实验6:开源控制器实践——RYU

一.基本要求需提交:回答基础要求2中有何不同,提交修改过的L2xxxxxxxxx.py代码和能够体现和验证修改的相关截图;
1.开启ryu控制器

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

2.搭建SDN拓扑,协议使用Open Flow 1.0,并连接Ryu控制器。

sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow10

3.创建L2Switch

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)

4.运行当中的L2Switch

ryu-manager L2Switch.py

5.h1 ping h2或h3,在目标主机使用 tcpdump 验证L2Switch

6.分析和POX的Hub模块有何不同
1)查看下发流表

dpctl dump-flows

2)运行ryu

ryu-manager L2Switch.py

3)运行pox(Hub模块)

./pox.py log.level --DEBUG forwarding.hub

·L2Switch查看下发流表

·pox的Hub模块查看下发流表

4)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

5.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
1)修改过后的L212002325.py代码

from ryu.base import app_manager
from ryu.controller import ofp_event
from ryu.controller.handler import MAIN_DISPATCHER, CONFIG_DISPATCHER
from ryu.controller.handler import set_ev_cls
from ryu.ofproto import ofproto_v1_3 #openflow版本:1.3(1.3才支持config协议)

#定义一个类L2Switch,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 L2Switch(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(L2Switch, self).__init__(*args, **kwargs)
 
#在Ryu控制器上,要写一个函数去处理openvswitch的连接,同时需要开启一个监听,用来监听交换机的事件。
    @set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER)
    def switch_feathers_handler(self, ev):
#解析数据
#datapath像数据平面的通道,等同于网桥
        dp = ev.msg.datapath
        ofp = dp.ofproto #版本
        ofp_parser = dp.ofproto_parser #基于此版本的一些库类
#接收到交换机的连接后,要下发一条tableentrys,一个默认的流表,来指挥所有匹配不到交换机的数据,将其上传到控制器
#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(ofp.OFPP_CONTROLLER, ofp.OFPCML_NO_BUFFER)]
        self.add_flow(dp, 0, match, actions)
 
#为了提高代码重用,对于添加流表,单独写一个函数。
    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
        ofp = dp.ofproto
        ofp_parser = dp.ofproto_parser
#1.3版本交换机中需要有指令
# install flow
# construct a flow_mod msg and sent it
        inst = [ofp_parser.OFPInstructionActions(ofp.OFPIT_APPLY_ACTIONS, actions)]
        mod = ofp_parser.OFPFlowMod(datapath=dp, priority=priority, match=match, instructions=inst)
        dp.send_msg(mod)
#需要定义packet in函数,用来处理交换机和控制器之间的流表交互,在执行之前要先对packetin事件进行监听。
    @set_ev_cls(ofp_event.EventOFPPacketIn, 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
        dp= msg.datapath
        ofp= dp.ofproto
        ofp_parser = dp.ofproto_parser
        in_port = msg.match['msg.in_port']#match匹配域中提取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,将其发出
#buffer_id是一个很重要的参数,因为数据包进入交换机,要有地方暂存,到了取的时候就需要有对应的id来指定
# to output the current packet. for install rules only output later packets
        out = ofp_parser.OFPPacketOut(datapath=dp, buffer_id=msg.buffer_id, in_port=msg.in_port, actions=actions, data = data)
# buffer id: locate the buffered packet
        dp.send_msg(out)

2)能够体现和验证修改的相关截图

二.进阶要求为选做,有完成的同学请提交相关问题回答、代码和运行结果,交换机流表项截图,代码保存目录同要求2,有完成比未完成的上机分数更高。
1)代码注释

# 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
# 继承ryu.base.app_manager.RyuApp

class SimpleSwitch13(app_manager.RyuApp):
    OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION]  # 版本号为1.3

    def __init__(self, *args, **kwargs):  # 初始化类
        super(SimpleSwitch13, self).__init__(*args, **kwargs)
        self.mac_to_port = {}  # 初始化mac_to_port数组

    @set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER)
    def switch_features_handler(self, ev):  # 安装无目标的流表条目
        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):  # 增加流表
        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)
        else:
            mod = 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):
        # 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  # 用packet library分析收到的数据包

        dpid = format(datapath.id, "d").zfill(16)  # 获得Datapath ID以便于识别OpenFlow交换机
        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  # 记录mac地址以避免下次的消息范洪

        if dst in self.mac_to_port[dpid]:  # 如果目标Mac地址已经被学习了,决定哪个从哪个端口发送数据包。否则范洪
            out_port = self.mac_to_port[dpid][dst]
        else:
            out_port = ofproto.OFPP_FLOOD

        actions = [parser.OFPActionOutput(out_port)]  # 构造action表

        # 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
        # 构造一个pack_out消息然后发送
        out = parser.OFPPacketOut(datapath=datapath, buffer_id=msg.buffer_id,
                                  in_port=in_port, actions=actions, data=data)
        datapath.send_msg(out)

2)对回答相关问题
a) 代码当中的mac_to_port的作用是什么?

学习mac地址,保存mac地址到交换机端口的映射,就不使用洪泛转发
b) simple_switch和simple_switch_13在dpid的输出上有何不同?

simple_switch_13对dpid进行了格式化,并填充为16位数字
c) 相比simple_switch,simple_switch_13增加的switch_feature_handler实现了什么功能?

安装无目标的流表条目
d) simple_switch_13是如何实现流规则下发的?

收到在接收到packetin事件后,首先获取包学习,交换机信息,以太网信息,协议信息等等。如果以太网类型是LLDP类型,则不予处理。否则,获取源端口的目的端口和交换机的id,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。如果没有则进行洪泛转发,否则为学习过该mac地址,那就查看是否有buffer_id,有则在添加流表信息动作时加上buffer_id,向交换机发送流表。
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发送的priority=0,_packet_in_handler发送的流表的priority设置为1
2、编程实现和ODL实验的一样的硬超时功能
a)simple_switch_13_212002325.py的代码

# 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.

# 引入包
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):
    # 指定OpenFlow版本为1.3
    OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION]

    def __init__(self, *args, **kwargs):
        super(SimpleSwitch13, self).__init__(*args, **kwargs)
        self.mac_to_port = {} # 一个保存(交换机id, mac地址)到转发端口的字典

    # 处理EventOFPSwitchFeatures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:流表项匹配,OFPMatch():不匹配任何信息
        actions = [parser.OFPActionOutput(ofproto.OFPP_CONTROLLER,
                                        ofproto.OFPCML_NO_BUFFER)]
        self.add_flow(datapath, 0, match, actions)#添加流表项

    # 添加流表
    def add_flow(self, datapath, priority, match, actions, buffer_id=None,hard_timeout=0):
        # 获取交换机信息
        ofproto = datapath.ofproto
        parser = datapath.ofproto_parser

        # 包装action 
        inst = [parser.OFPInstructionActions(ofproto.OFPIT_APPLY_ACTIONS,
                                            actions)]
        # 判断是否有buffer_id,生成相应的mod对象
        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)
        # 发送mod
        datapath.send_msg(mod)

    # 触发packet in事件时,调用_packet_in_handler函数
    @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)
        # 获取Packet_In报文中的各种信息:包信息,交换机信息,协议等等
        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]

        # 忽略LLDP类型
        if eth.ethertype == ether_types.ETH_TYPE_LLDP:
            # ignore lldp packet
            return

        # 获取源端口,目的端口
        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)

        # 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

        # 在字典中查找目的mac地址是否有对应的出端口 
        if dst in self.mac_to_port[dpid]:
            out_port = self.mac_to_port[dpid][dst]
        # 没有就进行洪泛
        else:
            out_port = ofproto.OFPP_FLOOD

        actions = [parser.OFPActionOutput(out_port)]
        actions_timeout = []

        # 下发流表处理后续包,不再触发 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, 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
    	# 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)



b)结果截图

三.个人总结,包括但不限于实验难度、实验过程遇到的困难及解决办法,个人感想,不少于200字。
本次实验主要考察部署RYU控制器;RYU控制器实现软件定义的集线器原理;RYU控制器实现软件定义的交换机原理,实验的基础部分难度比较简单主要是要对比分析L2Switch和POX的Hub模块的不同,而进阶要求难度较大,尤其在阅读源码部分进度较慢。

posted on 2022-10-03 18:40  Qwertyuzxc  阅读(106)  评论(0编辑  收藏  举报