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。
# del.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/'
headers = {'Content-Type': 'application/json'}
res = requests.delete(url, headers=headers, auth=HTTPBasicAuth('admin', 'admin'))
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
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("./timeout.json") as file:
str = file.read()
headers = {'Content-Type': 'application/json'}
res = requests.put(url, str, headers=headers, auth=HTTPBasicAuth('admin', 'admin'))
print (res.content)
# timeout.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": "flow",
"priority": "65535",
"hard-timeout": "20",
"cookie": "2",
"table_id": "0"
}
]
}
（4） 获取s1上活动的流表数。
# 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)
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） 实现上述OpenDaylight实验拓扑上相同的硬超时流表下发。
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关闭ODL控制器，关闭上次的拓扑并清除拓扑后
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使用命令
ryu-manager ryu.app.simple_switch_13 ryu.app.ofctl_rest打开Ryu控制器 -
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使用命令
sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13创建拓扑 
h1 ping h3，同时运行ryu硬超时运行ryu_timeout，h1 ping h3中断20秒
# ryu_timeout.py import requests if __name__ == "__main__": url = 'http://127.0.0.1:8080/stats/flowentry/add' with open("./ryu_timeout.json") as file: str = file.read() headers = {'Content-Type': 'application/json'} res = requests.post(url, str, headers=headers) print (res.content)# ryu_timeout.json { "dpid": 1, "cookie": 1, "cookie_mask": 1, "table_id": 0, "hard_timeout": 20, "priority": 65535, "flags": 1, "match":{ "in_port":1 }, "actions":[ ] }（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-
#ryu_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())}-
关闭控制器，关闭上一次实验的拓扑并清除拓扑
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使用命令
ryu-manager ryu.app.simple_switch_13 ryu.app.ofctl_rest打开Ryu控制器 -
使用命令
sudo mn --custom topo.py --topo mytopo --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13创建拓扑 -
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# ryu_vlan.py 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)
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（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。
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#getnodes.py import requests import time import re class GetNodes: def __init__(self, ip): self.ip = ip def get_switch_id(self): url = 'http://' + self.ip + '/stats/switches' re_switch_id = requests.get(url=url).json() switch_id_hex = [] for i in re_switch_id: switch_id_hex.append(hex(i)) return switch_id_hex def getflow(self): url = 'http://' + self.ip + '/stats/flow/%d' switch_list = self.get_switch_id() ret_flow = [] for switch in switch_list: new_url = format(url % int(switch, 16)) re_switch_flow = requests.get(url=new_url).json() ret_flow.append(re_switch_flow) return ret_flow def show(self): flow_list = self.getflow() for flow in flow_list: for dpid in flow.keys(): dp_id = dpid switchnum= '{1}'.format(hex(int(dp_id)), int(dp_id)) print('s'+switchnum,end = " ") switchnum = int(switchnum) for list_table in flow.values(): 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 switchnum == 1: print('h1',end = " ") if num == '1' and switchnum == 1: print('h2',end = " ") if num == '0' and switchnum == 2: print('h3',end = " ") if num == '1' and switchnum == 2: print('h4',end = " ") print("") flow_list = self.getflow() for flow in flow_list: 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 = GetNodes("127.0.0.1:8080") s1.show()
四、个人总结
本次实验是对前两次的进阶，进一步考验通过编程来控制控制器的使用，总体难度较大，需要查阅API文档较多。个人感觉本次的实验较为困难，综合了前面的几次实验，实验的过程可谓是一波三折，通过本次实验，进一步学习了OpenDaylight和ryu，进一步区分了两者的区别所在，同时在实验中遇到问题查看了相关文档，锻炼了阅读文档的能力。这次实验中是由几个小实验组成的，做完一个做下一个的时候，要记得把前一次的拓扑清空。实验中要记得先把流表清空，在实验中清除的看到了自己的不足和进步，这次实验是根据前面几次实验的总结，总的来说还是收获丰富。
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