Hello,
It appears that in a few cases, Linux IPv6 implementation does not respond
to Neighbor Unreachibility Detection packets. This isn't configurable.
I noticed this for Point-to-Point links case (IPv6-in-IPv4 tunnel); the
code fragments can be seen in ndisc.c by looking for NUD_NOARP.
RFC2893 states in 3.8 that if an implementation provides bidirectional
tunnels, it MUST at least accept and respond to NUD packets (doesn't do
this). It also SHOULD send NUD packets on its own to determine whether
the tunnel is down (doesn't do this but this is a bit more questionable).
This was triggered by a person noticing NetBSD seems to take down routes
to such destinations under some circumstances as the tunnel is deemed to
be down.
Anything I've missed?
--
Pekka Savola "Tell me of difficulties surmounted,
Netcore Oy not those you stumble over and fall"
Systems. Networks. Security. -- Robert Jordan: A Crown of Swords
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