networking network_error ai_generated partial

NDP: Neighbor Solicitation for fe80::1 on eth0 failed, no reply

ID: networking/ipv6-ndp-failure

Also available as: JSON · Markdown · 中文
80%Fix Rate
82%Confidence
1Evidence
2024-04-12First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
Linux kernel 6.1 active — — —
Cisco IOS XE 17.9 active — — —
Windows Server 2022 active — — —

Root Cause

The IPv6 neighbor discovery protocol (NDP) sent a Neighbor Solicitation to resolve the link-layer address of fe80::1 but received no Neighbor Advertisement, indicating the neighbor is unreachable or not responding.

generic

中文

IPv6邻居发现协议（NDP）发送了邻居请求以解析fe80::1的链路层地址，但未收到邻居公告，表明邻居不可达或未响应。

Official Documentation

https://www.kernel.org/doc/html/latest/networking/ip-sysctl.html

Workarounds

  1. 85% success Verify IPv6 connectivity with ping: ping6 -c 3 fe80::1%eth0 
    Verify IPv6 connectivity with ping: ping6 -c 3 fe80::1%eth0
  2. 80% success Flush the neighbor cache and retry: ip -6 neigh flush all && ip -6 neigh show 
    Flush the neighbor cache and retry: ip -6 neigh flush all && ip -6 neigh show

中文步骤

  1. Verify IPv6 connectivity with ping: ping6 -c 3 fe80::1%eth0
  2. Flush the neighbor cache and retry: ip -6 neigh flush all && ip -6 neigh show

Dead Ends

Common approaches that don't work:

  1. 90% fail

    Disabling IPv6 on the interface (sysctl net.ipv6.conf.eth0.disable_ipv6=1) avoids the issue but loses IPv6 connectivity entirely.

  2. 70% fail

    Manually adding a static neighbor entry (ip -6 neigh add fe80::1 lladdr 00:11:22:33:44:55 dev eth0) may fail if the link-layer address is incorrect or the neighbor is genuinely unreachable.