实验7：基于REST API的SDN北向应用实践

（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；

• 建立拓扑
  命令：sudo mn --topo=single,3 --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13
  
• 启动ODL
  命令：./distribution-karaf-0.4.4-Beryllium-SR4/bin/karaf
  
  （2） 下发指令删除s1上的流表数据。
• 实现上述OpenDaylight实验拓扑上相同的硬超时流表下发。
  在lab7中建立delete.py并编写,调用OpenDaylight的北向接口下发指令删除s1上的流表数据
  delete.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/'
    headers = {'Content-Type': 'application/json'}
    response = requests.delete(url=url, headers=headers, auth=HTTPBasicAuth('admin', 'admin'))
    print(response.content)

（3） 下发硬超时流表，实现拓扑内主机h1和h3网络中断20s。

• 编写timeout.py及timeout.json，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
  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)

timeout.json

（4） 获取s1上活动的流表数。

• 编写get_flows.py，调用OpenDaylight的北向接口获取s1上活动的流表数
  
  2、编写Python程序，调用Ryu的北向接口实现以下功能
  （1）编写ryu_timeout.py及ryu_timeout.json，调用Ryu的北向接口实现硬超时流表下发
  ryu_timeout.py

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)

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":[]
 }

• 启动ryu
  命令：ryu-manager ryu.app.simple_switch_13 ryu.app.ofctl_rest
  
• 建立拓扑
  命令：sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13
  
• 运行ryu_timeout.py
  
• 实现硬超时功能
  
  （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
  
• 根据VLAN网络拓扑编写ryu_topo.py
  ryu_topo.py

from mininet.topo import Topo
 
class ryu_topo(Topo):
    def __init__(self):
        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 = {'ryu_topo': (lambda: ryu_topo())}

• ryu_vlan.json

{
	"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
				}
			]
		}
	]
}

• 启动ryu
  命令：ryu-manager ryu.app.simple_switch_13 ryu.app.ofctl_rest
  
• 建立拓扑
  命令：sudo mn --custom ryu_topo.py --topo ryu_topo --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13
  
• 删除流表
  
  运行，实现配置
  
  （二）实验总结
  这次实验的难度较大，对python的代码掌握要求高，很多代码都是参考别人的，还综合了很多前几次实验的内容odl、ryu等，综合性强。通过这次实验加强了对调用OpenDaylight REST API实现特定网络功能、调用Ryu REST API实现特定网络功能的相关了解。