软件定义网络（SDN）第四次实验报告
目录
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、实验要求
-
学习 ovsSingleBr.py 和 ovsMultiBr.py，在上图拓扑中实现一个 VLAN。
- 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。
- 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。
- OVS 实现 VLAN 可参考博客：链接
-
在博客园发表一篇博客，记录主要步骤。
四、具体实验步骤
引导：新建并运行脚本文件 ovsSingleBr.py
$ touch ovsSingleBr.py
$ chmod u+x ovsSingleBr.py
$ sudo python ./ovsSingleBr.py
ovsSingleBr.py 代码如下：
#!/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()
引导：新建并运行脚本文件 ovsMultiBr.py
$ touch ovsMultiBr.py
$ chmod u+x ovsMultiBr.py
$ sudo python ./ovsMultiBr.py
ovsMultiBr.py 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\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()
实现 VLAN
新建并运行脚本文件 ovsVLAN.py，代码如下：
#!/usr/bin/python
from mininet.net import Mininet
from mininet.node import Node
from mininet.link import TCLink, 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 )
switch1 = Node( 's1', inNamespace=False )
h0 = Node( 'h0' )
h1 = Node( 'h1' )
h2 = Node( 'h2' )
h3 = Node( 'h3' )
info( "*** Creating links\n" )
Link( h0, switch0 )
Link( h1, switch0 )
Link( h2, switch1 )
Link( h3, switch1 )
Link( switch0, switch1 )
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' )
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 )
switch0.cmd( 'ovs-ofctl -O OpenFlow13 add-flow dp0 priority=1,in_port=1,actions=push_vlan:0x8100,set_field:4096-\>vlan_vid,output:3' )
switch0.cmd( 'ovs-ofctl -O OpenFlow13 add-flow dp0 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4097-\>vlan_vid,output:3' )
switch0.cmd( 'ovs-ofctl -O OpenFlow13 add-flow dp0 priority=1,dl_vlan=0,actions=pop_vlan,output=1' )
switch0.cmd( 'ovs-ofctl -O OpenFlow13 add-flow dp0 priority=1,dl_vlan=1,actions=pop_vlan,output=2' )
switch1.cmd( 'ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,in_port=1,actions=push_vlan:0x8100,set_field:4096-\>vlan_vid,output:3' )
switch1.cmd( 'ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4097-\>vlan_vid,output:3' )
switch1.cmd( 'ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,dl_vlan=0,actions=pop_vlan,output=1' )
switch1.cmd( 'ovs-ofctl -O OpenFlow13 add-flow dp1 priority=1,dl_vlan=1,actions=pop_vlan,output=2' )
info( "*** Running test\n" )
h0.cmdPrint( 'ping -Q 0x30 -c 3 ' + h1.IP() )
h0.cmdPrint( 'ping -Q 0x10 -c 3 ' + h2.IP() )
h0.cmdPrint( 'ping -Q 0x30 -c 3 ' + h3.IP() )
h1.cmdPrint( 'ping -Q 0x30 -c 3 ' + h2.IP() )
h1.cmdPrint( 'ping -Q 0x30 -c 3 ' + h3.IP() )
h2.cmdPrint( 'ping -Q 0x30 -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()
运行结果如下：
查看 ovs 流表，加入以下代码：
info( switch1.cmd( 'ovs-ofctl dump-flows dp0 -O OpenFlow13' ) )
info( switch1.cmd( 'ovs-ofctl dump-flows dp1 -O OpenFlow13' ) )
五、注意事项与心得体会
注意事项
- 每次出现 " RELINK " 错误必定需要：
$ sudo mn -c
- 先 link 主机与交换机，再连接交换机与交换机，会按照顺序赋予交换机上的端口号（从 1 开始），否则会影响后续 ovs 下发流表的端口值。
心得体会
- 这次实验难度适中，体验了一把 VLAN；
- 下发流表不仅可以通过 .py 脚本，还可以通过命令行直接下发流表。
