實驗7：基於REST API的SDN北向應用實踐

一、實驗目的

能夠編寫程序調用OpenDaylight REST API實現特定網絡功能；
能夠編寫程序調用Ryu REST API實現特定網絡功能。

二、實驗環境

下載虛擬機軟件Oracle VisualBox或VMware；
在虛擬機中安裝Ubuntu 20.04 Desktop amd64，並完整安裝Mininet、OpenDaylight（Carbon版本）、Postman和Ryu；

三、實驗要求

（一）基本要求

OpenDaylight

（1） 利用Mininet平台搭建下圖所示網絡拓撲，並連接OpenDaylight；

（2） 編寫Python程序，調用OpenDaylight的北向接口下發指令刪除s1上的流表數據。

#!/usr/bin/python
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/'
    headers = {'Content-Type': 'application/json'}
    res = requests.delete(url, headers=headers, auth=HTTPBasicAuth('admin', 'admin'))
    print (res.content)

（3） 編寫Python程序，調用OpenDaylight的北向接口下發硬超時流表，實現拓撲內主機h1和h3網絡中斷20s。

#!/usr/bin/python
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("./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)

flowtable.json文件

{
  "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"
    }
  ]
}

執行結果如下

（4） 編寫Python程序，調用OpenDaylight的北向接口獲取s1上活動的流表數。

#!/usr/bin/python
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)

執行結果如下：

Ryu

命令行運行ryu

ryu-manager  ryu.app.simple_switch_13 ryu.app.ofctl_rest

（1） 編寫Python程序，調用Ryu的北向接口，實現上述OpenDaylight實驗拓撲上相同的硬超時流表下發。

#!/usr/bin/python
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)

執行結果如下：

（2） 利用Mininet平台搭建下圖所示網絡拓撲，要求支持OpenFlow 1.3協議，主機名、交換機名以及端口對應正確。拓撲生成后需連接Ryu，且Ryu應能夠提供REST API服務。

#!/usr/bin/env python
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())}

命令行運行

sudo sudo mn  --custom topo.py --topo mytopo --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13

搭建拓撲

（3） 整理一個Shell腳本，參考Ryu REST API的文檔，利用curl命令，實現和實驗2相同的VLAN。
命令行運行
curl -X DELETE http://localhost:8080/stats/flowentry/clear/1
curl -X DELETE http://localhost:8080/stats/flowentry/clear/2
刪除流表

shell腳本：

# 將主機1，2發送來的數據包打上vlan標記
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

# 將主機3，4發送來的數據包取出vlan標記
 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

# 將主機3，4發送來的數據包打上vlan標記
 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

VLAN_ID	Hosts
0	h1 h3
1	h2 h4

（二）進階要求

編程實現基本要求第2部分Ryu（3）中的VLAN划分。
所編寫程序如下：

#!/usr/bin/python
import json

import requests

if __name__ == "__main__":
    url = 'http://127.0.0.1:8080/stats/flowentry/add'
    headers = {'Content-Type': 'application/json'}
    flow1 = {
        "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
            }
        ]
    }
    flow2 = {
        "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
            }
        ]
    }
    flow3 = {
        "dpid": 1,
        "priority": 1,
        "match":{
            "vlan_vid": 0
        },
        "actions":[
            {
                "type": "POP_VLAN",    
                "ethertype": 33024     
            },
            {
                "type": "OUTPUT",
                "port": 1
            }
        ]
    }
    flow4 = {
        "dpid": 1,
        "priority": 1,
        "match": {
            "vlan_vid": 1
        },
        "actions": [
            {
                "type": "POP_VLAN", 
                "ethertype": 33024  
            },
            {
                "type": "OUTPUT",
                "port": 2
            }
        ]
    }
    flow5 = {
        "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
            }
        ]
    }
    flow6 = {
        "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
            }
        ]
    }
    flow7 = {
        "dpid": 2,
        "priority": 1,
        "match": {
            "vlan_vid": 0
        },
        "actions": [
            {
                "type": "POP_VLAN", 
                "ethertype": 33024  
            },
            {
                "type": "OUTPUT",
                "port": 1
            }
        ]
    }
    flow8 = {
        "dpid": 2,
        "priority": 1,
        "match": {
            "vlan_vid": 1
        },
        "actions": [
            {
                "type": "POP_VLAN", 
                "ethertype": 33024  
            },
            {
                "type": "OUTPUT",
                "port": 2
            }
        ]
    }
    res1 = requests.post(url, json.dumps(flow1), headers=headers)
    res2 = requests.post(url, json.dumps(flow2), headers=headers)
    res3 = requests.post(url, json.dumps(flow3), headers=headers)
    res4 = requests.post(url, json.dumps(flow4), headers=headers)
    res5 = requests.post(url, json.dumps(flow5), headers=headers)
    res6 = requests.post(url, json.dumps(flow6), headers=headers)
    res7 = requests.post(url, json.dumps(flow7), headers=headers)
    res8 = requests.post(url, json.dumps(flow8), headers=headers)

（三）實驗總結

• 實驗難度：本次實驗涉及到OpenDaylight和Ryu的運用，需要編寫一系列的代碼文件，難度較大。
• 遇到的困難及解決辦法：

1. 運行ryu卻無法ping通
   
   查看ryu文檔，命令行運行curl -X GET http://localhost:8080/stats/flow/1查看流表（需要安裝curl）
   
   將OpenFlow協議由1.0改為1.3以后可以ping通
   2.運行ryu的問題
   來時不知道怎么在命令行運行ryu，百度上找到的命令也有一些問題，在詢問同學后得以解決

• 個人感想：本次實驗我們通過編寫程序分別調用了OpenDaylight REST API和Ryu REST API實現了特定的網絡功能，同時也復習了如何運行OpenDaylight和Ryu，在實驗中遇到了一些問題需要查看ryu的文檔，再次感嘆一下相比於OpenDaylight,Ryu的文檔閱讀起來簡單許多。這是倒數第二次實驗了，這么多次實驗下來對於一些基本的搭建拓撲的命令已經比較熟悉，也能夠通過編寫python文件搭建出需要的拓撲結構，但在編寫代碼這部分還是覺得難度較大，個人能力還有所欠缺。