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；
- （2） 下发指令删除s1上的流表数据。
- （3） 下发硬超时流表，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。
(1)建立拓扑：
(2)下发指令删除s1上的流表数据。
# -*- coding: utf-8 -*-
import requests
from requests.auth import HTTPBasicAuth
def http_delete():
url = 'http://127.0.0.1:8181/restconf/config/opendaylight-inventory:nodes/node/openflow:1'
headers = {'Content-Type': 'application/json'}
resp = requests.delete(url, headers=headers, auth=HTTPBasicAuth('admin', 'admin'))
return resp
if __name__ == "__main__":
resp = http_delete()
print (resp.content)
先任意下发一个流表，例如(3)中的硬超时20秒：
再执行delete.py，可以看到硬超时提前结束，即流表数据被删除：
(3) 下发硬超时流表，实现拓扑内主机h1和h3网络中断20s。
# -*- coding: utf-8 -*-
import requests
from requests.auth import HTTPBasicAuth
def http_put():
url = 'http://127.0.0.1:8181/restconf/config/opendaylight-inventory:nodes/node/openflow:1/flow-node-inventory:table/0/flow/1'
headers = {'Content-Type':'application/json'}
with open('json_file.json') as f:
jstr = f.read()
resp = requests.put(url,jstr,headers=headers,auth=HTTPBasicAuth('admin', 'admin'))
return resp
if __name__ == "__main__":
resp = http_put()
print (resp.content)
执行put.py，下发流表：
（4） 获取s1上活动的流表数。
# -*- coding: utf-8 -*-
import requests
from requests.auth import HTTPBasicAuth
def http_get():
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'))
return res
if __name__ == "__main__":
resp = http_get()
print (resp.content)
执行get.py，获取s1上活动的流表数：
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。
- （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。
先连接RYU控制器：ryu-manager ryu.app.ofctl_rest
（1） 实现上述OpenDaylight实验拓扑上相同的硬超时流表下发：
python代码：
# -*- coding: utf-8 -*-
import requests
from requests.auth import HTTPBasicAuth
if __name__ == "__main__":
url = 'http://127.0.0.1:8080/stats/flowentry/add'
with open("flowtable.json") as f:
jstr = f.read()
headers = {'Content-Type': 'application/json'}
res = requests.post(url, jstr, headers=headers)
print (res.content)
json文件：
{
"dpid": 1,
"cookie": 1,
"cookie_mask": 1,
"table_id": 0,
"hard_timeout": 20,
"priority": 65535,
"flags": 1,
"match":{
"in_port":1
},
"actions":[
]
}
执行ryu.py,实现硬超时流表下发：
（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。
先建立拓扑：sudo mn --custom mysdntopo.py --topo mytopo --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13
mysdntopo.py代码如下：
from mininet.topo import Topo
class MyTopo( Topo ):
def __init__( self ):
Topo.__init__(self)
# Add hosts and switches
host1 = self.addHost('h1')
host2 = self.addHost('h2')
host3 = self.addHost('h3')
host4 = self.addHost('h4')
switch1 = self.addSwitch('s1')
switch2 = self.addSwitch('s2')
# Add links
self.addLink(host1,switch1,1,1)
self.addLink(host2,switch1,1,2)
self.addLink(host3,switch2,1,1)
self.addLink(host4,switch2,1,2)
self.addLink(switch1,switch2,3,3)
topos = { 'mytopo': ( lambda: MyTopo() ) }
python代码如下：
import requests
import json
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)
执行ryuvlan.py后，进行pingall：
（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。
利用Ryu实现，代码如下：
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(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))
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= '{}'.format(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{}'.format(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()
执行结果：
四、个人总结
遇到的问题及解决方案
- 查看不了交换机上的流表：
阅读报错信息，发现是由于版本不匹配导致的。
解决方案：把指令更改为sudo ovs-ofctl dump-flows --protocols=Openflow13即可查看流表。
收获与心得体会
- 个人认为本次实验相当于之前的所有实验的综合，整体难度很高，而且代码量非常大，实现REST API的调用需要查阅英文文档以明确具体功能，虽然之前的实验中也有查阅过，但还在这一查阅过程中花费了大量时间。
- 但是通过本次实验，也让我复习到了之前所有学习过的知识，例如VLAN的设置、硬超时的设置等。我也对一些相关指令的操作更加熟练，例如利用指令查看交换机上的流表，同时对控制器下发流表、交换机与控制器间的沟通有了更深的认识，对SDN的架构有了进一步的理解。希望在接下来的大作业中能够继续学习巩固这些知识，能做到学以致用。