{
  "id": "embedded/lwip-tcp-retransmit-timeout",
  "signature": "lwIP: TCP connection to 192.168.1.100:80 timed out after 3 retransmissions",
  "signature_zh": "lwIP: 到192.168.1.100:80的TCP连接在3次重传后超时",
  "regex": "lwIP: TCP connection to \\d+\\.\\d+\\.\\d+\\.\\d+:\\d+ timed out after \\d+ retransmissions",
  "domain": "embedded",
  "category": "network_error",
  "subcategory": null,
  "root_cause": "The TCP remote host is unreachable or not responding due to network congestion, firewall blocking, or device power state.",
  "root_cause_type": "generic",
  "root_cause_zh": "由于网络拥塞、防火墙阻止或设备电源状态，TCP远程主机不可达或未响应。",
  "versions": [
    {
      "version": "lwIP v2.1.3",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "lwIP v2.2.0",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "FreeRTOS+TCP v3.0.0",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    }
  ],
  "os_specific": {},
  "dead_ends": [
    {
      "action": "Increase the TCP retransmission timeout in lwIP configuration (e.g., TCP_RTO_MIN)",
      "why_fails": "Longer timeouts only mask the problem; if the remote host is unreachable, the connection will still fail eventually.",
      "fail_rate": 0.8,
      "condition": "",
      "sources": []
    },
    {
      "action": "Disable TCP checksum offloading on the network interface",
      "why_fails": "Checksum offloading is unrelated to retransmission timeouts; the issue is network reachability, not data corruption.",
      "fail_rate": 0.95,
      "condition": "",
      "sources": []
    }
  ],
  "workarounds": [
    {
      "action": "Implement a TCP keepalive mechanism using tcp_keepalive() to detect connection failure earlier and reduce retransmission count.",
      "success_rate": 0.75,
      "how": "Implement a TCP keepalive mechanism using tcp_keepalive() to detect connection failure earlier and reduce retransmission count.",
      "condition": "",
      "sources": []
    },
    {
      "action": "Add a fallback DNS resolution check before connecting: if host resolution fails, abort and retry with exponential backoff.",
      "success_rate": 0.7,
      "how": "Add a fallback DNS resolution check before connecting: if host resolution fails, abort and retry with exponential backoff.",
      "condition": "",
      "sources": []
    }
  ],
  "workarounds_zh": [
    "Implement a TCP keepalive mechanism using tcp_keepalive() to detect connection failure earlier and reduce retransmission count.",
    "Add a fallback DNS resolution check before connecting: if host resolution fails, abort and retry with exponential backoff."
  ],
  "transition_graph": {
    "leads_to": [],
    "preceded_by": [],
    "frequently_confused_with": []
  },
  "official_doc_url": "https://savannah.nongnu.org/projects/lwip/",
  "official_doc_section": null,
  "error_code": "ERR_TIMEOUT",
  "verification_tier": "ai_generated",
  "confidence": 0.9,
  "fix_success_rate": 0.8,
  "resolvable": "partial",
  "first_seen": "2024-06-10",
  "last_confirmed": "2024-06-01",
  "last_updated": "2024-06-01",
  "evidence_count": 1,
  "tags": [],
  "locale": "en",
  "aliases": []
}