RYU+Mininet实现Hub泛洪

RYU+Mininet实现Hub泛洪
系统：Ubuntu20.10 ，已安装 ryu 和 mininet
在ryu/ryu/app下创建了文件hub.py，代码如下：
hub.py（含注释）

from ryu.base import app_manager
from ryu.ofproto import ofproto_v1_3 #openflow版本：1.3
from ryu.controller import ofp_event
from ryu.controller.handler import MAIN_DISPATCHER, CONFIG_DISPATCHER
from ryu.controller.handler import set_ev_cls

#定义一个类hub，继承app_manager，位于ryu下的base内，版本选择openflow1.3，然后初始化操作。
class hub(app_manager.RyuApp):
    OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION]#定义版本
 
	#类的初始化函数
    def __init__(self, *args, **kwargs):#最后一个是可变参数#
        super(hub, self).__init__(*args, **kwargs)
		
	
	#在Ryu控制器上，我们需要写一个函数去处理openvswitch的连接，同时需要开启一个监听，监听交换机事件。
	@set_ev_cls(ofp_event.EventOFPSwitchFeatures,CONFIG_DISPATCHER)
	def  switch_features_handler(self,ev):
		#解析数据
		#datapath如同数据平面的通道，可以等同于网桥
		datapath = ev.msg.datapath
		ofproto = datapath.ofproto#版本
		ofp_parser = datapath.ofproto_parser#基于此版本的一些库类
		
		
		#接收到交换机的连接之后，要下发一条tableentrys，一个默认流表，来指挥所有匹配不到交换机的数据，将其上传至控制器
		#install the table miss flow entry,即在ryu控制器里安装流表项 
		#匹配域
		match = ofp_parser.OFPMatch()
		#动作域,OFPActionOutPut将数据包发送出去
		#第一个参数：发送端口：控制器（把那些没有匹配的东西给控制器）
		#第二个参数：数据包在交换机上缓存buffer_id,由于我们将数据包全部传送到控制器，所以不在交换机上缓存
		actions = [ofp_parser.OFPActionOutput(ofproto.OFPP_CONTROLLER, ofproto.OFPCML_NO_BUFFER)]
		self.add_flow(datapath,0,match,actions)
		 
	
	#提高代码重用，对于添加流表，单独拿出了写一个函数。
	def add_flow(self,datapath,priority,match,actions):
		#add a flow entry and install it into datapath
		# 1\ datapath for the switch, 2\priority for flow entry, 3\match field, 4\action for packet
        ofproto = datapath.ofproto
        ofp_parser = datapath.ofproto_parser
		#1.3版本交换机中需有指令
        # install flow
		# construct a flow_mod msg and sent it
        inst = [ofp_parser.OFPInstructionActions(ofproto.OFPIT_APPLY_ACTIONS, actions)]#inst指令的缩写
        mod = ofp_parser.OFPFlowMod(datapath=datapath, priority=priority, match=match, instructions=inst)
        datapath.send_msg(mod)
	
	
	#需要定义packet in函数，用来处理交换机和控制器的流表交互，在执行之前需要先对packetin事件进行监听。
	
	
	
	@set_ev_cls(ofp_event.EventOFPPackIn,MAIN_DISPATCHER)#MAIN_DISPATCHER：主状态下监听事件
	def packet_in_handler(self,ev):
		#数据解析
		msg = ev.msg
		datapath = msg.datapath
		ofproto = datapath.ofproto
		ofp_parser = datapath.ofproto_parser
		#match匹配域中提取in_port
		in_port = msg.match['in_port']
		
		#发送出去（通过加一个流表）
		#construct a flow entry
		match = ofp_parser.OFPMatch()#匹配项为空，因为所有取到的内容都要泛洪出去
        actions = [ofp_parser.OFPActionOutput(ofproto.OFPP_FLOOD)]#泛洪动作
		#调用添加流表的函数，把流表发送出去
		# install flow mode to avoid match in next time
		self.add_flow(datapath,1,match,actions)
		
		
		#处理当下的pack_in，给他发出去
		#buffer_id是一个非常重要的参数，因为，数据包进入交换机，总得有个地方暂存，而取的时候就需要有id来指定
		# to output the current packet. for install rules only output later packets
        out = ofp_parser.OFPPacketOut(datapath=datapath, buffer_id=msg.buffer_id, in_port=in_port, actions=actions)
		 
		# buffer id: locate the buffered packet
        datapath.send_msg(out)	
		

hub.py（建议使用此版本运行）

from ryu.base import app_manager
from ryu.ofproto import ofproto_v1_3
from ryu.controller import ofp_event
from ryu.controller.handler import MAIN_DISPATCHER, CONFIG_DISPATCHER
from ryu.controller.handler import set_ev_cls
 
 
class hub(app_manager.RyuApp):
    OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION]
 
    def __init__(self, *args, **kwargs):
        super(hub, self).__init__(*args, **kwargs)
 
    @set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER)
    def switch_feathers_handler(self, ev):
        datapath = ev.msg.datapath
        ofproto = datapath.ofproto
        ofp_parser = datapath.ofproto_parser
 
        # install flow table-miss flow entry
        match = ofp_parser.OFPMatch()
        actions = [ofp_parser.OFPActionOutput(ofproto.OFPP_CONTROLLER, ofproto.OFPCML_NO_BUFFER)]
        # 1\OUTPUT PORT, 2\BUFF IN SWITCH?
        self.add_flow(datapath, 0, match, actions)
 
    def add_flow(self, datapath, priority, match, actions):
        # 1\ datapath for the switch, 2\priority for flow entry, 3\match field, 4\action for packet
        ofproto = datapath.ofproto
        ofp_parser = datapath.ofproto_parser
        # install flow
        inst = [ofp_parser.OFPInstructionActions(ofproto.OFPIT_APPLY_ACTIONS, actions)]
        mod = ofp_parser.OFPFlowMod(datapath=datapath, priority=priority, match=match, instructions=inst)
        datapath.send_msg(mod)
 
    @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
    def packet_in_handler(self, ev):
        msg = ev.msg
        datapath = msg.datapath
        ofproto = datapath.ofproto
        ofp_parser = datapath.ofproto_parser
        in_port = msg.match['in_port']  # get in port of the packet
 
        # add a flow entry for the packet
        match = ofp_parser.OFPMatch()
        actions = [ofp_parser.OFPActionOutput(ofproto.OFPP_FLOOD)]
        self.add_flow(datapath, 1, match, actions)
 
        # to output the current packet. for install rules only output later packets
        out = ofp_parser.OFPPacketOut(datapath=datapath, buffer_id=msg.buffer_id, in_port=in_port, actions=actions)
        # buffer id: locate the buffered packet
        datapath.send_msg(out)
        

运行hub.py成功：

启动mininet ，创建一个最简单的拓扑，pingall命令成功：

说实话还没get到这个实验核心…还是很懵