{
  "id": "networking/ipv6-ndp-duplicate-address",
  "signature": "NDP: Duplicate Address Detection failed for fe80::1 on eth0, address already in use by 00:1a:2b:3c:4d:5e",
  "signature_zh": "NDP：eth0上fe80::1的重复地址检测失败，地址已被00:1a:2b:3c:4d:5e使用",
  "regex": "NDP: Duplicate Address Detection failed for fe80::[0-9a-f:]+ on \\S+, address already in use by [0-9a-f:]{17}",
  "domain": "networking",
  "category": "layer2",
  "subcategory": null,
  "root_cause": "IPv6 Duplicate Address Detection (DAD) detected that the link-local address fe80::1 is already claimed by another host on the same link, preventing the interface from using that address.",
  "root_cause_type": "generic",
  "root_cause_zh": "IPv6重复地址检测（DAD）检测到链路本地地址fe80::1已被同一链路上的另一主机声明，阻止接口使用该地址。",
  "versions": [
    {
      "version": "Linux kernel 6.2.0",
      "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"
    },
    {
      "version": "Windows 11 IPv6 stack",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    }
  ],
  "os_specific": {},
  "dead_ends": [
    {
      "action": "",
      "why_fails": "Disabling DAD leads to network instability and packet loss as two hosts respond to the same address.",
      "fail_rate": 0.95,
      "condition": "",
      "sources": []
    },
    {
      "action": "",
      "why_fails": "Both hosts will conflict; only one can respond to neighbor solicitations, causing intermittent failures.",
      "fail_rate": 0.9,
      "condition": "",
      "sources": []
    },
    {
      "action": "",
      "why_fails": "Flushing caches does not resolve the underlying address duplication; the conflict persists.",
      "fail_rate": 0.8,
      "condition": "",
      "sources": []
    }
  ],
  "workarounds": [
    {
      "action": "Change the link-local address on one host by modifying the interface identifier: `ip link set dev eth0 address 02:00:00:00:00:01` (EUI-64 based), then reboot or restart networking.",
      "success_rate": 0.85,
      "how": "Change the link-local address on one host by modifying the interface identifier: `ip link set dev eth0 address 02:00:00:00:00:01` (EUI-64 based), then reboot or restart networking.",
      "condition": "",
      "sources": []
    },
    {
      "action": "Use a static link-local address with a unique suffix on each host: `ip -6 addr add fe80::1/64 dev eth0` but ensure no conflict by checking with `ndp -a`.",
      "success_rate": 0.9,
      "how": "Use a static link-local address with a unique suffix on each host: `ip -6 addr add fe80::1/64 dev eth0` but ensure no conflict by checking with `ndp -a`.",
      "condition": "",
      "sources": []
    },
    {
      "action": "Reconfigure the network to use globally routable IPv6 addresses instead of link-local for communication, and disable DAD for link-local only: `sysctl -w net.ipv6.conf.eth0.dad_transmits=0`.",
      "success_rate": 0.75,
      "how": "Reconfigure the network to use globally routable IPv6 addresses instead of link-local for communication, and disable DAD for link-local only: `sysctl -w net.ipv6.conf.eth0.dad_transmits=0`.",
      "condition": "",
      "sources": []
    }
  ],
  "workarounds_zh": [
    "Change the link-local address on one host by modifying the interface identifier: `ip link set dev eth0 address 02:00:00:00:00:01` (EUI-64 based), then reboot or restart networking.",
    "Use a static link-local address with a unique suffix on each host: `ip -6 addr add fe80::1/64 dev eth0` but ensure no conflict by checking with `ndp -a`.",
    "Reconfigure the network to use globally routable IPv6 addresses instead of link-local for communication, and disable DAD for link-local only: `sysctl -w net.ipv6.conf.eth0.dad_transmits=0`."
  ],
  "transition_graph": {
    "leads_to": [],
    "preceded_by": [],
    "frequently_confused_with": []
  },
  "official_doc_url": "https://datatracker.ietf.org/doc/html/rfc4862",
  "official_doc_section": null,
  "error_code": null,
  "verification_tier": "ai_generated",
  "confidence": 0.86,
  "fix_success_rate": 0.79,
  "resolvable": "true",
  "first_seen": "2024-03-05",
  "last_confirmed": "2024-06-01",
  "last_updated": "2024-06-01",
  "evidence_count": 1,
  "tags": [],
  "locale": "en",
  "aliases": []
}