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
-
![]()
- 使用命令在lab6中搭建拓扑图：
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
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
![复制代码]()
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)
![复制代码]()
- 在lab6中创建L2Switch.py
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
1.使用命令mininet> xterm h2 h3开启主机终端 2.在h2主机终端中输入tcpdump -nn -i h2-eth0 3.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
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）
1 from ryu.base import app_manage
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？
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？
两者的差别在于：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？
实现了交换机以特性应答消息来响应特性请求的功能，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。
1 from ryu.base import app_manager
2 from ryu.controller import ofp_event
3 from ryu.controller.handler import CONFIG_DISPATCHER, MAIN_DISPATCHER
4 from ryu.controller.handler import set_ev_cls
5 from ryu.ofproto import ofproto_v1_3
6 from ryu.lib.packet import packet
7 from ryu.lib.packet import ethernet
8 from ryu.lib.packet import ether_types
9
10
11 class SimpleSwitch13(app_manager.RyuApp):
12 OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION]
13
14 def __init__(self, *args, **kwargs):
15 super(SimpleSwitch13, self).__init__(*args, **kwargs)
16 self.mac_to_port = {}
17
18 @set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER)
19 def switch_features_handler(self, ev):
20 datapath = ev.msg.datapath
21 ofproto = datapath.ofproto
22 parser = datapath.ofproto_parser
23
24 match = parser.OFPMatch()
25 actions = [parser.OFPActionOutput(ofproto.OFPP_CONTROLLER,
26 ofproto.OFPCML_NO_BUFFER)]
27 self.add_flow(datapath, 0, match, actions)
28
29 def add_flow(self, datapath, priority, match, actions, buffer_id=None, hard_timeout=0):
30 ofproto = datapath.ofproto
31 parser = datapath.ofproto_parser
32
33 inst = [parser.OFPInstructionActions(ofproto.OFPIT_APPLY_ACTIONS,
34 actions)]
35 if buffer_id:
36 mod = parser.OFPFlowMod(datapath=datapath, buffer_id=buffer_id,
37 priority=priority, match=match,
38 instructions=inst, hard_timeout=hard_timeout)
39 else:
40 mod = parser.OFPFlowMod(datapath=datapath, priority=priority,
41 match=match, instructions=inst, hard_timeout=hard_timeout)
42 datapath.send_msg(mod)
43
44 @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
45 def _packet_in_handler(self, ev):
46 # If you hit this you might want to increase
47 # the "miss_send_length" of your switch
48 if ev.msg.msg_len < ev.msg.total_len:
49 self.logger.debug("packet truncated: only %s of %s bytes",
50 ev.msg.msg_len, ev.msg.total_len)
51 msg = ev.msg
52 datapath = msg.datapath
53 ofproto = datapath.ofproto
54 parser = datapath.ofproto_parser
55 in_port = msg.match['in_port']
56
57 pkt = packet.Packet(msg.data)
58 eth = pkt.get_protocols(ethernet.ethernet)[0]
59
60 if eth.ethertype == ether_types.ETH_TYPE_LLDP:
61 # ignore lldp packet
62 return
63 dst = eth.dst
64 src = eth.src
65
66 dpid = format(datapath.id, "d").zfill(16)
67 self.mac_to_port.setdefault(dpid, {})
68
69 self.logger.info("packet in %s %s %s %s", dpid, src, dst, in_port)
70
71 # learn a mac address to avoid FLOOD next time.
72 self.mac_to_port[dpid][src] = in_port
73
74 if dst in self.mac_to_port[dpid]:
75 out_port = self.mac_to_port[dpid][dst]
76 else:
77 out_port = ofproto.OFPP_FLOOD
78
79 actions = [parser.OFPActionOutput(out_port)]\
80
81 actions_timeout=[]
82
83 # install a flow to avoid packet_in next time
84 if out_port != ofproto.OFPP_FLOOD:
85 match = parser.OFPMatch(in_port=in_port, eth_dst=dst, eth_src=src)
86 # verify if we have a valid buffer_id, if yes avoid to send both
87 # flow_mod & packet_out
88 hard_timeout=10
89 if msg.buffer_id != ofproto.OFP_NO_BUFFER:
90 self.add_flow(datapath, 2, match,actions_timeout, msg.buffer_id,hard_timeout=10)
91 self.add_flow(datapath, 1, match, actions, msg.buffer_id)
92 return
93 else:
94 self.add_flow(datapath, 2, match, actions_timeout, hard_timeout=10)
95 self.add_flow(datapath, 1, match, actions)
96 data = None
97 if msg.buffer_id == ofproto.OFP_NO_BUFFER:
98 data = msg.data
99
100 out = parser.OFPPacketOut(datapath=datapath, buffer_id=msg.buffer_id,
101 in_port=in_port, actions=actions, data=data)
102 datapath.send_msg(out)
（三）实验小结
通过这次实验，我了解了如何入力部署RYU控制器、理解了RYU控制器实现软件定义的集线器原理与交换机原理，在实验过程中，还是出现了很多问题，比如在lab6下面运行ryu-manager L2Switch.py后，拓扑图执行pingall操作却ping不通，最后发现是开了太多的端口导致无法继续运行，关闭既可；在新建一个L2212106700.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；还有在进阶题中，hi ping h3也是无法ping 通，最后将openFlow10改成openflow13就可以了。只要再细心一些，就可以避免很多问题的出现。
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