2019 SDN上机第2次作业

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

(1)搭建如下拓扑

(2)python脚本代码

from mininet.topo import Topo
Hcount=3
Scount=2
class MyTopo(Topo):
    def __init__(self):
        Topo.__init__(self)
        global Hcount,Scount
        switchs = []
        for i in range(Scount):
            swit = self.addSwitch("s{}".format(i + 1))
            switchs.append(swit)
        c = 1
        for sw in switchs:
            for i in range(Hcount):
                hx = self.addHost("h{}".format(c))
                self.addLink(sw, hx)
                c+=1
        self.addLink(switchs[0], switchs[1])
topos = {"mytopo": (lambda : MyTopo()) }

(3)执行python脚本创建mininet网络拓扑

(4).测试端口连接情况

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

(1)s1的流表

sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,in_port=1,actions=push_vlan:0x8100,set_field:4096->vlan_vid,output:4
sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4097->vlan_vid,output:4
sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,in_port=3,actions=push_vlan:0x8100,set_field:4098->vlan_vid,output:4

sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,dl_vlan=0,actions=pop_vlan,output:1
sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,dl_vlan=1,actions=pop_vlan,output:2
sudo ovs-ofctl -O OpenFlow13 add-flow s1 priority=1,dl_vlan=2,actions=pop_vlan,output:3

(2)s2的流表

sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,in_port=1,actions=push_vlan:0x8100,set_field:4096->vlan_vid,output:4
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,in_port=2,actions=push_vlan:0x8100,set_field:4097->vlan_vid,output:4
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,in_port=3,actions=push_vlan:0x8100,set_field:4098->vlan_vid,output:4

sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,dl_vlan=0,actions=pop_vlan,output:1
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,dl_vlan=1,actions=pop_vlan,output:2
sudo ovs-ofctl -O OpenFlow13 add-flow s2 priority=1,dl_vlan=2,actions=pop_vlan,output:3

3. 直接在Open vSwitch查看流表，提交OVS命令执行结果

(1)查看s1的流表

**```sudo ovs-ofctl -O OpenFlow13 dump-flows s1

![](https://img2018.cnblogs.com/blog/1798373/201911/1798373-20191107011856904-758030700.png)

##(2)查看s2的流表
**```sudo ovs-ofctl -O OpenFlow13 dump-flows s2
```**

![](https://img2018.cnblogs.com/blog/1798373/201911/1798373-20191107011915271-946161613.png)

#4.提交主机连通性测试结果，验证流表的有效性
**```
pingall```**

![](https://img2018.cnblogs.com/blog/1798373/201911/1798373-20191107011936970-1038232119.png)

#5. 利用Wireshark抓包，分析验证特定报文
##(1)通过命令启动wireshark
**```sudo wireshark
```**
##(2)抓包
执行 pingall 命令，用wireshark抓包，在s1-eth4才能抓到vlan的包，而在s1-eth1、s1-eth2和s1-eth3均不能抓到vlan包(不知道为什么），
###vlan0:
![](https://img2018.cnblogs.com/blog/1798373/201911/1798373-20191107004946208-111545308.png)

###vlan1:
![](https://img2018.cnblogs.com/blog/1798373/201911/1798373-20191107004957453-198720679.png)

###vlan2:
![](https://img2018.cnblogs.com/blog/1798373/201911/1798373-20191107005011184-8080392.png)