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. 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;

    拓扑结构

    启动连接ODL控制器,查看图形界面

    (2) 下发指令删除s1上的流表数据。

    python代码

    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。

    python代码块

    #!/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('timeout.json') as f:
            jstr = f.read()
        resp = http_put(url,jstr)
        print (resp.content)
    
    

    json文件内容

    {
      "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"
        }
      ]
    }
    
    

    (4) 获取s1上活动的流表数。

    python代码

    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)
    
    

  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。

    python代码

    import requests
    
    if __name__ == "__main__":
        url = 'http://127.0.0.1:8080/stats/flowentry/add'
        with open("./RYUflowtable.json") as f:
            jstr = f.read()
        headers = {'Content-Type': 'application/json'}
        res = requests.post(url, jstr, headers=headers)
        print (res.content)
    
    

    json文件内容

    {
        "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。

    生成拓扑结构

    topo.py

    #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())}
    
    

    vlan.py

    # 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)
    
    

    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

(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。

getall.py

# 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()

四、实验总结

通过此次实验,我对OpenDaylight和Ryu的相关知识有了更加深入的了解。此次实验还是有一定的难度,对操作(诸如通过python编程来使用ODL REST API和Ryu Rest API ),文件的理解都有一定的要求,在整个实验过程中,我也遇到了一些问题。

比如说,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的要求里,我始终无法运行成功书写的ryuouttime.py的文件,后来才察觉到是我一开始就没有打开ryu,导致出现低级错误,这表明我对ryu的基本操作还不是十分的熟悉。后来在阅读相关文件后,我的实验过程进行得相对顺利了许多,后面有遇到无法识别“curl”的提示,只需按照系统的提示输入“sudo apt-get install curl ”的命令就能够解决。

总之,这次实验是一个比较综合的实验,对许多操作与认知的考察都比以往的实验要上一个层次,需要更多的学习与理解。

posted @ 2022-10-25 18:32  忆然BILL  阅读(25)  评论(0编辑  收藏  举报