3. 诊断数据采集：链路层、网络层、传输层关键指标

# 查看链路状态与协商信息
ethtool eth0

# 查看详细的错误统计（CRC、错帧等）
ethtool -S eth0 | grep -E "crc|error|drop"

# 查看接口级别的丢包与错误计数
ip -s link show eth0

# 查看 TCP 重传统计
netstat -s | grep -i "retransmit"

# 查看连接状态分布
ss -tan | awk '{print $1}' | sort | uniq -c

# 查看具体连接的 RTT 与窗口信息
ss -ti | grep -A 1 "ESTAB"

import subprocess
import time
from collections import deque

class LinkDiagnosticCollector:
    def __init__(self):
        self.metrics_buffer = deque(maxlen=3600)  # 1小时窗口
    
    def collect_link_layer(self):
        # 采集链路状态、CRC、丢包
        result = subprocess.run(['ethtool', '-S', 'eth0'], capture_output=True, text=True)
        return self._parse_ethtool_stats(result.stdout)
    
    def collect_network_layer(self, target_ip):
        # 采集 ICMP 可达性与 RTT
        result = subprocess.run(['ping', '-c', '5', target_ip], capture_output=True, text=True)
        return self._parse_ping_output(result.stdout)
    
    def collect_transport_layer(self):
        # 采集 TCP 重传与连接状态
        result = subprocess.run(['netstat', '-s'], capture_output=True, text=True)
        return self._parse_tcp_stats(result.stdout)
    
    def run_diagnostic_cycle(self, target_ip):
        link_metrics = self.collect_link_layer()
        if link_metrics['link_status'] != 'UP':
            return {'layer': 'L2', 'action': 'trigger_reconnect'}
        
        net_metrics = self.collect_network_layer(target_ip)
        if net_metrics['packet_loss'] > 5:
            return {'layer': 'L3', 'action': 'trigger_reconnect'}
        
        tcp_metrics = self.collect_transport_layer()
        if tcp_metrics['retransmit_rate'] > 2:
            return {'layer': 'L4', 'action': 'trigger_reconnect'}
        
        return {'layer': 'OK', 'action': 'continue'}