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。

点击查看代码

# delete.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/'
headers = {'Content-Type': 'application/json'}
res = requests.delete(url, headers=headers, auth=HTTPBasicAuth('admin', 'admin'))
print (res.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 import requests if __name__ == "__main__": url = 'http://127.0.0.1:8080/stats/flowentry/add' with open("./ryu_timeout.json") as file: str = file.read() headers = {'Content-Type': 'application/json'} res = requests.post(url, str, headers=headers) print (res.content)
# 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

点击查看代码

# ryu_topo.py 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())}

点击查看代码

# ryu_vlan.py 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)

VLAN_ID Hosts
0 h1 h3
1 h2 h4
（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。

点击查看代码

# getall.py 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）个人总结
本次实验操作难度较低，但比较难理解。本次实验需要有一定的Python基础，需要通过api来完成各种功能。实验过程中出现了一些问题，由于以前一直没有更改默认的python版本号，以前使用的python命令是python3，导致这次运行py文件时一直报错。curl也要先使用sudo apt install curl安装。安装curl时会出现锁的情况需要删除进程和删除锁ryu实验中创建的拓扑无法连接上控制器，需要使用命令ryu-manager ryu.app.simple_switch_13 ryu.app.ofctl_rest打开Ryu控制器。使用curl时需要sudo授权。这实验过程中也遇到不少问题，但是最后都通过老师和同学的帮助解决了，