创建名为SecondTime的py文件

from mininet.topo import Topo
class Mytopo(Topo):
    def __init__(self):
        Topo.__init__(self)
    	s=[]
        for i in range(2):
            sw = self.addSwitch('s{}'.format(i+1))
            s.append(sw)
	self.addLink(s[0],s[1])  /*连接两个表*/
        count=1 
        for two in s:  /*在整个列表内循环创建*/
            for i in range(3):
                host = self.addHost('h{}'.format(count))
                self.addLink(two,host)
                count += 1
topos = {'mytopo': (lambda:Mytopo())}

输入命令执行文件创建拓扑

sudo mn --custom SecondTime.py --topo mytopo --switch ovsk,protocols=OpenFlow13

输入net查看端口情况，再输入pingall查看目前连通情况

2. 直接在Open vSwitch下发流表，用vlan得到下列虚拟网段，请逐条说明所下发的流表含义

sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4096->vlan_vid,output:1
sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,in_port=3,actions=push_vlan:0x8100,set_field:4097->vlan_vid,output:1
sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,in_port=4,actions=push_vlan:0x8100,set_field:4098->vlan_vid,output:1
//让主机1,2,3进入交换机1的包打上vlan_tag转发到端口1
sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,dl_vlan=0,actions=pop_vlan,output:2
sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,dl_vlan=1,actions=pop_vlan,output:3
sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,dl_vlan=2,actions=pop_vlan,output:4
//将从端口1得到的包去除vlan_tag并依据tag转发到端口2,3，4

sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4096->vlan_vid,output:1
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,in_port=3,actions=push_vlan:0x8100,set_field:4097->vlan_vid,output:1
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,in_port=4,actions=push_vlan:0x8100,set_field:4098->vlan_vid,output:1
//让主机4，5,6进入交换机2的包打上vlan_tag转发到端口1
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,dl_vlan=0,actions=pop_vlan,output:2
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,dl_vlan=1,actions=pop_vlan,output:3
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,dl_vlan=2,actions=pop_vlan,output:4
//将从端口1得到的包去除vlan_tag并依据tag转发到端口2,3，4

3. 直接在Open vSwitch查看流表，提交OVS命令执行结果

输入以下命令查看流表

 sudo ovs-ofctl -O OpenFlow13 dump-flows s1 

 sudo ovs-ofctl -O OpenFlow13 dump-flows s2

4. 提交主机连通性测试结果，验证流表的有效性

再次输入pingall，效果如下

5. 利用Wireshark抓包，分析验证特定报文

选择S1-eth2抓取报文