SDN作业(4)

实验 4：Open vSwitch 实验——Mininet 中使用 OVS 命令

一、实验目的

Mininet安装之后，会连带安装 Open vSwitch，可以直接 通过 Python脚本调用 Open vSwitch命令 从而 直接控制 Open vSwitch 通过实验了解 调用控制 的方法 。

二、实验环境

• Oracle VM VirtualBox
• ubuntu-16.04.5-desktop-amd64

三、实验过程

创建 MyovsBr.py 脚本并添加内容

脚本对应的拓扑图如上图

代码如下：

#!/usr/bin/python
 
from mininet.net import Mininet
from mininet.node import Node
from mininet.link import TCLink
from mininet.log import  setLogLevel, info
 
def myNet():
    "Create network from scratch using Open vSwitch."
 
    info( "*** Creating nodes
" )
    switch0 = Node( 's0', inNamespace=False )
    switch1 = Node( 's1', inNamespace=False )
    h0 = Node( 'h0' )
    h1 = Node( 'h1' )
    h2 = Node( 'h2' )
    h3 = Node( 'h3' )
 
    info( "*** Creating links
" )
    linkopts0=dict(bw=100, delay='1ms', loss=0)
    linkopts1=dict(bw=100, delay='1ms', loss=0)
    TCLink( h0, switch0, **linkopts0)
    TCLink( h1, switch0, **linkopts0)
    TCLink( switch0, switch1, **linkopts1)
    TCLink( h2, switch1, **linkopts0)
    TCLink( h3, switch1, **linkopts0)
 
    info( "*** Configuring hosts
" )
    h0.setIP( '192.168.123.1/24' )
    h1.setIP( '192.168.123.2/24' )
    h2.setIP( '192.168.123.3/24' )
    h3.setIP( '192.168.123.4/24' )
    info( str( h0 ) + '
' )
    info( str( h1 ) + '
' )
    info( str( h2 ) + '
' )
    info( str( h3 ) + '
' )
       
    info( "*** Starting network using Open vSwitch
" )
    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 )


    print switch0.cmd(r'ovs-ofctl -O OpenFlow13 add-flow dp0 priority=1,in_port=1,actions=push_vlan:0x8100,set_field:4096->vlan_vid,output:3')
    print switch0.cmd(r'ovs-ofctl -O OpenFlow13 add-flow dp0 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4097->vlan_vid,output:3')
    print switch0.cmd(r'ovs-ofctl -O OpenFlow13 add-flow dp0 priority=1,dl_vlan=0,actions=pop_vlan,output:1')
    print switch0.cmd(r'ovs-ofctl -O OpenFlow13 add-flow dp0 priority=1,dl_vlan=1,actions=pop_vlan,output:2')

    print switch1.cmd(r'ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4096->vlan_vid,output:1')
    print switch1.cmd(r'ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,in_port=3,actions=push_vlan:0x8100,set_field:4097->vlan_vid,output:1')
    print switch1.cmd(r'ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,dl_vlan=0,actions=pop_vlan,output:2')
    print switch1.cmd(r'ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,dl_vlan=1,actions=pop_vlan,output:3')

    info( "*** Running test
" )
    h0.cmdPrint( 'ping -Q 0x10 -c 3 ' + h1.IP() )
    info( '
' )
    h0.cmdPrint( 'ping -Q 0x20 -c 3 ' + h2.IP() )
    info( '
' )
    h0.cmdPrint( 'ping -Q 0x30 -c 3 ' + h3.IP() )
    info( '
' )
    h1.cmdPrint( 'ping -Q 0x30 -c 3 ' + h2.IP() )
    info( '
' )
    h1.cmdPrint( 'ping -Q 0x30 -c 3 ' + h3.IP() )
    info( '
' )
    h2.cmdPrint( 'ping -Q 0x30 -c 3 ' + h3.IP() )
    

    
    info( "*** Stopping network
" )
    switch0.cmd( 'ovs-vsctl del-br dp0' )
    switch0.deleteIntfs()
    switch1.cmd( 'ovs-vsctl del-br dp1' )
    switch1.deleteIntfs()
    info( '
' )
 
if __name__ == '__main__':
    setLogLevel( 'info' )
    info( '*** Scratch network demo (kernel datapath)
' )
    Mininet.init()
    myNet()

上述代码将h0和 h2划分在 VLAN 0中， h1和 h3划分在 VLAN 1中，由于拓扑没有控制器，并且初始化时删除了交换机中的所有流表，因此除非下发流表，否则主机之间网络无法连通。 请尝试修改代码， 利用 ovs命令直接下发 VLAN设置的流表项，最终测试 h0 和h2互通， h1和 h3互通，其余主机均不通 ，结果如下图: