2019 SDN上机第五次作业

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？

实现将接收到的数据包发送到所有端口

控制器设定交换机支持什么版本的OpenFlow？

OpenFlow 1.0

控制器设定了交换机如何处理数据包？

当Ryu收到OpenFlow交换机送来的packet_in消息时调用，set_ev_cls的第一个参数也声明了。
set_ev_cls的第二个参数MAIN_DISPATCHER意味着当Ryu和交换机握手过程（即hello, features request/reply, Set Config等）完毕，才会调用packet_in_handler。
之后定义packet_in消息数据结构，交换机datapath，OpenFlow协议和解析过程；
定义发给交换机packet_out的动作，要求交换机将数据包泛洪广播；定义Ryu向交换机发送的packet_out内容，最后发送消息。
至此，一个能够接收packet和转发packet的交换机完成了（接收packet，广播packet）。
ev.msg是表示packet_in数据结构的对象。
msg.dp是代表数据路径（开关）的对象。
dp.ofproto和dp.ofproto_parser是代表Ryu和交换机协商的OpenFlow协议的对象。

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 SelfLearning(app_manager.RyuApp):
# TODO define OpenFlow 1.0 version for the switch
OFP_VERSIONS = [ofproto_v1_0.OFP_VERSION]

def __init__(self, *args, **kwargs):
    super(SelfLearning, 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)

@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)]

    # 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)

print("PACKET_OUT...")

3.在mininet创建一个最简拓扑，并连接RYU控制器

python脚本：
from mininet.topo import Topo

class Mytopo(Topo):

def __init__(self):

    Topo.__init__(self)

    sw=self.addSwitch('s1')

    count=1

    for i in range(2):

            host = self.addHost('h{}'.format(count))

            self.addLink(host,sw,1,count)

            count = count + 1

topos = {'mytopo': (lambda:Mytopo())}

4.验证自学习交换机的功能，提交分析过程和验证结果

5.写下你的实验体会

ryu的安装很坑，python的空格·····