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[#1351] Added doc section

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Tomek Mrugalski 2020-09-25 14:18:25 +02:00
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doc/sphinx/arm/dhcp4-srv.rst
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@ -3855,6 +3855,43 @@ Our tests reported best results when:
- ``packet-queue-size``: 11 * ``thread-pool-size`` when using ``postgresql`` for
storing leases. In our case it's 11 * 8 = 88.
IPv6-only Preferred Networks
----------------------------
A recent Internet-Draft `draft-ietf-dhc-v6only
<https://datatracker.ietf.org/doc/html/draft-ietf-dhc-v6only-08>`_ soon to be published by IETF as
RFC specifies a DHCPv4 option to indicate that a host supports an IPv6-only mode and is willing to
forgo obtaining an IPv4 address if the network provides IPv6 connectivity. The general idea is that
a network administrator can enable this option to signal to compatible dual-stack devices that the
IPv6 connectivity is available and they can shut down their IPv4 stack. The new option
`v6-only-preferred` is expressed as 32 bit unsigned integer and expressed for how long the device
should disable its stack for. The value is expressed in seconds.
The draft mentions V6ONLY_WAIT timer. This is implemented in Kea by setting the value of
v6-only-preferred option. This follows the usual practice of setting options. You can specify the
option value on pool, subnet, shared network, global levels or even specify it in host reservations.
Note there is no special processing involved. This follows the standard Kea option processing
regime. The option will not be sent back, unless the client explicitly requests it. For example, to
enable the option for the whole subnet, the following configuration can be used:
::
"subnet4": [
{
"pools": [ { "pool": "192.0.2.1 - 192.0.2.200" } ],
"subnet": "192.0.2.0/24",
"option-data": [
{
// This will make the v6-only capable devices to disable their
// v4 stack for half an hour and then try again
"name": "v6-only-preferred",
"data": "1800"
}
]
}
],
.. _host-reservation-v4:
Host Reservation in DHCPv4
@ -6121,6 +6158,11 @@ The following standards are currently supported:
message, remembers the UDP port and sends back reply to the same relay
agent using this UDP port.
- *IPv6-Only-Preferred Option for DHCPv4*, `draft-ietf-dhc-v6only-08
<https://datatracker.ietf.org/doc/html/draft-ietf-dhc-v6only-08>`__: The Kea
server is able to designate its pools and subnets as v6only-preferred and send
back the `v6-only-preferred` option to clients that requested it.
.. _dhcp4-limit:
DHCPv4 Server Limitations