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；
使用命令./distribution-karaf-0.6.4-Carbon/bin/karaf打开ODL控制器
使用命令sudo mn --topo=single,3 --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13创建拓扑并连接控制器

（2） 下发指令删除s1上的流表数据。

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/'
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:

点击查看代码

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:

点击查看代码

# 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。

getflow.py:

点击查看代码

# getflow.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)

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。

关闭ODL控制器，关闭上次的拓扑并清除拓扑后

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 --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13创建拓扑

ryu_timeout.py:

点击查看代码

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:

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":[

]
}

（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
使用命令

curl -X DELETE http://127.0.0.1:8080/stats/flowentry/clear/1

curl -X DELETE http://127.0.0.1:8080/stats/flowentry/clear/2

删除流表

关闭控制器，关闭上一次实验的拓扑并清除拓扑

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

topo.py:

点击查看代码

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())}

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'}
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)

（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:

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()

四、个人总结

通过这次实验，进一步学习了用OpenDaylight和Ryu的rest API来实现特定的网络功能。在实验中遇到问题查看了相关文档，做完一个做下一个的时候，要记得把前一次的拓扑清空。