4. Terminology
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Terminology
This sections defines terminology specific to IPv6 and DHCP used in this document.
4.1. IPv6 Terminology
IPv6 terminology relevant to this specification from the IPv6 Protocol [3], IPv6 Addressing Architecture [5], and IPv6 Stateless Address Autoconfiguration [17] is included below.
address An IP layer identifier for an interface
or a set of interfaces.
host Any node that is not a router.
IP Internet Protocol Version 6 (IPv6). The
terms IPv4 and IPv6 are used only in
contexts where it is necessary to avoid
ambiguity.
interface A node's attachment to a link.
link A communication facility or medium over
which nodes can communicate at the link
layer, i.e., the layer immediately
below IP. Examples are Ethernet (simple
or bridged); Token Ring; PPP links,
X.25, Frame Relay, or ATM networks; and
Internet (or higher) layer "tunnels",
such as tunnels over IPv4 or IPv6
itself.
link-layer identifier A link-layer identifier for an
interface. Examples include IEEE 802
addresses for Ethernet or Token Ring
network interfaces, and E.164 addresses
for ISDN links.
link-local address An IPv6 address having a link-only
scope, indicated by having the prefix
(FE80::/10), that can be used to reach
neighboring nodes attached to the same
link. Every interface has a link-local
address.
multicast address An identifier for a set of interfaces
(typically belonging to different
nodes). A packet sent to a multicast
address is delivered to all interfaces
identified by that address.
neighbor A node attached to the same link.
node A device that implements IP.
packet An IP header plus payload.
prefix The initial bits of an address, or a
set of IP addresses that share the same
initial bits.
prefix length The number of bits in a prefix.
router A node that forwards IP packets not
explicitly addressed to itself.
unicast address An identifier for a single interface.
A packet sent to a unicast address is
delivered to the interface identified by
that address.
4.2. DHCP Terminology
Terminology specific to DHCP can be found below.
appropriate to the link An address is "appropriate to the link"
when the address is consistent with the
DHCP server's knowledge of the network
topology, prefix assignment and address
assignment policies.
binding A binding (or, client binding) is a
group of server data records containing
the information the server has about
the addresses in an IA or configuration
information explicitly assigned to the
client. Configuration information that
has been returned to a client through a
policy - for example, the information
returned to all clients on the same
link - does not require a binding. A
binding containing information about
an IA is indexed by the tuple <DUID,
IA-type, IAID> (where IA-type is the
type of address in the IA; for example,
temporary). A binding containing
configuration information for a client
is indexed by <DUID>.
configuration parameter An element of the configuration
information set on the server and
delivered to the client using DHCP.
Such parameters may be used to carry
information to be used by a node to
configure its network subsystem and
enable communication on a link or
internetwork, for example.
DHCP Dynamic Host Configuration Protocol
for IPv6. The terms DHCPv4 and DHCPv6
are used only in contexts where it is
necessary to avoid ambiguity.
DHCP client (or client) A node that initiates requests on a link
to obtain configuration parameters from
one or more DHCP servers.
DHCP domain A set of links managed by DHCP and
operated by a single administrative
entity.
DHCP realm A name used to identify the DHCP
administrative domain from which a DHCP
authentication key was selected.
DHCP relay agent (or relay agent) A node that acts as an
intermediary to deliver DHCP messages
between clients and servers, and is on
the same link as the client.
DHCP server (or server) A node that responds to requests from
clients, and may or may not be on the
same link as the client(s).
DUID A DHCP Unique IDentifier for a DHCP
participant; each DHCP client and server
has exactly one DUID. See section 9 for
details of the ways in which a DUID may
be constructed.
Identity association (IA) A collection of addresses assigned to
a client. Each IA has an associated
IAID. A client may have more than one
IA assigned to it; for example, one for
each of its interfaces.
Each IA holds one type of address;
for example, an identity association
for temporary addresses (IA_TA) holds
temporary addresses (see "identity
association for temporary addresses").
Throughout this document, "IA" is used
to refer to an identity association
without identifying the type of
addresses in the IA.
Identity association identifier (IAID) An identifier for an IA,
chosen by the client. Each IA has an
IAID, which is chosen to be unique among
all IAIDs for IAs belonging to that
client.
Identity association for non-temporary addresses (IA_NA) An IA
that carries assigned addresses that are
not temporary addresses (see "identity
association for temporary addresses")
Identity association for temporary addresses (IA_TA) An IA that
carries temporary addresses (see RFC
3041 [12]).
message A unit of data carried as the payload
of a UDP datagram, exchanged among DHCP
servers, relay agents and clients.
Reconfigure key A key supplied to a client by a server
used to provide security for Reconfigure
messages.
relaying A DHCP relay agent relays DHCP messages
between DHCP participants.
transaction ID An opaque value used to match responses
with replies initiated either by a
client or server.