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Open vSwitch不用控制器直接控制主机

阅读：2903 输入：2020-03-29 11:06:33

1.实验目的

通过python脚本调用OpenvSwitch命令；

学习Mininet基于python脚本创建拓扑的实现；

进一步深度使用“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。使用默认的交换机泛洪规则，设置更高的优先级规则进行预先定义IP报文的转发。在多个交换机中通过设置不同TOS值的数据包将通过不同的方式到达目的地址，验证主机间的连通性及到达目的的时间。

3.实验任务

使用默认的交换机泛洪规则，设置更高的优先级规则进行预先定义IP报文的转发，不同TOS值的数据包将通过不同的方式到达目的地址。

4.实验步骤

4.1搭建环境

本实验创建一个带有Mininet镜像的虚拟机。

4.2实验任务一

通过vi ovsSingleBr.py创建脚本并添加内容。

#!/usr/bin/python
 
from mininet.net import Mininet
from mininet.node import Node
from mininet.link import Link
from mininet.log import  setLogLevel, info
 
def myNet():
    "Create network from scratch using Open vSwitch."
 
    info( "*** Creating nodes\n" )
    switch0 = Node( 's0', inNamespace=False )
 
    h0 = Node( 'h0' )
    h1 = Node( 'h1' )
    h2 = Node( 'h2' )
 
    info( "*** Creating links\n" )
    Link( h0, switch0)
    Link( h1, switch0)
    Link( h2, switch0)
 
    info( "*** Configuring hosts\n" )
    h0.setIP( '192.168.123.1/24' )
    h1.setIP( '192.168.123.2/24' )
    h2.setIP( '192.168.123.3/24' )
       
    info( "*** Starting network using Open vSwitch\n" )
    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 )
 
    # Note: controller and switch are in root namespace, and we
    # can connect via loopback interface
    #switch0.cmd( 'ovs-vsctl set-controller dp0 tcp:127.0.0.1:6633' )
  
    print switch0.cmd(r'ovs-vsctl show')
 
    print switch0.cmd(r'ovs-ofctl add-flow dp0 idle_timeout=0,priority=1,in_port=1,actions=flood' ) 
    print switch0.cmd(r'ovs-ofctl add-flow dp0 idle_timeout=0,priority=1,in_port=2,actions=flood' )
    print switch0.cmd(r'ovs-ofctl add-flow dp0 idle_timeout=0,priority=1,in_port=3,actions=flood' )
  
    print switch0.cmd(r'ovs-ofctl add-flow dp0 idle_timeout=0,priority=10,ip,nw_dst=192.168.123.1,actions=output:1' ) 
    print switch0.cmd(r'ovs-ofctl add-flow dp0 idle_timeout=0,priority=10,ip,nw_dst=192.168.123.2,actions=output:2' ) 
    print switch0.cmd(r'ovs-ofctl add-flow dp0 idle_timeout=0,priority=10,ip,nw_dst=192.168.123.3,actions=output:3')
 
    #switch0.cmd('tcpdump -i s0-eth0 -U -w aaa &')
    #h0.cmd('tcpdump -i h0-eth0 -U -w aaa &')
    info( "*** Running test\n" )
    h0.cmdPrint( 'ping -c 3 ' + h1.IP() )
    h0.cmdPrint( 'ping -c 3 ' + h2.IP() )
 
    #print switch0.cmd( 'ovs-ofctl show dp0' )    
    #print switch0.cmd( 'ovs-ofctl dump-tables  dp0' )
    #print switch0.cmd( 'ovs-ofctl dump-ports   dp0' )
    #print switch0.cmd( 'ovs-ofctl dump-flows  dp0' )
    #print switch0.cmd( 'ovs-ofctl dump-aggregate  dp0' )
    #print switch0.cmd( 'ovs-ofctl queue-stats dp0' )
 
    info( "*** Stopping network\n" )
    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()
    myNet()

通过命令chmod u+x ovsSingleBr.py将ovsSingleBr.py文件赋权限。此脚本并未连接控制器，只通过脚本中手动给交换机下发流表实现主机间的通信。

执行脚本命令：

# ./ ovsSingleBr.py

结果如下显示：

4.3实验任务二

通过vi ovsMultiBr.py创建脚本并添加内容。

#!/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\n" )
    switch0 = Node( 's0', inNamespace=False )
    switch1 = Node( 's1', inNamespace=False )
    switch2 = Node( 's2', inNamespace=False )
    switch3 = Node( 's3', inNamespace=False )
    switch4 = Node( 's4', inNamespace=False )
    h0 = Node( 'h0' )
    h1 = Node( 'h1' )
 
    info( "*** Creating links\n" )
    linkopts0=dict(bw=100, delay='1ms', loss=0)
    linkopts1=dict(bw=1, delay='100ms', loss=0)
    linkopts2=dict(bw=10, delay='50ms', loss=0)
    linkopts3=dict(bw=100, delay='1ms', loss=0)
    TCLink( h0, switch0, **linkopts0)
    TCLink( switch0, switch1, **linkopts0)
    TCLink( switch0, switch2, **linkopts0)
    TCLink( switch0, switch3, **linkopts0)
    TCLink( switch1, switch4,**linkopts1)
    TCLink( switch2, switch4,**linkopts2)
    TCLink( switch3, switch4,**linkopts3)
    TCLink( h1, switch4, **linkopts0)
 
    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" )
    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' )
    switch2.cmd( 'ovs-vsctl del-br dp2' )
    switch2.cmd( 'ovs-vsctl add-br dp2' )
    switch3.cmd( 'ovs-vsctl del-br dp3' )
    switch3.cmd( 'ovs-vsctl add-br dp3' )
    switch4.cmd( 'ovs-vsctl del-br dp4' )
    switch4.cmd( 'ovs-vsctl add-br dp4' )
 
    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 )
 
    for intf in switch2.intfs.values():
        print intf
        print switch2.cmd( 'ovs-vsctl add-port dp2 %s' % intf )
 
    for intf in switch3.intfs.values():
        print intf
        print switch3.cmd( 'ovs-vsctl add-port dp3 %s' % intf )
 
    for intf in switch4.intfs.values():
        print intf
        print switch4.cmd( 'ovs-vsctl add-port dp4 %s' % intf )
   
    print switch1.cmd(r'ovs-ofctl add-flow dp1 idle_timeout=0,priority=1,in_port=1,actions=flood' )
    print switch1.cmd(r'ovs-ofctl add-flow dp1 idle_timeout=0,priority=1,in_port=1,actions=output:2' ) 
    print switch1.cmd(r'ovs-ofctl add-flow dp1 idle_timeout=0,priority=1,in_port=2,actions=output:1' )
    print switch2.cmd(r'ovs-ofctl add-flow dp2 idle_timeout=0,priority=1,in_port=1,actions=output:2' )
    print switch2.cmd(r'ovs-ofctl add-flow dp2 idle_timeout=0,priority=1,in_port=2,actions=output:1' )
    print switch3.cmd(r'ovs-ofctl add-flow dp3 idle_timeout=0,priority=1,in_port=1,actions=output:2' )    
    print switch3.cmd(r'ovs-ofctl add-flow dp3 idle_timeout=0,priority=1,in_port=2,actions=output:1' )
    print switch4.cmd(r'ovs-ofctl add-flow dp4 idle_timeout=0,priority=1,in_port=1,actions=output:4' )
    print switch4.cmd(r'ovs-ofctl add-flow dp4 idle_timeout=0,priority=1,in_port=2,actions=output:4' )
    print switch4.cmd(r'ovs-ofctl add-flow dp4 idle_timeout=0,priority=1,in_port=3,actions=output:4' )
    print switch4.cmd(r'ovs-ofctl add-flow dp4 idle_timeout=0,priority=1,in_port=4,actions=output:3' )
   
    #print switch0.cmd(r'ovs-ofctl add-flow dp0 idle_timeout=0,priority=10,ip,nw_dst=192.168.123.2,actions=output:4')
    print switch0.cmd(r'ovs-ofctl add-flow dp0 idle_timeout=0,priority=10,ip,nw_dst=192.168.123.2,nw_tos=0x10,actions=output:2') 
    print switch0.cmd(r'ovs-ofctl add-flow dp0 idle_timeout=0,priority=10,ip,nw_dst=192.168.123.2,nw_tos=0x20,actions=output:3')
    print switch0.cmd(r'ovs-ofctl add-flow dp0 idle_timeout=0,priority=10,ip,nw_dst=192.168.123.2,nw_tos=0x30,actions=output:4') 
    #print switch0.cmd(r'ovs-ofctl add-flow dp0 idle_timeout=0,priority=10,ip,nw_dst=192.168.123.1,actions=output:1')
 
    #switch0.cmd('tcpdump -i s0-eth0 -U -w aaa &')
    #h0.cmd('tcpdump -i h0-eth0 -U -w aaa &')
    info( "*** Running test\n" )
    h0.cmdPrint( 'ping -Q 0x10 -c 3 ' + h1.IP() )
    h0.cmdPrint( 'ping -Q 0x20 -c 3 ' + h1.IP() )
    h0.cmdPrint( 'ping -Q 0x30 -c 3 ' + h1.IP() )
    #h1.cmdPrint('iperf -s -p 12345 -u &')
    #h0.cmdPrint('iperf -c ' + h1.IP() +' -u -b 10m -p 12345 -t 10 -i 1')
 
    #print switch0.cmd( 'ovs-ofctl show dp0' )    
    #print switch1.cmd( 'ovs-ofctl show dp1' )
    #print switch2.cmd( 'ovs-ofctl show dp2' )
    #print switch3.cmd( 'ovs-ofctl show dp3' )
    #print switch4.cmd( 'ovs-ofctl show dp4' )  
    #print switch0.cmd( 'ovs-ofctl dump-tables  dp0' )
    #print switch0.cmd( 'ovs-ofctl dump-ports   dp0' )
    #print switch0.cmd( 'ovs-ofctl dump-flows  dp0' )
    #print switch0.cmd( 'ovs-ofctl dump-aggregate  dp0' )
    #print switch0.cmd( 'ovs-ofctl queue-stats dp0' )
 
    #print "Testing video transmission between h1 and h2"
    #h1.cmd('./myrtg_svc -u > myrd &')
    #h0.cmd('./mystg_svc -trace st 192.168.123.2')
 
    info( "*** Stopping network\n" )
    switch0.cmd( 'ovs-vsctl del-br dp0' )
    switch0.deleteIntfs()
    switch1.cmd( 'ovs-vsctl del-br dp1' )
    switch1.deleteIntfs()
    switch2.cmd( 'ovs-vsctl del-br dp2' )
    switch2.deleteIntfs()
    switch3.cmd( 'ovs-vsctl del-br dp3' )
    switch3.deleteIntfs()
    switch4.cmd( 'ovs-vsctl del-br dp4' )
    switch4.deleteIntfs()
    info( '\n' )
 
if __name__ == '__main__':
    setLogLevel( 'info' )
    info( '*** Scratch network demo (kernel datapath)\n' )
    Mininet.init()
    myNet()

通过命令chmod u+x ovsMultiBr.py将ovsMultiBr.py文件赋权限。此脚本并未连接控制器，只通过脚本中手动给交换机下发流表实现主机间的通信。在此任务二中，给多个交换机下发流表，通过ping操作测试验证主机间的连通性，并通过-Q参数设置不通的tos值查看主机间的连通性。

5.实验结论

实验并未连接控制器，只通过脚本在单个/多个交换机中下发静态流表实现主机间的通信。在给多个交换机下发流表时，通过ping操作测试验证主机间的连通性，并通过-Q参数设置不同的tos值验证主机间的连通性及到达目的地址的时间，验证发现，tos值设置越大，时间使用越少。

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