
    info( '\n' )
    print switch0.cmd( 'ovs-ofctl show dp0' )
    print switch1.cmd( 'ovs-ofctl show dp1' )

    info( "*** Running test\n" )
    h0.cmdPrint( 'ping -c3 ' + h1.IP() )
    h1.cmdPrint( 'ping -c3 ' + h0.IP() )

    info( "*** Stopping network\n" )
    controller.cmd( 'kill %' + cname )
    switch0.cmd( 'ovs-vsctl del-br dp0' )
    switch0.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()
    scratchNet()

• 修改其为可执行文件并运行：

chmod +x mymininet2.py
./mymininet2.py

• mn -c命令清理进程。

实验小结

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• 这次实验很顺利，遇见的问题都通过陈翔学长和百度解决掉了。