实验7：基于REST API的SDN北向应用实践
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. OpenDaylight
（1） 利用Mininet平台搭建下图所示网络拓扑，并连接OpenDaylight；
（2） 编写Python程序，调用OpenDaylight的北向接口下发指令删除s1上的流表数据。
- 代码
#!/usr/bin/python import requests from requests.auth import HTTPBasicAuth def http_delete(url): url= 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) - 结果
（3） 编写Python程序，调用OpenDaylight的北向接口下发硬超时流表，实现拓扑内主机h1和h3网络中断20s。
- 代码
#!/usr/bin/python import requests from requests.auth import HTTPBasicAuth def http_put(url,jstr): url= url headers = {'Content-Type':'application/json'} resp = requests.put(url,jstr,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/flow-node-inventory:table/0/flow/1' with open("flowstable.json") as f: jstr = f.read() resp = http_put(url,jstr) print (resp.content) - 结果
（4） 编写Python程序，调用OpenDaylight的北向接口获取s1上活动的流表数。
- 代码
#！/usr/bin/python import requests from requests.auth import HTTPBasicAuth def http_get(url): url= url headers = {'Content-Type':'application/json'} resp = requests.get(url,headers=headers,auth=HTTPBasicAuth('admin','admin')) return resp 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' resp = http_get(url) print(resp.content) - 结果
2. Ryu
（1） 编写Python程序，调用Ryu的北向接口，实现上述OpenDaylight实验拓扑上相同的硬超时流表下发。
-
sendflows1
#!/usr/bin/python import requests if __name__ == "__main__": url = 'http://127.0.0.1:8080/stats/flowentry/add' with open("./flowstable1.json") as f: jstr = f.read() headers = {'Content-Type': 'application/json'} res = requests.post(url, jstr, headers=headers) print (res.content) -
flowstable1
{ "dpid": 1, "cookie": 1, "cookie_mask": 1, "table_id": 0, "hard_timeout": 20, "priority": 65535, "flags": 1, "match":{ "in_port":1 }, "actions":[ ] } -
结果
（2） 利用Mininet平台搭建下图所示网络拓扑，要求支持OpenFlow 1.3协议，主机名、交换机名以及端口对应正确。拓扑生成后需连接Ryu，且Ryu应能够提供REST API服务。
-
topo.py存入lab7
-
代码
#!/usr/bin/env python
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())}
- 创建拓扑成功
（3） 整理一个Shell脚本，参考Ryu REST API的文档，利用curl命令，实现和实验2相同的VLAN。
| VLAN_ID | Hosts |
|---|---|
| 0 | h1 h3 |
| 1 | h2 h4 |
- shell脚本
curl -X POST -d '{ "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 } ] }' http://localhost:8080/stats/flowentry/add curl -X POST -d '{ "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 } ] }' http://localhost:8080/stats/flowentry/add curl -X POST -d '{ "dpid": 1, "priority": 1, "match":{ "vlan_vid": 0 }, "actions":[ { "type": "POP_VLAN", "ethertype": 33024 }, { "type": "OUTPUT", "port": 1 } ] }' http://localhost:8080/stats/flowentry/add curl -X POST -d '{ "dpid": 1, "priority": 1, "match":{ "vlan_vid": 1 }, "actions":[ { "type": "POP_VLAN", "ethertype": 33024 }, { "type": "OUTPUT", "port": 2 } ] }' http://localhost:8080/stats/flowentry/add curl -X POST -d '{ "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 } ] }' http://localhost:8080/stats/flowentry/add curl -X POST -d '{ "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 } ] }' http://localhost:8080/stats/flowentry/add curl -X POST -d '{ "dpid": 2, "priority": 1, "match":{ "vlan_vid": 0 }, "actions":[ { "type": "POP_VLAN", "ethertype": 33024 }, { "type": "OUTPUT", "port": 1 } ] }' http://localhost:8080/stats/flowentry/add curl -X POST -d '{ "dpid": 2, "priority": 1, "match":{ "vlan_vid": 1 }, "actions":[ { "type": "POP_VLAN", "ethertype": 33024 }, { "type": "OUTPUT", "port": 2 } ] }' http://localhost:8080/stats/flowentry/add - 结果
（二）进阶要求
编程实现基本要求第2部分Ryu（3）中的VLAN划分。
- 代码
#!/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": 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
}
]
}
flow5 = {
"dpid": 1,
"priority": 1,
"match": {
"vlan_vid": 1
},
"actions": [
{
"type": "POP_VLAN",
"ethertype": 33024
},
{
"type": "OUTPUT",
"port": 2
}
]
}
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": 1
},
"actions": [
{
"type": "POP_VLAN",
"ethertype": 33024
},
{
"type": "OUTPUT",
"port": 2
}
]
}
flow8 = {
"dpid": 2,
"priority": 1,
"match": {
"vlan_vid": 0
},
"actions": [
{
"type": "POP_VLAN",
"ethertype": 33024
},
{
"type": "OUTPUT",
"port": 1
}
]
}
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)
- 结果
四、心得
遇到的困难及解决方法
- 出现Command ‘curl’ not found的错误，发现是没有安装curl，根据提示安装curl
- 运行shell脚本后ping全通，于是参考同学运行
curl -X DELETE http://localhost:8080/stats/flowentry/clear/1 curl-X DELETE http://localhost:8080/stats/flowentry/clear/2删除流表，再使用 Shell脚本后pingall，错误解决 - 忘记了在建立拓扑前要先连接ryu的教训，还好很快就反应过来了，没浪费多少时间
实验感想
- 这次试验难度较大，用上了前几次实验的知识经验，并且对API的查看要求很高，要学会查看文档，从一堆英文里面找到自己需要的接口、代码。这一次实验里编写代码十分困难且耗时间，需要一点一点去琢磨怎么写代码，不过还好有同学的可以参照、对比，这样按部就班来写好代码后也会有点成就感。不过还是会遇到很多莫名其妙的问题，所以到头来还是要学会用搜索引擎，我觉得这是学习中最重要的事情之一了。
