On Fri, Sep 18, 2026 at 10:13:23PM +0000, Lawrence Lee wrote: > Transition a FAILED neighbor entry to STALE upon receipt of an NA > message on routers when accept_untracked_na is enabled. This extends the > RFC 9131 accept_untracked_na behavior so that FAILED entries are treated > the same as non-existent entries. > > RFC 4861 section 7.3.3 says that an entry should be deleted when address > resolution fails. Linux instead retains the entry in NUD_FAILED, so > treating it as untracked is consistent with the protocol model. > > Trying to resolve FAILED neighbors via periodic probing (e.g. using > NTF_EXT_MANAGED) is more work compared to this approach which uses > information in NAs that the kernel may already be receiving. Note that > because this behavior in IPv6 is dependent on the accept_untracked_na > sysctl setting, this approach is more conservative than IPv4 which > transitions FAILED neighbors to STALE by default upon receiving GARPs. > > Link: https://lore.kernel.org/r/[email protected] > Assisted-by: LLM Sashiko sparse > Signed-off-by: Lawrence Lee <[email protected]>
Reviewed-by: Ido Schimmel <[email protected]>
