一、基本要求
二、进阶要求
- 1、阅读Ryu关于simple_switch.py和simple_switch_1x.py的实现，以simple_switch_13.py为例，完成其代码的注释工作，并回答下列问题：
  - · 代码注释
  - · 回答下列问题
- 2、编程实现和ODL实验的一样的硬超时功能。
  - · 创建文件Hard_timeout.py
  - · 运行结果
三、心得体会

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

· 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并pingall

· 开启主机终端

· 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

3、编编程修改L2Switch.py，另存为L2xxxxxxxxx.py，使之和POX的Hub模块的变得一致？（xxxxxxxxx为学号）

· 创建文件L2032002629.py

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

二、进阶要求

1、阅读Ryu关于simple_switch.py和simple_switch_1x.py的实现，以simple_switch_13.py为例，完成其代码的注释工作，并回答下列问题：

· 代码注释

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# 引入数据包
from ryu.base import app_manager
from ryu.controller import ofp_event
from ryu.controller.handler import CONFIG_DISPATCHER, MAIN_DISPATCHER
from ryu.controller.handler import set_ev_cls
from ryu.ofproto import ofproto_v1_3
from ryu.lib.packet import packet
from ryu.lib.packet import ethernet
from ryu.lib.packet import ether_types


class SimpleSwitch13(app_manager.RyuApp):
  # 定义openflow版本
  OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION]

  def __init__(self, *args, **kwargs):
      super(SimpleSwitch13, self).__init__(*args, **kwargs)
      self.mac_to_port = {}  # 定义保存mac地址到端口的一个映射

  # 处理SwitchFeatures事件
  @set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER)
  def switch_features_handler(self, ev):
      datapath = ev.msg.datapath
      ofproto = datapath.ofproto
      parser = datapath.ofproto_parser

      # install table-miss flow entry
      #
      # We specify NO BUFFER to max_len of the output action due to
      # OVS bug. At this moment, if we specify a lesser number, e.g.,
      # 128, OVS will send Packet-In with invalid buffer_id and
      # truncated packet data. In that case, we cannot output packets
      # correctly.  The bug has been fixed in OVS v2.1.0.
      match = parser.OFPMatch()  # match指流表项匹配，OFPMatch()指不匹配任何信息
      actions = [parser.OFPActionOutput(ofproto.OFPP_CONTROLLER,
                                        ofproto.OFPCML_NO_BUFFER)]
      self.add_flow(datapath, 0, match, actions)

  # add_flow()增加流表项
  # datapath：指定的 Switch
  # priority：此规则的优先权
  # match：此规则的 Match 条件
  # actions：动作
  def add_flow(self, datapath, priority, match, actions, buffer_id=None):
      # 获取交换机信息
      ofproto = datapath.ofproto
      parser = datapath.ofproto_parser
      # 对action进行包装
      inst = [parser.OFPInstructionActions(ofproto.OFPIT_APPLY_ACTIONS,
                                           actions)]
      # 判断是否存在buffer_id，并生成mod对象
      if buffer_id:
          mod = parser.OFPFlowMod(datapath=datapath, buffer_id=buffer_id,
                                  priority=priority, match=match,
                                  instructions=inst)
      else:
          mod = parser.OFPFlowMod(datapath=datapath, priority=priority,
                                  match=match, instructions=inst)
      # 发送出去
      datapath.send_msg(mod)

  # 处理PacketIn事件
  @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
  def _packet_in_handler(self, ev):
      # If you hit this you might want to increase
      # the "miss_send_length" of your switch
      if ev.msg.msg_len < ev.msg.total_len:
          self.logger.debug("packet truncated: only %s of %s bytes",
                            ev.msg.msg_len, ev.msg.total_len)
      # 解析数据结构
      msg = ev.msg    # ev.msg 是代表packet_in data structure对象
      datapath = msg.datapath
      # dp. ofproto 和 dp.ofproto_parser 是代表 Ryu 和交换机谈判的 OpenFlow 协议的对象
      # dp.ofproto and dp.ofproto_parser are objects that represent the OpenFlow protocol that Ryu and the switch negotiated
      ofproto = datapath.ofproto
      parser = datapath.ofproto_parser
      in_port = msg.match['in_port']  # 获取源端口

      pkt = packet.Packet(msg.data)
      eth = pkt.get_protocols(ethernet.ethernet)[0]

      if eth.ethertype == ether_types.ETH_TYPE_LLDP:
          # 忽略LLDP类型的数据包
          # ignore lldp packet
          return
      dst = eth.dst  # 获取目的端口
      src = eth.src  # 获取源端口

      dpid = format(datapath.id, "d").zfill(16)
      self.mac_to_port.setdefault(dpid, {})

      self.logger.info("packet in %s %s %s %s", dpid, src, dst, in_port)

      # 学习包的源地址，和交换机上的入端口绑定
      # learn a mac address to avoid FLOOD next time.
      self.mac_to_port[dpid][src] = in_port

      # 查看是否已经学习过该目的mac地址
      if dst in self.mac_to_port[dpid]:  # 如果目的地址存在于mac_to_port中
          out_port = self.mac_to_port[dpid][dst]
      # 否则，洪泛
      else:
          out_port = ofproto.OFPP_FLOOD  # OFPP_FLOOD标志表示应在所有端口发送数据包，即洪泛

      actions = [parser.OFPActionOutput(out_port)]

      # 下发流表避免下次触发 packet in 事件
      # install a flow to avoid packet_in next time
      if out_port != ofproto.OFPP_FLOOD:
          match = parser.OFPMatch(in_port=in_port, eth_dst=dst, eth_src=src)
          # verify if we have a valid buffer_id, if yes avoid to send both
          # flow_mod & packet_out
          if msg.buffer_id != ofproto.OFP_NO_BUFFER:
              self.add_flow(datapath, 1, match, actions, msg.buffer_id)
              return
          else:
              self.add_flow(datapath, 1, match, actions)
      data = None
      if msg.buffer_id == ofproto.OFP_NO_BUFFER:
          data = msg.data

      # 发送Packet_out数据包
      out = parser.OFPPacketOut(datapath=datapath, buffer_id=msg.buffer_id,
                                in_port=in_port, actions=actions, data=data)
      # 发送流表
      datapath.send_msg(out)

· 回答下列问题

a) 代码当中的mac_to_port的作用是什么？

mac_to_port的作用是保存mac地址到交换机端口的映射

b) simple_switch和simple_switch_13在dpid的输出上有何不同？

在simple_switch_13.py中为dpid = format(datapath.id, "d").zfill(16)
在simple_switch.py中为dpid = datapath.id
在simple_switch_13.py中使用了zfill() 方法返回指定长度为16的字符串，原字符串右对齐，前面填充0；而simple_switch.py直接输出dpid

c) 相比simple_switch，simple_switch_13增加的switch_feature_handler实现了什么功能？

增加了实现交换机以特性应答消息响应特性请求功能

d) simple_switch_13是如何实现流规则下发的？

在触发PacketIn事件后，首先解析相关数据结构，获取协议信息、获取源端口、包学习，交换机信息，以太网信息，等。如果以太网类型是LLDP类型，则忽略。如果不是LLDP类型，则获取目的端口和源端口还有交换机id，然后进行交换机自学习，先学习源地址对应的交换机的入端口，再查看是否已经学习目的mac地址，如果没有就洪泛转发。如果学习过，则查看是否有buffer_id，如果有则在添加流时加上buffer_id，向交换机发送数据包和流表。

e) switch_features_handler和_packet_in_handler两个事件在发送流规则的优先级上有何不同？

switch_features_handler下发流表的优先级比_packet_in_handler高

2、编程实现和ODL实验的一样的硬超时功能。

· 创建文件Hard_timeout.py

# Copyright (C) 2011 Nippon Telegraph and Telephone Corporation.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from ryu.base import app_manager
from ryu.controller import ofp_event
from ryu.controller.handler import CONFIG_DISPATCHER, MAIN_DISPATCHER
from ryu.controller.handler import set_ev_cls
from ryu.ofproto import ofproto_v1_3
from ryu.lib.packet import packet
from ryu.lib.packet import ethernet
from ryu.lib.packet import ether_types


class SimpleSwitch13(app_manager.RyuApp):
    OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION]

    def __init__(self, *args, **kwargs):
        super(SimpleSwitch13, self).__init__(*args, **kwargs)
        self.mac_to_port = {}

    @set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER)
    def switch_features_handler(self, ev):
        datapath = ev.msg.datapath
        ofproto = datapath.ofproto
        parser = datapath.ofproto_parser

        # install table-miss flow entry
        #
        # We specify NO BUFFER to max_len of the output action due to
        # OVS bug. At this moment, if we specify a lesser number, e.g.,
        # 128, OVS will send Packet-In with invalid buffer_id and
        # truncated packet data. In that case, we cannot output packets
        # correctly.  The bug has been fixed in OVS v2.1.0.
        match = parser.OFPMatch()
        actions = [parser.OFPActionOutput(ofproto.OFPP_CONTROLLER,
                                          ofproto.OFPCML_NO_BUFFER)]
        self.add_flow(datapath, 0, match, actions)

    def add_flow(self, datapath, priority, match, actions, buffer_id=None, hard_timeout=0):
        ofproto = datapath.ofproto
        parser = datapath.ofproto_parser

        inst = [parser.OFPInstructionActions(ofproto.OFPIT_APPLY_ACTIONS,
                                             actions)]
        if buffer_id:
            mod = parser.OFPFlowMod(datapath=datapath, buffer_id=buffer_id,
                                    priority=priority, match=match,
                                    instructions=inst, hard_timeout=hard_timeout)
        else:
            mod = parser.OFPFlowMod(datapath=datapath, priority=priority,
                                    match=match, instructions=inst, hard_timeout=hard_timeout)
        datapath.send_msg(mod)

    @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
    def _packet_in_handler(self, ev):
        # If you hit this you might want to increase
        # the "miss_send_length" of your switch
        if ev.msg.msg_len < ev.msg.total_len:
            self.logger.debug("packet truncated: only %s of %s bytes",
                              ev.msg.msg_len, ev.msg.total_len)
        msg = ev.msg
        datapath = msg.datapath
        ofproto = datapath.ofproto
        parser = datapath.ofproto_parser
        in_port = msg.match['in_port']

        pkt = packet.Packet(msg.data)
        eth = pkt.get_protocols(ethernet.ethernet)[0]

        if eth.ethertype == ether_types.ETH_TYPE_LLDP:
            # ignore lldp packet
            return
        dst = eth.dst
        src = eth.src

        dpid = format(datapath.id, "d").zfill(16)
        self.mac_to_port.setdefault(dpid, {})

        self.logger.info("packet in %s %s %s %s", dpid, src, dst, in_port)

        # learn a mac address to avoid FLOOD next time.
        self.mac_to_port[dpid][src] = in_port

        if dst in self.mac_to_port[dpid]:
            out_port = self.mac_to_port[dpid][dst]
        else:
            out_port = ofproto.OFPP_FLOOD

        actions = [parser.OFPActionOutput(out_port)]\

        actions_timeout=[]

        # install a flow to avoid packet_in next time
        if out_port != ofproto.OFPP_FLOOD:
            match = parser.OFPMatch(in_port=in_port, eth_dst=dst, eth_src=src)
            # verify if we have a valid buffer_id, if yes avoid to send both
            # flow_mod & packet_out
            hard_timeout=10
            if msg.buffer_id != ofproto.OFP_NO_BUFFER:
                self.add_flow(datapath, 2, match,actions_timeout, msg.buffer_id,hard_timeout=10)
                self.add_flow(datapath, 1, match, actions, msg.buffer_id)
                return
            else:
                self.add_flow(datapath, 2, match, actions_timeout, hard_timeout=10)
                self.add_flow(datapath, 1, match, actions)
        data = None
        if msg.buffer_id == ofproto.OFP_NO_BUFFER:
            data = msg.data

        out = parser.OFPPacketOut(datapath=datapath, buffer_id=msg.buffer_id,
                                  in_port=in_port, actions=actions, data=data)
        datapath.send_msg(out)

· 运行结果

三、心得体会

通过这次实验，初步学习了ryu的应用。通过对ryu的实际使用流表的查询和对比，理解了pox与ryu转发流表的区别，pox是直接向交换机发送流表项的，而ryu要经过处理packet_in事件后，才向交换机下发流表，且更加深入得理解了mininet控制流表下发和硬超时。本次实验较难，遇到了不少小问题，但通过文档的阅读和查阅资料基本都能顺利解决。
遇到的问题：运行ryu后pingall时ping不通
解决的方法：运行顺序出错，应该先运行.py文件再运行ryu，最后建立拓扑。
遇到的问题：Hard_timeout.py运行完无法硬超时
解决的方法：先建立拓扑再运行Hard_timeout.py

posted on 2022-10-18 20:25 aaagain 阅读(72) 评论(0) 编辑收藏举报

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公告

导航

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

· 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文件并添加代码

· 运行L2Switch并pingall

· 开启主机终端

· h1 ping h2

· h1 ping h3

· 分析L2Switch和POX的Hub模块有何不同

3、编编程修改L2Switch.py，另存为L2xxxxxxxxx.py，使之和POX的Hub模块的变得一致？（xxxxxxxxx为学号）

· 创建文件L2032002629.py

· 运行结果

二、进阶要求

1、阅读Ryu关于simple_switch.py和simple_switch_1x.py的实现，以simple_switch_13.py为例，完成其代码的注释工作，并回答下列问题：

· 代码注释

· 回答下列问题

a) 代码当中的mac_to_port的作用是什么？

b) simple_switch和simple_switch_13在dpid的输出上有何不同？

c) 相比simple_switch，simple_switch_13增加的switch_feature_handler实现了什么功能？

d) simple_switch_13是如何实现流规则下发的？

e) switch_features_handler和_packet_in_handler两个事件在发送流规则的优先级上有何不同？

2、编程实现和ODL实验的一样的硬超时功能。

· 创建文件Hard_timeout.py

· 运行结果

三、心得体会