Commit b939bf7d authored by Tomek Mrugalski's avatar Tomek Mrugalski 🛰
Browse files

[4518] User's Guide, examples updated for DHCPv4

parent 208e7fb0
......@@ -30,28 +30,88 @@
# "renew-timer": 1000,
# "rebind-timer": 2000,
# Define a subnet with two reservations for the 192.0.2.202 and
# 192.0.2.100 address. Note that the latter is a reservation for the
# address which is within the range of the pool of the dynamically
# allocated address. The server will exclude this address from this
# pool and only assign it to the client which has a reservation for
# it.
# Kea supports several reservations by several different types of identifiers:
# hw-address (hardware/MAC address of the client), duid (DUID inserted by the
# client), client-id (client identifier inserted by the client) and circuit-id
# (circuit identifier inserted by the relay agent). When told to do so, Kea can
# check for all of those identifier types, but it takes a costly database lookup
# to do so. It is therefore useful from performance perspective to use only
# that reservation types that are actually used in a given network.
# This example below is not the best from performance perspective, but it
# showcases the capabilities nicely. Please use the minimum set of identifier
# types used in your network.
"host-reservation-identifiers": [ "circuit-id", "hw-address", "duid", "client-id" ],
# Define a subnet with four reservations. Some of the reservations belong
# to the dynamic pool. Kea is able to handle this case, but it is not
# recommended from performance perspective, as Kea would not only need to
# check if given address is free, but also whether it is reserved for anyone.
# To avoid this check, one change reservation-mode to out-of-pool, rather
# than 'all'. If a subnet does not have reservations at all, the reservation
# lookup can be skipped altogether (reservation-mode set to 'disabled').
# Note that the second reservation is for the address which is within the
# range of the pool of the dynamically allocated address. The server will
# exclude this address from this pool and only assign it to the client which
# has a reservation for it.
"subnet4": [
{
"pools": [ { "pool": "192.0.2.1 - 192.0.2.200" } ],
"subnet": "192.0.2.0/24",
"interface": "eth0",
"reservations": [
"reservations": [
# This is a reservation for specific hardware/MAC address. It's a very
# simple reservation: just an address and nothing else.
{
"hw-address": "1a:1b:1c:1d:1e:1f",
"ip-address": "192.0.2.202"
},
# This is a reservation for specific client-id. It also shows
# the this client will get reserved hostname. Hostname can be defined
# for any identifier type, not just client-id.
{
"client-id": "01:11:22:33:44:55:66",
"ip-address": "192.0.2.100",
"hostname": "special-snowflake"
},
# The third reservation is based on DUID. This reservation also
# defines special option values for this particular client. If
# domain-name-servers option would be defined on global, subnet or class level,
# the host specific values take preference.
{
"duid": "01:02:03:04:05",
"ip-address": "192.0.2.203",
"option-data": [ {
"name": "domain-name-servers",
"data": "10.1.1.202,10.1.1.203"
} ]
},
# The fourth reservation is based on circuit-id. This is an option inserted
# by relay agent that forwards the packet from client. In this example the
# host is also assigned vendor specific options.
{
"hw-address": "0a:0b:0c:0d:0e:0f",
"ip-address": "192.0.2.100"
"client-id": "01:11:22:33:44:55:66",
"ip-address": "192.0.2.204",
"option-data": [
{
"name": "vivso-suboptions",
"data": "4491"
},
{
"name": "tftp-servers",
"space": "vendor-4491",
"data": "10.1.1.202,10.1.1.203"
}
]
}
]
}
}
]
},
......
......@@ -148,9 +148,85 @@
<section>
<title>Supported Databases</title>
<para>The following table presents capabilities of available
backends. Please refer to specific sections dedicated to each backend to
better understand the capabilities and limitations. Choosing the right
backend may be essential for success or failure of your deployment.</para>
<para>
<table frame="all" id="backends">
<title>List of available backends</title>
<tgroup cols='2'>
<colspec colname='feature'/>
<colspec colname='memfile'/>
<colspec colname='mysql'/>
<colspec colname='pgsql'/>
<colspec colname='cql'/>
<thead>
<row>
<entry>Feature</entry>
<entry>Memfile</entry>
<entry>MySQL</entry>
<entry>PostgreSQL</entry>
<entry>CQL(Cassandra)</entry>
</row>
</thead>
<tbody>
<row>
<entry>Status</entry>
<entry>Stable</entry>
<entry>Stable</entry>
<entry>Stable</entry>
<entry>Experimental</entry>
</row>
<row>
<entry>Data format</entry>
<entry>coma separated file</entry>
<entry>SQL RMDB</entry>
<entry>SQL RMDB</entry>
<entry>NoSQL database (CQL)</entry>
</row>
<row>
<entry>Leases</entry>
<entry>yes</entry>
<entry>yes</entry>
<entry>yes</entry>
<entry>yes</entry>
</row>
<row>
<entry>Host Reservations</entry>
<entry>no</entry>
<entry>yes</entry>
<entry>no</entry>
<entry>no</entry>
</row>
<row>
<entry>Options defined on per host basis</entry>
<entry>no</entry>
<entry>yes</entry>
<entry>no</entry>
<entry>no</entry>
</row>
</tbody>
</tgroup>
</table>
</para>
<section>
<title>memfile</title>
<para>
Memfile backend is able to store leases information, but is not able to
store host reservation details. There are no plans to add the
reservations storage capability to memfile. Host reservations can be
defined in the configuration file.
</para>
<para>
There are no special initialization steps necessary
for the memfile backend. During the first run, both
......@@ -158,6 +234,7 @@
will create an empty lease file if one is not
present. Necessary disk write permission is required.
</para>
<section id="memfile-upgrade">
<title>Upgrading Memfile Lease Files from an Earlier Version of Kea</title>
<para>
......@@ -185,13 +262,17 @@
<section>
<title>MySQL</title>
<para>
MySQL is able to store leases, host reservations and options defined on
a per host basis.
</para>
<para>
The MySQL database must be properly set up if you want Kea to
store information in MySQL. This section can be safely ignored
if you chose to store the data in other backends.
</para>
<section id="mysql-database-create">
<title>First Time Creation of Kea Database</title>
......@@ -327,6 +408,12 @@ $ <userinput>kea-admin lease-upgrade mysql -u <replaceable>database-user</replac
<section>
<title>PostgreSQL</title>
<para>
PostgreSQL is able to store leases. The capability to store host
reservations (that include addresses, prefixes and options) is planned
for upcoming Kea 1.1.0.
</para>
<para>
A PostgreSQL database must be set up if you want Kea to store
lease and other information in PostgreSQL. This step can be
......@@ -496,6 +583,15 @@ $ <userinput>kea-admin lease-init pgsql -u <replaceable>database-user</replaceab
<section>
<title>CQL (Cassandra)</title>
<para>
Cassandra, or Cassandra Query Language (CQL), is the newest backend
added to Kea. Since it was added recently and have not undergone as much
testing as other backends, it is considered experimental. Please use
with caution. CQL backend is currently able to store leases only. The
ability to store host reservations will likely be added some time in the
future.
</para>
<para>
The CQL database must be properly set up if you want Kea to store
information in CQL. This section can be safely ignored if you chose to
......
......@@ -90,9 +90,9 @@ strings <userinput>path</userinput>/kea-dhcp4 | sed -n 's/;;;; //p'
</para>
<para>
When running in a console, the server can be shut down by
pressing ctrl-c. It detects the key combination and shuts
down gracefully.
When running in a console, the server can be shut down by
pressing ctrl-c. It detects the key combination and shuts
down gracefully.
</para>
<para>
......@@ -750,8 +750,8 @@ temporarily override a list of interface names and listen on all interfaces.
manually specify a unique identifier for each subnet.
</para>
<para>
The following configuration will assign the specified subnet
identifier to the newly configured subnet:
The following configuration will assign the specified subnet
identifier to the newly configured subnet:
<screen>
"Dhcp4": {
......@@ -2444,7 +2444,7 @@ It is merely echoed by the server
near future.</para>
<para>Hosts reservations are defined as parameters for each subnet. Each host
has to be identified by its hardware/MAC address. There is an optional
has to be identified by an identifier, for example hardware/MAC address. There is an optional
<command>reservations</command> array in the <command>Subnet4</command>
element. Each element in that array is a structure, that holds information
about reservations for a single host. In particular, such a structure has
......@@ -2453,14 +2453,9 @@ It is merely echoed by the server
will be specified. It is possible to specify a hostname. Additional
capabilities are planned.</para>
<note><para>In Kea 1.0.0 it is only possible to create host reservations
using client's hardware address. Host reservations by client identifier
(or DUID) are not supported in this version of Kea. This capability will
be implemented in Kea 1.1.0. Currently, the configuration parsing code
will accept the "duid" parameter in the reservation configuration, but
the server will misinterpret its value. Therefore, this parameter MUST
NOT be used until the client identifier based host reservations are
properly implemented and documented.</para></note>
<para>In Kea 1.1.0 it was only possible to create host reservations
using client's hardware address. Host reservations by client
identifier, DUID and circuit-id have been added in Kea 1.1.0.</para>
<para>The following example shows how to reserve addresses for specific
hosts:
......@@ -2477,9 +2472,17 @@ It is merely echoed by the server
"ip-address": "192.0.2.202"
},
{
"hw-address": "0a:0b:0c:0d:0e:0f",
"duid": "0a:0b:0c:0d:0e:0f",
"ip-address": "192.0.2.100",
"hostname": "alice-laptop"
},
{
"circuit-id": "'charter950'",
"ip-address": "192.0.2.203"
},
{
"client-id": "01:11:22:33:44:55:66\","
"ip-address": "192.0.2.204"
}
]</userinput>
}
......@@ -2487,10 +2490,19 @@ It is merely echoed by the server
</screen>
The first entry reserves the 192.0.2.202 address for the client that uses
MAC address of 1a:1b:1c:1d:1e:1f. The second entry reserves the address
192.0.2.100 and the hostname of alice-laptop for client using MAC
address 0a:0b:0c:0d:0e:0f. Note that if you plan to do DNS updates, it
is strongly recommended for the hostnames to be unique.
</para>
192.0.2.100 and the hostname of alice-laptop for client using DUID
0a:0b:0c:0d:0e:0f. Note that if you plan to do DNS updates, it
is strongly recommended for the hostnames to be unique. The third
example reserves address 192.0.3.203 to a client whose request
would be relayed by a relay agent that inserts circuid-it option
with value 'charter950'. The fourth entry reserves address
192.0.2.204 for a client that uses client identifier with value
01:11:22:33:44:55:66.</para>
<para>Note that the above example is used for ilustrational purposes only
and in actual deployments it is recommended to use as few types as possible
(preferably just one). See <xref linkend="reservation-tuning4"/> for detailed
discussion.</para>
<para>Making a reservation for a mobile host that may visit multiple subnets
requires a separate host definition in each subnet it is expected to visit.
......@@ -2670,21 +2682,61 @@ It is merely echoed by the server
<section id="reservation4-options">
<title>Reserving specific options</title>
<!-- @todo: replace this with the actual text once #3572 is implemented -->
<para>Currently it is not possible to specify options in host
reservation. Such a feature will be added in the upcoming Kea
releases.</para>
<para>Kea 1.1.0 introduced the ability to specify options on a
per host basis. The options follow the same rules as any other
options. These can be standard options (see <xref
linkend="dhcp4-std-options" />), custom options (see <xref
linkend="dhcp4-custom-options"/>) or vendor specific options
(see <xref linkend="dhcp4-vendor-opts" />). The following
example showcases how standard options can be defined.</para>
<screen>
"reservations": [
{
"hw-address": "aa:bb:cc:dd:ee:ff",
"ip-address": "192.0.2.1",
<userinput>"option-data": [
{
"name": "cookie-servers",
"data": "10.1.1.202,10.1.1.203"
},
{
"name": "log-servers",
"data": "10.1.1.200,10.1.1.201"
} ]</userinput>
} ]</screen>
<para>Vendor specific options can be reserved in similar manner:</para>
<screen>
"reservations": [
{
"hw-address": "aa:bb:cc:dd:ee:ff",
"ip-address": "10.0.0.7",
<userinput>"option-data": [
{
"name": "vivso-suboptions","
"data": "4491"
},
{
"name": "tftp-servers",
"space": "vendor-4491",
"data": "10.1.1.202,10.1.1.203"
}
]</userinput>
} ]</screen>
<para>
Options defined on host level have the highest priority. In other words,
if there are option defined with the same type on global, subnet, class and
host level, the host specific values will be used.
</para>
</section>
<section id="reservation4-mode">
<section id="reservation-tuning4">
<title>Fine Tuning IPv4 Host Reservation</title>
<note>
<para><command>reservation-mode</command> configuration parameter in DHCPv4
server is accepted, but not used in the Kea 0.9.1 beta. Full implementation
will be available in the upcoming releases.</para>
</note>
<para>Host reservation capability introduces additional restrictions for the
allocation engine during lease selection and renewal. In particular, three
major checks are necessary. First, when selecting a new lease, it is not
......@@ -2745,6 +2797,46 @@ It is merely echoed by the server
}
</screen>
</para>
<para>Another aspect of the host reservations are different types of
identifiers. Currently (June 2016) Kea supports four types of identifiers
(hw-address, duid, client-id and circuit-id), but more identifier types
are likely to be added in the future. This is beneficial from the
usability perspective. However, there is a drawback. For each incoming
packet Kea has to to extract each identifier type and then query the
database to see if there's a reservation done by this particular
identifier. If there is not, the next identifier is extracted and next
query is issued. This process continues until either a reservation is
found or all identifier types were checked. Over time with increasing
number of supported identifier types, Kea would become slower and
slower.</para>
<para>To address this problem, a parameter called
<command>host-reservation-identifiers</command> has been introduced. It
takes a list of identifier types as a parameter. Kea will check only those
identifier types enumerated in host-reservation-identifiers. From the
performance perspective the number of identifier types should be kept to
minimum, ideally limited to one. If your deployment uses several
reservation types, please enumerate them from most to least frequently
used as this increases the chances of Kea finding the reservation using
fewer number of queries. An example of host reservation identifiers looks
as follows:
<screen>
<userinput>"host-reservation-identifiers": [ "circuit-id", "hw-address", "duid", "client-id" ],</userinput>
"subnet4": [
{
"subnet": "192.0.2.0/24",
...
}
]</screen>
</para>
<para>If not specified, the default value is <command>hw-address, duid,
circuit-id</command>.</para> <!-- see CfgHostOperations::createConfig4() in
src/lib/dhcpsrv/cfg_host_operations.cc -->
</section>
</section>
......@@ -3283,12 +3375,12 @@ It is merely echoed by the server
</para>
<para>
The length of the path specified by the <command>socket-name</command>
parameter is restricted by the maximum length for the unix socket name
on your operating system, i.e. the size of the <command>sun_path</command>
field in the <command>sockaddr_un</command> structure, decreased by 1.
This value varies on different operating systems between 91 and 107
characters. The typical values are 107 on Linux and 103 on FreeBSD.
The length of the path specified by the <command>socket-name</command>
parameter is restricted by the maximum length for the unix socket name
on your operating system, i.e. the size of the <command>sun_path</command>
field in the <command>sockaddr_un</command> structure, decreased by 1.
This value varies on different operating systems between 91 and 107
characters. The typical values are 107 on Linux and 103 on FreeBSD.
</para>
<para>
......
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