实验7：基于REST API的SDN北向应用实践

2023-11-22 19:24:16

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

OpenDaylight

（1）利用Mininet平台搭建下图所示网络拓扑，并连接OpenDaylight；

（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
    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'}
	resp = requests.delete(url,headers=headers,auth=HTTPBasicAuth('admin', 'admin'))
	print(resp.content)

（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.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("./flowtable.json") as f:
		jstr = f.read()
	headers = {'Content-Type':'application/json'}
	resp = requests.put(url,jstr,headers=headers,auth=HTTPBasicAuth('admin', 'admin'))
	print(resp.content)

（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
    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'}
	resp = requests.get(url,headers=headers, auth=HTTPBasicAuth('admin', 'admin'))
	print(resp.content)

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

（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。

（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

# 将主机1，2发送来的数据包打上vlan标记
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

# 将主机3，4发送来的数据包取出vlan标记
 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

# 将主机3，4发送来的数据包打上vlan标记
 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

四、个人总结

实验难度：个人认为本次实验有一定难度，难度主要体现在python程序与shell脚本的编写上
实验中遇到的困难及解决办法：

困难1：在获取流表时出现以下报错信息：

解决办法：后发现是python文件编写出错，经修改后运行成功
困难2：调用shell脚本时出现以下报错信息：curl command not found
解决方法：使用apt-get install curl命令完成curl安装即可运行成功
困难3：在实现Ryu实验拓扑上的硬超时流表下发时调用python程序不影响通信。
解决办法：在开启ryu控制器时使用组件simple_switch_13.py,ofctl_rest.py

个人感想：在完成这项实验的时候因为不懂python语言还是遇到了比较多的问题吧，后来时根据文档示例和其他同学的程序慢慢摸索出来了。在整个实验中初步学习到了怎么去调用OpenDaylight REST API/Ryu REST API实现特定网络功能，收获颇丰，但在下一次实验中一些细节上的问题还用多多注意。

码农公寓

一、实验目的

二、实验环境

三、实验要求

四、个人总结

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