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
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；
（2） 下发指令删除s1上的流表数据。
- delete.py
import requests as rq from requests.auth import HTTPBasicAuth if __name__ == '__main__': url = 'http://127.0.0.1:8181/restconf/operational/opendaylight-inventory:nodes/node/openflow:1/' headers = {'Content-Type': 'application/json'} response = rq.delete(url=url, headers=headers, auth=HTTPBasicAuth('admin', 'admin')) print(response.content)- 运行结果
（3） 下发硬超时流表，实现拓扑内主机h1和h3网络中断20s。
- put_hard_timeout.py
import requests as rq from requests.auth import HTTPBasicAuth def http_put(url,jstr): url= url headers = {'Content-Type':'application/json'} resp = rq.put(url,jstr,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/flow-node-inventory:table/0/flow/1' with open('./flowTable1.json') as f: jstr = f.read() resp = http_put(url,jstr) print (resp.content)- flowTable1.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" } ] }- 运行结果
（4） 获取s1上活动的流表数。
- get_flows.py
import requests as rq from requests.auth import HTTPBasicAuth def http_get(url): url= url headers = {'Content-Type':'application/json'} resp = rq.get(url,headers=headers,auth=HTTPBasicAuth('admin','admin')) return resp 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' resp = http_get(url) print(resp.content)
- 运行结果
-
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。- put_hard_timeout_ryu.py
import requests as rq if __name__ == "__main__": url = 'http://127.0.0.1:8080/stats/flowentry/add' with open("./flowTable2.json") as f: jstr = f.read() headers = {'Content-Type': 'application/json'} res = rq.post(url, jstr, headers=headers) print (res.content)- flowTable2.json
{ "dpid": 1, "cookie": 1, "cookie_mask": 1, "table_id": 0, "hard_timeout": 20, "priority": 65535, "flags": 1, "match":{ "in_port":1 }, "actions":[ ] }- 运行结果
（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_ryu.py
import json import requests as rq if __name__ == '__main__': url = 'http://127.0.0.1:8080/stats/flowentry/add' headers = {'Content-Type': 'application/json'} f = open('flowTable3.json').read() flows = json.loads(f)['flows'] [rq.post(url, data=json.dumps(flows[i]), headers=headers) for i in range(0, 8)]- flowTable3.json
{ "flows": [{ "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 } ] }, { "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 } ] }, { "dpid": 1, "priority": 1, "match": { "vlan_vid": 0 }, "actions": [{ "type": "POP_VLAN", "ethertype": 33024 }, { "type": "OUTPUT", "port": 1 } ] }, { "dpid": 1, "priority": 1, "match": { "vlan_vid": 1 }, "actions": [{ "type": "POP_VLAN", "ethertype": 33024 }, { "type": "OUTPUT", "port": 2 } ] }, { "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 } ] }, { "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 } ] }, { "dpid": 2, "priority": 1, "match": { "vlan_vid": 0 }, "actions": [{ "type": "POP_VLAN", "ethertype": 33024 }, { "type": "OUTPUT", "port": 1 } ] }, { "dpid": 2, "priority": 1, "match": { "vlan_vid": 1 }, "actions": [{ "type": "POP_VLAN", "ethertype": 33024 }, { "type": "OUTPUT", "port": 2 } ] } ] }- 运行结果
（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。
- get_info.py
import requests as rq
import time
import re
class Get_Info:
def __init__(self, ip):
self.ip = ip
# 通过get()获取交换机的dpid
def get_switch_id(self):
url = 'http://' + self.ip + '/stats/switches'
re_switch_id = rq.get(url=url).json()
switch_id_hex = []
for i in re_switch_id:
switch_id_hex.append(hex(i))
return switch_id_hex
# 通过get()和获取的dpid得到每一个交换机的流表项
def get_flow_table(self):
url = 'http://' + self.ip + '/stats/flow/%d'
switch_list = self.get_switch_id()
all_flow = []
for switch in switch_list:
new_url = format(url % int(switch, 16))
re_switch_flow = rq.get(url=new_url).json()
all_flow.append(re_switch_flow)
return all_flow
def show_names(self):
list_flow = self.get_flow_table()
for flow in list_flow:
for dpid in flow.keys():
dp_id = dpid
switch_num= '{1}'.format(hex(int(dp_id)), int(dp_id))
print('s'+switch_num)
switch_num = int(switch_num)
for list_table in flow.values():
count = 0
for table in list_table:
string1 = str(table)
if re.search("'dl_vlan': '(.*?)'", string1) is not None:
num = re.search("'dl_vlan': '(.*?)'", string1).group(1);
if num == '0' and switch_num == 1:
print('h1')
if num == '1' and switch_num == 1:
print('h2')
if num == '0' and switch_num == 2:
print('h3')
if num == '1' and switch_num == 2:
print('h4')
def show_flows(self):
list_flow = self.get_flow_table()
for flow in list_flow:
for dpid in flow.keys():
dp_id = dpid
print('switch_name:s{1}'.format(hex(int(dp_id)), int(dp_id)))
for list_table in flow.values():
for table in list_table:
print(table)
s1 = Get_Info("127.0.0.1:8080");
s1.show_names();
s1.show_flows();
- 运行结果
四、个人总结
北向接口是sdn应用层与sdn控制器层之间进行数据交互的接口，使用北向接口协议可以直接调用控制器来实现网络功能。本次实验是基于REST API的sdn北向应用实践，结合了前面几次实验所学的知识，所以综合性较强，难度上也增加了许多。实验中最困难的部分就是参照文档编写实现所要求的功能，不得不说查阅文档一开始并不太熟练，所以磕磕绊绊花费了不少时间。但总体来说通过这次的作业还是收获了很多，我觉得sdn未来应该成为我们计算机专业的一项必修课。
