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

Python脚本

#!/usr/bin/python
#创建网络拓扑

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 ):
    "Simple topology example."

    def __init__( self ):
        "Create custom topo."

       
        Topo.__init__( self )
        s = []
          
         
        for i in range( 2 ):
                sw = self.addSwitch( 's{}'.format( i + 1 ) )
                s.append( sw )
    
        
        count = 1
        for sw1 in s:
                for i in range(3):
                	host = self.addHost( 'h{}'.format( count ) )
                	self.addLink( sw1, host )
                	count += 1
	self.addLink(s[0],s[1])
topos = { 'mytopo': ( lambda: MyTopo() ) }

运行以下代码创建拓扑并查看拓扑

sudo mn --custom shiyan2.py --topo mytopo --switch ovsk,protoclols=OpenFlow13

使用pingall命令查看连通性

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

• h1 -- h4互通
• h2 -- h5互通
• h3 -- h6互通
• 其余主机不通

#将h1,h2,h3进入s1的包打上vlan tag，转发端口4
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
#将从端口4的包去除vlan tag， 并根据tag进行转发
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
#将h4,h5,h6进入s2的包打上vlan tag，转发端口4
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
#将从端口4的包去除vlan tag， 并根据tag进行转发
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

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

sudo wireshark