[6bed4-devel] ICMPv6 Neighbor discovery and tunnels over the Ipv4 internet

[<ebi...@xm...>]

So I took a good hard look at what it would take to get ICMPv6
relatively safe and have the property that it worked reasonably
well over the NATed internet.

You have to add support for multiple source and destination addresses.
You have to require support for nonces, and use them to prevent
problems with source address spoofing.

You have to change the semantics so that you don't trust source and
destination addresses that have been provided until you have verified
them.

And there are a whole host of slight differences in semantics that
you have to handle very carefully.

And ultimately you have what is effectively a whole new protocol.

If ipv6 was likely to run over networks with these perverse
characteristics on a regular basis it would be worth specifying
the necessary extensions.  As IPv6 is mostly likely to run over
ethernet links and other similar links that have similar properties
I just don't think it makes sense to upgrade Neighbor Discovery
to the extent it is barely recognizable.

Instead something simpler should be implemented.

Eric