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

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 、实验任务

​ 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地址的时间。

三 、 实验步骤

1. 实验环境

安装了 Ubuntu 18.04.5 Desktop amd64 的虚拟机

2. 实验过程

(1) 创建 ovsSingleBr.py 脚本并添加内容 ，代码参考 SDNLAB

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()

image-20200926223630744

脚本对应的拓扑如上图所示，执行 ovsSingleBr.py，在没有控制器的情况下，在Mininet 脚本中通过调用 ovs 命令直接向 switch0 交换机下发流表，将入端口号为1/2/3 的数据包泛洪广播，并对目的地址为 192.168.123.1/2/3 的数据包分别从1/2/3 端口转发出去。之后测试 h0 ping h1，h0 ping h2，网络连通。

$ sudo python ovsSingleBr.py

(2) 创建 ovsMultiBr.py 脚本并添加内容 ，代码参考 SDNLAB

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()

image-20200926224428705

脚本对应的拓扑如上图所示，执行 ovsMultiBr.py，在没有控制器的情况下，在Mininet 脚本中通过调用 ovs 命令给多个交换机下发流表，通过 h0 ping h1 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。通过验证发现，tos 值设置越大，时间使用越少。

四 、实验要求

1. 学习 ovsSingleBr.py 和 ovsMultiBr.py，在下图拓扑中实现一个 VLAN。

OVS 实现 VLAN 可参考博客：https://www.cnblogs.com/fjlinww/p/11791846.html

# ./ovsVLAN.py

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 )
    h0 = Node( 'h0' )
    h1 = Node( 'h1' )
    h2 = Node( 'h2' )
    h3 = Node( 'h3' )
 
    info( "*** Creating links\n" )
    linkopts0=dict(bw=100, delay='1ms', loss=0)
    linkopts1=dict(bw=1, delay='100ms', 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\n" )
    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 ) + '\n' )
    info( str( h1 ) + '\n' )
    info( str( h2 ) + '\n' )
    info( str( h3 ) + '\n' )
       
    info( "*** Starting network using Open vSwitch\n" )
    switch0.cmd( 'ovs-vsctl del-br dp0' )
    switch0.cmd( 'ovs-vsctl add-br dp0' )
    switch0.cmd( 'ovs-vsctl del-br dp1' )
    switch0.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=1,actions=push_vlan:0x8100,set_field:4096-\>vlan_vid,output:3' )
    print switch1.cmd(r'ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4097-\>vlan_vid,output:3' )
    print switch1.cmd(r'ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,dl_vlan=0,actions=pop_vlan,output:1' )
    print switch1.cmd(r'ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,dl_vlan=1,actions=pop_vlan,output:2' )

    info( "*** Running test\n" )
    h0.cmdPrint( 'ping -c 3 ' + h1.IP() )
    h0.cmdPrint( 'ping -c 3 ' + h2.IP() )
    h0.cmdPrint( 'ping -c 3 ' + h3.IP() )
    h1.cmdPrint( 'ping -c 3 ' + h2.IP() )
    h1.cmdPrint( 'ping -c 3 ' + h3.IP() )
    h2.cmdPrint( 'ping -c 3 ' + h3.IP() )
 
    info( "*** Stopping network\n" )
    switch0.cmd( 'ovs-vsctl del-br dp0' )
    switch0.deleteIntfs()
    switch1.cmd( 'ovs-vsctl del-br dp1' )
    switch1.deleteIntfs()
    info( '\n' )
 
if __name__ == '__main__':
    setLogLevel( 'info' )
    info( '*** Scratch network demo (kernel datapath)\n' )
    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。

image-20200926224823159

总结

​ 以上就是实验4的全部内容！

posted @ 2020-09-26 23:05  小野狗  阅读(350)  评论(0)  编辑  收藏  举报