实验6:开源控制器实践——RYU
一、实验目的
能够独立部署RYU控制器;
能够理解RYU控制器实现软件定义的集线器原理;
能够理解RYU控制器实现软件定义的交换机原理。
二、实验环境
Ubuntu 20.04 Desktop amd64
三、实验要求
(一)基本要求
1.搭建下图所示SDN拓扑,协议使用Open Flow 1.0,并连接Ryu控制器,通过Ryu的图形界面查看网络拓扑。
2.阅读Ryu文档的The First Application一节,运行当中的L2Switch,h1 ping h2或h3,在目标主机使用 tcpdump 验证L2Switch,分析L2Switch和POX的Hub模块有何不同 创建L2Switch.py文件,并保存在目录/home/用户名/学号/lab6/中
from ryu.base import app_manager from ryu.controller import ofp_event from ryu.controller.handler import MAIN_DISPATCHER from ryu.controller.handler import set_ev_cls from ryu.ofproto import ofproto_v1_0 class L2Switch(app_manager.RyuApp): OFP_VERSIONS = [ofproto_v1_0.OFP_VERSION] def __init__(self, *args, **kwargs): super(L2Switch, self).__init__(*args, **kwargs) @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER) def packet_in_handler(self, ev): msg = ev.msg dp = msg.datapath ofp = dp.ofproto ofp_parser = dp.ofproto_parser actions = [ofp_parser.OFPActionOutput(ofp.OFPP_FLOOD)] data = None if msg.buffer_id == ofp.OFP_NO_BUFFER: data = msg.data out = ofp_parser.OFPPacketOut( datapath=dp, buffer_id=msg.buffer_id, in_port=msg.in_port, actions=actions, data = data) dp.send_msg(out) ![image](uploading...)
RYU的L2Switch模块和POX的Hub模块都采用洪泛转发,但不同之处在于:可以在pox的Hub模块运行时查看流表,而无法在ryu的L2Switch模块运行时查看到流表
1.编程修改L2Switch.py,另存为L2xxxxxxxxx.py,使之和POX的Hub模块的变得一致?(xxxxxxxxx为学号)
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)
四、个人总结
先验证ryu基本功能,RYU控制器在下发流表时和POX控制器都是对数据包进行泛洪转发,而且RYU不能查看对应流表项,在操作硬超时部分时,需要将openflow的版本改为1.3,并且在测试icmp时,再开启硬超时代码,就可以实现主机之间硬超时访问。