标签：控制器 ryu parser 开源 datapath msg ofp ofproto RYU

实验6：开源控制器实践——RYU

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。

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

• 建立拓扑

sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk

• 连接Ryu控制器

ryu-manager ryu/ryu/app/gui_topology/gui_topology.py --observe-links

• 通过Ryu的图形界面查看网络拓扑
  在浏览器中输入地址http://127.0.0.1:8080即可打开ryu的图形界面
  

（二）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文件并添加代码

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)

• 运行L2Switch

ryu-manager L2Switch.py

• pingall可以ping通
  
• 开启主机终端

mininet>xterm h2 h3

• 在h2主机终端中输入

tcpdump -nn -i h2-eth0

• 在h3主机终端中输入

tcpdump -nn -i h3-eth0

• h1 ping h2
  
• h1 ping h3
  
• 分析L2Switch和POX的Hub模块有何不同
  Hub和L2Switch模块都是洪泛转发，但L2Switch模块下发的流表无法查看，而Hub模块下发的流表可以查看

(三)编程修改L2Switch.py，另存为L2132002143.py，使之和POX的Hub模块的变得一致

• 代码

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)

• 运行结果：
  运行

ryu-manager L2132002143.py
mininet>dpctl dump-flows

自我小结

• 本次实验对我来说较有难度，首先是对ryu不太熟悉，在做实验时比较茫然，不知道该怎么做，都是在借鉴他人的情况下将此次实验完成。最重要的是实验过程中我遇到了不少困难与问题。比如，在运行L2Switch文件时，一直pingall不通，试了很多方法，后来是在网上查询到应该先打开ryu控制器和运行L2Switch.py文件后再建立拓扑进行pingall,而且有时候还需要多试几次才能ping通。。本次实验让我对ryu的学习更加深入，让我能够独立部署RYU控制器，且能够理解RYU控制器实现软件定义的集线器原理和交换机原理，收获满满。

标签：控制器,ryu,parser,开源,datapath,msg,ofp,ofproto,RYU
From： https://www.cnblogs.com/yiguan123668/p/16805772.html