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Mininet脚本实现控制交换机行为

阅读：3361 输入：2020-04-01 11:07:19

1.实验目的

熟悉Mininet自定义拓扑脚本的编写；

掌握使用“ovs-vsctl”命令直接控制Open vSwitch。

2.实验原理

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。

3.实验任务

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。

4.实验步骤

4.1 搭建环境

本实验需要两台虚拟机，分别安装OpenDaylight（6G）和支持OpenFlow1.3协议的Mininet。

4.2 实验操作

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。

1 在Mininet里新建文件mymininet1.py。

#touch mymininet1.py

2 查看OpenDaylight所在虚拟机的IP为10.0.0.8。

3 编辑文件mymininet1.py，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()

4 将文件mymininet1.py设置成可执行文件。

#chmod +x mymininet1.py

5 执行文件mymininet1.py。

#./mymininet1.py

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。

1 在Mininet里新建文件mymininet2.py。

#touch mymininet2.py

2 编辑文件mymininet2.py，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()

3 将文件mymininet2.py设置成可执行文件。

#chmod +x mymininet2.py

4 执行文件mymininet2.py。

#./mymininet2.py

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。

1 在Mininet里新建文件mymininet3.py。

#touch mymininet3.py

2 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 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()

3 将文件mymininet3.py设置成可执行文件。

#chmod +x mymininet3.py

4 执行文件mymininet3.py。

#./mymininet3.py

5.实验结论

在Mininet脚本中，可以通过使用“ovs-vsctl”命令直接控制Open vSwitch，实现通信。

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