Wojciech Dec (wdec) wrote:
Indeed, not checking uniqueness of IPv6 addresses when they are
MAC-address derived would be a bad idea: MAC addresses cannot be
assumed to be really universal because they can be administratively
configured in some hosts.
Under the EUI-64 scheme, a non unique IPv6 address is the result of a
non-unique MAC address. When having the latter in a shared bridge
domain is a bit of a problem to say the least and doing or not doing
IPv6 DAD doesn't change things.
Right: it's only where there is no shared bridge to detect the problem
that the DAD is alone to do the job and, since hosts ignore whether
there is such a bridge, it's logical that, as required by the
introduction of RFC 2462, address uniqueness be always checked.
Where checking for uniquness makes sense is whenever there is some
involvment of randomness or administrative fiat in
configuring/creating the IPv6 address.
Hence in a perfect world where
the EUI-64 interface-id rules apply, checking for uniquness wouldn't
be needed. In mandating the check the authors evidently thought of
the cases where the EUI-64 rule doesn't hold.
Yes.
To be on the safe side in the real world, they were right to do so .
RD
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