实验7：基于REST API的SDN北向应用实践

2024-01-04 11:16:52

实验7：基于REST API的SDN北向应用实践

一、实验目的

  1. 能够编写程序调用OpenDaylight REST API实现特定网络功能；
  2. 能够编写程序调用Ryu REST API实现特定网络功能。

二、实验环境

  1. 下载虚拟机软件Oracle VisualBox或VMware；
  2. 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；

实验7：基于REST API的SDN北向应用实践

sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13

（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。

import requests
headers = {'Content-Type': 'application/json'}

def del_flowtable(url): 
resp = requests.delete(url, headers=headers) 
return resp 
if __name__ == "__main__": 
url = "http://127.0.0.1:8181/restconf/config/opendaylight-inventory:nodes/node/openflow:1/" 
resp = del_flowtable(url)
print(resp.content)
  • 执行结果

实验7：基于REST API的SDN北向应用实践

（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。

import requests
from requests.authhttps://img-community.csdnimg.cn/images/b0db6392f4d34260b0c797fc198256f9.png "=600 #left")
import HTTPBasicAuth

headers = {'Content-Type': 'application/json'}

def dump_flowtable(url, jstr):
	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("./flowtable.json") as f:
		jstr = f.read()
	resp = dump_flowtable(url, jstr)
	print(resp.content)

flowtable.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": "flow1",
      "priority": "65535",
      "hard-timeout": "20",
      "cookie": "2",
      "table_id": "0"
    }
  ]
}
  • 执行结果

实验7：基于REST API的SDN北向应用实践

（4) 编写Python程序，调用OpenDaylight的北向接口获取s1上活动的流表数。

import requests
from requests.auth import HTTPBasicAuth

headers = {'Content-Type': 'application/json'}

def get_flowtable(url):
	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 = get_flowtable(url)
	print(resp.content)
  • 执行结果

实验7：基于REST API的SDN北向应用实践

  1. 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。

    import requests

headers = {'Content-Type': 'application/json'}

def dump_flowtable(url, jstr):
	resp = requests.put(url, jstr, headers=headers)
	return resp

if __name__ == "__main__":
	url = "http://127.0.0.1:8080/stats/flowentry/add"
	with open("./flowtable.json") as f:
		jstr = f.read()
	resp = dump_flowtable(url, jstr)
	print(resp.content)

    flowtable.json

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

    ]
 }

    命令行终端输入

    ryu-manager ryu.app.simple_switch_13 ryu.app.ofctl_rest

    启动RYU控制器

    • 执行结果

实验7：基于REST API的SDN北向应用实践

（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。
实验7：基于REST API的SDN北向应用实践

拓扑建立代码：

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())}

构建拓扑：

sudo sudo mn --custom mytopo.py --topo mytopo --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13

实验7：基于REST API的SDN北向应用实践

（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

删除流表

curl -X DELETE http://localhost:8080/stats/flowentry/clear/1
curl -X DELETE http://localhost:8080/stats/flowentry/clear/2

运行shell脚本 vlan.sh

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
  • 运行结果：

实验7：基于REST API的SDN北向应用实践

四、实验心得

本次实验的主要内容是能够编写程序调用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。

实验难度：比较困难

本次实验的实验内容是以先前几次实验为基础进行的，因此在进行实验时需要回顾之前所学习的内容与知识，因此实验的内容也比较多并且要编写程序，编写代码的难度比较大。并且新学习了SHELL脚本，以及如何运行shell脚本。

  • 问题
  1. RYU在运行经常[ERROR 98] Address already in use，通过重新启动虚拟机或者将运行中的ODL退出。
  2. ryu实验用系统内置的simple_switch_13.py和ofctl_rest.py。
  3. Command ‘curl’ not found，没有安装curl，需要根据提示安装curl。使用sh脚本要用到CRUL命令删除流表后在运行脚本。
  4. ping的时候，显示主机不可达，重启虚拟机然后重新建立拓扑解决问题。
  • 收获
  1. 本次实验通过实践动手进行python编程，练习了如何使用OpenDaylight REST API和Ryu REST API实现调用网络功能。
  2. 对于Open DayLight 和 Ryu的使用和北向API都有更好的理解。
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