实验7：基于REST API的SDN北向应用实践

一、实验目的

能够编写程序调用OpenDaylight REST API实现特定网络功能；
能够编写程序调用Ryu REST API实现特定网络功能。

二、实验环境

下载虚拟机软件Oracle VisualBox或VMware；
在虚拟机中安装Ubuntu 20.04 Desktop amd64，并完整安装Mininet、OpenDaylight（Carbon版本）、Postman和Ryu；

三、实验要求

（一）基本要求

编写Python程序，调用OpenDaylight的北向接口实现以下功能
（1）利用Mininet平台搭建下图所示网络拓扑，并连接OpenDaylight；

生成拓扑并连接控制器:sudo mn --topo=single,3 --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13

运行 karaf 启动 ODL: ./distribution-karaf-0.6.4-Carbon/bin/karaf

浏览器访问：http://127.0.0.1:8181/index.html 访问查看。

（2）下发指令删除s1上的流表数据。

delete.py代码

1 #!/usr/bin/python
2 import requests
3 from requests.auth import HTTPBasicAuth
4 if __name__ == "__main__":
5     url = 'http://127.0.0.1:8181/restconf/config/opendaylight-inventory:nodes/node/openflow:1/'
6     headers = {'Content-Type': 'application/json'}
7     res = requests.delete(url, headers=headers, auth=HTTPBasicAuth('admin', 'admin'))
8     print (res.content)

（3）下发硬超时流表，实现拓扑内主机h1和h3网络中断20s。

timeout.py代码

 1 #!/usr/bin/python
 2 import requests
 3 from requests.auth import HTTPBasicAuth
 4 if __name__ == "__main__":
 5     url = 'http://127.0.0.1:8181/restconf/config/opendaylight-inventory:nodes/node/openflow:1/flow-node-inventory:table/0/flow/1'
 6     with open("./timeout.json") as file:
 7         str = file.read()
 8     headers = {'Content-Type': 'application/json'}
 9     res = requests.put(url, str, headers=headers, auth=HTTPBasicAuth('admin', 'admin'))
10     print (res.content)

 1 # timeout.json
 2 {
 3     "flow": [
 4       {
 5         "id": "1",
 6         "match": {
 7           "in-port": "1",
 8           "ethernet-match": {
 9             "ethernet-type": {
10               "type": "0x0800"
11             }
12           },
13           "ipv4-destination": "10.0.0.3/32"
14         },
15         "instructions": {
16           "instruction": [
17             {
18               "order": "0",
19               "apply-actions": {
20                 "action": [
21                   {
22                     "order": "0",
23                     "drop-action": {}
24                   }
25                 ]
26               }
27             }
28           ]
29         },
30         "flow-name": "flow",
31         "priority": "65535",
32         "hard-timeout": "20",
33         "cookie": "2",
34         "table_id": "0"
35       }
36     ]
37   }

（4）获取s1上活动的流表数。

get.py代码

1 #!/usr/bin/python
2 import requests
3 from requests.auth import HTTPBasicAuth
4 if __name__ == "__main__":
5     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'
6     headers = {'Content-Type': 'application/json'}
7     res = requests.get(url,headers=headers, auth=HTTPBasicAuth('admin', 'admin'))
8     print (res.content)

编写Python程序，调用Ryu的北向接口实现以下功能
（1）实现上述OpenDaylight实验拓扑上相同的硬超时流表下发。

①生成拓扑并连接控制器: sudo mn --topo=single,3 --controller=remote,ip=127.0.0.1,port=6633 --

switch ovsk,protocols=OpenFlow13

②运行ryu:ryu-manager ryu/ryu/app/ofctl_rest.py ryu/ryu/app/simple_switch_13.py

ryu_timeout.py代码

1 #!/usr/bin/python
2 import requests
3 if __name__ == "__main__":
4     url = 'http://127.0.0.1:8080/stats/flowentry/add'
5     with open("./ryu_timeout.json") as file:
6         str = file.read()
7     headers = {'Content-Type': 'application/json'}
8     res = requests.post(url, str, headers=headers)
9     print (res.content)

 1 # ryu_timeout.json
 2 {
 3     "dpid": 1,
 4     "cookie": 1,
 5     "cookie_mask": 1,
 6     "table_id": 0,
 7     "hard_timeout": 20,
 8     "priority": 65535,
 9     "flags": 1,
10     "match":{
11         "in_port":1
12     },
13     "actions":[]
14  }

（2）参考Ryu REST API的文档，基于VLAN实验的网络拓扑，编程实现相同的VLAN配置。
提示：拓扑生成后需连接Ryu，且Ryu应能够提供REST API服务

VLAN_ID	Hosts
0	h1 h3
1	h2 h4

建立拓扑图：mytopo.py代码

 1 from mininet.topo import Topo
 2 
 3 class MyTopo(Topo):
 4     def __init__(self):
 5         # initilaize topology
 6         Topo.__init__(self)
 7 
 8         self.addSwitch("s1")
 9         self.addSwitch("s2")
10 
11         self.addHost("h1")
12         self.addHost("h2")
13         self.addHost("h3")
14         self.addHost("h4")
15 
16         self.addLink("s1", "h1")
17         self.addLink("s1", "h2")
18         self.addLink("s2", "h3")
19         self.addLink("s2", "h4")
20         self.addLink("s1", "s2")
21 
22 topos = {'mytopo': (lambda: MyTopo())}

vlan.py代码

  1 import json
  2 import requests
  3 
  4 if __name__ == "__main__":
  5     url = 'http://127.0.0.1:8080/stats/flowentry/add'
  6     headers = {'Content-Type': 'application/json'}
  7     flow1 = {
  8         "dpid": 1,
  9         "priority": 1,
 10         "match":{
 11             "in_port": 1
 12         },
 13         "actions":[
 14             {
 15                 "type": "PUSH_VLAN",    
 16                 "ethertype": 33024      
 17             },
 18             {
 19                 "type": "SET_FIELD",
 20                 "field": "vlan_vid",    
 21                 "value": 4096           
 22             },
 23             {
 24                 "type": "OUTPUT",
 25                 "port": 3
 26             }
 27         ]
 28     }
 29     flow2 = {
 30         "dpid": 1,
 31         "priority": 1,
 32         "match":{
 33             "in_port": 2
 34         },
 35         "actions":[
 36             {
 37                 "type": "PUSH_VLAN",     
 38                 "ethertype": 33024      
 39             },
 40             {
 41                 "type": "SET_FIELD",
 42                 "field": "vlan_vid",     
 43                 "value": 4097           
 44             },
 45             {
 46                 "type": "OUTPUT",
 47                 "port": 3
 48             }
 49         ]
 50     }
 51     flow3 = {
 52         "dpid": 1,
 53         "priority": 1,
 54         "match":{
 55             "vlan_vid": 0
 56         },
 57         "actions":[
 58             {
 59                 "type": "POP_VLAN",    
 60                 "ethertype": 33024     
 61             },
 62             {
 63                 "type": "OUTPUT",
 64                 "port": 1
 65             }
 66         ]
 67     }
 68     flow4 = {
 69         "dpid": 1,
 70         "priority": 1,
 71         "match": {
 72             "vlan_vid": 1
 73         },
 74         "actions": [
 75             {
 76                 "type": "POP_VLAN", 
 77                 "ethertype": 33024  
 78             },
 79             {
 80                 "type": "OUTPUT",
 81                 "port": 2
 82             }
 83         ]
 84     }
 85     flow5 = {
 86         "dpid": 2,
 87         "priority": 1,
 88         "match": {
 89             "in_port": 1
 90         },
 91         "actions": [
 92             {
 93                 "type": "PUSH_VLAN", 
 94                 "ethertype": 33024 
 95             },
 96             {
 97                 "type": "SET_FIELD",
 98                 "field": "vlan_vid", 
 99                 "value": 4096  
100             },
101             {
102                 "type": "OUTPUT",
103                 "port": 3
104             }
105         ]
106     }
107     flow6 = {
108         "dpid": 2,
109         "priority": 1,
110         "match": {
111             "in_port": 2
112         },
113         "actions": [
114             {
115                 "type": "PUSH_VLAN",  
116                 "ethertype": 33024  
117             },
118             {
119                 "type": "SET_FIELD",
120                 "field": "vlan_vid",  
121                 "value": 4097 
122             },
123             {
124                 "type": "OUTPUT",
125                 "port": 3
126             }
127         ]
128     }
129     flow7 = {
130         "dpid": 2,
131         "priority": 1,
132         "match": {
133             "vlan_vid": 0
134         },
135         "actions": [
136             {
137                 "type": "POP_VLAN", 
138                 "ethertype": 33024  
139             },
140             {
141                 "type": "OUTPUT",
142                 "port": 1
143             }
144         ]
145     }
146     flow8 = {
147         "dpid": 2,
148         "priority": 1,
149         "match": {
150             "vlan_vid": 1
151         },
152         "actions": [
153             {
154                 "type": "POP_VLAN", 
155                 "ethertype": 33024  
156             },
157             {
158                 "type": "OUTPUT",
159                 "port": 2
160             }
161         ]
162     }
163     res1 = requests.post(url, json.dumps(flow1), headers=headers)
164     res2 = requests.post(url, json.dumps(flow2), headers=headers)
165     res3 = requests.post(url, json.dumps(flow3), headers=headers)
166     res4 = requests.post(url, json.dumps(flow4), headers=headers)
167     res5 = requests.post(url, json.dumps(flow5), headers=headers)
168     res6 = requests.post(url, json.dumps(flow6), headers=headers)
169     res7 = requests.post(url, json.dumps(flow7), headers=headers)
170     res8 = requests.post(url, json.dumps(flow8), headers=headers)

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

（二）进阶要求

OpenDaylight或Ryu任选其一，编程实现查看前序VLAN实验拓扑中所有节点（含交换机、主机）的名称，以及显示每台交换机的所有流表项。

getall.py代码

 1 import requests
 2 import time
 3 import re
 4 
 5 class GetNodes:
 6     def __init__(self, ip):
 7         self.ip = ip
 8 
 9     def get_switch_id(self):
10         url = 'http://' + self.ip + '/stats/switches'
11         re_switch_id = requests.get(url=url).json()
12         switch_id_hex = []
13         for i in re_switch_id:
14             switch_id_hex.append(hex(i))
15 
16         return switch_id_hex
17 
18     def getflow(self):
19         url = 'http://' + self.ip + '/stats/flow/%d'
20         switch_list = self.get_switch_id()
21         ret_flow = []
22         for switch in switch_list:
23             new_url = format(url % int(switch, 16))
24             re_switch_flow = requests.get(url=new_url).json()
25             ret_flow.append(re_switch_flow)
26         return ret_flow
27 
28     def show(self):
29         flow_list = self.getflow()
30         for flow in flow_list:
31             for dpid in flow.keys():
32                 dp_id = dpid
33                 switchnum= '{1}'.format(hex(int(dp_id)), int(dp_id))
34                 print('s'+switchnum,end = " ")
35                 switchnum = int(switchnum)
36             for list_table in flow.values():
37                 for table in list_table:
38                     string1 = str(table)
39                     if re.search("'dl_vlan': '(.*?)'", string1) is not None:
40                        num = re.search("'dl_vlan': '(.*?)'", string1).group(1);
41                        if num == '0' and switchnum == 1:
42                           print('h1',end = " ")
43                        if num == '1' and switchnum == 1:
44                           print('h2',end = " ")
45                        if num == '0' and switchnum == 2:
46                           print('h3',end = " ")
47                        if num == '1' and switchnum == 2:
48                           print('h4',end = " ")
49         print("")
50         flow_list = self.getflow()
51         for flow in flow_list:
52             for dpid in flow.keys():
53                 dp_id = dpid
54                 print('switch_name:s{1}'.format(hex(int(dp_id)), int(dp_id)))
55             for list_table in flow.values():
56                 for table in list_table:
57                     print(table)
58 s1 = GetNodes("127.0.0.1:8080")
59 s1.show()

（三）个人总结

通过本次实验，我已经能够大概编写程序调用OpenDaylight REST API实现特定网络功能和Ryu REST API实现特定网络功能。对我来说，实验还是挺难的，实验过程中出现了很多问题，比如在下发指令删除s1上的流表数据的时候，一直出现错误，最后更改python运行方式才行，因为python和python3是不兼容的，所以一些可以在python上运行的代码不一定可以在python3上运行；第二个问题是ryu一直运行不出来，出现“OSError: [Errno 98] Address already in use"的错误，最后发现需要把OpenDaylight 控制器关掉，才可以运行。总的来说，实验有难度，需要有很好的基础，并且结合前几次的实验。