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Re: Dealing with ICMPv6 network unreachable.



Dennis Ferguson <dennis.c.ferguson%gmail.com@localhost> writes:

> I'm not sure the first bit is right.  I think TCP connections using the
> LL address are okay, even when the remote address is global scope, as
> long as the remote host is connected to the same wire.  Since a host
> can't necessarily tell whether the global addressee is on the same wire,
> however, the only thing it can do is attempt to open the connection and
> let the router tell it whether this is okay or not.  This doesn't work
> so well if the host entirely ignores the unreachables the router sends back.

There's some notion, on which I am fuzzy, about doing ND for prefixes
not known to be on-link.  Sending a LL->global packet to a router seems
odd, because unless the global is on link, it's not going to get a
reply.  And it seems bad to forward a packet with a LL source address in
general.

> I do think that if IPv6, or IPv4 for that matter, is broken for you then
> a good solution is just to configure the broken protocol off, use the
> one that works and just get on with it.  That the IPv6 implementation
> makes it hard to do this is a problem.

So we probably need two sysctls to disable v4 and v6.

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