实验7:基于REST API的SDN北向应用实践

实验7:基于REST API的SDN北向应用实践

基本实验

实验步骤1

  • 利用Mininet平台搭建下图所示网络拓扑,并连接OpenDaylight;

  • 首先运行ODL

  • 在终端输入sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13

  • 在浏览器中访问http://127.0.0.1:8181/index.html查看拓扑

实验步骤2

  • 编写Python程序,调用OpenDaylight的北向接口下发指令删除s1上的流表数据。
  • 编写代码并命名为delete.py
  • 在终端执行该代码删除流表数据
#delete.py
import requests
from requests.auth import HTTPBasicAuth
def http_delete(url):
    url= url
    headers = {'Content-Type':'application/json'}
    resp = requests.delete(url,headers=headers,auth=HTTPBasicAuth('admin', 'admin'))
    return resp

if __name__ == "__main__":
    url='http://127.0.0.1:8181/restconf/config/opendaylight-inventory:nodes/node/openflow:1/'
    resp = http_delete(url)
    print (resp.content)

执行结果

实验步骤3

  • 编写Python程序,调用OpenDaylight的北向接口下发硬超时流表,实现拓扑内主机h1和h3网络中断20s。
  • 编写代码并命名为puts.py以及ODL_flowtable.json文件
  • mininet命令行内输入h1 ping h3 ,终端输入python3 puts.py执行该程序
#puts.py
import requests
from requests.auth import HTTPBasicAuth

if __name__ == "__main__":
    url = 'http://127.0.0.1:8181/restconf/config/opendaylight-inventory:nodes/node/openflow:1/flow-node-inventory:table/0/flow/1'
    with open("./ODL_flowtable.json") as f:
        jstr = f.read()
    headers = {'Content-Type': 'application/json'}
    res = requests.put(url, jstr, headers=headers, auth=HTTPBasicAuth('admin', 'admin'))
    print (res.content) 
  • ODL_flowtable.json
{
  "flow": [
    {
      "id": "1",
      "match": {
        "in-port": "1",
        "ethernet-match": {
          "ethernet-type": {
            "type": "0x0800"
          }
        },
        "ipv4-destination": "10.0.0.3/32"
      },
      "instructions": {
        "instruction": [
          {
            "order": "0",
            "apply-actions": {
              "action": [
                {
                  "order": "0",
                  "drop-action": {}
                }
              ]
            }
          }
        ]
      },
      "flow-name": "flow1",
      "priority": "65535",
      "hard-timeout": "20",
      "cookie": "2",
      "table_id": "0"
    }
  ]
}

执行结果

实验步骤4

  • 编写Python程序,调用OpenDaylight的北向接口获取s1上活动的流表数。
  • 编写代码并命名为get.py
  • 在终端执行该代码获取流表数
#get.py
import requests
from requests.auth import HTTPBasicAuth

if __name__ == "__main__":
    url = 'http://127.0.0.1:8181/restconf/operational/opendaylight-inventory:nodes/node/openflow:1/flow-node-inventory:table/0/opendaylight-flow-table-statistics:flow-table-statistics'
    headers = {'Content-Type': 'application/json'}
    res = requests.get(url,headers=headers, auth=HTTPBasicAuth('admin', 'admin'))
    print (res.content)

执行结果

实验步骤5

  • 编写Python程序,调用Ryu的北向接口,实现上述OpenDaylight实验拓扑上相同的硬超时流表下发。
  • 编写代码并命名为ryu_put.py以及flowtable.json
  • 首先终端输入命令:ryu-manager ryu/ryu/app/gui_topology/gui_topology.py --observe-links 连接ryu控制器
  • 在ryu/ryu/app/文件夹内运行终端输入命令:ryu-manager ryu.app.simple_switch_13 ryu.app.ofctl_rest 运行ryu
  • 终端输入curl -X GET http://localhost:8080/stats/flow/1查看流表
  • 终端输入命令:sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13建立拓扑
  • mininet命令行下输入h1 ping h3
  • 终端执行程序,产生中断
#ryu_put.py
import requests

if __name__ == "__main__":
    url = 'http://127.0.0.1:8080/stats/flowentry/add'
    with open("./flowtable.json") as f:
        jstr = f.read()
    headers = {'Content-Type': 'application/json'}
    res = requests.post(url, jstr, headers=headers)
    print (res.content)
  • flowtable.json
{
    "dpid": 1,
    "cookie": 1,
    "cookie_mask": 1,
    "table_id": 0,
    "hard_timeout": 20,
    "priority": 65535,
    "flags": 1,
    "match":{
        "in_port":1
    },
    "actions":[

    ]
 }

执行结果

实验步骤6

  • 利用Mininet平台搭建下图所示网络拓扑,要求支持OpenFlow 1.3协议,主机名、交换机名以及端口对应正确。拓扑生成后需连接Ryu,且Ryu应能够提供REST API服务。
  • 编写以下代码,命名为topo.py
#topo.py
from mininet.topo import Topo

class MyTopo(Topo):
    def __init__(self):
        # initilaize topology
        Topo.__init__(self)

        self.addSwitch("s1")
        self.addSwitch("s2")

        self.addHost("h1")
        self.addHost("h2")
        self.addHost("h3")
        self.addHost("h4")

        self.addLink("s1", "h1")
        self.addLink("s1", "h2")
        self.addLink("s2", "h3")
        self.addLink("s2", "h4")
        self.addLink("s1", "s2")

topos = {'mytopo': (lambda: MyTopo())}
  • 首先终端输入命令:ryu-manager ryu/ryu/app/gui_topology/gui_topology.py --observe-links 连接ryu控制器
  • 在ryu/ryu/app/文件夹内运行终端输入命令:ryu-manager ryu.app.simple_switch_13 ryu.app.ofctl_rest 运行ryu
  • 终端输入curl -X GET http://localhost:8080/stats/flow/1查看流表
  • 终端输入命令:sudo sudo mn --custom topo.py --topo mytopo --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13建立拓扑

执行结果

实验步骤7

# 将主机1,2发送来的数据包打上vlan标记
curl -X POST -d '{
    "dpid": 1,
    "priority": 1,
    "match":{
        "in_port": 1
    },
    "actions":[
        {
            "type": "PUSH_VLAN",     
            "ethertype": 33024       
        },
        {
            "type": "SET_FIELD",
            "field": "vlan_vid",    
            "value": 4096            
        },
        {
            "type": "OUTPUT",
            "port": 3
        }
    ]
 }' http://localhost:8080/stats/flowentry/add

 curl -X POST -d '{
    "dpid": 1,
    "priority": 1,
    "match":{
        "in_port": 2
    },
    "actions":[
        {
            "type": "PUSH_VLAN",    
            "ethertype": 33024      
        },
        {
            "type": "SET_FIELD",
            "field": "vlan_vid",     
            "value": 4097           
        },
        {
            "type": "OUTPUT",
            "port": 3
        }
    ]
 }' http://localhost:8080/stats/flowentry/add

# 将主机3,4发送来的数据包取出vlan标记
 curl -X POST -d '{
    "dpid": 1,
    "priority": 1,
    "match":{
        "vlan_vid": 0
    },
    "actions":[
        {
            "type": "POP_VLAN",    
            "ethertype": 33024       
        },
        {
            "type": "OUTPUT",
            "port": 1
        }
    ]
 }' http://localhost:8080/stats/flowentry/add

 curl -X POST -d '{
    "dpid": 1,
    "priority": 1,
    "match":{
        "vlan_vid": 1
    },
    "actions":[
        {
            "type": "POP_VLAN",    
            "ethertype": 33024      
        },
        {
            "type": "OUTPUT",
            "port": 2
        }
    ]
 }' http://localhost:8080/stats/flowentry/add

# 将主机3,4发送来的数据包打上vlan标记
 curl -X POST -d '{
    "dpid": 2,
    "priority": 1,
    "match":{
        "in_port": 1
    },
    "actions":[
        {
            "type": "PUSH_VLAN",    
            "ethertype": 33024      
        },
        {
            "type": "SET_FIELD",
            "field": "vlan_vid",    
            "value": 4096          
        },
        {
            "type": "OUTPUT",
            "port": 3
        }
    ]
 }' http://localhost:8080/stats/flowentry/add

 curl -X POST -d '{
    "dpid": 2,
    "priority": 1,
    "match":{
        "in_port": 2
    },
    "actions":[
        {
            "type": "PUSH_VLAN",    
            "ethertype": 33024      
        },
        {
            "type": "SET_FIELD",
            "field": "vlan_vid",   
            "value": 4097           
        },
        {
            "type": "OUTPUT",
            "port": 3
        }
    ]
 }' http://localhost:8080/stats/flowentry/add

 curl -X POST -d '{
    "dpid": 2,
    "priority": 1,
    "match":{
        "vlan_vid": 0
    },
    "actions":[
        {
            "type": "POP_VLAN",    
            "ethertype": 33024      
        },
        {
            "type": "OUTPUT",
            "port": 1
        }
    ]
 }' http://localhost:8080/stats/flowentry/add

 curl -X POST -d '{
    "dpid": 2,
    "priority": 1,
    "match":{
        "vlan_vid": 1
    },
    "actions":[
        {
            "type": "POP_VLAN",    
            "ethertype": 33024      
        },
        {
            "type": "OUTPUT",
            "port": 2
        }
    ]
 }' http://localhost:8080/stats/flowentry/add
  • 运行脚本程序,可在mininet中通过pingall检验VLAN划分结果

执行结果

个人总结

实验难度:

  • 较难

实验过程遇到的困难及解决办法

  • 第一个遇见的困难是在下发硬超时流表时候,中断的产生忘记了要先ping测试。
  • 第二个困难是运行了ryu,但是ping测试却显示各主机均不连通,上网查不到答案,之后看了同学的博客,发现了一样的问题,于是试着做了一遍发现成功了,
    命令行需要运行curl -X GET http://localhost:8080/stats/flow/1 查看流表(虽然只是查看流表的操作,可是不知道为啥,运行了以后就能成功ping测试了,还是疑惑)
    刚开始会提示要安装curl,如下图,输入命令sudo snap install curl即可完成安装
  • 第三个困难,在利用自己代码建立拓扑时候,终端输入时候没有加上custom参数,导致一直连接出错。
  • 第四个困难是在最后一个实验步骤一直无法得到正确的VLAN划分结果,查看同学的个人总结,发现是由于没有删除之前遗留的流表所致。

个人感想

  • 经过本次实验,通过自己编程来调用ODL的北向接口实现部分功能,使我对基于REST API的SDN北向应用有了深刻的认识,也对流表遗留的危害有了深刻印象,
    下次遇见类似问题,必能及时排查出来。对了curl命令部分运用也有了初步学习,对于虚拟网的实现有了更深层次的理解和掌握了。
posted @ 2021-10-25 01:05  运动ing的美食探险家  阅读(90)  评论(0编辑  收藏  举报