实验6：开源控制器实践——RYU
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。
- 使用命令在lab6中搭建拓扑图：
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
- 通过Ryu的图形界面查看网络拓
- 使用命令在lab6中搭建拓扑图：
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。
-
- 在lab6中创建L2Switch.py
1 from ryu.base import app_manager 2 from ryu.controller import ofp_event 3 from ryu.controller.handler import MAIN_DISPATCHER 4 from ryu.controller.handler import set_ev_cls 5 from ryu.ofproto import ofproto_v1_0 6 7 class L2Switch(app_manager.RyuApp): 8 OFP_VERSIONS = [ofproto_v1_0.OFP_VERSION] 9 10 def __init__(self, *args, **kwargs): 11 super(L2Switch, self).__init__(*args, **kwargs) 12 13 @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER) 14 def packet_in_handler(self, ev): 15 msg = ev.msg 16 dp = msg.datapath 17 ofp = dp.ofproto 18 ofp_parser = dp.ofproto_parser 19 20 actions = [ofp_parser.OFPActionOutput(ofp.OFPP_FLOOD)] 21 22 data = None 23 if msg.buffer_id == ofp.OFP_NO_BUFFER: 24 data = msg.data 25 26 out = ofp_parser.OFPPacketOut( 27 datapath=dp, buffer_id=msg.buffer_id, in_port=msg.in_port, 28 actions=actions, data = data) 29 dp.send_msg(out)
- 运行ryu：
ryu-manager L2Switch.py
- 重新搭建拓扑图：
sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow10
- 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。
- 在lab6中创建L2Switch.py
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
3.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）
L2212106691.py
1 from ryu.base import app_manager 2 from ryu.ofproto import ofproto_v1_3 3 from ryu.controller import ofp_event 4 from ryu.controller.handler import MAIN_DISPATCHER,CONFIG_DISPATCHER 5 from ryu.controller.handler import set_ev_cls 6 7 8 class Hub(app_manager.RyuApp): 9 OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION] 10 11 def __init__(self,*args,**kwargs): 12 super(Hub,self).__init__(*args,**kwargs) 13 14 15 @set_ev_cls(ofp_event.EventOFPSwitchFeatures,CONFIG_DISPATCHER) 16 def switch_features_handler(self,ev): 17 datapath = ev.msg.datapath 18 ofproto = datapath.ofproto 19 ofp_parser = datapath.ofproto_parser 20 21 match = ofp_parser.OFPMatch() 22 actions = [ofp_parser.OFPActionOutput(ofproto.OFPP_CONTROLLER,ofproto.OFPCML_NO_BUFFER)] 23 24 self.add_flow(datapath,0,match,actions,"default flow entry") 25 26 def add_flow(self,datapath,priority,match,actions,remind_content): 27 ofproto = datapath.ofproto 28 ofp_parser = datapath.ofproto_parser 29 30 inst = [ofp_parser.OFPInstructionActions(ofproto.OFPIT_APPLY_ACTIONS, 31 actions)] 32 33 mod = ofp_parser.OFPFlowMod(datapath=datapath,priority=priority, 34 match=match,instructions=inst); 35 print("install to datapath,"+remind_content) 36 datapath.send_msg(mod); 37 38 39 @set_ev_cls(ofp_event.EventOFPPacketIn,MAIN_DISPATCHER) 40 def packet_in_handler(self,ev): 41 msg = ev.msg 42 datapath = msg.datapath 43 ofproto = datapath.ofproto 44 ofp_parser = datapath.ofproto_parser 45 46 in_port = msg.match['in_port'] 47 48 print("get packet in, install flow entry,and lookback parket to datapath") 49 50 match = ofp_parser.OFPMatch(); 51 actions = [ofp_parser.OFPActionOutput(ofproto.OFPP_FLOOD)] 52 53 self.add_flow(datapath,1,match,actions,"hub flow entry") 54 55 out = ofp_parser.OFPPacketOut(datapath=datapath,buffer_id=msg.buffer_id, 56 in_port=in_port,actions=actions) 57 58 datapath.send_msg(out);
（二）进阶要求
- 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：
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
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
c) 相比simple_switch，simple_switch_13增加的switch_feature_handler实现了什么功能？
switch_features_handler函数是新增缺失流表项到流表中，当封包没有匹配到流表时，就触发packet_in
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。
1 # Copyright (C) 2011 Nippon Telegraph and Telephone Corporation. 2 # 3 # Licensed under the Apache License, Version 2.0 (the "License"); 4 # you may not use this file except in compliance with the License. 5 # You may obtain a copy of the License at 6 # 7 # http://www.apache.org/licenses/LICENSE-2.0 8 # 9 # Unless required by applicable law or agreed to in writing, software 10 # distributed under the License is distributed on an "AS IS" BASIS, 11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or 12 # implied. 13 # See the License for the specific language governing permissions and 14 # limitations under the License. 15 16 from ryu.base import app_manager 17 from ryu.controller import ofp_event 18 from ryu.controller.handler import CONFIG_DISPATCHER, MAIN_DISPATCHER 19 from ryu.controller.handler import set_ev_cls 20 from ryu.ofproto import ofproto_v1_3 21 from ryu.lib.packet import packet 22 from ryu.lib.packet import ethernet 23 from ryu.lib.packet import ether_types 24 # 引入包 25 26 class SimpleSwitch13(app_manager.RyuApp): 27 28 OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION] 29 # 定义openflow版本 30 def __init__(self, *args, **kwargs): 31 super(SimpleSwitch13, self).__init__(*args, **kwargs) 32 # 定义保存mac地址到端口的一个映射 33 self.mac_to_port = {} 34 35 # 处理SwitchFeatures事件 36 @set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER) 37 def switch_features_handler(self, ev): 38 datapath = ev.msg.datapath 39 ofproto = datapath.ofproto 40 parser = datapath.ofproto_parser 41 42 # install table-miss flow entry 43 # We specify NO BUFFER to max_len of the output action due to 44 # OVS bug. At this moment, if we specify a lesser number, e.g., 45 # 128, OVS will send Packet-In with invalid buffer_id and 46 # truncated packet data. In that case, we cannot output packets 47 # correctly. The bug has been fixed in OVS v2.1.0. 48 match = parser.OFPMatch() 49 actions = [parser.OFPActionOutput(ofproto.OFPP_CONTROLLER,ofproto.OFPCML_NO_BUFFER)] 50 self.add_flow(datapath, 0, match, actions) 51 52 # 添加流表的函数 53 def add_flow(self, datapath, priority, match, actions, buffer_id=None): 54 ofproto = datapath.ofproto 55 parser = datapath.ofproto_parser 56 # 获取交换机信息 57 58 inst = [parser.OFPInstructionActions(ofproto.OFPIT_APPLY_ACTIONS,actions)] 59 # 对action进行包装 60 61 # 判断是否有buffer_id，并生成mod对象 62 if buffer_id: 63 mod = parser.OFPFlowMod(datapath=datapath, buffer_id=buffer_id, 64 priority=priority, match=match, 65 instructions=inst) 66 else: 67 mod = parser.OFPFlowMod(datapath=datapath, priority=priority, 68 match=match, instructions=inst) 69 70 datapath.send_msg(mod)# 发送mod 71 72 # 处理PacketIn事件 73 @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER) 74 def _packet_in_handler(self, ev): 75 # If you hit this you might want to increase 76 # the "miss_send_length" of your switch 77 if ev.msg.msg_len < ev.msg.total_len: 78 self.logger.debug("packet truncated: only %s of %s bytes", 79 ev.msg.msg_len, ev.msg.total_len) 80 81 msg = ev.msg 82 datapath = msg.datapath 83 ofproto = datapath.ofproto 84 parser = datapath.ofproto_parser 85 in_port = msg.match['in_port'] 86 # 获取包信息，交换机信息，协议等等 87 88 pkt = packet.Packet(msg.data) 89 eth = pkt.get_protocols(ethernet.ethernet)[0] 90 91 if eth.ethertype == ether_types.ETH_TYPE_LLDP: 92 # ignore lldp packet# 忽略LLDP类型的数据包 93 return 94 95 # 获取源端口，目的端口 96 dst = eth.dst 97 src = eth.src 98 99 dpid = format(datapath.id, "d").zfill(16) 100 self.mac_to_port.setdefault(dpid, {}) 101 102 self.logger.info("packet in %s %s %s %s", dpid, src, dst, in_port) 103 104 # 学习包的源地址，和交换机上的入端口绑定 105 # learn a mac address to avoid FLOOD next time. 106 self.mac_to_port[dpid][src] = in_port 107 108 # 查看是否已经学习过该目的mac地址 109 if dst in self.mac_to_port[dpid]: 110 out_port = self.mac_to_port[dpid][dst] 111 # 如果没有则进行洪泛 112 else: 113 out_port = ofproto.OFPP_FLOOD 114 115 actions = [parser.OFPActionOutput(out_port)] 116 117 # 下发流表处理后续包，不再触发PACKETIN事件 118 # install a flow to avoid packet_in next time 119 if out_port != ofproto.OFPP_FLOOD: 120 match = parser.OFPMatch(in_port=in_port, eth_dst=dst, eth_src=src) 121 # verify if we have a valid buffer_id, if yes avoid to send both 122 # flow_mod & packet_out 123 if msg.buffer_id != ofproto.OFP_NO_BUFFER: 124 self.add_flow(datapath, 1, match, actions, msg.buffer_id) 125 return 126 else: 127 self.add_flow(datapath, 1, match, actions) 128 data = None 129 if msg.buffer_id == ofproto.OFP_NO_BUFFER: 130 data = msg.data 131 132 out = parser.OFPPacketOut(datapath=datapath, buffer_id=msg.buffer_id, 133 in_port=in_port, actions=actions, data=data) 134 # 发送流表 135 datapath.send_msg(out)
2.编程实现和ODL实验的一样的硬超时功能。
Timeout.py
1 # Copyright (C) 2011 Nippon Telegraph and Telephone Corporation. 2 # 3 # Licensed under the Apache License, Version 2.0 (the "License"); 4 # you may not use this file except in compliance with the License. 5 # You may obtain a copy of the License at 6 # 7 # http://www.apache.org/licenses/LICENSE-2.0 8 # 9 # Unless required by applicable law or agreed to in writing, software 10 # distributed under the License is distributed on an "AS IS" BASIS, 11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or 12 # implied. 13 # See the License for the specific language governing permissions and 14 # limitations under the License. 15 16 from ryu.base import app_manager 17 from ryu.controller import ofp_event 18 from ryu.controller.handler import CONFIG_DISPATCHER, MAIN_DISPATCHER 19 from ryu.controller.handler import set_ev_cls 20 from ryu.ofproto import ofproto_v1_3 21 from ryu.lib.packet import packet 22 from ryu.lib.packet import ethernet 23 from ryu.lib.packet import ether_types 24 25 26 class SimpleSwitch13(app_manager.RyuApp): 27 OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION] 28 29 def __init__(self, *args, **kwargs): 30 super(SimpleSwitch13, self).__init__(*args, **kwargs) 31 self.mac_to_port = {} 32 33 @set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER) 34 def switch_features_handler(self, ev): 35 datapath = ev.msg.datapath 36 ofproto = datapath.ofproto 37 parser = datapath.ofproto_parser 38 39 # install table-miss flow entry 40 # 41 # We specify NO BUFFER to max_len of the output action due to 42 # OVS bug. At this moment, if we specify a lesser number, e.g., 43 # 128, OVS will send Packet-In with invalid buffer_id and 44 # truncated packet data. In that case, we cannot output packets 45 # correctly. The bug has been fixed in OVS v2.1.0. 46 match = parser.OFPMatch() 47 actions = [parser.OFPActionOutput(ofproto.OFPP_CONTROLLER, 48 ofproto.OFPCML_NO_BUFFER)] 49 self.add_flow(datapath, 0, match, actions) 50 51 def add_flow(self, datapath, priority, match, actions, buffer_id=None, hard_timeout=0): 52 ofproto = datapath.ofproto 53 parser = datapath.ofproto_parser 54 55 inst = [parser.OFPInstructionActions(ofproto.OFPIT_APPLY_ACTIONS, 56 actions)] 57 if buffer_id: 58 mod = parser.OFPFlowMod(datapath=datapath, buffer_id=buffer_id, 59 priority=priority, match=match, 60 instructions=inst, hard_timeout=hard_timeout) 61 else: 62 mod = parser.OFPFlowMod(datapath=datapath, priority=priority, 63 match=match, instructions=inst, hard_timeout=hard_timeout) 64 datapath.send_msg(mod) 65 66 @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER) 67 def _packet_in_handler(self, ev): 68 # If you hit this you might want to increase 69 # the "miss_send_length" of your switch 70 if ev.msg.msg_len < ev.msg.total_len: 71 self.logger.debug("packet truncated: only %s of %s bytes", 72 ev.msg.msg_len, ev.msg.total_len) 73 msg = ev.msg 74 datapath = msg.datapath 75 ofproto = datapath.ofproto 76 parser = datapath.ofproto_parser 77 in_port = msg.match['in_port'] 78 79 pkt = packet.Packet(msg.data) 80 eth = pkt.get_protocols(ethernet.ethernet)[0] 81 82 if eth.ethertype == ether_types.ETH_TYPE_LLDP: 83 # ignore lldp packet 84 return 85 dst = eth.dst 86 src = eth.src 87 88 dpid = format(datapath.id, "d").zfill(16) 89 self.mac_to_port.setdefault(dpid, {}) 90 91 self.logger.info("packet in %s %s %s %s", dpid, src, dst, in_port) 92 93 # learn a mac address to avoid FLOOD next time. 94 self.mac_to_port[dpid][src] = in_port 95 96 if dst in self.mac_to_port[dpid]: 97 out_port = self.mac_to_port[dpid][dst] 98 else: 99 out_port = ofproto.OFPP_FLOOD 100 101 actions = [parser.OFPActionOutput(out_port)]\ 102 103 actions_timeout=[] 104 105 # install a flow to avoid packet_in next time 106 if out_port != ofproto.OFPP_FLOOD: 107 match = parser.OFPMatch(in_port=in_port, eth_dst=dst, eth_src=src) 108 # verify if we have a valid buffer_id, if yes avoid to send both 109 # flow_mod & packet_out 110 hard_timeout=10 111 if msg.buffer_id != ofproto.OFP_NO_BUFFER: 112 self.add_flow(datapath, 2, match,actions_timeout, msg.buffer_id,hard_timeout=10) 113 self.add_flow(datapath, 1, match, actions, msg.buffer_id) 114 return 115 else: 116 self.add_flow(datapath, 2, match, actions_timeout, hard_timeout=10) 117 self.add_flow(datapath, 1, match, actions) 118 data = None 119 if msg.buffer_id == ofproto.OFP_NO_BUFFER: 120 data = msg.data 121 122 out = parser.OFPPacketOut(datapath=datapath, buffer_id=msg.buffer_id, 123 in_port=in_port, actions=actions, data=data) 124 datapath.send_msg(out)
重新构建：
sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13
（三）实验小结
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L2Switch模块查看流表时报错，通过找资料发现，应该先打开L2Switch模块在启动ryu控制器，构建拓扑图，改正后也成功的ping通，也实现了无法查看流表的效果。还有就是新建一个L2212106691.py，使之和POX的Hub模块的变得一致，创建后无法开启，经过多次排查问题，发现将新建的拓扑图的命令中去掉protocols=OpenFlow10就可以启动，完整的命令为sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow10。在完成进阶的代码注释时，感觉有几分吃力，源码中使用很多RYU中定义的数据结构并不是很能理解，只能通过查阅资料的来完成注释，还有就是做进阶的硬超时要使用OpenFlow=13，使用OpenFlow=10是会报错。
