How are you doing DHCPv6 ?

Karl Auer kauer at
Mon Jan 23 23:35:08 UTC 2012

On Mon, 2012-01-23 at 18:12 -0500, Randy Carpenter wrote:
> Controlled by software = not constant.

OK - fair point. But these days many MACs can be controlled by software
too. In the world of virtual computing they don't exist in hardware at
all. The world hasn't ended.

Examples abound of codes that are software controlled but long-lived.
SSIDs and other access codes on commodity wifi routers, for example. Or
licence numbers for some operating systems e.g., Windows. Written on the
box, too.

> It is also not likely to be something that is knowable on a piece of
> electronic gear that is not a PC, nor will it be something that can be
> printed on the outside of the device, like most today.

Well, that's not really true. There is nothing stopping OEMs shipping
equipment with preconfigured DUIDs and printing those DUIDs on the side
of the box or the bottom of the device or whatever.

As to being "knowable", well, neither is a MAC. Short of starting up a
device and seeing what MAC it uses, there is no way to know ahead of
time what MAC addresses a device has unless the manufacturer was kind
enough to print them on the box.

Don't get me wrong; I'm not trying to be an apologist for DUIDs. But I
think we do need to see the problems clearly in order to solve them.

Regards, K.

Karl Auer (kauer at

GPG fingerprint: AE1D 4868 6420 AD9A A698 5251 1699 7B78 4EEE 6017
Old fingerprint: DA41 51B1 1481 16E1 F7E2 B2E9 3007 14ED 5736 F687
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 230 bytes
Desc: This is a digitally signed message part
URL: <>

More information about the NANOG mailing list