Open vSwitch系列实验（一）：Open vSwitch使用案例扩展实验
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。
TOS包括共8位，包括3 bit的优先权字段（取值可以从000-111所有值），4 bit的TOS子字段和1 bit未用位但必须置0。
3bit的8个优先级的定义如下：
111--Network Control（网络控制）；
110--Internetwork Control（网间控制）；
101--Critic（关键）；
100--Flash Override（疾速）；
011--Flash（闪速）；
010--Immediate（快速）；
001--Priority（优先）；
000--Routine（普通）。
优先级6和7一般保留给网络控制数据使用，如路由。
优先级5推荐给语音数据使用。
优先级4由视频会议和视频流使用。
优先级3给语音控制数据使用。
优先级1和2给数据业务使用。
优先级0为默认标记值。
1.ovsSingleBr
#!/usr/bin/python
#调用mininet模块
from mininet.net import Mininet
from mininet.node import Node
from mininet.link import Link
from mininet.log import setLogLevel, info
#mynet函数
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' )
#print all the intf of the values
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()
2.ovsMultiBr
这里通过设置不通的tos值和和不通的优先级来改变数据包的转发方式，其中在代码中可以看出priority的值，然后tos的值用的是16进制来表示，TOS表示服务类型，一共8bits，比如0x30：00110000，然后有相应的对照，http://www.mamicode.com/info-detail-542445.html
#!/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()
总结：
1.泛洪规则是根据优先级以及tos值而定
2.tos值设置越大，时间使用越少