[Kea-users] Kea-dhcp6 always warns with ALLOC_ENGINE_V6_ALLOC_FAIL_SUBNET when allocating reserved address

[Darren Ankney]

Hi Andrew,

This is also probably not the solution to these logs, but I notice you
also have: "reservation-mode": "out-of-pool",  See here:
https://kea.readthedocs.io/en/kea-2.4.1/arm/dhcp6-srv.html#fine-tuning-dhcpv6-host-reservation
where it explains that this is deprecated: "Since Kea 1.9.1, the
reservation-mode parameter is replaced by the reservations-global,
reservations-in-subnet and reservations-out-of-pool flags. The flags
can be activated independently and can produce various combinations,
some of them being unsupported by the deprecated reservation-mode."

Additionally, you may want to move the reservations-global,
reservations-in-subnet and reservations-out-of-pool flags to the
global area.  Their intention is to make allocations happen with less
CPU by telling Kea where it might find reservations.  So, at least the
"reservations-global": false, parameter should be global to prevent
kea from wasting time looking there for a reservation.

You can, of course, suppress these log messages by setting a specific
logger for kea-dhcp6.alloc-engine and setting severity to ERROR which
will cause only ERROR and FATAL messages from the
kea-dhcp6.alloc-engine logger to be logged see here:
https://kb.isc.org/docs/kea-logging-configuration and here:
https://kea.readthedocs.io/en/kea-2.4.1/arm/logging.html for further
information.

Thank you,

Darren Ankney

On Thu, Jan 4, 2024 at 12:51 PM Andrew Rowson via Kea-users
<kea-users at lists.isc.org> wrote:
>
> My bad - typo in the email. It's correct on the server:
>
>     "subnet": "2001:123:456:e8b0::/64",
>     "reservations-global": false,
>     "reservations-in-subnet": true,
>     "reservations-out-of-pool": true,
>     "reservations": [
>
> On Thu, 4 Jan 2024, at 5:17 PM, Bob Harold wrote:
> > On Thu, Jan 4, 2024 at 12:10 PM Andrew Rowson via Kea-users
> > <kea-users at lists.isc.org> wrote:
> >> Hi,
> >>
> >> I'm using isc-kea-dhcp6 (2.4.1-isc20231123184533) on Debian bookworm and am having a minor logging issue. I've got a minimal config that defines a single subnet, an allocatable pool within that subnet and a single reservation.
> >>
> >> The host gets its reserved IP successfully, but there's always a WARN log dance in the kea logs with ALLOC_ENGINE_V6_ALLOC_FAIL_SUBNET, ALLOC_ENGINE_V6_ALLOC_FAIL_NO_POOLS and ALLOC_ENGINE_V6_ALLOC_FAIL_CLASSES.
> >>
> >> Are these warnings expected, or have I misunderstood something about the configuration?
> >>
> >> Thanks,
> >> Andrew
> >>
> >> Config:
> >>
> >>     {
> >>         "Dhcp6": {
> >>             "interfaces-config": {
> >>                 "interfaces": [
> >>                     "enp1s0.2",
> >>                 ]
> >>             },
> >>             "lease-database": {
> >>                 "lfc-interval": 1800,
> >>                 "name": "/var/lib/kea/kea-leases6.csv",
> >>                 "type": "memfile"
> >>             },
> >>             "subnet6": [
> >>                 {
> >>                     "interface": "enp1s0.2",
> >>                     "reservation-mode": "out-of-pool",
> >>                     "pools": [
> >>                         {
> >>                             "pool": "2001:123:456:e8b0:beef:f00f::/112"
> >>                         }
> >>                     ],
> >>                     "reservations-global": false,
> >>                     "reservations-in-subnet": true,
> >>                     "eservations-out-of-pool": true,
> >
> > Probably not the solution, but the line above seems to be missing the
> > first letter.  Is it that way on the server?
> >
> >>                     "subnet": "2001:123:456:e8b0::/64",
> >>                     "reservations": [
> >>                         {
> >>                             "duid": "00:03:00:01:b8:27:eb:bf:db:dd",
> >>                             "hostname": "myhost",
> >>                             "ip-addresses": [
> >>                                 "2001:123:456:e8b0::f"
> >>                             ]
> >>                         }
> >>                     ]
> >>                 }
> >>             ],
> >>             "valid-lifetime": 1800
> >>         }
> >>     }
> >>
> >> Logs:
> >>
> >>     INFO [kea-dhcp6.dhcp6/182198.139733472774592] DHCP6_STARTED Kea DHCPv6 server version 2.4.1 started
> >>     INFO  [kea-dhcp6.leases/182198.139733433005760] DHCP6_LEASE_ADVERT duid=[00:03:00:01:b8:27:eb:bf:db:dd], tid=0x3e9640: lease for address 2001:123:456:e8b0::f and iaid=1746070577 will be advertised
> >>     WARN  [kea-dhcp6.alloc-engine/182198.139733433005760] ALLOC_ENGINE_V6_ALLOC_FAIL_SUBNET duid=[00:03:00:01:b8:27:eb:bf:db:dd], tid=0x3e9640: failed to allocate an IPv6 lease in the subnet 2001:123:456:e8b0::/64, subnet-id 1, shared network (none)
> >>     WARN  [kea-dhcp6.alloc-engine/182198.139733433005760] ALLOC_ENGINE_V6_ALLOC_FAIL_NO_POOLS duid=[00:03:00:01:b8:27:eb:bf:db:dd], tid=0x3e9640: no pools were available for the lease allocation
> >>     WARN  [kea-dhcp6.alloc-engine/182198.139733433005760] ALLOC_ENGINE_V6_ALLOC_FAIL_CLASSES duid=[00:03:00:01:b8:27:eb:bf:db:dd], tid=0x3e9640: Failed to allocate an IPv6 address for client with classes: ALL, KNOWN
> >>     INFO  [kea-dhcp6.leases/182198.139733424613056] DHCP6_LEASE_ALLOC duid=[00:03:00:01:b8:27:eb:bf:db:dd], tid=0x137d91: lease for address 2001:123:456:e8b0::f and iaid=1746070577 has been allocated for 1800 seconds
> >> --
> >>
> > --
> > Bob Harold
> --
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