DHCPv6 client classification based on DUID.
dhcp1 at thehobsons.co.uk
Thu Sep 20 07:11:45 UTC 2012
êþÁýÌÂ ÄÌÂÈ wrote:
>Well thats confusing a little bit. I was hoping
>that most of the clients should obey dhcpv6
>protocol as stated in RFC 3315. And that
>document says that DUID types 0x1 and 0x3 are
>containing link-layer address.
Yes, *A* MAC address, not necessarily *THE* MAC
address of the interface you are configuring, nor
even of a MAC address still installed in the
device. As long as the device has persistent
(which is most systems), it should generate a
DUID the first time one is needed (or at system
startup) - and then store it 'forever' even if
the interface(s) change later. If it has multiple
interfaces, the DUID (note the singular) will
only use the MAC address from one of them, and
the DUID should not change if the interface it
took the MAC address from is removed from the
Thus you a) have no guarantee that a device
encodes a MAC address in the DUID, and b) where
it does, you have no guarantee that it's from the
interface you are interested in.
If you've followed this list for a while, there
has been some "intense" discussion regarding the
lack of MAC address from the interface being
configured and how this impacts on various
operating setups (work flows) already in place.
Mainly, for many, the MAC address is considered
the least bad persistent identifier we have
available - and is usually known before even
plugging in the system, where any DUID generally
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