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[#226] Updated doc

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Francis Dupont 2025-08-13 23:30:20 +02:00
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7
changelog_unreleased/266-adaptive-lease-time-threshold Normal file
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[func] fdupont
Added the new "adaptive-lease-time-threshold" parameter
for the FLQ (Free Lease Queue) allocator which reduces
lifetime of leases when pools of a subnet have an
occupancy rate above a configured threshold (new feature
from ISC DHCP).
(Gitlab #226)

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doc/sphinx/arm/dhcp4-srv.rst
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@ -8985,3 +8985,20 @@ avoiding unnecessary impact on the server's startup time.
As a result, the servers will not be able to offer some of the available
leases to the clients. Only a server reclaiming a particular lease will
be able to offer it.
In Kea 3.1 a new parameter ``adaptive-lease-time-threshold`` was added.
It can be specified at global, shared network and subnet levels and
takes a floating point value between ``0.`` (excluded) and ``1.``.
It is disabled by default or when set to ``1.``. It is active only with
he FLQ allocator and when the occupancy rate of pools of subnet is
above the specified value the server decreases the lease valid lifetime
to the applicable ``min-valid-lifetime`` for new clients. Clients
renewing an already existing lease get at least the remaining lifetime
from the current lease. Since the leases expire faster, the server may
either recover more quickly or avoid pool exhaustion entirely.
The occupancy rate is defined as being the number of already assigned
addresses (including the address being assigned) divided by the total
number of addresses in pools where the address can be allocated from
(i.e. if the query is not member of a ``client-classes`` guard of a pool
this pool is not taken into account).

18
doc/sphinx/arm/dhcp6-srv.rst
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@ -8730,3 +8730,21 @@ avoiding unnecessary impact on the server's startup time.
As a result, the servers will not be able to offer some of the available
leases to the clients. Only a server reclaiming a particular lease will
be able to offer it.
In Kea 3.1 a new parameter ``adaptive-lease-time-threshold`` was added.
It can be specified at global, shared network and subnet levels and
takes a floating point value between ``0.`` (excluded) and ``1.``.
It is disabled by default or when set to ``1.``. It is active only with
he FLQ allocator and when the occupancy rate of pools of subnet is
above the specified value the server decreases the lease valid lifetime
to the applicable ``min-valid-lifetime`` for new clients. Clients
renewing an already existing lease get at least the remaining lifetime
from the current lease. Since the leases expire faster, the server may
either recover more quickly or avoid pool exhaustion entirely.
The occupancy rate is defined as being the number of already assigned
delegated prefixes (including the address being assigned) divided by the total
number of prefixes in pools where the address can be allocated from
(i.e. if the query is not member of a ``client-classes`` guard of a pool,
or if the delegated prefix length is not compatible this pool is not taken
into account).