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  • 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
" )
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
" )
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
" )
29     h0.setIP( '192.168.123.1/24' )
30     h1.setIP( '192.168.123.2/24' )
31     info( str( h0 ) + '
' )
32     info( str( h1 ) + '
' )
33  
34     # 开启控制器和s0的链路
35     info( "*** Starting network using Open vSwitch
" )
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( '
' )
54  
55     # 两个互ping6次
56     info( "*** Running test
" )
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
" )
62     controller.cmd( 'kill %' + cname )
63     switch0.cmd( 'ovs-vsctl del-br dp0' )
64     switch0.deleteIntfs()
65     info( '
' )
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)
' )
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
" )
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
" )
21     Link( h0, switch0 )
22     Link( h1, switch1 )
23     Link( switch0, switch1 )
24  
25     info( "*** Configuring hosts
" )
26     h0.setIP( '192.168.123.1/24' )
27     h1.setIP( '192.168.123.2/24' )
28     info( str( h0 ) + '
' )
29     info( str( h1 ) + '
' )
30  
31     info( "*** Starting network using Open vSwitch
" )
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( '
' )
60     print switch0.cmd( 'ovs-ofctl show dp0' )
61     print switch1.cmd( 'ovs-ofctl show dp1' )
62  
63  
64     info( "*** Running test
" )
65     h0.cmdPrint( 'ping -c3 ' + h1.IP() )
66     h1.cmdPrint( 'ping -c3 ' + h0.IP() )
67  
68     info( "*** Stopping network
" )
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( '
' )
75  
76 if __name__ == '__main__':
77     setLogLevel( 'info' )
78     info( '*** Scratch network demo (kernel datapath)
' )
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
" )
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
" )
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
" )
30     h0.setIP( '192.168.123.1/24' )
31     h1.setIP( '192.168.123.2/24' )
32     info( str( h0 ) + '
' )
33     info( str( h1 ) + '
' )
34  
35     info( "*** Starting network using Open vSwitch
" )
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( '
' )
64     print switch0.cmd( 'ovs-ofctl show dp0' )
65     print switch1.cmd( 'ovs-ofctl show dp1' )
66  
67  
68     info( "*** Running test
" )
69     h0.cmdPrint( 'ping -c3 ' + h1.IP() )
70     h1.cmdPrint( 'ping -c3 ' + h0.IP() )
71  
72     info( "*** Stopping network
" )
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( '
' )
79  
80 if __name__ == '__main__':
81     setLogLevel( 'info' )
82     info( '*** Scratch network demo (kernel datapath)
' )
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
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  • 原文地址：https://www.cnblogs.com/a1164520408/p/9629231.html
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