[Kea-users] IA_PD without IA_NA and reserved Prefixes

Marcin Siodelski marcin at isc.org
Mon Apr 25 15:49:37 UTC 2016



On 20.04.2016 20:07, Wido den Hollander wrote:
> 
> 
>> Op 20 apr. 2016 om 19:17 heeft Marcin Siodelski <marcin at isc.org> het volgende geschreven:
>>
>>
>>
>>> On 20.04.2016 07:39, Wido den Hollander wrote:
>>>
>>>> Op 20 april 2016 om 16:06 schreef Wido den Hollander <wido at widodh.nl>:
>>>>
>>>>
>>>> Hello,
>>>>
>>>> My use-case is where I want to run a DHCPv6 server which does IA_PD, but
>>>> doesn't
>>>> do IA_NA.
>>>>
>>>> The clients in this case obtain their address through SLAAC and additionally
>>>> can
>>>> get a prefix through IA_PD.
>>>>
>>>> Additionally I only want assigned prefixes to be allowed. Only if a
>>>> reservation
>>>> is present I want to hand it out. Otherwise no prefix is assigned. That part
>>>> seems to work by using the 'out-of-pool' mode for reservations.
>>>>
>>>> In Kea I can't get this configured since it always requires a subnet.
>>>>
>>>> "subnet6": [
>>>>        {
>>>>            "subnet": null,
>>>>            "interface-id": "VLAN709",
>>>>            "reservation-mode": "out-of-pool",
>>>>            "reservations": [
>>>>                {
>>>>
>>>> This doesn't work, the same as leaving 'subnet' out of the configuration.
>>>>
>>>> Is this possible with Kea?
>>>
>>> I actually found out that this already works. Just define a 'subnet', but do not
>>> define a 'pool' inside the subnet6 section.
>>>
>>> My clients are now able to obtain a prefix through IA_PD but never get a answer
>>> for IA_NA:
>>>
>>> [kea-dhcp6.alloc-engine/1856] ALLOC_ENGINE_V6_ALLOC_FAIL
>>> duid=[00:01:00:01:1e:94:17:e8:06:d4:36:00:04:87], tid=0x189a81: failed to
>>> allocate an IPv6 address after 0 attempt(s)
>>>
>>> Wido
>>
>> Hi Wido,
>>
>> From your second email it sounds that you were able to configure Kea to
>> do what you want. Do you need any more assistance on this?
>>
> 
> Yes, it works now. However, it would be nice if you could omit the subnet in the configuration.
> 
> This way Kea knows you only use it for IA_PD and will not respond on IA_NA.
> 

Even if you're not doing IA_NA, the "subnet" declaration is still
required (without address pools as you say), because you need to be able
to define "pd-pools" (pools for prefix delegation). The "pd-pools" are
defined per-subnet.

Marcin


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