mininet➕ryu实现负载均衡代码

以下是使用Mininet和Ryu实现负载均衡的示例代码：

1. 在Mininet中创建拓扑

sudo mn --topo linear,3 --mac --switch ovsk --controller remote

2. 在Ryu中编写控制器代码

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, ethernet
from ryu.lib.packet import ipv4, tcp, udp

class LoadBalancer(app_manager.RyuApp):
  OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION]

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

    # 模拟交换机上的流表
    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):
    ofproto = datapath.ofproto
    parser = datapath.ofproto_parser

    # 安装流表项
    inst = [parser.OFPInstructionActions(ofproto.OFPIT_APPLY_ACTIONS,
                                          actions)]
    mod = 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):
    # 解析数据包
    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_protocol(ethernet.ethernet)

    # 仅处理IP数据包
    if eth.ethertype == ether_types.ETH_TYPE_IP:
      ip = pkt.get_protocol(ipv4.ipv4)

      # 仅处理TCP和UDP数据包
      if ip.proto == in_proto.IPPROTO_TCP or ip.proto == in_proto.IPPROTO_UDP:
        tp = pkt.get_protocol(tcp.tcp) or pkt.get_protocol(udp.udp)

        # 计算哈希值
        src_ip = ip.src
        dst_ip = ip.dst
        src_port = tp.src_port
        dst_port = tp.dst_port
        hash_val = hash((src_ip, dst_ip, src_port, dst_port)) % 3

        # 根据哈希值选择输出端口
        out_port = hash_val + 1

        # 安装流表项，将数据包转发到相应的输出端口
        actions = [parser.OFPActionOutput(out_port)]
        match = parser.OFPMatch(in_port=in_port, eth_type=eth.ethertype,
                                ipv4_src=src_ip, ipv4_dst=dst_ip,
                                ip_proto=ip.proto, tcp_src=src_port,
                                tcp_dst=dst_port)
        self.add_flow(datapath, 1, match, actions)

        # 发送数据包到对应的交换机端口
        out = parser.OFPPacketOut(datapath=datapath, buffer_id=msg.buffer_id,
                                  in_port=in_port, actions=actions)
        datapath.send_msg(out)

3. 运行控制器

ryu-manager load_balancer.py

4. 在Mininet中启动HTTP服务器

h1 python -m SimpleHTTPServer 80 &
h2 python -m SimpleHTTPServer 80 &
h3 python -m SimpleHTTPServer 80 &

5. 在浏览器中测试负载均衡

http://<controller_ip>/h1
http://<controller_ip>/h2
http://<controller_ip>/h3

其中，`<controller_ip>`是控制器的IP地址，可以使用以下命令获取：

ifconfig

这个示例代码将会根据哈希值将HTTP请求分配给3个主机中的一个，从而实现了负载均衡。