实验6：开源控制器实践——RYU

  • 实验6： 开源控制器实践——RYU](https://www.cnblogs.com/yjcblogs/p/16803784.html)

    一.实验目的

    1.能够独立部署RYU控制器；
    2.能够理解RYU控制器实现软件定义的集线器原理；
    3.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
    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。
    img

    • 建立拓扑
      img
    • 连接ryu控制器
      img
    • 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
      img

    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
    点击查看代码
    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)

    • h1 ping h2
      img
    • h1 ping h3
      img
    • 分析L2Switch和POX的Hub模块有何不同
      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

    -创建L2032002136.py

    点击查看代码
    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
      img

    （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：

    点击查看代码

    a) 代码当中的mac_to_port的作用是什么？
    保存mac地址到交换机端口的映射，为交换机自学习功能提供数据结构进行mac端口的存储

    b) simple_switch和simple_switch_13在dpid的输出上有何不同？
    差别在于：simple_switch直接输出dpid，而simple_switch_13则在dpid前端填充0直至满16位

    点击查看代码

    c) 相比simple_switch，simple_switch_13增加的switch_feature_handler实现了什么功能？
    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？
    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。若以太网类型是LLDP类型，则不予处理。如果不是，则获取源端口的目的端口和交换机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，则在添加流表信息时加上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下发流表的优先级比_packet_in_handler的优先级高。

    2.编程实现和ODL实验的一样的硬超时功能。

    • 代码
    点击查看代码
    # 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.

    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)

    • h1 ping h2

个人总结
这次基本要求倒是中规中矩，没什么感想。而进阶要求难度不小，有些问题需要真正去阅读代码以及查一些资料相结合才能搞明白，花了不少时间，看来如何高效使用搜索引擎也是一门必修课，还有就是发现注释很重要。通过本次实验，也使得我对RYU的控制机制有了深入的认识，同时也对SDN有了更深刻的认识。总之，收获颇丰！
本次实验遇到了TypeError: cannot set 'is_timeout' attribute of immutable type 'TimeoutError'和AttributeError: module 'collections' has no attribute 'MutableMapping'，通过阅读同学的博客成功解决。
通过本次实验学会了独立部署Ryu控制器，对RYU的控制机制有了更为形象和深入的认识。

posted @ 2022-10-19 16:21  F_ool  阅读(133)  评论(2)    收藏  举报