实验6：开源控制器实践——RYU
（一）基本要求
-
L2Switch和POX的Hub模板有何不同？
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。-
L2Switch
-
Hub
-
-
修改过的L2212006193.py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)
（二）进阶要求
- simple_switch_13.py的代码注释
# 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 class SimpleSwitch13(app_manager.RyuApp): OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION] # 指定OpenFlow 1.3版本 def __init__(self, *args, **kwargs): super(SimpleSwitch13, self).__init__(*args, **kwargs) self.mac_to_port = {} # mac地址映射到转发端口的字典，可用于交换机自学习。 @set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER) def switch_features_handler(self, ev): datapath = ev.msg.datapath # ev.msg 是用来存储对应事件的 OpenFlow 消息类别实体 ofproto = datapath.ofproto # ofproto表示使用的OpenFlow版本所对应的ryu.ofproto.ofproto_v1_3 parser = datapath.ofproto_parser # 使用对应版本的ryu.ofproto.ofproto_v1_3_parser来解析协议 # 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) # priority = 0表示优先级最低，即若所有流表都匹配不到时，才会把数据包发送到controller # 执行 add_flow() 方法以发送 Flow Mod 消息 def add_flow(self, datapath, priority, match, actions, buffer_id=None): 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) # 处理PacketIn事件 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) #从事件类里取出一些参数 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 #dpid是交换机的id，src是数据包的源mac地址，in_port是交换机接受到包的端口 #检验目的地址是否已经学习 if dst in self.mac_to_port[dpid]: # 如果已经学习到，则向交换机下发流表,并让交换机向相应端口转发包 out_port = self.mac_to_port[dpid][dst] else: # 如果还没有学习到，则无法下发流表，让交换机洪泛转发包。 out_port = ofproto.OFPP_FLOOD actions = [parser.OFPActionOutput(out_port)] # 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: # buffer_id不为None，控制器只需下发流表的命令，交换机增加了流表项后，位于缓冲区的数据包会自动转发出去。 self.add_flow(datapath, 1, match, actions, msg.buffer_id) return else: # buffer_id为None，那么控制器不仅要更改交换机的流表项，还要把数据包的信息传给交换机，让交换机把数据包转发出去 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)- 代码当中的mac_to_port的作用是什么？
mac_to_port是mac地址映射到转发端口的字典，可用于交换机自学习。 - simple_switch和simple_switch_13在dpid的输出上有何不同？
simple_switch直接输出dpid。
simple_switch_13会在dpid前端加上0将其填充至16位。 - 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。 - 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。 - 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。
- 代码当中的mac_to_port的作用是什么？
- 编程实现和ODL实验的一样的硬超时功能。
# 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)
个人总结
- 打开L2Switch，拓扑构建完成后进行pingall指令，出现了ping不通的问题
解决方法：先启用ryu控制器，而后打开L2Switch，最后再进行拓扑构建，问题顺利解决 - 打开L2212006193和Timeout，构建拓扑后一直pingall不通
解决方法：Openflow协议原因，构建拓扑的命令改成sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk - 在本次实验中，通过阅读RYU文档并查看相关模块的源代码，了解了RYU控制器的工作原理，并比较了RYU的L2Switch模块与POX的Hub模块的异同。
