实验7：基于REST API的SDN北向应用实践
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搭建拓扑，并连接OpenDaylight
OpenDaylight连接拓扑
2)下发指令删除s1上的流表数据
这里不知道什么原因，首先Ptyhon执行Delete.py时，会报数据模型不存在的错误。然后不执行python程序的环境下，直接用OLD自带的YangUI查找（或删除）流表时，自己也找不到这个数据模型。然而对于Mininet或者ODL的数据库来说，确实有收到一个流表。
deletel.py
#!/usr/bin/python
import requests
from requests.auth import HTTPBasicAuth
def http_delete(url):
headers = {'Content-Type':'application/json'}
resp = requests.delete(url,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/'
resp = http_delete(url)
print (resp.content)
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
2.编写Python程序，调用Ryu的北向接口实现以下功能
1)实现第1步上相同的硬超时流表下发。
- 1).搭建拓扑
$ sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13
- 2).开启ryu控制器
$ ryu-manager ryu.app.simple_switch_13 ryu.app.ofctl_rest
- 3).测试拓扑连通性，并开启（任意）两设备ping命令
mininet> pingall
mininet> h1 ping h3
- 4).下发硬超时流表
$ python3 timeout.py
timeout.py
#!/usr/bin/python
import requests
from requests.auth import HTTPBasicAuth
def http_post(url,jstr):
url = url
headers = {'Content-Type':'application/json'}
resp = requests.post(url,jstr,headers=headers)
return resp
if __name__ == "__main__":
url = 'http://127.0.0.1:8080/stats/flowentry/add'
with open("./timeout.json") as f:
jstr = f.read()
resp = http_post(url,jstr)
print (resp.content)
timeout.json
{
"dpid": 1,
"cookie": 1,
"cookie_mask": 1,
"table_id": 0,
"hard_timeout": 20,
"priority": 65535,
"flags": 1,
"match":{
"in_port":1
},
"actions":[]
}
</code>
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。
- 1).搭建topo
- 略v
- 2）.开启ryu控制器
- 略
- 3）.测试拓扑连通性
- 略
- 4).下发VLAN划分流表
$ python VLANCreat.py
VLANCreate.py
#!/usr/bin/python
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)
三、实验总结
1.实验心得
这次实验大部分时间花在第一步上，可能由于环境有问题，或者操作不当。导致第一步中OpenDaylight流表的数据没办法通过URL进行正常获取、修改等操作。这里试过重装系统、更换版本、用Debian系统等等一系列办法，虽然最后仍然没有解决这个问题，但也算是几次不错的尝试吧（尤其是Debian的sudo用户要手动配置）。
第二步相对来说比较一帆风顺一点。
2.实验问题
- ODL流表模型不存在
- 至今未解决
- ryu下发流表VLAN后Mininet设备仍然全部是连通状态
- ryu的流表似乎并不会因为ryu关闭而删除，这里需要curl将旧有的（第一步中的硬超时）流表删掉
$ sudo apt install curl #安装curl
$ curl -X DELETE http://127.0.0.1:8080/stats/flowentry/clear/1 http://127.0.0.1:8080/stats/flowentry/clear/2
$ #删除流表
