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
- 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。
搭建拓扑
sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow10
启动控制器
ryu-manager ryu/ryu/app/gui_topology/gui_topology.py --observe-links
运行ryu并重新加载拓扑
- ryu-manager L2Switch.py
- sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow10
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)
对p1和p2进行抓包，在目标主机中验证验证L2Switch
使用命令mininet> xterm h2 h3开启主机终端
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
L2Switch和POX的Hub模块的不同
相同之处：两个模块使用的是洪泛转发ICMP报文，所以无论h1 ping h2还是h3，都能收到数据包。
不同之处：L2Switch下发的流表无法在mininet上查看，而Hub可以查看，如图所示
重新启动拓扑
sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13
查看流表
dpctl dump-flows -O OpenFlow13
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_features_handler(self,ev):
datapath = ev.msg.datapath
ofproto = datapath.ofproto
ofp_parser = datapath.ofproto_parser
match = ofp_parser.OFPMatch()
actions = [ofp_parser.OFPActionOutput(ofproto.OFPP_CONTROLLER,ofproto.OFPCML_NO_BUFFER)]
self.add_flow(datapath,0,match,actions,"default flow entry")
def add_flow(self,datapath,priority,match,actions,remind_content):
ofproto = datapath.ofproto
ofp_parser = datapath.ofproto_parser
inst = [ofp_parser.OFPInstructionActions(ofproto.OFPIT_APPLY_ACTIONS,
actions)]
mod = ofp_parser.OFPFlowMod(datapath=datapath,priority=priority,
match=match,instructions=inst);
print("install to datapath,"+remind_content)
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']
print("get packet in, install flow entry,and lookback parket to datapath")
match = ofp_parser.OFPMatch();
actions = [ofp_parser.OFPActionOutput(ofproto.OFPP_FLOOD)]
self.add_flow(datapath,1,match,actions,"hub flow entry")
out = ofp_parser.OFPPacketOut(datapath=datapath,buffer_id=msg.buffer_id,
in_port=in_port,actions=actions)
datapath.send_msg(out);
（二）进阶要求
a)代码当中的mac_to_port的作用是什么？
答：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？
答：simple_switch直接输出dpid，simple_switch_13对dpid进行了格式化，并填充为16位数字，会在不满16位的dpid前补0直到满16位。
c)相比simple_switch，simple_switch_13增加的switch_feature_handler实现了什么功能？
答：实现了交换机以特性应答消息来响应特性请求的功能。
d)simple_switch_13是如何实现流规则下发的？
答：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。如果以太网类型是LLDP类型，则不予处理。如果不是，则获取源端口目的端口，以及交换机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。如果学习过该mac地址，则查看是否有buffer_id，如果有的话，则在添加流动作时加上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？
答:switch_features_handler下发流表的优先级比_packet_in_handler的优先级高。
# 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)
（三）个人总结
通过本次实验，让我熟悉了RYU控制器实现软件定义的集线器和交换机原理。在进阶内容中使用OpenFlow=10是会报错，需要使用OpenFlow=13进行解决。拓扑pingall会无法实现，经过查询需要关掉拓扑，启动L2Switch模块后再创建拓扑从而解决。
标签：控制器,self,parser,datapath,msg,开源,ofproto,RYU,port From： https://www.cnblogs.com/daichenxuan/p/16838174.html