一、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 vSwit
一、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。
二、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。
三、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。
四、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。本实验通过python脚本自定义拓扑：
#!/usr/bin/python from mininet.net import Mininetfrom mininet.node import Nodefrom mininet.link import Linkfrom 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 a+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、结果如下显示：
$ sudo ./ovsSingleBr.py *** Scratch network demo (kernel datapath)*** Creating nodes*** Creating links*** Configuring hosts*** Starting network using Open vSwitchs0-eth0s0-eth1s0-eth22b05a0c0-015b-44cd-8ce8-d540d9f551c4 Bridge "dp0" Port "s0-eth0" Interface "s0-eth0" Port "dp0" Interface "dp0" type: internal Port "s0-eth1" Interface "s0-eth1" Port "s0-eth2" Interface "s0-eth2" ovs_version: "2.5.2"*** Running test*** h0 : ('ping -c 3 192.168.123.2',)PING 192.168.123.2 (192.168.123.2) 56(84) bytes of data.64 bytes from 192.168.123.2: icmp_seq=1 ttl=64 time=1.27 ms64 bytes from 192.168.123.2: icmp_seq=2 ttl=64 time=0.082 ms64 bytes from 192.168.123.2: icmp_seq=3 ttl=64 time=0.076 ms--- 192.168.123.2 ping statistics ---3 packets transmitted, 3 received, 0% packet loss, time 2010msrtt min/avg/max/mdev = 0.076/0.478/1.276/0.564 ms*** h0 : ('ping -c 3 192.168.123.3',)PING 192.168.123.3 (192.168.123.3) 56(84) bytes of data.64 bytes from 192.168.123.3: icmp_seq=1 ttl=64 time=0.599 ms64 bytes from 192.168.123.3: icmp_seq=2 ttl=64 time=0.080 ms64 bytes from 192.168.123.3: icmp_seq=3 ttl=64 time=0.042 ms--- 192.168.123.3 ping statistics ---3 packets transmitted, 3 received, 0% packet loss, time 2045msrtt min/avg/max/mdev = 0.042/0.240/0.599/0.254 ms*** Stopping network...
4.3 实验任务二
通过vi ovsMultiBr.py创建脚本并添加内容。本实验通过python脚本自定义拓扑：
#!/usr/bin/python from mininet.net import Mininetfrom mininet.node import Nodefrom mininet.link import TCLinkfrom 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 a+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。
执行脚本命令,结果如下显示：
$ sudo ./ovsMultiBr.py *** Scratch network demo (kernel datapath)*** Creating nodes*** Creating links(100.00Mbit 1ms delay 0.00000% loss) (100.00Mbit 1ms delay 0.00000% loss) (100.00Mbit 1ms delay 0.00000% loss) (100.00Mbit 1ms delay 0.00000% loss) (100.00Mbit 1ms delay 0.00000% loss) (100.00Mbit 1ms delay 0.00000% loss) (100.00Mbit 1ms delay 0.00000% loss) (100.00Mbit 1ms delay 0.00000% loss) (1.00Mbit 100ms delay 0.00000% loss) (1.00Mbit 100ms delay 0.00000% loss) (10.00Mbit 50ms delay 0.00000% loss) (10.00Mbit 50ms delay 0.00000% loss) (100.00Mbit 1ms delay 0.00000% loss) (100.00Mbit 1ms delay 0.00000% loss) (100.00Mbit 1ms delay 0.00000% loss) (100.00Mbit 1ms delay 0.00000% loss) *** Configuring hostsh0h1*** Starting network using Open vSwitchs0-eth0s0-eth1s0-eth2s0-eth3s1-eth0s1-eth1s2-eth0s2-eth1s3-eth0s3-eth1s4-eth0s4-eth1s4-eth2s4-eth3*** Running test*** h0 : ('ping -Q 0x10 -c 3 192.168.123.2',)PING 192.168.123.2 (192.168.123.2) 56(84) bytes of data.64 bytes from 192.168.123.2: icmp_seq=1 ttl=64 time=117 ms64 bytes from 192.168.123.2: icmp_seq=2 ttl=64 time=107 ms64 bytes from 192.168.123.2: icmp_seq=3 ttl=64 time=107 ms--- 192.168.123.2 ping statistics ---3 packets transmitted, 3 received, 0% packet loss, time 2002msrtt min/avg/max/mdev = 107.461/110.712/117.011/4.462 ms*** h0 : ('ping -Q 0x20 -c 3 192.168.123.2',)PING 192.168.123.2 (192.168.123.2) 56(84) bytes of data.64 bytes from 192.168.123.2: icmp_seq=1 ttl=64 time=57.8 ms64 bytes from 192.168.123.2: icmp_seq=2 ttl=64 time=57.4 ms64 bytes from 192.168.123.2: icmp_seq=3 ttl=64 time=57.6 ms--- 192.168.123.2 ping statistics ---3 packets transmitted, 3 received, 0% packet loss, time 2002msrtt min/avg/max/mdev = 57.469/57.664/57.879/0.167 ms*** h0 : ('ping -Q 0x30 -c 3 192.168.123.2',)PING 192.168.123.2 (192.168.123.2) 56(84) bytes of data.64 bytes from 192.168.123.2: icmp_seq=1 ttl=64 time=8.82 ms64 bytes from 192.168.123.2: icmp_seq=2 ttl=64 time=8.41 ms64 bytes from 192.168.123.2: icmp_seq=3 ttl=64 time=8.40 ms--- 192.168.123.2 ping statistics ---3 packets transmitted, 3 received, 0% packet loss, time 2003msrtt min/avg/max/mdev = 8.400/8.545/8.826/0.212 ms*** Stopping network..............
五、实验结论
此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，通过验证发现，tos值设置越大，时间使用越少。
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