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

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