AW: Serving DHCPv6 requests from an IPv4 network - possible?

[David Jennings]

Hi Harald. I think I've got the answer from Steven but just to clarify 
the question...

The client will be dual-stack: IPv4 and IPv6. It will be a router behind 
which is a dual-stack client network. The DHCP server is currently in an 
IPv4-only network. The simplest solution, for initial tests, is to run a 
DHCPv6 server process on the existing machine, and have the router make 
a DHCPv6 request to the IPv4 address of the DHCP server. I couldn't 
think of any fundamental reason why that wouldn't be possible but it 
appears to be out of the configuration possibilities of the ISC DHCP 
server, as Steven has confirmed.

So we will probably bite the bullet and set up the DHCP server as 
dual-stack also.

Thanks,

David.

On 05/05/14 17:09, Albrecht, Harald wrote:
> I'm not exactly clear what perceived problem you are wanting to
> solve.  As IPv6 comes with (for several data link layers) automatically
> generated link-local addresses, you don't need to manually assign any
> IPv6 addresses to the DHCPv6 server. In particular, as you are deploying
> the DHCPv6 server in the same network as your DHCPv6 client. Next,
> DHCPv6 is completely separate from DHCPv4. There are also important
> changes in the client model in that identification uses DUIDs instead of
> MACs. A DUID can be a MAC, but for Win7+ it actually is DUID-LLT, that
> is, MAC+timestamp. As DHCPv6 is a separate beast, you will run a
> separate DHCPv6 server. No need to mix the servers in the same process.
>
> Best regards,
> Harald
>
>> -----Ursprüngliche Nachricht-----
>> Von: dhcp-users-bounces at lists.isc.org [mailto:dhcp-users-
>> bounces at lists.isc.org] Im Auftrag von David Jennings
>> Gesendet: Montag, 5. Mai 2014 04:33
>> An: dhcp-users at lists.isc.org
>> Betreff: Serving DHCPv6 requests from an IPv4 network - possible?
>>
>> Hello all,
>>
>> We have a DHCP server on an all-IPv4 network. We would like to start
>> experimenting with IPv6 configuration and as an initial step I would like to be
>> able to configure the DHCP server to respond to DHCPv6 requests without
>> moving the server itself from it's IPv4-only address.
>>
>> Is this possible?
>>
>> I know that I need to configure a subrange that contains the address of the
>> interface upon which the server is running, which I've done as follows:
>>
>> -------------
>>
>> # dhcpd6.conf
>>
>> shared-network "local" {
>>           deny booting;
>>           not authoritative;
>>           subnet 10.116.74.0 netmask 255.255.255.0 {} }
>>
>> subnet6 2406:DC01:1:1::/64 {
>>           range6 2406:DC01:1:1::10 2406:DC01:1:1::200; }
>>
>> -------------
>>
>> however when starting the server with the "-6" option I then get the error:
>>
>> subnet_number():inet.c:53: Addr/mask length mismatch.
>>
>> which is presumably because I'm mixing IPv4 and IPv6 in the configuration.
>>
>> So is what I'm trying to do possible? Or do I have to host the DHCP server on
>> a dual-stack IPv4/IPv6 address?
>>
>> Thanks,
>>
>> David.
>>
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