Packet-In数量比较规则示例 代码

以下是一个简单的示例代码，展示如何编写一个规则来限制Packet-In的数量：

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 PacketInLimiter(app_manager.RyuApp):
    OFP_VERSIONS = [ofproto_v1_0.OFP_VERSION]

    def __init__(self, *args, **kwargs):
        super(PacketInLimiter, self).__init__(*args, **kwargs)
        self.packet_in_count = 0

    @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
    def packet_in_handler(self, ev):
        self.packet_in_count += 1

        if self.packet_in_count > 100:
            self.logger.info("Packet-In limit exceeded: %d", self.packet_in_count)
            return

        # process packet normally
        msg = ev.msg
        datapath = msg.datapath
        ofproto = datapath.ofproto
        parser = datapath.ofproto_parser

        # build flow mod message to send back to switch
        actions = [parser.OFPActionOutput(ofproto.OFPP_CONTROLLER, ofproto.OFPCML_NO_BUFFER)]
        out = parser.OFPPacketOut(datapath=datapath, buffer_id=msg.buffer_id, in_port=msg.in_port, actions=actions, data=msg.data)

        datapath.send_msg(out)

这个代码使用了 Ryu 框架来处理 OpenFlow 协议消息。它会记录 Packet-In 消息的数量，如果超过100个，就会停止处理并打印一条日志信息。否则，它会构建一个 Flow Mod 消息，将其发送给交换机，使交换机将数据包直接转发到控制器。