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
1.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；
——启动ODL
命令： ./distribution-karaf-0.6.4-Carbon/bin/karaf
——创建topo
命令“sudo mn --topo=single,3 --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13
（2） 下发指令删除s1上的流表数据。
——编写delete.py，删除s1上的流表数据
点击查看代码
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/'
headers = {'Content-Type': 'application/json'}
response = requests.delete(url=url, headers=headers, auth=HTTPBasicAuth('admin', 'admin'))
print(response.content)
（3） 下发硬超时流表，实现拓扑内主机h1和h3网络中断20s。
——编写timeout.py
点击查看代码
#!/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("./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)
——编写timeout.json
点击查看代码
{
"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"
}
]
}
——实现拓扑内主机h1和h3网络中断20s
（4） 获取s1上活动的流表数。
——编写get_flows.py
点击查看代码
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'}
response = requests.get(url=url, headers=headers, auth=HTTPBasicAuth('admin', 'admin'))
print(response.content)
2.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。
——编写ryu_timeout.py
点击查看代码
import requests
from requests.auth import HTTPBasicAuth
if __name__ == '__main__':
url = 'http://127.0.0.1:8080/stats/flowentry/add'
headers = {'Content-Type': 'application/json'}
json = open('ryu_timeout.json').read()
response = requests.post(url, data=json, headers=headers)
print(response.content)
——编写ryu_timeout.json
点击查看代码
{
"dpid": 1,
"cookie": 1,
"cookie_mask": 1,
"table_id": 0,
"hard_timeout": 20,
"priority": 65535,
"flags": 1,
"match":{
"in_port":1
},
"actions":[]
}
——打开RYU
命令：ryu-manager ryu.app.simple_switch_13 ryu.app.ofctl_rest
——创建topo
命令：sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13
——运行ryu_timeout.py，实现硬超时功能
（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
——编写ryu_topo.py
点击查看代码
from mininet.topo import Topo
class ryu_topo(Topo):
def __init__(self):
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 = {'ryu_topo': (lambda: ryu_topo())}
——编写ryu_vlan.py
点击查看代码
import json
import requests
if __name__ == '__main__':
url = 'http://127.0.0.1:8080/stats/flowentry/add'
headers = {'Content-Type': 'application/json'}
f = open('ryu_vlan.json').read()
flows = json.loads(f)['flows']
[requests.post(url, data=json.dumps(flows[i]), headers=headers) for i in range(0, 8)]
——编写ryu_vlan.json
点击查看代码
{
"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
}
]
}
]
}
——打开RYU
命令：ryu-manager ryu.app.simple_switch_13 ryu.app.ofctl_rest
——将创建的topo连接到控制器
命令：sudo mn --custom ryu_topo.py --topo ryu_topo --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13
——运行ryu_vlan.py代码，实现相同的VLAN配置
（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。
——编写getnodes.py,实现查看节点信息
点击查看代码
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()
——运行getnodes.py查看节点信息
三、个人感想
1.本次实验主要是综合了之前学习过的实验内容，进一步加深了对QDL和RYU的学习，在编写代码的时候发现很多错误，花了很多时间排错，也咨询了一下同学，虽然不明白自己哪里错了，但是排完之后能运行就很nice!
2.在做基础部分的2（2）的时候，应该要先运行ryu_vlan.py代码，实现相同的VLAN配置在测试连通性，如果先测试的话，就得先删除已经学习到的流表，为此安装了CURL
