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。
