{
  "id": "networking/ip-fragment-timeout-reassembly-failed",
  "signature": "IP fragment reassembly timeout: packet dropped (fragmentation timeout exceeded)",
  "signature_zh": "IP分片重组超时：数据包被丢弃（分片超时）",
  "regex": "IP fragment reassembly timeout.*|fragmentation timeout exceeded",
  "domain": "networking",
  "category": "network_error",
  "subcategory": null,
  "root_cause": "A fragmented IP packet was not fully reassembled within the system's timeout (typically 30-60 seconds), causing all received fragments to be discarded, often due to high packet loss or mismatched PMTU.",
  "root_cause_type": "generic",
  "root_cause_zh": "一个IP分片数据包未能在系统超时时间（通常30-60秒）内完成重组，导致所有已接收的分片被丢弃，通常由高丢包率或PMTU不匹配引起。",
  "versions": [
    {
      "version": "Linux kernel 5.15",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "Linux kernel 6.1",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "FreeBSD 13.2",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    }
  ],
  "os_specific": {},
  "dead_ends": [
    {
      "action": "",
      "why_fails": "This only delays the inevitable; if the underlying packet loss is not fixed, fragments will still be dropped after the longer timeout, and it may cause memory exhaustion from pending fragments.",
      "fail_rate": 0.6,
      "condition": "",
      "sources": []
    },
    {
      "action": "",
      "why_fails": "This breaks legitimate fragmented traffic like large UDP datagrams or certain VPN protocols, leading to connectivity loss for those applications.",
      "fail_rate": 0.8,
      "condition": "",
      "sources": []
    },
    {
      "action": "",
      "why_fails": "Rebooting resets state temporarily but does not address the root cause of packet loss (e.g., a faulty link or MTU mismatch), so the error returns quickly.",
      "fail_rate": 0.9,
      "condition": "",
      "sources": []
    }
  ],
  "workarounds": [
    {
      "action": "Reduce the MTU on the interface to avoid fragmentation entirely: `ip link set dev eth0 mtu 1400`",
      "success_rate": 0.85,
      "how": "Reduce the MTU on the interface to avoid fragmentation entirely: `ip link set dev eth0 mtu 1400`",
      "condition": "",
      "sources": []
    },
    {
      "action": "Enable PMTU discovery and set the DF (Don't Fragment) flag on UDP sockets: `sysctl -w net.ipv4.ip_no_pmtu_disc=0` and ensure firewalls do not block ICMP 'Fragmentation Needed' messages.",
      "success_rate": 0.8,
      "how": "Enable PMTU discovery and set the DF (Don't Fragment) flag on UDP sockets: `sysctl -w net.ipv4.ip_no_pmtu_disc=0` and ensure firewalls do not block ICMP 'Fragmentation Needed' messages.",
      "condition": "",
      "sources": []
    },
    {
      "action": "Increase the reassembly queue size to handle bursts: `sysctl -w net.ipv4.ipfrag_max_dist=64` and `sysctl -w net.ipv4.ipfrag_high_thresh=8388608`",
      "success_rate": 0.7,
      "how": "Increase the reassembly queue size to handle bursts: `sysctl -w net.ipv4.ipfrag_max_dist=64` and `sysctl -w net.ipv4.ipfrag_high_thresh=8388608`",
      "condition": "",
      "sources": []
    }
  ],
  "workarounds_zh": [
    "Reduce the MTU on the interface to avoid fragmentation entirely: `ip link set dev eth0 mtu 1400`",
    "Enable PMTU discovery and set the DF (Don't Fragment) flag on UDP sockets: `sysctl -w net.ipv4.ip_no_pmtu_disc=0` and ensure firewalls do not block ICMP 'Fragmentation Needed' messages.",
    "Increase the reassembly queue size to handle bursts: `sysctl -w net.ipv4.ipfrag_max_dist=64` and `sysctl -w net.ipv4.ipfrag_high_thresh=8388608`"
  ],
  "transition_graph": {
    "leads_to": [],
    "preceded_by": [],
    "frequently_confused_with": []
  },
  "official_doc_url": "https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt",
  "official_doc_section": null,
  "error_code": "ETIMEDOUT",
  "verification_tier": "ai_generated",
  "confidence": 0.85,
  "fix_success_rate": 0.75,
  "resolvable": "partial",
  "first_seen": "2024-03-15",
  "last_confirmed": "2024-06-01",
  "last_updated": "2024-06-01",
  "evidence_count": 1,
  "tags": [],
  "locale": "en",
  "aliases": []
}