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。
下发硬超时流表:
#!/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('./hto.json') as f:
jstr = f.read()
resp = http_put(url,jstr)
print (resp.content)
{
"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": "flow1",
"priority": "65535",
"hard-timeout": "20",
"cookie": "2",
"table_id": "0"
}
]
}
查看流表数量:
#！/usr/bin/python
import requests
import json
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/config/opendaylight-inventory:nodes/node/openflow:1/flow-node-inventory:table/0'
resp = http_get(url)
res = json.loads(resp.text)
print(len(res['flow-node-inventory:table'][0]['flow']))
删除流表：
#!/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)
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。
提示：拓扑生成后需连接Ryu，且Ryu应能够提供REST API服务
下发硬超时流表:
#!/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('./ryu_hto.json') as f:
jstr = f.read()
resp = http_post(url,jstr)
print (resp.content)
{
"dpid": 1,
"cookie": 1,
"cookie_mask": 1,
"table_id": 0,
"hard_timeout": 20,
"priority": 65535,
"flags": 1,
"match":{
"in_port":1
},
"actions":[
]
}
VLAN配置：
#!/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)
（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。
import requests
import time
import re
class GetInformation:
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 get_flow_table(self):
url = 'http://' + self.ip + '/stats/flow/%d'
list_switch = self.get_switch_id()
all_flow = []
for switch in list_switch:
new_url = format(url % int(switch, 16))
re_switch_flow = requests.get(url=new_url).json()
all_flow.append(re_switch_flow)
return all_flow
def show_flow(self):
list_flow = self.get_flow_table()
for flow in list_flow:
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)
def show_name(self):
list_flow = self.get_flow_table()
for flow in list_flow:
for dpid in flow.keys():
dp_id = dpid
switchnum= '{1}'.format(hex(int(dp_id)), int(dp_id))
print('s'+switchnum)
switchnum = int(switchnum)
for list_table in flow.values():
count = 0
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')
if num == '1' and switchnum == 1:
print('h2')
if num == '0' and switchnum == 2:
print('h3')
if num == '1' and switchnum == 2:
print('h4')
S1 = GetInformation("127.0.0.1:8080");
S1.show_name();
S1.show_flow();
个人总结
本次实验我学到了编写程序调用OpenDaylight REST API和Ryu REST API实现特定网络功能。本次实验的编写程序对我来说比较困难。在启动 simple_switch_13.py 时没有一起运行 ofctl_rest.py 开启控制器的北向接口，导致下发流表失败。在编程实现相同的VLAN配置时，运行Python代码后无法实现相同的VLAN配置，经过上网查询后得知需要先使用 curl -X DELETE http://localhost:8080/stats/flowentry/clear/1 和 curl -X DELETE http://localhost:8080/stats/flowentry/clear/2 删除流表。在进阶实验查看流表时报错 s1.mgmt: version negotiation failed (we support version 0x01, peer supports version 0x04)ovs-ofctl: s1: failed to connect to socket (Broken pipe) ，经过上网查询后发现原因是mininet创建拓扑的命令使用了OpenFlow 1.3版本而 dpctl dump-flows 命令默认是1.0版本，因此需要在 dpctl dump-flows 命令中指定OpenFlow 版本，即 dpctl dump-flows -O -OpenFlow13 。
