SDN 實驗 4：Open vSwitch 實驗——Mininet 中使用 OVS 命令

一、實驗目的

• Mininet 安裝之后，會連帶安裝 Open vSwitch，可以直接通過 Python 腳本調用Open vSwitch 命令，從而直接控制 Open vSwitch，通過實驗了解調用控制的方法。

二、實驗任務

• 在本實驗中，使用 Mininet 基於 Python 的腳本，調用“ovs-vsctl”命令直接控制Open vSwitch。使用默認的交換機泛洪規則，設置更高的優先級規則進行預先定義 IP 報文的轉發。在多個交換機中通過設置不同 TOS 值的數據包將通過不同的方式到達目的地址，驗證主機間的連通性及到達目的地址的時間。

三、實驗步驟

1. 實驗環境

• 安裝了 Ubuntu 18.04.5 Desktop amd64 的虛擬機

2. 實驗步驟

（1）創建 ovsSingleBr.py 腳本並運行

• 實驗內容
  執行 ovsSingleBr.py，在沒有控制器的情況下，在Mininet 腳本中通過調用 ovs 命令直接向 switch0 交換機下發流表，將入端口號為1/2/3 的數據包泛洪廣播，並對目的地址為 192.168.123.1/2/3 的數據包分別從1/2/3 端口轉發出去。之后測試 h0 ping h1，h0 ping h2，網絡連通。

• ovsSingleBr.py 對應拓撲

• ovsSingleBr.py 對應代碼

#!/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() 

• 運行結果

（2）創建 ovsMultiBr.py 腳本並運行

• 實驗內容

在沒有控制器的情況下，在Mininet 腳本中通過調用 ovs 命令給多個交換機下發流表，通過 h0 ping h1 操作測試驗證主機間的連通性，並通過-Q 參數設置不通的 tos 值查看主機間的連通性。通過驗證發現，tos 值設置越大，時間使用越少。

• ovsMultiBr.py 對應拓撲

• ovsMultiBr.py 對應代碼

#!/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() 

• 運行結果

（3） 創建 vlanBr.py 腳本並運行

• 實驗內容

嘗試修改代碼，利用 ovs 命令直接下發 VLAN 設置的流表項，最終測試 h0 和 h2 互通，h1 和 h3 互通，其余主機均不通

• vlanBr.py對應拓撲

• vlanBr.py對應代碼

#!/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 ) 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) linkopts2=dict(bw=10, delay='50ms', loss=0) TCLink( switch0, switch1, **linkopts0) TCLink( h0, switch0, **linkopts1) TCLink( h2, switch1, **linkopts1) TCLink( h1, switch0, **linkopts2) TCLink( h3, switch1, **linkopts2) 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 ) 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'sudo ovs-ofctl -O OpenFlow13 add-flow dp0 priority=1,dl_vlan=0,actions=pop_vlan,output:1' ) print switch0.cmd(r'sudo 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' ) #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 ' + h2.IP() ) h0.cmdPrint( 'ping -Q 0x30 -c 3 ' + h3.IP() ) h1.cmdPrint( 'ping -Q 0x40 -c 3 ' + h2.IP() ) h1.cmdPrint( 'ping -Q 0x50 -c 3 ' + h3.IP() ) h2.cmdPrint( 'ping -Q 0x60 -c 3 ' + h3.IP() ) #h1.cmdPrint('iperf -s -p 12345 -u &') #h0.cmdPrint('iperf -c ' + h1.IP() +' -u -b 10m -p 12345 -t 10 -i 1') 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() 

• 運行結果