Mininet流表操作

秒速五厘米 2022-03-27 08:16 202阅读 0赞

参考链接：[https://www.bilibili.com/video/av24111964/?p=5][https_www.bilibili.com_video_av24111964_p_5]  
mininet脚本代码

#!/usr/bin/python
    
    from mininet.net import Mininet
    from mininet.node import Controller, RemoteController, OVSController
    from mininet.node import CPULimitedHost, Host, Node
    from mininet.node import OVSKernelSwitch, UserSwitch
    from mininet.node import IVSSwitch
    from mininet.cli import CLI
    from mininet.log import setLogLevel, info
    from mininet.link import TCLink, Intf
    from subprocess import call
    
    def myNetwork():
    
        net = Mininet( topo=None,
                       build=False,
                       ipBase='10.0.0.0/8')
    
        info( '*** Adding controller\n' )
        c0=net.addController(name='c0',
                          controller=RemoteController,
                          ip='127.0.0.1',
                          protocol='tcp',
                          port=6633)
    
        info( '*** Add switches\n')
        s2 = net.addSwitch('s2', cls=OVSKernelSwitch, dpid='0000000000000002')
        s1 = net.addSwitch('s1', cls=OVSKernelSwitch, dpid='0000000000000001')
    
        info( '*** Add hosts\n')
        h3 = net.addHost('h3', cls=Host, ip='10.0.0.3', defaultRoute=None)
        h2 = net.addHost('h2', cls=Host, ip='10.0.0.2', defaultRoute=None)
        h1 = net.addHost('h1', cls=Host, ip='10.0.0.1', defaultRoute=None)
    
        info( '*** Add links\n')
        net.addLink(s1, h1)
        net.addLink(s1, h2)
        net.addLink(s1, s2)
        net.addLink(s2, h3)
    
        info( '*** Starting network\n')
        net.build()
        info( '*** Starting controllers\n')
        for controller in net.controllers:
            controller.start()
    
        info( '*** Starting switches\n')
        net.get('s2').start([c0])
        net.get('s1').start([c0])
    
        info( '*** Post configure switches and hosts\n')
    
        CLI(net)
        net.stop()
    
    if __name__ == '__main__':
        setLogLevel( 'info' )
        myNetwork()

使用命令启动脚本。

> sudo mn --custom test\_ryu.py --topo mytopo --controller=remote,ip=127.0.0.1,port=6633

如果出现Caught exception. Cleaning up… Exception: Invalid topo name mytopo错误的话，需要在代码里面更改topo名称

TOPOS = { 'mytopo' : (lambda : myNetwork())}

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zNjM3Mjg3OQ_size_16_color_FFFFFF_t_70]  
这样就建立完成了。

#### 查看流表 ####

> dpctl dump-flows  
> ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zNjM3Mjg3OQ_size_16_color_FFFFFF_t_70 1]

通信原理：  
h1发送信息给s1，s1会上报给控制器，由控制器对数据进行处理，控制器给交换机下发流表。相关的数据根据流表将数据包发送出去。当数据包到达s2的时候，s2也会给控制器上报一个消息，这时候控制器也会给s2下发流表数据

#### 删除流表 ####

> dpctl del-flows  
> ![在这里插入图片描述][20190113135736523.png]

这时候就会发现，两个交换机里面的流表是空的。  
对某一个流表进行单独的操作：

> sh ovs-ofctl del-flows s1 in\_port=2

或

> dpctl del-flows in\_port=1  
> dpctl del-flows in\_port=2

#### 手动添加流表 ####

> dpctl add-flow in\_port=1,actions=output:2  
> dpctl add-flow in\_port=2,actions=output:1

可以看到h1又能够ping通h2了  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zNjM3Mjg3OQ_size_16_color_FFFFFF_t_70 2]  
![在这里插入图片描述][20190113143321424.png]

#### 添加丢弃数据包的流表 ####

让交换机丢弃从二号端口发来的所有数据包

> dpctl add-flow in\_port=2,actions=drop

增加之后，主机将无法通信

[https_www.bilibili.com_video_av24111964_p_5]: https://www.bilibili.com/video/av24111964/?p=5
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zNjM3Mjg3OQ_size_16_color_FFFFFF_t_70]: /images/20220327/312a5553080945c99efd735a0fb4244c.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zNjM3Mjg3OQ_size_16_color_FFFFFF_t_70 1]: /images/20220327/5732554ad49e42ccaa3ec88489b18bd1.png
[20190113135736523.png]: /images/20220327/8d3408729fc54a1e8720a5e35e5fe6bc.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl8zNjM3Mjg3OQ_size_16_color_FFFFFF_t_70 2]: /images/20220327/27682e4f765b4c72ad3ccea66475cc2b.png
[20190113143321424.png]: /images/20220327/73a5eada62af46a8a2fb5e8662729a4c.png