2019 SDN上机第5次作业

1.浏览RYU官网学习RYU控制器的安装和RYU开发入门教程，提交你对于教程代码的理解，包括但不限于：

描述官方教程实现了一个什么样的交换机功能？
答：将接收到的数据包发送到所有端口的交换机功能。
控制器设定交换机支持什么版本的OpenFlow？
答：主持openflow的全部版本。
控制器设定了交换机如何处理数据包？
答：1.当Ryu收到OpenFlow packet_in消息时，调用“packet_in_handler”方法
2.之后定义packet_in数据结构对象，数据路径对象datapath，OpenFlow协议和解析过程
3.定义要发送数据包的交换机端口。
4.定义Ryu向交换机发送的packet_out内容，最后发送到交换机
ryu的安装：

2.根据官方教程和提供的示例代码（SimpleSwitch.py），将具有自学习功能的交换机代码（SelfLearning.py）补充完整

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

from ryu.lib.mac import haddr_to_bin
from ryu.lib.packet import packet
from ryu.lib.packet import ethernet
from ryu.lib.packet import ether_types

class SimpleSwitch(app_manager.RyuApp):
# TODO define OpenFlow 1.0 version for the switch
OFP_VERSIONS = [ofproto_v1_0.OFP_VERSION]
# add your code here

def init(self, args, **kwargs):
super(SimpleSwitch, self).init(args, **kwargs)
self.mac_to_port = {}

def add_flow(self, datapath, in_port, dst, src, actions):
ofproto = datapath.ofproto

match = datapath.ofproto_parser.OFPMatch(
in_port=in_port,
dl_dst=haddr_to_bin(dst), dl_src=haddr_to_bin(src))

mod = datapath.ofproto_parser.OFPFlowMod(
datapath=datapath, match=match, cookie=0,
command=ofproto.OFPFC_ADD, idle_timeout=0, hard_timeout=0,
priority=ofproto.OFP_DEFAULT_PRIORITY,
flags=ofproto.OFPFF_SEND_FLOW_REM, actions=actions)
# TODO send modified message out
datapath.send_msg(mod)
# add your code here

@set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
def _packet_in_handler(self, ev):
msg = ev.msg
datapath = msg.datapath
ofproto = datapath.ofproto

pkt = packet.Packet(msg.data)
eth = pkt.get_protocol(ethernet.ethernet)

if eth.ethertype == ether_types.ETH_TYPE_LLDP:
# ignore lldp packet
return
if eth.ethertype == ether_types.ETH_TYPE_IPV6:
# ignore ipv6 packet
return

dst = eth.dst
src = eth.src
dpid = datapath.id
self.mac_to_port.setdefault(dpid, {})

self.logger.info("packet in DPID:%s MAC_SRC:%s MAC_DST:%s IN_PORT:%s", dpid, src, dst, msg.in_port)

learn a mac address to avoid FLOOD next time.

self.mac_to_port[dpid][src] = msg.in_port

if dst in self.mac_to_port[dpid]:
out_port = self.mac_to_port[dpid][dst]
else:
out_port = ofproto.OFPP_FLOOD

TODO define the action for output

actions = [datapath.ofproto_parser.OFPActionOutput(out_port)]
# add your code here

install a flow to avoid packet_in next time

if out_port != ofproto.OFPP_FLOOD:
self.logger.info("add flow s:DPID:%s Match:[ MAC_SRC:%s MAC_DST:%s IN_PORT:%s ], Action:[OUT_PUT:%s] ", dpid, src, dst, msg.in_port, out_port)
self.add_flow(datapath, msg.in_port, dst, src, actions)

data = None
if msg.buffer_id == ofproto.OFP_NO_BUFFER:
data = msg.data

TODO define the OpenFlow Packet Out

out = datapath.ofproto_parser.OFPPacketOut(datapath=datapath, buffer_id=msg.buffer_id, in_port=msg.in_port, actions=actions, data=data)
datapath.send_msg(out)
# add your code here

print ("PACKET_OUT...")