1. 利用mininet创建如下拓扑，要求拓扑支持OpenFlow 1.3协议，主机名、交换机名以及端口对应正确，请给出拓扑Mininet执行结果，展示端口连接情况
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=1,actions=push_vlan:0x8100,set_field:4096-\>vlan_vid,output:4
//转发S1端口1的包到端口4，并打上vlan_tag
sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4097-\>vlan_vid,output:4
//转发S1端口2的包到端口4，并打上vlan_tag
sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,in_port=3,actions=push_vlan:0x8100,set_field:4098-\>vlan_vid,output:4
//转发S1端口3的包到端口4，并打上vlan_tag
sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,dl_vlan=0,actions=pop_vlan,output:1
//转发S1端口4的包到端口1，并去除vlan_tag
sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,dl_vlan=1,actions=pop_vlan,output:2
//转发S1端口4的包到端口2，并去除vlan_tag
sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,dl_vlan=2,actions=pop_vlan,output:3
//转发S1端口4的包到端口3，并去除vlan_tag
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,in_port=1,actions=push_vlan:0x8100,set_field:4096-\>vlan_vid,output:4
//转发S2端口1的包到端口4，并打上vlan_tag
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4097-\>vlan_vid,output:4
//转发S2端口2的包到端口4，并打上vlan_tag
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,in_port=3,actions=push_vlan:0x8100,set_field:4098-\>vlan_vid,output:4
//转发S2端口3的包到端口4，并打上vlan_tag
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,dl_vlan=0,actions=pop_vlan,output:1
//转发S2端口4的包到端口1，并去除vlan_tag
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,dl_vlan=1,actions=pop_vlan,output:2
//转发S2端口4的包到端口2，并去除vlan_tag
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,dl_vlan=2,actions=pop_vlan,output:3
//转发S2端口4的包到端口3，并去除vlan_tag3.直接在Open vSwitch查看流表，提交OVS命令执行结果
4.提交主机连通性测试结果，验证流表的有效性
5.利用Wireshark抓包，分析验证特定报文
