Re: Is 00:00:00:00:00:00 special?

[David Brownlee <abs%netbsd.org@localhost>]

On Thu, 20 Nov 2025 at 03:59, Mouse <mouse%rodents-montreal.org@localhost> wrote:
>
> Is the all-zero MAC address special?  Thanks to an unusual hardware
> situation, I just booted a SPARC such that le0 thinks its MAC is
> all-0-bits.  (Booted from disk, not netboot, to be sure.)
>
> But IPv6 failed to attach at boot time, saying it failed to get EUI64,
> which is why I'm asking.  I can't recall hearing of any way in which
> the all-0 MAC would be invalid, but _something_ seems to think it is;
> it looks to me like a perfectly good globally-administered unicast
> address.  It seems to work fine for IPv4, though of course (like any
> MAC) there can be at most one such in any broadcast domain unless
> you're doing something fancy.
>
> Anybody happen to know?

It used to be supported by NetBSD, but IIRC sometime in the late
1990's something was adjusted to reject it.

On one hand it was quite annoying when booting a sparcstation with a
dead NVRAM, but on the other hand booting *two* of those would end up
in an unhappy place :)

David