进入ryu/ryu/app目录，然后启动相应模块：
ryu-manager --verbose simple_switch_13.py ofctl_rest.py rest_topology.py
simple_switch_13.py模块是一个简单的交换机，是openflow1.3的交换机。后面的两个文件是为了进行restapi的调用加载的，方便直接用浏览器查看。
再启动mininet，远程连接ryu控制器（ip地址：192.168.231.131，如果是在一台虚拟机里，则为本地ip：127.0.0.1）：
sudo mn --controller=remote,ip=192.168.231.131,port=6653 --switch=ovsk,protocols=OpenFlow13
相应的，ryu控制器打开的终端输出信息：
下面参考https://blog.csdn.net/qq_34415266/article/details/92795959
在浏览器中调用ryu的api
①得到某台交换机的状态信息：http://192.168.231.131（这里是控制器ip地址）:8080/stats/desc/1
②查看交换机当前的流表：http://192.168.231.131（这里是控制器ip地址）:8080/stats/flow/1
查询指定交换机上所有流表的统计信息：http://192.168.231.131（这里是控制器ip地址）:8080/stats/table/1
得到端口的统计信息：http://192.168.231.131（这里是控制器ip地址）:8080/stats/port/1
得到端口配置信息：http://192.168.231.131（这里是控制器ip地址）:8080/stats/portdesc/1
在浏览器中除了可以查询流表信息外，还可以对流表进行操作，但需要支持构造post、delete等请求的浏览器插件，如httprequester、restclient等。
我这里使用的是火狐的restclient。
安装restclient：附件组件-扩展-restclient-安装
点击该插件进行使用。
例如，查看交换机1的状态信息：
其他例如：获取交换机流表
# 获取交换机列表
GET /stats/switches
# 获取某台交换机的设备信息
GET /stats/desc/<dpid>
# get flows desc stats of the switch
GET /stats/flowdesc/<dpid>
# get flows desc stats of the switch filtered by the fields
POST /stats/flowdesc/<dpid>
# 得到指定交换机的所有flow的状态信息
GET /stats/flow/<dpid>
# 有条件地查询某台交换机的流表
POST /stats/flow/<dpid>
# 查询指定交换机的全局统计流表的字段
GET /stats/aggregateflow/<dpid>
# 有条件的查询指定交换机的全局统计流表的字段
POST /stats/aggregateflow/<dpid>
# 查询指定交换机上所有流表的统计信息
GET /stats/table/<dpid>
# get table features stats of the switch
GET /stats/tablefeatures/<dpid>
# 得到端口的统计信息
GET /stats/port/<dpid>[/<port>]
# Note: Specification of port number is optional
# get queues stats of the switch
GET /stats/queue/<dpid>[/<port>[/<queue_id>]]
# Note: Specification of port number and queue id are optional
# If you want to omitting the port number and setting the queue id,
# please specify the keyword "ALL" to the port number
# e.g. GET /stats/queue/1/ALL/1
# get queues config stats of the switch
GET /stats/queueconfig/<dpid>[/<port>]
# Note: Specification of port number is optional
# get queues desc stats of the switch
GET /stats/queuedesc/<dpid>[/<port>[/<queue_id>]]
# Note: Specification of port number and queue id are optional
# If you want to omitting the port number and setting the queue id,
# please specify the keyword "ALL" to the port number
# e.g. GET /stats/queuedesc/1/ALL/1
# get meter features stats of the switch
GET /stats/meterfeatures/<dpid>
# get meter config stats of the switch
GET /stats/meterconfig/<dpid>[/<meter_id>]
# Note: Specification of meter id is optional
# get meter desc stats of the switch
GET /stats/meterdesc/<dpid>[/<meter_id>]
# Note: Specification of meter id is optional
# get meters stats of the switch
GET /stats/meter/<dpid>[/<meter_id>]
# Note: Specification of meter id is optional
# get group features stats of the switch
GET /stats/groupfeatures/<dpid>
# get groups desc stats of the switch
GET /stats/groupdesc/<dpid>[/<group_id>]
# Note: Specification of group id is optional (OpenFlow 1.5 or later)
# get groups stats of the switch
GET /stats/group/<dpid>[/<group_id>]
# Note: Specification of group id is optional
# get ports description of the switch
GET /stats/portdesc/<dpid>[/<port_no>]
# Note: Specification of port number is optional (OpenFlow 1.5 or later)
再比如更新交换机流表项
# 添加流表项
POST /stats/flowentry/add
# 修改所有匹配的流表项
POST /stats/flowentry/modify
# modify flow entry strictly matching wildcards and priority
POST /stats/flowentry/modify_strict
# delete all matching flow entries
POST /stats/flowentry/delete
# delete flow entry strictly matching wildcards and priority
POST /stats/flowentry/delete_strict
# delete all flow entries of the switch
DELETE /stats/flowentry/clear/<dpid>
# add a meter entry
POST /stats/meterentry/add
# modify a meter entry
POST /stats/meterentry/modify
# delete a meter entry
POST /stats/meterentry/delete
# add a group entry
POST /stats/groupentry/add
# modify a group entry
POST /stats/groupentry/modify
# delete a group entry
POST /stats/groupentry/delete
# modify behavior of the physical port
POST /stats/portdesc/modify
# modify role of controller
POST /stats/role
# send a experimeter message
POST /stats/experimenter/<dpid>