interface
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... This document specifies the steps a host takes in deciding how to
autoconfigure its interfaces in IP version 6. The autoconfiguration
...
... link, while
hosts generate an "interface identifier" that uniquely identifies an
interface on a subnet ...
... hosts generate an "interface identifier" that uniquely identifies an
interface on a subnet. An address is formed by combining the two. In
...
... In the stateful autoconfiguration model, hosts obtain interface
addresses and/or configuration information ...
...
IPv6 addresses are leased to an interface for a fixed (possibly
infinite) length of time. Each address has an associated lifetime ...
... lifetime
that indicates how long the address is bound to an interface. When a
lifetime expires, the binding ...
... address) become invalid and the
address may be reassigned to another interface elsewhere in the
Internet. To handle the expiration of address bindings ...
... address goes through two distinct phases while assigned to an
interface. Initially, an address is "preferred", meaning that its use
in arbitrary communication is unrestricted. Later, an address ...
... in arbitrary communication is unrestricted. Later, an address becomes
"deprecated" in anticipation that its current interface binding will
become invalid. While in a deprecated state ...
... algorithm on
addresses before assigning them to an interface. The Duplicate
Address Detection algorithm is performed on all addresses ...
... Duplicate Address Detection procedure described in this document on
all addresses prior to assigning them to an interface.
...
... unicast address - an identifier for a single interface. A packet sent
to a unicast address is delivered to the interface ...
... single interface. A packet sent
to a unicast address is delivered to the interface identified by
that address.
...
... multicast address - an identifier for a set of interfaces (typically
belonging to different nodes). A packet sent to a multicast
address ...
... belonging to different nodes). A packet sent to a multicast
address is delivered to all interfaces identified by that
address.
...
... anycast address - an identifier for a set of interfaces (typically
belonging to different nodes). A packet sent to an anycast
address ...
... belonging to different nodes). A packet sent to an anycast
address is delivered to one of the interfaces identified by that
address (the "nearest" one, according to the routing protocol ...
... link-layer address - a link-layer identifier for an interface.
Examples include IEEE 802 addresses ...
... address whose uniqueness on a link is being
verified, prior to its assignment to an interface. A tentative
address is not considered assigned to an interface in the usual
...
... verified, prior to its assignment to an interface. A tentative
address is not considered assigned to an interface in the usual
sense. An interface discards received packets addressed to a
...
... tentative
address is not considered assigned to an interface in the usual
sense. An interface discards received packets addressed to a
tentative address, but accepts Neighbor Discovery ...
... preferred address - an address assigned to an interface whose use by
upper layer protocols is unrestricted. Preferred addresses ...
... deprecated address - An address assigned to an interface whose use is
discouraged, but not forbidden. A deprecated address should no
...
... address becomes invalid.
interface identifier - a link-dependent identifier for an interface ...
... interface identifier - a link-dependent identifier for an interface
that is (at least) unique per link [ADDR-ARCH ...
... link [ADDR-ARCH]. Stateless
address autoconfiguration combines an interface identifier with
a prefix to form an address ...
... address. From address autoconfiguration's
perspective, an interface identifier is a bit string of known
length. The exact length of an interface identifier ...
... interface identifier is a bit string of known
length. The exact length of an interface identifier and the way
it is created is defined in a separate link ...
... create
unique addresses for each of its interfaces. Address
autoconfiguration assumes that each interface can provide a
...
... addresses for each of its interfaces. Address
autoconfiguration assumes that each interface can provide a
unique identifier for that interface ...
... interface can provide a
unique identifier for that interface (i.e., an "interface
identifier"). In the simplest case, an interface identifier
...
... unique identifier for that interface (i.e., an "interface
identifier"). In the simplest case, an interface identifier
consists of the interface ...
... unique identifier for that interface (i.e., an "interface
identifier"). In the simplest case, an interface identifier
consists of the interface's link-layer address ...
... interface
identifier"). In the simplest case, an interface identifier
consists of the interface's link-layer address. An interface
identifier can be combined with a prefix ...
... consists of the interface's link-layer address. An interface
identifier can be combined with a prefix to form an address.
...
... host forms a link-local address by appending its
interface identifier to the link-local prefix.
...
... network service
provider. Renumbering is achieved through the leasing of
addresses to interfaces and the assignment of multiple addresses
to the same interface ...
... interfaces and the assignment of multiple addresses
to the same interface. Lease lifetimes provide the mechanism
through which a site phases out old prefixes. The assignment of
...
... prefixes. The assignment of
multiple addresses to an interface provides for a transition
period during which both a new address and the one being phased
...
...
This section provides an overview of the typical steps that take
place when an interface autoconfigures itself. Autoconfiguration is
performed only on multicast-capable ...
... links and begins when a
multicast-capable interface is enabled, e.g., during system startup.
Nodes (both hosts ...
... autoconfiguration process by
generating a link-local address for the interface. A link-local
address is formed by appending the interface's identifier ...
... link-local address for the interface. A link-local
address is formed by appending the interface's identifier to the
well-known ...
...
Before the link-local address can be assigned to an interface and
used, however, a node must attempt to verify that this "tentative"
...
... autoconfiguration stops and manual configuration of the
interface is required. To simplify recovery in this case, it should
be possible for an administrator to supply an alternate interface
identifier ...
... interface is required. To simplify recovery in this case, it should
be possible for an administrator to supply an alternate interface
identifier that overrides the default identifier in such a way that
the autoconfiguration ...
... the autoconfiguration mechanism can then be applied using the new
(presumably unique) interface identifier. Alternatively, link-local
and other addresses ...
... node ascertains that its tentative link-local address is
unique, it assigns it to the interface. At this point, the node has
IP-level ...
... For safety, all addresses must be tested for uniqueness prior to
their assignment to an interface. In the case of addresses created
...
... is determined primarily by the portion of the address formed from an
interface identifier. Thus, if a node has already verified the
uniqueness of a link-local address ...
... addresses created from
the same interface identifier need not be tested individually. In
contrast, all addresses obtained manually or via stateful address
autoconfiguration ...
... Duplicate
Address Detection outweighs its benefits, the use of Duplicate
Address Detection can be disabled through the administrative setting
of a per-interface configuration flag.
...
... Address leasing facilitates site renumbering by providing a mechanism
to time-out addresses assigned to interfaces in hosts. At present,
upper layer protocols ...
... per-interface basis on
multicast-capable interfaces. For multihomed hosts,
autoconfiguration ...
... hosts,
autoconfiguration is performed independently on each interface.
Autoconfiguration applies primarily to hosts ...
... link-local address and using Duplicate
Address Detection, how routers (auto)configure their interfaces is
beyond the scope of this document.
...
...
Hosts maintain the following variables on a per-interface basis:
...
... A node forms a link-local address whenever an interface becomes
enabled. An interface may become enabled after any of the
...
... link-local address whenever an interface becomes
enabled. An interface may become enabled after any of the
following
events:
...
... The interface is initialized at system startup time.
...
... The interface is reinitialized after a temporary interface
failure or after being temporarily disabled by system
...
... The interface is reinitialized after a temporary interface
failure or after being temporarily disabled by system
management ...
... The interface becomes enabled by system management after
having been administratively
...
... prefix FE80::0 [ADDR-ARCH] (of appropriate length) to the
interface identifier. If the interface identifier has a length of N
bits ...
... ADDR-ARCH] (of appropriate length) to the
interface identifier. If the interface identifier has a length of N
bits, the interface identifier ...
... interface identifier has a length of N
bits, the interface identifier replaces the right-most N zero bits of
the link-local ...
... the link-local prefix. If the interface identifier is more than 118
bits in length, autoconfiguration ...
... autoconfiguration fails and manual configuration is
required. Note that interface identifiers will typically be 64-bits
long and based on EUI-64 ...
... Duplicate Address Detection is performed on unicast addresses prior
to assigning them to an interface whose DupAddrDetectTransmits
variable is greater than zero. Duplicate Address Detection MUST take
...
... stateless address autoconfiguration is used,
address uniqueness is determined solely by the interface
identifier, assuming that subnet prefixes are assigned correctly
(i.e., if all of an interface ...
... interface
identifier, assuming that subnet prefixes are assigned correctly
(i.e., if all of an interface's addresses are generated from the
same identifier ...
... duplicates). Thus, for a set of addresses formed from the same
interface identifier, it is sufficient to check that the link-
local address ...
... Duplicate Address Detection
for additional addresses derived from the same interface
identifier.
...
... address is discovered during the procedure, the address
cannot be assigned to the interface. If the address is derived from
an interface identifier ...
... interface. If the address is derived from
an interface identifier, a new identifier will need to be assigned to
the interface ...
... interface identifier, a new identifier will need to be assigned to
the interface, or all IP addresses for the interface will need to be
...
... the interface, or all IP addresses for the interface will need to be
manually configured. Note that the method for detecting duplicates
...
... successfully. A tentative address is not considered "assigned to an
interface" in the traditional sense. That is, the interface must
accept Neighbor Solicitation ...
... tentative address is not considered "assigned to an
interface" in the traditional sense. That is, the interface must
accept Neighbor Solicitation and Advertisement messages ...
... Target Address matches an
address assigned to the interface. Other packets addressed to the
tentative address should be silently discarded.
...
... Duplicate Address Detection must be
performed prior to assigning an address to an interface in order to
prevent multiple nodes from using the same address ...
... Neighbor Solicitations. Once an address is determined to be unique,
it may be assigned to an interface.
...
... If the Neighbor Solicitation is the first message to be sent from an
interface after interface (re)initialization, the node ...
... Neighbor Solicitation is the first message to be sent from an
interface after interface (re)initialization, the node should delay
...
... Duplicate Address Detection algorithm, an interface MUST receive and
process datagrams sent to the all-nodes ...
... On receipt of a valid Neighbor Solicitation message on an interface,
node behavior depends on whether the target address ...
... target address is not tentative (i.e., it is assigned to
the receiving interface), the solicitation is processed as described
in [DISCOVERY]. If the target address ...
...
Implementor's Note: many interfaces provide a way for upper layers to
selectively enable and disable the looping back of multicast packets ...
... loopback semantics (e.g., the
interface does not loopback packet, yet one or more
solicitations was received), the tentative address ...
... On receipt of a valid Neighbor Advertisement message on an interface,
node behavior depends on whether the target address ...
... matches a unicast or anycast address assigned to the interface. If
the target address is assigned to the receiving ...
... the target address is assigned to the receiving interface, the
solicitation is processed as described in [DISCOVERY]. If the target
address ...
... A tentative address that is determined to be a duplicate as described
above, MUST NOT be assigned to an interface and the node SHOULD log a
system management ...
... address is a link-local address
formed from an interface identifier, the interface SHOULD be
disabled.
...
...
Global and site-local addresses are formed by appending an interface
identifier to a prefix of appropriate length. Prefixes are obtained
...
... | link prefix | interface identifier |
+----------------------------------------------------------------+
...
...
If the sum of the prefix length and interface identifier length
does not equal 128 bits, the Prefix ...
... prefixes contained in
Router Advertisements are consistent with the length of interface
identifiers for that link type. Note that interface identifiers
...
... Router Advertisements are consistent with the length of interface
identifiers for that link type. Note that interface identifiers
will typically be 64-bits long and based on EUI-64 ...
... host adds it to the
list of addresses assigned to the interface, initializing its
preferred and valid lifetime values ...
... stateful address
autoconfiguration) in the list of addresses associated with the
interface, the specific action to perform depends on the Valid
Lifetime ...
... deprecated address is still a valid address for the interface. An
implementation MAY prevent any new communication from using a
deprecated address ...
... sender or actually came from another node is implementation-
dependent. A problematic case occurs when two interfaces attached to
the same link happen to have the same identifier ...
... multicast specification [RFC1112] recommends that the
service interface provide a way for an upper-layer protocol to
inhibit local delivery ...
... by the hardware), with packets looped back (if requested) by
software. On interfaces in which the hardware itself suppresses
loopbacks, a node ...
... source address is the
same as the receiving interface's. Unfortunately, use of that
criteria also results in the discarding of all packets sent by
another node ...
... layer address. Duplicate Address
Detection will fail on interfaces that filter received packets in
this manner:
...
... link-layer address as
the receiving interface, it will also discard packets from other
nodes also using the same link ...
... layer source address as
the interface, it will also discard Duplicate Address
Detection-related Neighbor Solicitation messages sent by another
...
... Thus, to perform Duplicate Address Detection correctly in the case
where two interfaces are using the same link-layer address ...
... layer address, an
implementation must have a good understanding of the interface's
multicast loopback ...
... multicast loopback semantics, and the interface cannot discard
received packets simply because the source link-layer address is the
...
... received packets simply because the source link-layer address is the
same as the interfaces.
...
... Changed document to use term "interface identifier" rather than
"interface token" for consistency with other IPv6 ...