[Kea-users] Kea-DHCPv6: No static reservations available

Wed Dec 3 02:07:43 UTC 2025

Hi Darren,

please find the log attached. You can see that after around 6min KEA uses
the defined hostname.
Could you please elaborate a bit more on the prefix delegation part. Why
would I need it?

Thank you.
Best,
C.

Am Mi., 3. Dez. 2025 um 08:20 Uhr schrieb <kea-users-request at lists.isc.org>:

> Send Kea-users mailing list submissions to
>         kea-users at lists.isc.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
>         https://lists.isc.org/mailman/listinfo/kea-users
> or, via email, send a message with subject or body 'help' to
>         kea-users-request at lists.isc.org
>
> You can reach the person managing the list at
>         kea-users-owner at lists.isc.org
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Kea-users digest..."
>
>
> Today's Topics:
>
>    1. Re: Kea-DHCPv6: No static reservations available (Darren Ankney)
>    2. KEA HA failover - dhcpv6 particularly (Aaron Gould)
>    3. Re: KEA HA failover - dhcpv6 particularly (Darren Ankney)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 2 Dec 2025 15:23:45 -0500
> From: Darren Ankney <darren.ankney at gmail.com>
> To: "Kea user's list" <kea-users at lists.isc.org>
> Subject: Re: [Kea-users] Kea-DHCPv6: No static reservations available
> Message-ID:
>         <CAKabWHgTotJFnpDu6b=fR=Jwj6G=
> WudO3ynKXmLXe2_04b+Wwg at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> Hi Christoph,
>
> Looking at your configuration, I note that there are no dynamic pools.
> I notice your client is reserved address fd00:192:168:3::3 I further
> notice that there is no prefix delegation configured and none reserved
> for the client.  The log messages of
> ALLOC_ENGINE_V6_ALLOC_NO_LEASES_HR correspond to the client asking for
> a prefix delegation (IA_PD) but not receiving one as noted in the logs
> here:
>
> msg_type=SOLICIT (1), trans_id=0xaeccc3,
> options:
> [...]
> type=00025(IA_PD), len=00012: iaid=1448103320, t1=0, t2=0
>
> and in the response:
>
> msg_type=ADVERTISE (2), trans_id=0xaeccc3,
> [...]
> type=00025(IA_PD), len=00056: iaid=1448103320, t1=0, t2=0,
> options:
>     type=00013, len=00040: NoPrefixAvail(6) "Sorry, no prefixes could
> be allocated."
>
> The reservation is clearly used for the IA_NA (fd00:192:168:3::3) or
> the client would not receive an IP address at all.
>
> As far as the failure of hostname, that is a separate issue.
> According to your ddns settings, you should be replacing the hostname
> supplied by the client and it should use the one found in your
> reservation. You said it eventually obtains the correct hostname.  Can
> you send the logs showing this?
>
> Thank you,
> Darren Ankney
>
> On Mon, Dec 1, 2025 at 5:27?PM Christoph Markert <maggiv8 at gmail.com>
> wrote:
> >
> > Hi Darren,
> >
> > please find my configuration below:
> > {
> >
> > "Dhcp6":
> > {
> > "dhcp-ddns": {
> > "enable-updates": true
> > },
> > "ddns-replace-client-name": "always",
> > "ddns-generated-prefix": "v6",
> > "ddns-qualifying-suffix": "local.markert.live",
> > "ddns-override-client-update": true,
> > "ddns-override-no-update": true,
> >
> > "hostname-char-set": "[^A-Za-z0-9.-]",
> > "hostname-char-replacement": "x",
> > "client-classes": [
> > {
> > "name": "Default",
> > "test": "not (option[1].hex == '0x00020000AB11D087EFD048F95BBD')",
> > "option-data":
> > [
> > {
> > "name": "dns-servers",
> > "data": "fd00:192:168:3::1"
> > },
> > {
> > "name": "domain-search",
> > "data": "local.markert.live"
> > }
> > ]
> > }
> > ],
> > "loggers": [
> > {
> > "name": "kea-dhcp6",
> > "severity": "DEBUG",
> > "debuglevel": 99,
> > "output_options": [
> > {
> > "output": "kea-dhcp6.log",
> > "maxver": 10
> > }
> > ]
> > },
> > {
> > "name": "kea-dhcp6.dhcpsrv",
> > "severity": "DEBUG",
> > "debuglevel": 99,
> > "output_options": [
> > {
> > "output": "dhcp6-dhcpsrv.log",
> > "maxver": 10
> > }
> > ]
> > },
> >
> > {
> > "name": "kea-dhcp6.leases",
> > "severity": "DEBUG",
> > "debuglevel": 99,
> > "output_options": [
> > {
> > "output": "dhcp6-leases.log",
> > "maxver": 10
> > }
> > ]
> > }
> > ],
> > "interfaces-config":
> > {
> > "interfaces": ["enp2s0"], // This is the internal interface
> > "service-sockets-max-retries": 10,
> > "service-sockets-retry-wait-time": 3000
> > },
> > "lease-database":
> > {
> > "type": "memfile",
> > "persist": true,
> > "name": "kea-leases6.csv",
> > "lfc-interval": 3600
> > },
> >
> > "renew-timer": 15840,
> > "rebind-timer": 27720,
> > "valid-lifetime": 31680,
> > "shared-networks":
> > [
> > {
> > # Name of the shared network. It may be an arbitrary string
> > # and it must be unique among all shared networks.
> > "name": "markert-live-local",
> >
> > # The subnet selector can be specified at the shared-network level.
> > # Subnets from this shared network will be selected for directly
> > # connected clients sending requests to the server's "enp2s0" interface.
> > "interface": "enp2s0",
> >
> > # This starts a list of subnets in this shared network.
> > # There are two subnets in this example.
> > "subnet6":
> > [
> >
> > {
> > // Internal ID to identify subnet internally
> > "id": 19216810,
> > // Subnet for fd00:192:168:0::/48 - static IPs (usable host IP range:
> fd00:192:168:0::1 - fd00:192:168:0::ffff)
> > "subnet": "fd00:192:168:0::/48",
> > // Add DHCP IPv6 Pool
> > "pools":
> > [ ],
> > // Add reservations here for subnet
> > "reservations":
> > [
> > {
> > "duid": "00:02:00:00:ab:11:d0:87:ef:d0:48:f9:5b:bd",
> > "ip-addresses": [ "fd00:192:168:0::1" ],
> > "hostname": "v6-vmhomeserver"
> > }
> > ],
> > // Additional information for subnet
> > "option-data":
> > [
> > {
> > "name": "dns-servers",
> > "data": "fd00:192:168:3::1"
> > },
> > {
> > "name": "domain-search",
> > "data": "local.markert.live"
> > }
> > ]
> > },
> > {
> > "id": 1921681,
> > // Subnet for fd00:192:168:1::/48 - static IPs (usable host IP range:
> fd00:192:168:1::1 - fd00:192:168:1::ffff)
> > "subnet": "fd00:192:168:1::/48",
> > "client-class": "Default",
> > // Add DHCP IPv6 Pool
> > "pools":
> > [ ],
> > // Add reservations here for subnet
> > "reservations":
> > [
> > {
> > "hw-address": "52:54:00:74:f6:13",
> > "ip-addresses": [ "fd00:192:168:1::1" ],
> > "hostname": "v6-vmhomeserver"
> > }
> > ]
> > },
> > {
> > "id": 1921682,
> > // Subnet for fd00:192:168:2::/48 - static IPs (usable host IP range:
> fd00:192:168:2::1 - fd00:192:168:2::ffff)
> > "subnet": "fd00:192:168:2::/48",
> > "client-class": "Default",
> > // Add DHCP IPv6 Pool
> > "pools":
> > [ ],
> > // Add reservations here for subnet
> > "reservations":
> > [
> > {
> > "hw-address": "52:54:00:74:f6:13",
> > "ip-addresses": [ "fd00:192:168:2::1" ],
> > "hostname": "v6-vmhomeserver"
> > }
> > ]
> > // Additional information for subnet
> > //"option-data":
> > },
> > {
> > "id": 1921683,
> > // Subnet for fd00:192:168:3::/48 - static IPs (usable host IP range:
> fd00:192:168:3::1 - fd00:192:168:3::ffff)
> > "subnet": "fd00:192:168:3::/48",
> > "client-class": "Default",
> > // Add DHCP IPv6 Pool
> > "pools":
> > [ ],
> > // Add reservations here for subnet
> > "reservations":
> > [
> >
> > {
> > "hw-address": "52:54:00:74:f6:13",
> > "ip-addresses": [ "fd00:192:168:3::1" ],
> > "hostname": "v6-vmhomeserver"
> > },
> > {
> > "duid": "00:04:71:7d:ec:24:45:86:f2:f8:07:fd:6a:c2:53:b6:be:da",
> > "ip-addresses": [ "fd00:192:168:3::2" ],
> > "hostname": "v6-homeserver"
> > },
> > // VMDatabaseServer
> > {
> > //"hw-address": "52:54:00:ef:57:d9",
> > "duid": "00:03:00:01:52:54:00:ef:57:d9",
> > "ip-addresses": [ "fd00:192:168:3::3" ],
> > "hostname": "v6-vmdatabaseserver"
> > //"option-data":
> > },
> > // VMHomeHub
> > {
> > //"hw-address": "52:54:00:ed:13:86",
> > "duid": "00:03:00:01:52:54:00:ed:13:86",
> > "ip-addresses": [ "fd00:192:168:3::4" ],
> > "hostname": "v6-vmhomehub"
> > //"option-data":
> > }
> > ]
> > // Additional information for subnet
> > //"option-data":
> > },
> > {
> > "id": 19216816,
> > "subnet": "fd00:192:168:f::/48",
> > "client-class": "Default",
> > "pools":
> > [
> > {
> > "pool": "fd00:192:168:f::5-fd00:192:168:f::ffff"
> > }
> > ],
> > // Add reservations here for subnet
> > "reservations":
> > [
> > // VMHomeServer - interface 'enp2s0'
> > {
> > "hw-address": "52:54:00:74:f6:13",
> > "ip-addresses": [ "fd00:192:0168:f::1" ],
> > "hostname": "v6-vmhomeserver"
> > //"option-data":
> > }
> > ]
> > // Additional information for subnet
> > //"option-data":
> > }
> > ]
> > }
> > ]
> > # end of shared-networks
> > }
> > }
> >
> >
> > However, after a few hours the right host name is assigned again, so
> that is strange. It seems to happen primarily after Debian updates on
> 'homehub' and 'databaseserver' (and occasionally restarts of those)
> >
> > Best,
> > C.
> >
>
>
> ------------------------------
>
> Message: 2
> Date: Tue, 2 Dec 2025 14:49:46 -0600
> From: Aaron Gould <aaron1 at gvtc.com>
> To: kea-users at lists.isc.org
> Subject: [Kea-users] KEA HA failover - dhcpv6 particularly
> Message-ID: <1d77cd9c-b5c0-441f-800a-9d4f2ef69135 at gvtc.com>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> Hi KEA Users, my 2 server engineer coworkers and I (i'm the network guy)
> are trying to setup KEA HA Failover for the first time, in our lab.? We
> have lab endpoints and perfdhcp to test with.? We are generating
> hundreds of dhcpv6 ia_na and ia_pd requests, and the juniper dhcpv6
> relay router is logging the binding states just fine.? We try to
> failover the primary kea server, and see if the backup kea server will
> start replying to dhcpv6 requests, but the backup never seems to respond.
>
> I read some of a previous post from April 2016, but need a bit more
> guidance, lessons learned, and perhaps up-to-date 2025 info.
>
> I would appreciate any guidance any of you all could provide.
>
>
> --
> -Aaron
>
>
>
> ------------------------------
>
> Message: 3
> Date: Tue, 2 Dec 2025 16:19:33 -0500
> From: Darren Ankney <darren.ankney at gmail.com>
> To: "Kea user's list" <kea-users at lists.isc.org>
> Subject: Re: [Kea-users] KEA HA failover - dhcpv6 particularly
> Message-ID:
>         <
> CAKabWHjQu4x3Lw_MmVJ-LUNDEJCxVagSgmLfZ_z6QiesYdCesg at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> Hi Aaron,
>
> This is just a guess. Assuming you have something in (or have accepted
> the defaults of) "max-unacked-clients" and "max-ack-delay" (see here:
>
> https://kea.readthedocs.io/en/stable/arm/hooks.html#load-balancing-configuration
> )
> then you'll need to make use of -y and -Y (see here:
> https://kea.readthedocs.io/en/stable/man/perfdhcp.8.html) in perfdhcp
> to simulate a failover event + actually have Kea failover.  Something
> like:
>
> perfdhcp -6 -e address-and-prefix -r 1 -R 100 -Y 5 -y 300 -p 300
>
> would send dhcp6 queries with ia_na and ia_pd requests at the rate of
> 1 per second simulating a total of 100 clients.  five seconds into the
> test it will start increasing the dhcp6 elapsed seconds option.  It
> will do this for 300 seconds.  The -p causes the test to run for 300
> seconds.  Shut down your primary Kea server sometime after starting
> perfdhcp and failover should occur.
>
> You should see log messages like this one:
>
> https://kea.readthedocs.io/en/stable/kea-messages.html#ha-communication-interrupted-client6-unacked
> until more clients than "max-unacked-clients" are encountered at which
> point the standby or secondary server should start to answer the
> clients.
>
> Thank you,
> Darren Ankney
>
> On Tue, Dec 2, 2025 at 3:49?PM Aaron Gould <aaron1 at gvtc.com> wrote:
> >
> > Hi KEA Users, my 2 server engineer coworkers and I (i'm the network guy)
> > are trying to setup KEA HA Failover for the first time, in our lab.  We
> > have lab endpoints and perfdhcp to test with.  We are generating
> > hundreds of dhcpv6 ia_na and ia_pd requests, and the juniper dhcpv6
> > relay router is logging the binding states just fine.  We try to
> > failover the primary kea server, and see if the backup kea server will
> > start replying to dhcpv6 requests, but the backup never seems to respond.
> >
> > I read some of a previous post from April 2016, but need a bit more
> > guidance, lessons learned, and perhaps up-to-date 2025 info.
> >
> > I would appreciate any guidance any of you all could provide.
> >
> >
> > --
> > -Aaron
> >
> > --
> > ISC funds the development of this software with paid support
> subscriptions. Contact us at https://www.isc.org/contact/ for more
> information.
> >
> > To unsubscribe visit https://lists.isc.org/mailman/listinfo/kea-users.
> > Kea-users at lists.isc.org
>
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
>
> ISC funds the development of this software with paid support
> subscriptions. Contact us at https://www.isc.org/contact/ for more
> information.
>
> Kea-users mailing list
> Kea-users at lists.isc.org
> https://lists.isc.org/mailman/listinfo/kea-users
>
>
> ------------------------------
>
> End of Kea-users Digest, Vol 138, Issue 4
> *****************************************
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.isc.org/pipermail/kea-users/attachments/20251203/f79aeba0/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: kea-dhcpv6.log
Type: text/x-log
Size: 62981 bytes
Desc: not available
URL: <https://lists.isc.org/pipermail/kea-users/attachments/20251203/f79aeba0/attachment-0001.bin>