Experiment 7: SDN northbound application practice based on REST API
1. The purpose of the experiment
- Ability to write programs to call OpenDaylight REST API to implement specific network functions;
- Ability to write programs to call Ryu REST API to implement specific network functions.
2. Experimental environment
- Download the virtual machine software Oracle VisualBox or VMware;
- Install Ubuntu 20.04 Desktop amd64 in a virtual machine, and fully install Mininet, OpenDaylight (Carbon version), Postman and Ryu;
3. Experimental requirements
(1) Basic requirements
- Write a Python program to call the northbound interface of OpenDaylight to achieve the following functions
(1) Use the Mininet platform to build the network topology shown in the figure below, and connect to OpenDaylight;
(2) Issue an instruction to delete the flow table data on s1.
Create del.py file
Click to view codeimport requests
from requests.auth import HTTPBasicAuth
if __name__ == '__main__':
url = 'http://127.0.0.1:8181/restconf/operational/opendaylight-inventory:nodes/node/openflow:1/'
headers = {'Content-Type': 'application/json'}
response = requests.delete(url=url, headers=headers, auth=HTTPBasicAuth('admin', 'admin'))
print(response.content)
(3) Distribute the hard timeout flow table to realize the network interruption of hosts h1 and h3 in the topology for 20s.
timeout.py#!/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/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)
{
"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) Get the number of active flow tables on s1.
Create the file flows.py
Click to view code#!/usr/bin/python
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)
- Write a Python program to call Ryu's northbound interface to achieve the following functions
(1) Implement the same hard timeout flow table delivery on the OpenDaylight experimental topology above.
import requests
from requests.auth import HTTPBasicAuth
if __name__ == '__main__':
url = 'http://127.0.0.1:8080/stats/flowentry/add'
headers = {'Content-Type': 'application/json'}
json = open('ryu_timeout.json').read()
response = requests.post(url, data=json, headers=headers)
print(response.content)
{
"dpid": 1,
"cookie": 1,
"cookie_mask": 1,
"table_id": 0,
"hard_timeout": 20,
"priority": 65535,
"flags": 1,
"match":{
"in_port":1
},
"actions":[]
}
(2) Refer to the documentation of Ryu REST API, based on the network topology of the VLAN experiment, program the same VLAN configuration.
Tip: Ryu needs to be connected after topology generation, and Ryu should be able to provide REST API services
| VLAN_ID | Hosts |
|---|---|
| 0 | h1 h3 |
| 1 | h2 h4 |
from mininet.topo import Topo
class MyTopo(Topo):
def __init__(self):
#initilaize topology
Topo.__init__(self)
#add hosts
h1=self.addHost('h1')
h2=self.addHost('h2')
h3=self.addHost('h3')
h4=self.addHost('h4')
#add Switches
s1=self.addSwitch('s1')
s2=self.addSwitch('s2')
#add Links
self.addLink(h1,s1,1,1)
self.addLink(h2,s1,1,2)
self.addLink(h3,s2,1,1)
self.addLink(h4,s2,1,2)
self.addLink(s1,s2,3,3)
topos = {'mytopo' : (lambda:MyTopo())}
import json
import requests
if __name__ == '__main__':
url = 'http://127.0.0.1:8080/stats/flowentry/add'
headers = {'Content-Type': 'application/json'}
f = open('ryu_vlan.json').read()
flows = json.loads(f)['flows']
[requests.post(url, data=json.dumps(flows[i]), headers=headers) for i in range(0, 8)]
{
"flows": [
{
"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
}
]
},
{
"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
}
]
},
{
"dpid": 1,
"priority": 1,
"match": {
"vlan_vid": 0
},
"actions": [{
"type": "POP_VLAN",
"ethertype": 33024
},
{
"type": "OUTPUT",
"port": 1
}
]
},
{
"dpid": 1,
"priority": 1,
"match": {
"vlan_vid": 1
},
"actions": [{
"type": "POP_VLAN",
"ethertype": 33024
},
{
"type": "OUTPUT",
"port": 2
}
]
},
{
"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
}
]
},
{
"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
}
]
},
{
"dpid": 2,
"priority": 1,
"match": {
"vlan_vid": 0
},
"actions": [{
"type": "POP_VLAN",
"ethertype": 33024
},
{
"type": "OUTPUT",
"port": 1
}
]
},
{
"dpid": 2,
"priority": 1,
"match": {
"vlan_vid": 1
},
"actions": [{
"type": "POP_VLAN",
"ethertype": 33024
},
{
"type": "OUTPUT",
"port": 2
}
]
}
]
}
(2) Advanced requirements
Choose either OpenDaylight or Ryu, and programmatically view the names of all nodes (including switches and hosts) in the pre-order VLAN experimental topology, and display all flow entries of each switch.
Click to view codeimport 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()
(3) Personal summary
- Most of this experiment needs to be implemented by code, which is quite difficult for me. With the help of constant review of materials and classmates, this experiment is completed.
- Through this experiment, I further learned the use of ODL REST API and Ryu REST API, and further learned the use of ODL and Ryu northbound interface.