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:
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#!/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:
1 |
# ./ 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。本实验通过python脚本自定义拓扑:
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#!/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。
执行脚本命令:
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# ./ovsMultiBr.py |
结果如下显示:
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。