host-identifier with IPv6

Simon Hobson dhcp1 at
Tue Mar 3 23:08:54 UTC 2009

sthaug at wrote:

>  > As a long term solution, how would you feel about a proposal to add a new
>>  DHCPv6 field containing the link-layer address on which the packet was sent?
>>  This could, from the protocol point of view, be sent as a simple 
>>  attribute, with no guarantee of uniqueness, while the DUID semantics remain
>>  unchanged.  If I've understood your other comments correctly, this 
>>means that
>>  the DUID could still be used as the primary identifier, but the DHCP server
>>  would optionally be able to use the link-layer address, if present, as an
>>  input to administratively configured policy decisions about which 
>>options and
>>  values should be handed back to the client.
>>  This should let those of us with MAC centric workflows (including many, many
>>  EDU networks) migrate to IPv6 with far less pain and suffering, while still
>>  leaving the million client per server ISPs able to freely ignore 
>>the MAC address.
>>  Does that sound like a reasonable idea to you?  If so, I'd be more 
>>than happy
>>  to work on it, in whatever the appropriate forum is.

>I think this sounds like an excellent idea, and should be followed up.
>However, I'm afraid it may not be deployable/deployed quickly enough for
>the majority of the clients (before we hit the big IPv4 crunch). Thus we
>also need an interim solution, something like the "hackish" version
>based on the relay agent looking at the MAC address of the DHCPv6 request.

It only needs one relay agent & server to support it to be usable. 
OK, it would mean that (for example) large sites wouldn't be able to 
use their Cisco routers embedded relay agents until they got updated, 
but it's generally not hard to find a suitable host to carry a relay 
agent - and if there isn't one, it doesn't take a lot of cost/cpu to 
run a minimal install of Linux/Solaris/BSD/Whatever on a basic 

Simon Hobson

Visit for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.

More information about the dhcp-users mailing list