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... architecture of the IP
Version 6 protocol. It includes a detailed description of the
currently defined address formats for IPv6 [IPV6].
...
... identifier for a single interface. A packet sent to
a unicast address is delivered to the interface
identified by that address ...
... belonging to different nodes). A packet sent to an
anycast address is delivered to one of the interfaces
identified by that address ...
... anycast address is delivered to one of the interfaces
identified by that address (the "nearest" one, according
to the routing protocols' measure of distance).
...
... belonging to different nodes). A packet sent to a
multicast address is delivered to all interfaces
identified by that address ...
...
There are no broadcast addresses in IPv6, their function being
superseded by multicast addresses ...
...
In this document, fields in addresses are given a specific name, for
example "subscriber". When this name is used with the term "ID" for
...
... All interfaces are required to have at least one link-local unicast
address (see section 2.8 for additional required addresses). A
single interface ...
... interfaces are required to have at least one link-local unicast
address (see section 2.8 for additional required addresses). A
single interface may also be assigned multiple IPv6 addresses ...
... addresses). A
single interface may also be assigned multiple IPv6 addresses of any
type (unicast, anycast ...
... unicast, anycast, and multicast) or scope. Unicast addresses
with scope greater than link-scope are not needed for interfaces ...
...
An unicast address or a set of unicast addresses may be assigned to
multiple physical interfaces ...
...
An unicast address or a set of unicast addresses may be assigned to
multiple physical interfaces if the implementation treats the
...
... Text Representation of Addresses ...
...
There are three conventional forms for representing IPv6 addresses as
text strings:
...
... 1. The preferred form is x:x:x:x:x:x:x:x, where the 'x's are the
hexadecimal values of the eight 16-bit pieces of the address.
Examples:
...
...
2. Due to some methods of allocating certain styles of IPv6
addresses, it will be common for addresses to contain long strings
of zero bits ...
... 2. Due to some methods of allocating certain styles of IPv6
addresses, it will be common for addresses to contain long strings
of zero bits. In order to make writing addresses ...
... addresses to contain long strings
of zero bits. In order to make writing addresses containing zero
bits easier a special syntax is available to compress the zeros.
...
... groups of 16-bits of zeros.
The "::" can only appear once in an address. The "::" can also be
used to compress the leading and/or trailing zeros in an address.
...
... The "::" can only appear once in an address. The "::" can also be
used to compress the leading and/or trailing zeros in an address.
For example the following addresses ...
... addresses:
1080:0:0:0:8:800:200C:417A a unicast address
FF01:0:0:0:0:0:0:101 a multicast address
...
... 1080:0:0:0:8:800:200C:417A a unicast address
FF01:0:0:0:0:0:0:101 a multicast address
0:0:0:0:0:0:0:1 the loopback address ...
... multicast address
0:0:0:0:0:0:0:1 the loopback address
0:0:0:0:0:0:0:0 the unspecified addresses
...
... may be represented as:
1080::8:800:200C:417A a unicast address
FF01::101 a multicast address
...
... 1080::8:800:200C:417A a unicast address
FF01::101 a multicast address
::1 the loopback address ...
... loopback address
:: the unspecified addresses
3. An alternative form that is sometimes more convenient when dealing
...
... x:x:x:x:x:x:d.d.d.d, where the 'x's are the hexadecimal values of
the six high-order 16-bit pieces of the address, and the 'd's are
the decimal values of the four low-order 8-bit pieces of the
...
... the decimal values of the four low-order 8-bit pieces of the
address (standard IPv4 representation). Examples:
...
... Text Representation of Address Prefixes ...
... IPv6 address prefixes is similar to the
way IPv4 addresses prefixes are written in CIDR notation. An IPv6
address ...
... IPv4 addresses prefixes are written in CIDR notation. An IPv6
address prefix is represented by the notation:
...
...
ipv6-address/prefix-length
...
...
ipv6-address is an IPv6 address in any of the notations listed
in section 2.2.
...
...
ipv6-address is an IPv6 address in any of the notations listed
in section 2.2.
...
... prefix-length is a decimal value specifying how many of the
leftmost contiguous bits of the address comprise
the prefix.
...
... 12AB:0:0:CD3/60 may drop leading zeros, but not trailing zeros,
within any 16-bit chunk of the address
12AB::CD30/60 address ...
... address
12AB::CD30/60 address to left of "/" expands to
12AB:0000:0000:0000:0000:000:0000:CD30
...
... 12AB:0000:0000:0000:0000:000:0000:CD30
12AB::CD3/60 address to left of "/" expands to
12AB:0000:0000:0000:0000:000:0000:0CD3
...
... Address Type Representation ...
... IPv6 address is indicated by the leading bits
in the address. The variable-length field comprising these leading
bits ...
... Allocation Prefix Fraction of
(binary) Address Space
----------------------------------- -------- -------------
Reserved 0000 0000 1/256
...
...
Aggregatable Global Unicast Addresses 001 1/8
Unassigned 010 1/8
Unassigned 011 1/8
...
...
Link-Local Unicast Addresses 1111 1110 10 1/1024
Site-Local Unicast Addresses 1111 1110 11 1/1024
...
... Link-Local Unicast Addresses 1111 1110 10 1/1024
Site-Local Unicast Addresses 1111 1110 11 1/1024
Multicast Addresses ...
... address" (see section 2.5.2), the loopback
address (see section 2.5.3), and the IPv6 Addresses with
Embedded IPv4 Addresses ...
... loopback
address (see section 2.5.3), and the IPv6 Addresses with
Embedded IPv4 Addresses (see section 2.5.4), are assigned out
...
... loopback
address (see section 2.5.3), and the IPv6 Addresses with
Embedded IPv4 Addresses (see section 2.5.4), are assigned out
...
... address (see section 2.5.3), and the IPv6 Addresses with
Embedded IPv4 Addresses (see section 2.5.4), are assigned out
of the 0000 0000 format prefix space.
...
... prefix space.
(2) The format prefixes 001 through 111, except for Multicast
Addresses (1111 1111), are all required to have to have 64-bit
interface identifiers ...
... This allocation supports the direct allocation of aggregation
addresses, local use addresses, and multicast addresses. Space is
...
... aggregation
addresses, local use addresses, and multicast addresses. Space is
reserved for NSAP addresses ...
... addresses, local use addresses, and multicast addresses. Space is
reserved for NSAP addresses and IPX ...
... reserved for NSAP addresses and IPX addresses. The remainder of the
address space is unassigned for future use. This can be used for
...
... address space is unassigned for future use. This can be used for
expansion of existing use (e.g., additional aggregatable addresses,
etc.) or new uses (e.g., separate locators and identifiers). Fifteen
...
... etc.) or new uses (e.g., separate locators and identifiers). Fifteen
percent of the address space is initially allocated. The remaining
85% is reserved for future use.
...
...
Unicast addresses are distinguished from multicast addresses by the
value of the high-order octet ...
...
Unicast addresses are distinguished from multicast addresses by the
value of the high-order octet of the addresses ...
... multicast addresses by the
value of the high-order octet of the addresses: a value of FF
(11111111) identifies an address ...
... addresses: a value of FF
(11111111) identifies an address as a multicast address; any other
value identifies an address ...
... FF
(11111111) identifies an address as a multicast address; any other
value identifies an address as a unicast address ...
... address as a multicast address; any other
value identifies an address as a unicast address. Anycast addresses
...
... multicast address; any other
value identifies an address as a unicast address. Anycast addresses
are taken from the unicast address ...
... value identifies an address as a unicast address. Anycast addresses
are taken from the unicast address space, and are not syntactically
...
... unicast address. Anycast addresses
are taken from the unicast address space, and are not syntactically
distinguishable from unicast addresses.
...
... are taken from the unicast address space, and are not syntactically
distinguishable from unicast addresses.
...
... Unicast Addresses ...
...
IPv6 unicast addresses are aggregatable with contiguous bit-wise
masks similar to IPv4 addresses ...
... unicast addresses are aggregatable with contiguous bit-wise
masks similar to IPv4 addresses under Class-less Interdomain Routing
...
...
There are several forms of unicast address assignment in IPv6,
including the global aggregatable global unicast ...
... IPv6,
including the global aggregatable global unicast address, the NSAP
address, the IPX hierarchical address ...
... including the global aggregatable global unicast address, the NSAP
address, the IPX hierarchical address, the site-local address ...
... address, the NSAP
address, the IPX hierarchical address, the site-local address, the
link-local address ...
... NSAP
address, the IPX hierarchical address, the site-local address, the
link-local address, and the IPv4-capable ...
... link-local address, and the IPv4-capable host address. Additional
address types can be defined in the future.
...
... IPv6 nodes may have considerable or little knowledge of the internal
structure of the IPv6 address, depending on the role the node plays
...
... router). At a minimum, a node may
consider that unicast addresses (including its own) have no internal
structure:
...
... +-----------------------------------------------------------------+
| node address |
+-----------------------------------------------------------------+
...
... subnet prefix(es) for the link(s) it is
attached to, where different addresses may have different values for
n:
...
... Still more sophisticated hosts may be aware of other hierarchical
boundaries in the unicast address. Though a very simple router may
have no knowledge of the internal structure of IPv6 ...
... router may
have no knowledge of the internal structure of IPv6 unicast
addresses, routers will more generally have knowledge of one or more
of the hierarchical boundaries for the operation of routing
protocols ...
... interfaces of a single node does not affect the interface
identifier's global uniqueness or each IPv6 addresses global
uniqueness created using that interface identifier ...
... The Unspecified Address ...
...
The address 0:0:0:0:0:0:0:0 is called the unspecified address. It
must never be assigned to any node ...
...
The address 0:0:0:0:0:0:0:0 is called the unspecified address. It
must never be assigned to any node. It indicates the absence of an
...
... must never be assigned to any node. It indicates the absence of an
address. One example of its use is in the Source Address field of
any IPv6 packets ...
... node. It indicates the absence of an
address. One example of its use is in the Source Address field of
any IPv6 packets sent by an initializing host ...
...
The unspecified address must not be used as the destination address
of IPv6 packets or in IPv6 Routing ...
... The unicast address 0:0:0:0:0:0:0:1 is called the loopback address.
It may be used by a node to send an IPv6 packet ...
...
The loopback address must not be used as the source address in IPv6
packets that are sent outside of a single node ...
... The loopback address must not be used as the source address in IPv6
packets that are sent outside of a single node. An IPv6 packet ...
... node. An IPv6 packet with
a destination address of loopback must never be sent outside of a
single node ...
... IPv6 Addresses with Embedded IPv4 Addresses ...
... IPv6 Addresses with Embedded IPv4 Addresses ...
... IPv6 nodes that utilize this technique are assigned
special IPv6 unicast addresses that carry an IPv4 address in the low-
order 32-bits ...
... special IPv6 unicast addresses that carry an IPv4 address in the low-
order 32-bits. This type of address ...
... IPv4 address in the low-
order 32-bits. This type of address is termed an "IPv4-compatible
IPv6 address ...
... 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|0000| IPv4 address |
+--------------------------------------+----+---------------------+
...
...
A second type of IPv6 address which holds an embedded IPv4 address is
also defined. This address ...
...
A second type of IPv6 address which holds an embedded IPv4 address is
also defined. This address is used to represent the addresses ...
... IPv6 address which holds an embedded IPv4 address is
also defined. This address is used to represent the addresses of
IPv4-only ...
... IPv4 address is
also defined. This address is used to represent the addresses of
IPv4-only nodes ...
... IPv4-only nodes (those that *do not* support IPv6) as IPv6 addresses.
This type of address is termed an "IPv4-mapped ...
... IPv6) as IPv6 addresses.
This type of address is termed an "IPv4-mapped IPv6 address" and has
...
... 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|FFFF| IPv4 address |
+--------------------------------------+----+---------------------+
...
... NSAP Addresses ...
...
This mapping of NSAP address into IPv6 addresses is defined in
[NSAP]. This document recommends that network ...
... addressing in an IPv6
network. These mechanisms are the ones that must be used if such
support is required. This document also defines a mapping of IPv6
addresses within the OSI address format, should this be required.
...
... support is required. This document also defines a mapping of IPv6
addresses within the OSI address format, should this be required.
...
... Aggregatable Global Unicast Addresses ...
... global unicast address is defined in [AGGR].
This address format is designed to support both the current provider
based aggregation ...
... Local-Use IPv6 Unicast Addresses ...
...
There are two types of local-use unicast addresses defined. These
are Link-Local and Site-Local ...
... link and the Site-Local is for use in a single site. Link-Local
addresses have the following format:
...
... addressing on a
single link for purposes such as auto-address configuration, neighbor
discovery, or when no routers are present.
...
... Routers must not forward any packets with link-local source or
destination addresses to other links.
...
...
Site-Local addresses have the following format:
...
...
Site-Local addresses are designed to be used for addressing inside of
a site without the need for a global prefix ...
... Routers must not forward any packets with site-local source or
destination addresses outside of the site.
...
... Anycast Addresses ...
... An IPv6 anycast address is an address that is assigned to more than
one interface (typically belonging to different nodes ...
... interface (typically belonging to different nodes), with the
property that a packet sent to an anycast address is routed to the
"nearest" interface having that address ...
... anycast address is routed to the
"nearest" interface having that address, according to the routing
protocols' measure of distance.
...
...
Anycast addresses are allocated from the unicast address space, using
any of the defined unicast address ...
...
Anycast addresses are allocated from the unicast address space, using
any of the defined unicast address formats. Thus, anycast addresses ...
... Anycast addresses are allocated from the unicast address space, using
any of the defined unicast address formats. Thus, anycast addresses
are syntactically indistinguishable from unicast addresses ...
... unicast address space, using
any of the defined unicast address formats. Thus, anycast addresses
are syntactically indistinguishable from unicast addresses. When a
...
... unicast address formats. Thus, anycast addresses
are syntactically indistinguishable from unicast addresses. When a
unicast address is assigned to more than one interface ...
... are syntactically indistinguishable from unicast addresses. When a
unicast address is assigned to more than one interface, thus turning
it into an anycast address ...
... unicast address is assigned to more than one interface, thus turning
it into an anycast address, the nodes to which the address is
...
... it into an anycast address, the nodes to which the address is
assigned must be explicitly configured to know that it is an anycast
address.
...
... nodes to which the address is
assigned must be explicitly configured to know that it is an anycast
address.
...
...
For any assigned anycast address, there is a longest address prefix P
that identifies the topological region in which all interfaces ...
...
For any assigned anycast address, there is a longest address prefix P
that identifies the topological region in which all interfaces
...
... that identifies the topological region in which all interfaces
belonging to that anycast address reside. Within the region
identified by P, each member of the anycast set must be advertised as
...
... "host route"); outside the region identified by P, the anycast
address may be aggregated into the routing advertisement for prefix
...
... the null prefix, i.e., the members of the set may have no topological
locality. In that case, the anycast address must be advertised as a
separate routing entry throughout the entire internet ...
...
One expected use of anycast addresses is to identify the set of
routers belonging to an organization providing internet service ...
... routers belonging to an organization providing internet service.
Such addresses could be used as intermediate addresses in an IPv6
Routing header ...
... internet service.
Such addresses could be used as intermediate addresses in an IPv6
Routing header, to cause a packet to be delivered via a particular
...
... There is little experience with widespread, arbitrary use of internet
anycast addresses, and some known complications and hazards when
using them in their full generality [ANYCST]. Until more experience
...
... has been gained and solutions agreed upon for those problems, the
following restrictions are imposed on IPv6 anycast addresses:
...
... An anycast address must not be assigned to an IPv6 host, that
is, it may be assigned to an IPv6 ...
... Required Anycast Address ...
... prefix which
identifies a specific link. This anycast address is syntactically
the same as a unicast address for an interface ...
... link. This anycast address is syntactically
the same as a unicast address for an interface on the link with the
...
... Packets sent to the Subnet-Router anycast address will be delivered
to one router on the subnet ...
... The subnet-router anycast address is intended to be used for
applications where a node needs to communicate with one of a set of
...
... Multicast Addresses ...
... node may belong to any number of multicast groups. Multicast
addresses have the following format:
...
...
T = 0 indicates a permanently-assigned ("well-known") multicast
address, assigned by the global internet numbering authority.
...
...
T = 1 indicates a non-permanently-assigned ("transient")
multicast address.
scop is a 4-bit ...
...
The "meaning" of a permanently-assigned multicast address is
independent of the scope value. For example, if the "NTP servers
...
... NTP servers
group" is assigned a permanent multicast address with a group ID of
101 (hex), then:
...
...
Non-permanently-assigned multicast addresses are meaningful only
within a given scope. For example, a group identified by the non-
...
... group identified by the non-
permanent, site-local multicast address FF15:0:0:0:0:0:0:101 at one
site bears no relationship to a group using the same address ...
... multicast address FF15:0:0:0:0:0:0:101 at one
site bears no relationship to a group using the same address at a
different site, nor to a non-permanent group using the same group ...
...
Multicast addresses must not be used as source addresses in IPv6
packets or appear in any routing header ...
...
Multicast addresses must not be used as source addresses in IPv6
packets or appear in any routing header.
...
... Pre-Defined Multicast Addresses ...
...
The following well-known multicast addresses are pre-defined:
...
...
Reserved Multicast Addresses: FF00:0:0:0:0:0:0:0
FF01:0:0:0:0:0:0:0
FF02:0:0:0:0:0:0:0
...
...
The above multicast addresses are reserved and shall never be
assigned to any multicast group.
...
... unicast and anycast addresses. The solicited-node multicast address
is formed by taking the low-order 24 bits of the address ...
... multicast address
is formed by taking the low-order 24 bits of the address (unicast or
anycast ...
...
For example, the solicited node multicast address corresponding to
the IPv6 address 4037::01:800:200E:8C6C is FF02::1:FF0E:8C6C. IPv6
addresses ...
... node multicast address corresponding to
the IPv6 address 4037::01:800:200E:8C6C is FF02::1:FF0E:8C6C. IPv6
addresses that differ only in the high-order bits, e.g. due to
...
... multicast address corresponding to
the IPv6 address 4037::01:800:200E:8C6C is FF02::1:FF0E:8C6C. IPv6
addresses that differ only in the high-order bits, e.g. due to
multiple high-order prefixes ...
... aggregations,
will map to the same solicited-node address thereby reducing the
number of multicast addresses a node ...
... join the associated Solicited-Node
multicast addresses for every unicast and anycast address it is
...
... Assignment of New IPv6 Multicast Addresses ...
... addresses into
IEEE 802 MAC addresses takes the low order 32 bits of the IPv6
multicast address ...
... MAC addresses takes the low order 32 bits of the IPv6
multicast address and uses it to create a MAC address. Note that
...
... IPv6
multicast address and uses it to create a MAC address. Note that
Token Ring networks are handled differently. This is defined in
...
... Group ID's less than or equal to 32 bits will generate
unique MAC addresses. Due to this new IPv6 multicast addresses
...
... unique MAC addresses. Due to this new IPv6 multicast addresses
should be assigned so that the group identifier is always in the low
...
... Its Link-Local Address for each interface ...
... Assigned Unicast Addresses ...
... All-Nodes Multicast Addresses ...
...
A router is required to recognize all addresses that a host is
required to recognize, plus the following addresses ...
... addresses that a host is
required to recognize, plus the following addresses as identifying
itself:
...
... All other Anycast addresses with which the router has been
configured. ...
... All-Routers Multicast Addresses ...
...
The only address prefixes which should be predefined in an
implementation are the:
...
... Unspecified Address ...
... Pre-Defined Multicast Addresses ...
...
Implementations should assume all other addresses are unicast unless
specifically configured (e.g., anycast addresses ...
...
This appendix defines the text representation of IPv6 addresses and
prefixes in Augmented BNF ...
... Clarification of Address Model based on comments. ...
... Added rules for defining new multicast addresses. ...
... Added site scope all routers multicast address. ...
... Added section on Interface ID definition for unicast addresses.
Requires use of EUI-64 in range ...
... Removed section "Unicast Address Example". Had become OBE. ...
... Hinden, R., O'Dell, M., and S. Deering, "An Aggregatable Global Unicast Address Format", RFC 2374hist(-> 3587), July 1998. ...
... Fuller, V., Li, T., Yu, J., and K. Varadhan, "Classless Inter-Domain Routing (CIDR): An Address Assignment and Aggregation Strategy", RFC 1519(-> 4632), September 1993. ...
... AUTHORS' ADDRESSES ...