Commit 725013cf authored by Marcin Siodelski's avatar Marcin Siodelski
Browse files

[3947] Updated Kea Guide with the information about support for RFC7550.

parent ddb442f7
......@@ -2379,6 +2379,53 @@ should include options from the isc option space:
even if it is not used.</para>
<section id="dhcp6-rfc7550">
<title>Support for RFC 7550</title>
<para>The <ulink url="">RFC 7550</ulink>
has introduced some changes to the DHCPv6 protocol to resolve a few issues
with the coexistence of multiple stateful options in the messages sent
between the clients and servers.</para>
<para>The typical example is when the client (being also a requesting
router) requests an allocation of both addresses and prefixes when
it performs the 4-way (SARR) exchange with the server. If the
server is not configured to allocate any prefixes but it can allocate
some addresses, it will respond with the IA_NA(s) containing allocated
addresses and the IA_PD(s) containing the NoPrefixAvail status code. If
the client can operate without prefixes it may transition to the
'bound' state when it sends Renew/Rebind messages to the server,
according to the T1 and T2 times, to extend the lifetimes of the
allocated addresses. If the client is still interested in obtaining
prefixes from the server it may also include IA_PD in the Renew/Rebind
to request allocation of the prefixes. If the server still cannot
allocate the prefixes, it will respond with the IA_PD(s) containing
NoPrefixAvail status code. However, if the server can now allocate
the prefixes it will do so, and send them in the IA_PD(s) to the client.
Allocation of leases during the Renew/Rebind was not supported in the
<ulink url="">RFC 3315</ulink>
and <ulink url="">RFC 3633</ulink>,
and has been introduced in
<ulink url="">RFC 7550</ulink>.
Kea supports this new behavior and it doesn't provide any configuration
mechanisms to disable it.
The following are the other behaviors specified in the
<ulink url="">RFC 7550</ulink>
supported by the Kea DHCPv6 server:
<listitem><simpara>set T1/T2 timers to the same value for all
stateful (IA_NA and IA_PD) options to facilitate renewal of all
client's leases at the same time (in a single message exchange),
<listitem><simpara>NoAddrsAvail and NoPrefixAvail status codes
are placed in the IA_NA and IA_PD options in the Advertise message,
rather than as the top level options.</simpara></listitem>
<section id="dhcp6-relay-override">
<title>Using specific relay agent for a subnet</title>
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