How are you doing DHCPv6 ?

Ray Soucy rps at
Mon Jan 23 23:07:55 UTC 2012

Yes, DUID and IAID should be persistent on systems.  If they are not
then they are not following the RFC.

Note that bad practices, though, can remove that persistence (e.g.
deleting the DUID, or replicating the DUID on other systems).

On Mon, Jan 23, 2012 at 5:56 PM, Karl Auer <kauer at> wrote:
> On Mon, 2012-01-23 at 17:26 -0500, Randy Carpenter wrote:
>> One major issue is that there is no way to associate a user's MAC (for
>> IPv4) with their DUID. I haven't been able to find a way to account
>> for this without making the user authenticate once for IPv4, and then
>> again for IPv6. This is cumbersome to the user. Also, in the past
>> there have been various reason why we want to pre-authenticate a
>> client's MAC address (mostly for game consoles, and such, which have
>> the MAC written on the outside of the machine). How can this be done
>> with IPv6, which the DUID is not constant?
> Perhaps I misunderstand you (or the RFCs) but it seems to me that the
> DUID *is* constant. Reading section 9 of RFC 3315, it's pretty clear
> that a DUID is generated once, according to simple rules, and does not
> change once it has been generated. Barring intervention, of course.
> The problem is how to either find out ahead of time what DUID a client
> has OR how to impose a specific DUID on a client as part of provisioning
> it. Neither of those issues looks particularly intractable, especially
> if vendors start shipping with pre-configured DUIDs that are written on
> the boxes.
> What do you mean by "authenticate"? Do you mean something like 802.1x?
> 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

Ray Soucy

Epic Communications Specialist

Phone: +1 (207) 561-3526

Networkmaine, a Unit of the University of Maine System

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