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

创建fattree2.py文档,并编写py代码，代码如下：

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

输入如下命令，创建拓扑：

sudo mn --custom ./fattree2.py --topo mytopo --switch ovsk,protocols=OpenFlow13

结果如下：

并使用net查看拓扑，如下

使用pingall命令测试所有节点连通性，结果如图

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

以下三句话分别是将h1，h2，h3三个主机进入的包转打上vlan tag，转发到s1的四号端口号，in_port是指进来的端口号，actions指的是要进行的动作，set field值为4096+vlan_id，priority是优先级。

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

以下三句话是将从之前打上的包vlan tag的包去除vlan tag，然后根据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

以下三句话分别是将h4，h5，h6三个主机进入的包转打上vlan tag，转发到s2的四号端口号，in_port是指进来的端口号，actions指的是要进行的动作，set field值为4096+vlan_id，priority是优先级。

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

以下三句话是将从之前打上的包vlan tag的包去除vlan tag，然后根据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