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
编写如下python脚本后运行，得到与预期端口号相符的网络拓扑：
#!/usr/bin/python
#Creating Inernet Topo
from mininet.topo import Topo
from mininet.net import Mininet
from mininet.node import RemoteController,CPULimitedHost
from mininet.link import TCLink
from mininet.util import dumpNodeConnections
class MyTopo(Topo):
def __init__(self):
#Initialize Topology
Topo.__init__(self)
L1 = 2
L3 = 3
c = []
#add core ovs
for i in range(L1):
sw = self.addSwitch('s{}'.format(i+1))
c.append(sw)
#add Hosts
count = 1
for sw1 in c:
for i in range(0, 3):
host = self.addHost('h{}'.format(count))
count+=1
self.addLink(sw1,host,i+1,1)
#add Links
sw3=c[0]
sw4=c[1]
self.addLink(sw3,sw4,4,4)
topos = {'mytopo':(lambda:MyTopo())}
运行以下代码创建拓扑：
sudo mn -custom 2.1.py --topo mytopo --switch ovsk,protocols=OpenFlow13
pingall测试主机连通性：
2. 直接在Open vSwitch下发流表，实现如下连通性要求，请逐条说明所下发的流表含义
实现：
- h1--h4互通
- h2--h5互通
- h3--h6互通
- 其余不通
步骤：
-
Step1:给s1添加流表
将进入s1 1、2、3端口的数据包打上vlan_tag从端口4向s2转发：
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
将接收到的数据包去除vlan_tag，根据数据包的vlan_id，像指定数据端口转发：
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
-
Step2:给s2添加流表
将进入s2 1、2、3端口的数据包打上vlan_tag从端口4向s1转发：
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
将接收到的数据包去除vlan_tag，根据数据包的vlan_id，像指定数据端口转发：
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
输入命令：
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
5. 利用Wireshark抓包，分析验证特定报文
输入命令：
sudo wireshark &打开界面，选择s1的4端口进行抓包：
