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
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。

!/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)
（3） 下发硬超时流表，实现拓扑内主机h1和h3网络中断20s。

timeout.py

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)

timeout.json

{
"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） 获取s1上活动的流表数。

getflow.py

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)
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。

ryu_timeOut.py

1 # ryu_timeout.py
2 import requests
3 if name == "main":
4 url = 'http://127.0.0.1:8080/stats/flowentry/add'
5 with open("./ryu_timeOut.json") as file:
6 str = file.read()
7 headers = {'Content-Type': 'application/json'}
8 res = requests.post(url, str, headers=headers)
9 print (res.content)

ryu_timeOut.json

ryu_timeout.json

{
"dpid": 1,
"cookie": 1,
"cookie_mask": 1,
"table_id": 0,
"hard_timeout": 20,
"priority": 65535,
"flags": 1,
"match":{
"in_port":1
},
"actions":[

]

}

（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
VLAN_ID Hosts
0 h1 h3
1 h2 h4

!/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())}

curl -X POST -d '{
"dpid": 1,
"priority": 1,
"match":{
"in_port": 1
},
"actions":[
{
"type": "PUSH_VLAN", # Push a new VLAN tag if a input frame is non-VLAN-tagged
"ethertype": 33024 # Ethertype 0x8100(=33024): IEEE 802.1Q VLAN-tagged frame
},
{
"type": "SET_FIELD",
"field": "vlan_vid", # Set VLAN ID
"value": 4096 # Describe sum of vlan_id(e.g. 6) | OFPVID_PRESENT(0x1000=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", # Push a new VLAN tag if a input frame is non-VLAN-tagged
"ethertype": 33024 # Ethertype 0x8100(=33024): IEEE 802.1Q VLAN-tagged frame
},
{
"type": "SET_FIELD",
"field": "vlan_vid", # Set VLAN ID
"value": 4097 # Describe sum of vlan_id(e.g. 6) | OFPVID_PRESENT(0x1000=4096)
},
{
"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", # Push a new VLAN tag if a input frame is non-VLAN-tagged
"ethertype": 33024 # Ethertype 0x8100(=33024): IEEE 802.1Q VLAN-tagged frame
},
{
"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", # Push a new VLAN tag if a input frame is non-VLAN-tagged
"ethertype": 33024 # Ethertype 0x8100(=33024): IEEE 802.1Q VLAN-tagged frame
},
{
"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", # Push a new VLAN tag if a input frame is non-VLAN-tagged
"ethertype": 33024 # Ethertype 0x8100(=33024): IEEE 802.1Q VLAN-tagged frame
},
{
"type": "SET_FIELD",
"field": "vlan_vid", # Set VLAN ID
"value": 4096 # Describe sum of vlan_id(e.g. 6) | OFPVID_PRESENT(0x1000=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", # Push a new VLAN tag if a input frame is non-VLAN-tagged
"ethertype": 33024 # Ethertype 0x8100(=33024): IEEE 802.1Q VLAN-tagged frame
},
{
"type": "SET_FIELD",
"field": "vlan_vid", # Set VLAN ID
"value": 4097 # Describe sum of vlan_id(e.g. 6) | OFPVID_PRESENT(0x1000=4096)
},
{
"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", # Push a new VLAN tag if a input frame is non-VLAN-tagged
"ethertype": 33024 # Ethertype 0x8100(=33024): IEEE 802.1Q VLAN-tagged frame
},
{
"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", # Push a new VLAN tag if a input frame is non-VLAN-tagged
"ethertype": 33024 # Ethertype 0x8100(=33024): IEEE 802.1Q VLAN-tagged frame
},
{
"type": "OUTPUT",
"port": 2
}
]
}' http://localhost:8080/stats/flowentry/add

（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 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)

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(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()
（三）实验报告
本次实验内容难度是这几次实验中最大的，问题的存在也是最多的，在这次实验中，要写的代码特别多，作业量很大。
在实现流表超时操作时，OpenDaylight忘记关掉会导致ryu的流表超时操作失效，一开始我检查了好几次，都没发现这个问题，一直对代码进行查找，后面是同学提醒才得以解决，还有在写代码是也是要非常细心，一不小心就容易把代码打错，导致在运行的时候都没按预期的运行，后面查找很是麻烦，在此次实验中我吃了不少这样的亏。
总的来说本次实验考的是我们对本门课的总体知识点的集合，综合性很强。