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... IP version 6. The autoconfiguration
process includes creating a link-local address and verifying its
uniqueness on a link, determining what information should be
...
... process includes creating a link-local address and verifying its
uniqueness on a link, determining what information should be
autoconfigured (addresses, other information, or both), and in the
...
... stateless mechanism, the stateful mechanism, or both. This document
defines the process for generating a link-local address, the process
for generating site-local and global addresses ...
... prefixes that identify the subnet(s) associated with a link, while
hosts generate an "interface identifier ...
... the absence of routers, a host can only generate link-local
addresses. However, link-local addresses are sufficient for allowing
communication among nodes ...
... routers, a host can only generate link-local
addresses. However, link-local addresses are sufficient for allowing
communication among nodes attached to the same link ...
... link-local addresses are sufficient for allowing
communication among nodes attached to the same link.
...
... To insure that all configured addresses are likely to be unique on a
given link, nodes run a "duplicate address detection" algorithm ...
... by some other means. However, it is expected that routers will
generate link-local addresses using the mechanism described in this
document. In addition, routers are expected to successfully pass the
...
... communication facility or medium over which nodes can
communicate at the link layer, i.e., the layer immediately below
IP ...
... link-local address - an address having link-only scope that can be
used to reach neighboring nodes attached to the same link ...
... link-only scope that can be
used to reach neighboring nodes attached to the same link. All
interfaces have a link-local ...
... tentative address - an address whose uniqueness on a link is being
verified, prior to its assignment to an interface. A tentative
address ...
... identifier for an interface
that is (at least) unique per link [ADDR-ARCH]. Stateless
address autoconfiguration combines an interface identifier ...
... interface identifier and the way
it is created is defined in a separate link-type specific
document that covers issues related to the transmission of IP
...
... document that covers issues related to the transmission of IP
over a particular link type (e.g., [IPv6-ETHER]). In many
cases, the identifier ...
... interface identifier
consists of the interface's link-layer address. An interface
identifier can be combined with a prefix to form an address ...
... Small sites consisting of a set of machines attached to a single
link should not require the presence of a stateful server or
router as a prerequisite for communicating. Plug-and-play
...
... router as a prerequisite for communicating. Plug-and-play
communication is achieved through the use of link-local
addresses. Link-local addresses have a well-known prefix ...
... router as a prerequisite for communicating. Plug-and-play
communication is achieved through the use of link-local
addresses. Link-local addresses have a well-known prefix that
...
... well-known prefix that
identifies the (single) shared link to which a set of nodes
attach. A host ...
... nodes
attach. A host forms a link-local address by appending its
interface identifier to the link-local ...
... Autoconfiguration is
performed only on multicast-capable links and begins when a
multicast-capable interface ...
... routers) begin the autoconfiguration process by
generating a link-local address for the interface. A link-local
address is formed by appending the interface ...
... generating a link-local address for the interface. A link-local
address is formed by appending the interface's identifier to the
...
... address is not already in use by another node on the link.
Specifically, it sends a Neighbor Solicitation message containing the
...
... times the Neighbor Solicitation is (re)transmitted and the delay time
between consecutive solicitations is link-specific and may be set by
system management.
...
...
If a node determines that its tentative link-local address is not
unique, autoconfiguration stops and manual configuration ...
... autoconfiguration mechanism can then be applied using the new
(presumably unique) interface identifier. Alternatively, link-local
and other addresses will need to be configured manually.
...
...
Once a node ascertains that its tentative link-local address is
unique, it assigns it to the interface. At this point, the node ...
... interface identifier. Thus, if a node has already verified the
uniqueness of a link-local address, additional addresses created from
...
... autoconfiguration process, a host may generate its
link-local address (and verify its uniqueness) in parallel with
waiting for a Router Advertisement. Because a router ...
... hosts, with two exceptions.
Routers are expected to generate a link-local address using the
procedure outlined below. In addition, routers perform Duplicate
Address Detection ...
... retransmissions.
Default: 1, but may be overridden by a link-type
specific value in the document that covers issues
related to the transmission of IP ...
...
Beyond the formation of a link-local address and using Duplicate
Address Detection, how routers (auto)configure their interfaces ...
... Creation of Link-Local Addresses ...
... A link-local address is formed by prepending the well-known link-
local prefix FE80::0 [ADDR-ARCH ...
... interface identifier replaces the right-most N zero bits of
the link-local prefix. If the interface identifier is more than 118
...
... addresses formed from the same
interface identifier, it is sufficient to check that the link-
local address generated from the identifier ...
... local address generated from the identifier is unique on the
link. In such cases, the link-local address MUST be tested for
uniqueness, and if no duplicate address ...
... identifier is unique on the
link. In such cases, the link-local address MUST be tested for
uniqueness, and if no duplicate address is detected, an
...
... is not completely reliable, and it is possible that duplicate
addresses will still exist (e.g., if the link was partitioned while
Duplicate Address Detection was performed).
...
... congestion when many nodes start up on the link at the
same time, such as after a power failure, and may help to avoid race
conditions when more than one node ...
... system management error. If the address is a link-local address
formed from an interface identifier, the interface ...
... default SHOULD be enabled. From the perspective of
autoconfiguration, a link has no routers if no Router Advertisements
...
... address (and add it to the list) by combining the advertised
prefix with the link's interface identifier as follows:
...
... bits |
+---------------------------------------+------------------------+
| link prefix | interface identifier |
...
... Router Advertisements are consistent with the length of interface
identifiers for that link type. Note that interface identifiers
will typically be 64-bits ...
... dependent. A problematic case occurs when two interfaces attached to
the same link happen to have the same identifier and link-layer
address, and they both send out packets with identical contents at
...
... the same link happen to have the same identifier and link-layer
address, and they both send out packets with identical contents at
roughly the same time (e.g., Neighbor Solicitations for a tentative
address ...
... heuristic to filter out unwanted loopbacks is
to discard any received packet whose link-layer source address is the
same as the receiving ...
... criteria also results in the discarding of all packets sent by
another node using the same link-layer address. Duplicate Address
Detection ...
... node performing Duplicate Address Detection discards
received packets having the same source link-layer address as
the receiving interface ...
... interface, it will also discard packets from other
nodes also using the same link-layer address, including Neighbor
Advertisement ...
... node that is already using a particular IP address discards
received packets having the same link-layer source address as
...
... Neighbor Solicitation messages sent by another
node also using the same link-layer address. Consequently,
...
... Duplicate Address Detection correctly in the case
where two interfaces are using the same link-layer address, an
...
... semantics, and the interface cannot discard
received packets simply because the source link-layer address is the
same as the interfaces.
...