Mininet系列实验（七）：Mininet脚本实现控制交换机行为

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。

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。

还是那个流程：

打开mininet文件夹——创建mymininet1.py——编辑脚本保存——改为可执行——清内存——开发者模式内打开

 1 # !/usr/bin/python 
 2 from mininet.net import Mininet
 3 from mininet.node import Node
 4 from mininet.link import Link
 5 from mininet.log import setLogLevel, info
 6 from mininet.util import quietRun
 7 # 调用Mininet相关模块
 8  
 9 from time import sleep
10 # 调用sleep模块 
11  
12 def scratchNet( cname='controller', cargs='-v ptcp:' ):
13     "Create network from scratch using Open vSwitch."
14  
15     # 创建网络节点其中有两个主机，一个交换机，一个控制器
16     info( "*** Creating nodes\n" )
17     controller = Node( 'c0', inNamespace=False )
18     switch0 = Node( 's0', inNamespace=False )
19     h0 = Node( 'h0' )
20     h1 = Node( 'h1' )
21  
22     # 创建网络连接，分别是h0-s0和h1-s0
23     info( "*** Creating links\n" )
24     Link( h0, switch0 )
25     Link( h1, switch0 )
26  
27     # 设置主机的IP地址，然后再诊断的同时打印出string化的h0h1
28     info( "*** Configuring hosts\n" )
29     h0.setIP( '192.168.123.1/24' )
30     h1.setIP( '192.168.123.2/24' )
31     info( str( h0 ) + '\n' )
32     info( str( h1 ) + '\n' )
33  
34     # 开启控制器和s0的链路
35     info( "*** Starting network using Open vSwitch\n" )
36     controller.cmd( cname + ' ' + cargs + '&' )
37     switch0.cmd( 'ovs-vsctl del-br dp0' )
38     switch0.cmd( 'ovs-vsctl add-br dp0' )
39  
40     # 在交换机的信息库里面依次打出信息
41     for intf in switch0.intfs.values():
42         print intf
43         print switch0.cmd( 'ovs-vsctl add-port dp0 %s' % intf )
44     switch0.cmd( 'ovs-vsctl set-controller dp0 tcp:10.0.0.8:6633' )
45     switch0.cmd( 'ovs-ofctl add-flow dp0 \"in_port=1 actions=output:2\"' )
46     switch0.cmd( 'ovs-ofctl add-flow dp0 \"in_port=2 actions=output:1\"' )
47  
48     # 等待连接的小程序
49     info( '*** Waiting for switch to connect to controller' )
50     while 'is_connected' not in quietRun( 'ovs-vsctl show' ):
51         sleep( 1 )
52         info( '.' )
53     info( '\n' )
54  
55     # 两个互ping6次
56     info( "*** Running test\n" )
57     h0.cmdPrint( 'ping -c6 ' + h1.IP() )
58     h1.cmdPrint( 'ping -c6 ' + h0.IP() )
59  
60     # 关闭这个网络
61     info( "*** Stopping network\n" )
62     controller.cmd( 'kill %' + cname )
63     switch0.cmd( 'ovs-vsctl del-br dp0' )
64     switch0.deleteIntfs()
65     info( '\n' )
66  
67 # 主函数部分，设置打印等级，还有调用以上的一些函数
68 if __name__ == '__main__':
69     setLogLevel( 'info' )
70     info( '*** Scratch network demo (kernel datapath)\n' )
71     Mininet.init()
72     scratchNet()

 

 

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。

和前者的脚本大同小异，这里就解释mymininet1.py没有的，print switch0.cmd( 'ovs-ofctl show dp0' )意思就是打出关于s0的信息

1.  1 #!/usr/bin/python  
    2 from mininet.net import Mininet
    3 from mininet.node import Node
    4 from mininet.link import Link
    5 from mininet.log import setLogLevel, info
    6 from mininet.util import quietRun
    7  
    8 from time import sleep
    9  
   10 def scratchNet( cname='controller', cargs='-v ptcp:' ):
   11     "Create network from scratch using Open vSwitch."
   12  
   13     info( "*** Creating nodes\n" )
   14     controller = Node( 'c0', inNamespace=False )
   15     switch0 = Node( 's0', inNamespace=False )
   16     switch1 = Node( 's1', inNamespace=False )
   17     h0 = Node( 'h0' )
   18     h1 = Node( 'h1' )
   19  
   20     info( "*** Creating links\n" )
   21     Link( h0, switch0 )
   22     Link( h1, switch1 )
   23     Link( switch0, switch1 )
   24  
   25     info( "*** Configuring hosts\n" )
   26     h0.setIP( '192.168.123.1/24' )
   27     h1.setIP( '192.168.123.2/24' )
   28     info( str( h0 ) + '\n' )
   29     info( str( h1 ) + '\n' )
   30  
   31     info( "*** Starting network using Open vSwitch\n" )
   32     controller.cmd( cname + ' ' + cargs + '&' )
   33     switch0.cmd( 'ovs-vsctl del-br dp0' )
   34     switch0.cmd( 'ovs-vsctl add-br dp0' )
   35     switch1.cmd( 'ovs-vsctl del-br dp1' )
   36     switch1.cmd( 'ovs-vsctl add-br dp1' )
   37  
   38  
   39     for intf in switch0.intfs.values():
   40         print intf
   41         print switch0.cmd( 'ovs-vsctl add-port dp0 %s' % intf )
   42  
   43     for intf in switch1.intfs.values():
   44         print intf
   45         print switch1.cmd( 'ovs-vsctl add-port dp1 %s' % intf )
   46  
   47     switch0.cmd( 'ovs-vsctl set-controller dp0 tcp:10.0.0.8:6633' )
   48     switch1.cmd( 'ovs-vsctl set-controller dp1 tcp: 10.0.0.8:6633' )
   49     switch0.cmd( 'ovs-ofctl add-flow dp0 \"in_port=1 actions=output:2\"' )
   50     switch0.cmd( 'ovs-ofctl add-flow dp0 \"in_port=2 actions=output:1\"' )
   51     switch1.cmd( 'ovs-ofctl add-flow dp1 \"in_port=1 actions=output:2\"' )
   52     switch1.cmd( 'ovs-ofctl add-flow dp1 \"in_port=2 actions=output:1\"' )
   53  
   54  
   55     info( '*** Waiting for switch to connect to controller' )
   56     while 'is_connected' not in quietRun( 'ovs-vsctl show' ):
   57         sleep( 1 )
   58         info( '.' )
   59     info( '\n' )
   60     print switch0.cmd( 'ovs-ofctl show dp0' )
   61     print switch1.cmd( 'ovs-ofctl show dp1' )
   62  
   63  
   64     info( "*** Running test\n" )
   65     h0.cmdPrint( 'ping -c3 ' + h1.IP() )
   66     h1.cmdPrint( 'ping -c3 ' + h0.IP() )
   67  
   68     info( "*** Stopping network\n" )
   69     controller.cmd( 'kill %' + cname )
   70     switch0.cmd( 'ovs-vsctl del-br dp0' )
   71     switch0.deleteIntfs()
   72     switch1.cmd( 'ovs-vsctl del-br dp1' )
   73     switch1.deleteIntfs()
   74     info( '\n' )
   75  
   76 if __name__ == '__main__':
   77     setLogLevel( 'info' )
   78     info( '*** Scratch network demo (kernel datapath)\n' )
   79     Mininet.init()
   80     scratchNet()

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 #!/usr/bin/python 
 2 from mininet.net import Mininet
 3 from mininet.node import Node
 4 from mininet.link import TCLink
 5 from mininet.log import setLogLevel, info
 6 from mininet.util import quietRun
 7  
 8 from time import sleep
 9  
10 def scratchNet( cname='controller', cargs='-v ptcp:' ):
11     "Create network from scratch using Open vSwitch."
12  
13     info( "*** Creating nodes\n" )
14     controller = Node( 'c0', inNamespace=False )
15     switch0 = Node( 's0', inNamespace=False )
16     switch1 = Node( 's1', inNamespace=False )
17     h0 = Node( 'h0' )
18     h1 = Node( 'h1' )
19  
20     info( "*** Creating links\n" )
21  
22     linkopts0=dict(bw=10)
23     linkopts1=dict(bw=10, delay='5ms', loss=10)
24     TCLink( h0, switch0,**linkopts0)
25     TCLink( h1, switch1,**linkopts0)
26     TCLink( switch0, switch1,**linkopts1)
27  
28  
29     info( "*** Configuring hosts\n" )
30     h0.setIP( '192.168.123.1/24' )
31     h1.setIP( '192.168.123.2/24' )
32     info( str( h0 ) + '\n' )
33     info( str( h1 ) + '\n' )
34  
35     info( "*** Starting network using Open vSwitch\n" )
36     controller.cmd( cname + ' ' + cargs + '&' )
37     switch0.cmd( 'ovs-vsctl del-br dp0' )
38     switch0.cmd( 'ovs-vsctl add-br dp0' )
39     switch1.cmd( 'ovs-vsctl del-br dp1' )
40     switch1.cmd( 'ovs-vsctl add-br dp1' )
41  
42  
43     for intf in switch0.intfs.values():
44         print intf
45         print switch0.cmd( 'ovs-vsctl add-port dp0 %s' % intf )
46  
47     for intf in switch1.intfs.values():
48         print intf
49         print switch1.cmd( 'ovs-vsctl add-port dp1 %s' % intf )
50  
51     switch0.cmd( 'ovs-vsctl set-controller dp0 tcp:10.0.0.8:6633' )
52     switch1.cmd( 'ovs-vsctl set-controller dp1 tcp: 10.0.0.8:6633' )
53     switch0.cmd( 'ovs-ofctl add-flow dp0 \"in_port=1 actions=output:2\"' )
54     switch0.cmd( 'ovs-ofctl add-flow dp0 \"in_port=2 actions=output:1\"' )
55     switch1.cmd( 'ovs-ofctl add-flow dp1 \"in_port=1 actions=output:2\"' )
56     switch1.cmd( 'ovs-ofctl add-flow dp1 \"in_port=2 actions=output:1\"' )
57  
58  
59     info( '*** Waiting for switch to connect to controller' )
60     while 'is_connected' not in quietRun( 'ovs-vsctl show' ):
61         sleep( 1 )
62         info( '.' )
63     info( '\n' )
64     print switch0.cmd( 'ovs-ofctl show dp0' )
65     print switch1.cmd( 'ovs-ofctl show dp1' )
66  
67  
68     info( "*** Running test\n" )
69     h0.cmdPrint( 'ping -c3 ' + h1.IP() )
70     h1.cmdPrint( 'ping -c3 ' + h0.IP() )
71  
72     info( "*** Stopping network\n" )
73     controller.cmd( 'kill %' + cname )
74     switch0.cmd( 'ovs-vsctl del-br dp0' )
75     switch0.deleteIntfs()
76     switch1.cmd( 'ovs-vsctl del-br dp1' )
77     switch1.deleteIntfs()
78     info( '\n' )
79  
80 if __name__ == '__main__':
81     setLogLevel( 'info' )
82     info( '*** Scratch network demo (kernel datapath)\n' )
83     Mininet.init()
84     scratchNet()

 

 

 

总结：

1.对ovs加深理解

2.能够完全看懂脚本

3.需要更深一步了解mininet的模块的函数