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

(一）基本要求

下载虚拟机软件Oracle VisualBox或VMware；
在虚拟机中安装Ubuntu 20.04 Desktop amd64，并完整安装Mininet；

(二)、实验要求

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

• 在对应文件夹下执行

ryu-manager gui_topology.py --observe-links

启动控制器

使用以下命令搭建拓扑

sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow10

2.阅读Ryu文档的The First Application一节，运行并使用 tcpdump 验证L2Switch，分析和POX的Hub模块有何不同

• 创建L2Switch.py文件,并保存在目录/home/用户名/学号/lab6/中

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)

• 执行命令

ryu-manager L2Switch.py

 

 

• 重新创建拓扑

sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow10

• 再利用mininet的xterm开启h1，h2，h3的命令行终端，并在h2和h3使用开启抓包（抓取eth0端口）

• 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

• h1 ping h2 注: 在h1的窗口输入ping 10.0.0.2

 

 

由图可见，h1 ping h2时h3也能收到数据包，h1 ping h3时h2也能收到数据包，说明L2Switch模块的功能同hub模块：为每一个交换机建立通配的洪泛规则，让交换机拥有集线器的功能

• 分析和POX的Hub模块有何不同

  1.结合拓扑,分别运行ryu和运行pox（Hub模块）

ryu-manager L2Switch.py
./pox.py log.level --DEBUG forwarding.hub

2.查看拓扑下发流表

dpctl dump-flows

3.无法查看L2Switch下发的流表

4.而hub模块下发的流表可以查看

4.继下面的.py文件一起,先执行.py文件再创拓扑

sudo mn --topo=single,3 --mac --controller=remote,ip=127.0.0.1,port=6633 --switch ovsk,protocols=OpenFlow13

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）

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)