INTERNET-DRAFT R. Hinden, Ipsilon Networks
May 16, 1997 S. Deering, Cisco Systems
IP Version 6 Addressing Architecture
<draft-ietf-ipngwg-addr-arch-v2-00.txt>
Status of this Memo
This document is an Internet-Draft. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet- Drafts as reference
material or to cite them other than as ``work in progress.''
To learn the current status of any Internet-Draft, please check the
``1id-abstracts.txt'' listing contained in the Internet- Drafts
Shadow Directories on ds.internic.net (US East Coast), nic.nordu.net
(Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific
Rim).
This Internet Draft expires November 16, 1997.
Abstract
This specification defines the addressing architecture of the IP
Version 6 protocol [IPV6]. The document includes the IPv6 addressing
model, text representations of IPv6 addresses, definition of IPv6
unicast addresses, anycast addresses, and multicast addresses, and an
IPv6 nodes required addresses.
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 1]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
Table of Contents
1. Introduction.................................................3
2. IPv6 Addressing..............................................3
2.1 Addressing Model.........................................4
2.2 Text Representation of Addresses.........................4
2.3 Text Representation of Address Prefixes..................5
2.4 Address Type Representation..............................6
2.5 Unicast Addresses........................................8
2.5.1 Interface Identifiers................................9
2.5.2 The Unspecified Address.............................10
2.5.3 The Loopback Address................................10
2.5.4 IPv6 Addresses with Embedded IPv4 Addresses.........10
2.5.5 NSAP Addresses......................................11
2.5.6 IPX Addresses.......................................11
2.5.7 Aggregatable Global Unicast Addresses...............11
2.5.8 Local-use IPv6 Unicast Addresses....................12
2.6 Anycast Addresses.......................................13
2.6.1 Required Anycast Address............................14
2.7 Multicast Addresses.....................................14
2.7.1 Pre-Defined Multicast Addresses.....................16
2.8 A Node's Required Addresses.............................17
REFERENCES.....................................................19
SECURITY CONSIDERATIONS........................................20
AUTHOR'S ADDRESSES.............................................20
CHANGES FROM RFC-1884..........................................21
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 2]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
1.0 INTRODUCTION
This specification defines the addressing architecture of the IP
Version 6 protocol. It includes a detailed description of the
currently defined address formats for IPv6 [IPV6].
The authors would like to acknowledge the contributions of Paul
Francis, Scott Bradner, Jim Bound, Brian Carpenter, Matt Crawford,
Deborah Estrin, Bob Fink, Peter Ford, Bob Gilligan, Christian
Huitema, Tony Li, Greg Minshall, Thomas Narten, Erik Nordmark, Yakov
Rekhter, Bill Simpson, and Sue Thomson.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC 2119].
2.0 IPv6 ADDRESSING
IPv6 addresses are 128-bit identifiers for interfaces and sets of
interfaces. There are three types of addresses:
Unicast: An identifier for a single interface. A packet sent to a
unicast address is delivered to the interface identified
by that address.
Anycast: An identifier for a set of interfaces (typically
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 protocols' measure of distance).
Multicast: 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.
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
identifier after the name (e.g., "subscriber ID"), it refers to the
contents of the named field. When it is used with the term "prefix"
(e.g. "subscriber prefix") it refers to all of the address up to and
including this field.
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 3]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
In IPv6, all zeros and all ones are legal values for any field,
unless specifically excluded. Specifically, prefixes may contain
zero-valued fields or end in zeros.
2.1 Addressing Model
IPv6 Addresses of all types are assigned to interfaces, not nodes.
Since each interface belongs to a single node, any of that node's
interfaces' unicast addresses may be used as an identifier for the
node.
An IPv6 unicast address refers to a single interface. A single
interface may be assigned multiple IPv6 addresses of any type
(unicast, anycast, and multicast). There are two exceptions to this
model. These are:
1) A single address may be assigned to multiple physical interfaces
if the implementation treats the multiple physical interfaces as
one interface when presenting it to the internet layer. This is
useful for load-sharing over multiple physical interfaces.
2) Routers may have unnumbered interfaces (i.e., no IPv6 address
assigned to the interface) on point-to-point links to eliminate
the necessity to manually configure and advertise the addresses.
Addresses are not needed for point-to-point interfaces on routers
if those interfaces are not to be used as the origins or
destinations of any IPv6 datagrams.
Currently IPv6 continues the IPv4 model that a subnet is associated
with one link. Multiple subnets may be assigned to the same link.
2.2 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:
FEDC:BA98:7654:3210:FEDC:BA98:7654:3210
1080:0:0:0:8:800:200C:417A
Note that it is not necessary to write the leading zeros in an
individual field, but there must be at least one numeral in every
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 4]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
field (except for the case described in 2.).
2. Due to the method 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 containing zero bits
easier a special syntax is available to compress the zeros. The
use of "::" indicates multiple 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.
For example the following addresses:
1080:0:0:0:8:800:200C:417A a unicast address
FF01:0:0:0:0:0:0:43 a 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::43 a multicast address
::1 the loopback address
:: the unspecified addresses
3. An alternative form that is sometimes more convenient when dealing
with a mixed environment of IPv4 and IPv6 nodes is
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
address (standard IPv4 representation). Examples:
0:0:0:0:0:0:13.1.68.3
0:0:0:0:0:FFFF:129.144.52.38
or in compressed form:
::13.1.68.3
::FFFF:129.144.52.38
2.3 Text Representation of Address Prefixes
The text representation of IPv6 address prefixes is similar to the
way IPv4 addresses prefixes are written in CIDR notation. An IPv6
address prefix is represented by the notation:
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 5]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
ipv6-address/prefix-length
where
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.
For example, the following are legal representations of the 60-bit
prefix 12AB00000000CD3 (hexadecimal):
12AB:0000:0000:CD30:0000:0000:0000:0000/60
12AB::CD30:0:0:0:0/60
12AB:0:0:CD30::/60
The following are NOT legal representations of the above 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 to left of "/" expands to
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
When writing both a node address and a prefix of that node address
(e.g., the node's subnet prefix), the two can combined as follows:
the node address 12AB:0:0:CD30:123:4567:89AB:CDEF
and its subnet number 12AB:0:0:CD30::/60
can be abbreviated as 12AB:0:0:CD30:123:4567:89AB:CDEF/60
2.4 Address Type Representation
The specific type of an IPv6 address is indicated by the leading bits
in the address. The variable-length field comprising these leading
bits is called the Format Prefix (FP). The initial allocation of
these prefixes is as follows:
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 6]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
Allocation Prefix Fraction of
(binary) Address Space
----------------------------------- -------- -------------
Reserved 0000 0000 1/256
Unassigned 0000 0001 1/256
Reserved for NSAP Allocation 0000 001 1/128
Reserved for IPX Allocation 0000 010 1/128
Unassigned 0000 011 1/128
Unassigned 0000 1 1/32
Unassigned 0001 1/16
Aggregatable Global Unicast Addresses 001 1/8
Unassigned 010 1/8
Unassigned 011 1/8
Unassigned 100 1/8
Unassigned 101 1/8
Unassigned 110 1/8
Unassigned 1110 1/16
Unassigned 1111 0 1/32
Unassigned 1111 10 1/64
Unassigned 1111 110 1/128
Unassigned 1111 1110 0 1/512
Link-Local Unicast Addresses 1111 1110 10 1/1024
Site-Local Unicast Addresses 1111 1110 11 1/1024
Multicast Addresses 1111 1111 1/256
Notes:
(1) The "unspecified address" (see section 2.4.2), the loopback
address (see section 2.4.3), and the IPv6 Addresses with
Embedded IPv4 Addresses (see section 2.4.4), are assigned out
of the 0000 0000 format prefix space.
(2) The format prefixes 001 and higher, except for Multicast
Addresses (1111 1111), are all required to have to have 64-bit
interface identifiers in EUI-64 format. See section 2.5.1 for
definitions.
This allocation supports the direct allocation of aggregation
addresses, local use addresses, and multicast addresses. Space is
reserved for NSAP addresses and IPX addresses. The remainder of the
address space is unassigned for future use. This can be used for
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 7]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
expansion of existing use (e.g., additional aggregatable addresses,
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 of the addresses: a value of FF
(11111111) identifies an address as a multicast address; any other
value identifies an address as a unicast address. Anycast addresses
are taken from the unicast address space, and are not syntactically
distinguishable from unicast addresses.
2.5 Unicast Addresses
The IPv6 unicast address is contiguous bit-wise maskable, similar to
IPv4 addresses under Class-less Interdomain Routing [CIDR].
There are several forms of unicast address assignment in IPv6,
including the global aggregatable global unicast address, the NSAP
address, the IPX hierarchical address, the site-local address, the
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
(for instance, host versus router). At a minimum, a node may
consider that unicast addresses (including its own) have no internal
structure:
| 128 bits |
+-----------------------------------------------------------------+
| node address |
+-----------------------------------------------------------------+
A slightly sophisticated host (but still rather simple) may
additionally be aware of subnet prefix(es) for the link(s) it is
attached to, where different addresses may have different values for
n:
| n bits | 128-n bits |
+------------------------------------------------+----------------+
| subnet prefix | interface ID |
+------------------------------------------------+----------------+
Still more sophisticated hosts may be aware of other hierarchical
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 8]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
boundaries in the unicast address. Though a very simple 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. The known boundaries will differ from router to router,
depending on what positions the router holds in the routing
hierarchy.
2.5.1 Interface Identifiers
Interface identifiers in IPv6 unicast addresses are used to identify
interfaces on a link. They are required to be unique on that link.
They may also be unique over a broader scope. In many cases an
interface's identifier will be the same as that interface's link-
layer address.
In a number of the format prefixes (see section 2.4) Interface IDs
are required to be 64 bits long and to be constructed in IEEE EUI-64
format [EUI-64]. EUI-64 based Interface identifiers may have global
scope when a global token is available or may have local scope where
a global token is not available (e.g., serial links, tunnel end-
points, etc.). It is required that the "u" bit (universal/local bit
in IEEE EUI-64 terminology) be set correctly in the IEEE EUI-64
address. The "u" bit is set to zero (0) to indicate global scope,
and it is set to one (1) to indicate local scope. The first three
bytes in binary of an EUI-64 identifier are as follows:
0 0 0 1 1 2
|0 7 8 5 6 3|
+----+----+----+----+----+----+
|cccc|ccug|cccc|cccc|cccc|cccc|
+----+----+----+----+----+----+
written in Internet standard bit-order , where "u" is the
universal/local bit, "g" is the group/individual bit, and "c" are the
bits of the company_id.
This use of the universal/local bit in the IEEE EUI-64 identifier is
to allow development of future technology that can take advantage of
interface identifiers with global scope.
The details on forming interface identifiers is defined in the
appropriate "IPv6 over <link>" specification such as "IPv6 over
Ethernet" [ETHER], "IPv6 over FDDI" [FDDI], etc.
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 9]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
2.5.2 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. It indicates the absence of an
address. One example of its use is in the Source Address field of
any IPv6 datagrams sent by an initializing host before it has learned
its own address.
The unspecified address must not be used as the destination address
of IPv6 datagrams or in IPv6 Routing Headers.
2.5.3 The Loopback Address
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 datagram to itself. It may
never be assigned to any interface.
The loopback address must not be used as the source address in IPv6
datagrams that are sent outside of a single node. An IPv6 datagram
with a destination address of loopback must never be sent outside of
a single node and must never be forwarded by an IPv6 router.
2.5.4 IPv6 Addresses with Embedded IPv4 Addresses
The IPv6 transition mechanisms include a technique for hosts and
routers to dynamically tunnel IPv6 packets over IPv4 routing
infrastructure. IPv6 nodes that utilize this technique are assigned
special IPv6 unicast addresses that carry an IPv4 address in the low-
order 32-bits. This type of address is termed an "IPv4-compatible
IPv6 address" and has the format:
| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|0000| IPv4 address |
+--------------------------------------+----+---------------------+
A second type of IPv6 address which holds an embedded IPv4 address is
also defined. This address is used to represent the addresses of
IPv4-only nodes (those that *do not* support IPv6) as IPv6 addresses.
This type of address is termed an "IPv4-mapped IPv6 address" and has
the format:
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 10]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
| 80 bits | 16 | 32 bits |
+--------------------------------------+--------------------------+
|0000..............................0000|FFFF| IPv4 address |
+--------------------------------------+----+---------------------+
2.5.5 NSAP Addresses
This mapping of NSAP address into IPv6 addresses is defined in
[NSAP]. This document recommends that network implementors who have
planned or deployed an OSI NSAP addressing plan, and who wish to
deploy or transition to IPv6, should redesign a native IPv6
addressing plan to meet their needs. However, it also defines a set
of mechanisms for the support of OSI NSAP 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.
2.5.6 IPX Addresses
This mapping of IPX address into IPv6 addresses is as follows:
| 7 | 121 bits |
+-------+---------------------------------------------------------+
|0000010| to be defined |
+-------+---------------------------------------------------------+
The draft definition, motivation, and usage are under study.
2.5.7 Aggregatable Global Unicast Addresses
The global aggregatable global unicast address is defined in [AGGR].
This address format is designed to support both the current provider
based aggregation and a new type of aggregation called exchanges.
The combination will allow efficient routing aggregation for both
sites which connect directly to providers and who connect to
exchanges. Sites will have the choice to connect to either type of
aggregation point.
The IPv6 aggregatable global unicast address format is as follows:
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 11]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
+---+-----+-----------+--------+--------------------------------+
|001| TLA | NLA* | SLA* | Interface ID |
+---+-----+-----------+--------+--------------------------------+
Where
001 Format Prefix (3 bit) for Aggregatable Global
Unicast Addresses
TLA Top Level Aggregator
NLA* Next Level Aggregator(s)
SLA* Site-Local Aggregator(s)
INTERFACE ID Interface Identifier
The contents, field sizes, and assignment rules are defined in
[AGGR].
2.5.8 Local-Use IPv6 Unicast Addresses
There are two types of local-use unicast addresses defined. These
are Link-Local and Site-Local. The Link-Local is for use on a single
link and the Site-Local is for use in a single site. Link-Local
addresses have the following format:
| 10 |
| bits | 54 bits | 64 bits |
+----------+-------------------------+----------------------------+
|1111111010| 0 | interface ID |
+----------+-------------------------+----------------------------+
Link-Local addresses are designed to be used for 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:
| 10 |
| bits | 38 bits | 16 bits | 64 bits |
+----------+-------------+-----------+----------------------------+
|1111111011| 0 | subnet ID | interface ID |
+----------+-------------+-----------+----------------------------+
Site-Local addresses are designed to be used for addressing inside of
a site without the need for a global prefix.
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 12]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
Routers MUST not forward any packets with site-local source or
destination addresses outside of the site.
2.6 Anycast Addresses
An IPv6 anycast address is an address that is assigned to more than
one 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, according to the routing
protocols' measure of distance.
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. When a
unicast address is assigned to more than one interface, thus turning
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.
For any assigned anycast address, there is a longest address prefix P
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
a separate entry in the routing system (commonly referred to as a
"host route"); outside the region identified by P, the anycast
address may be aggregated into the routing advertisement for prefix
P.
Note that in, the worst case, the prefix P of an anycast set may be
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, which presents
a severe scaling limit on how many such "global" anycast sets may be
supported. Therefore, it is expected that support for global anycast
sets may be unavailable or very restricted.
One expected use of anycast addresses is to identify the set of
routers belonging to an internet service aggregation. Such addresses
could be used as intermediate addresses in an IPv6 Routing header, to
cause a packet to be delivered via a particular aggregation or
sequence of aggregations. Some other possible uses are to identify
the set of routers attached to a particular subnet, or the set of
routers providing entry into a particular routing domain.
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
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 13]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
following restrictions are imposed on IPv6 anycast addresses:
o An anycast address MUST NOT be used as the source address of an
IPv6 packet.
o An anycast address MUST NOT be assigned to an IPv6 host, that
is, it may be assigned to an IPv6 router only.
2.6.1 Required Anycast Address
The Subnet-Router anycast address is predefined. Its format is as
follows:
| n bits | 128-n bits |
+------------------------------------------------+----------------+
| subnet prefix | 00000000000000 |
+------------------------------------------------+----------------+
The "subnet prefix" in an anycast address is the prefix which
identifies a specific link. This anycast address is syntactically
the same as a unicast address for an interface on the link with the
interface identifier set to zero.
Packets sent to the Subnet-Router anycast address will be delivered
to one router on the subnet. All routers are required to support the
Subnet-Router anycast addresses for the subnets which they have
interfaces.
The subnet-router anycast address is intended to be used for
applications where a node needs to communicate with one of a set of
routers on a remote subnet. For example when a mobile host needs to
communicate with one of the mobile agents on its "home" subnet.
2.7 Multicast Addresses
An IPv6 multicast address is an identifier for a group of nodes. A
node may belong to any number of multicast groups. Multicast
addresses have the following format:
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 14]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
| 8 | 4 | 4 | 112 bits |
+------ -+----+----+---------------------------------------------+
|11111111|flgs|scop| group ID |
+--------+----+----+---------------------------------------------+
11111111 at the start of the address identifies the address as
being a multicast address.
+-+-+-+-+
flgs is a set of 4 flags: |0|0|0|T|
+-+-+-+-+
The high-order 3 flags are reserved, and must be
initialized to 0.
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 multicast scope value used to limit the scope of
the multicast group. The values are:
0 reserved
1 node-local scope
2 link-local scope
3 (unassigned)
4 (unassigned)
5 site-local scope
6 (unassigned)
7 (unassigned)
8 organization-local scope
9 (unassigned)
A (unassigned)
B (unassigned)
C (unassigned)
D (unassigned)
E global scope
F reserved
group ID identifies the multicast group, either permanent or
transient, within the given scope.
The "meaning" of a permanently-assigned multicast address is
independent of the scope value. For example, if the "NTP servers
group" is assigned a permanent multicast address with a group ID of
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 15]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
43 (hex), then:
FF01:0:0:0:0:0:0:43 means all NTP servers on the same node as
the sender.
FF02:0:0:0:0:0:0:43 means all NTP servers on the same link as
the sender.
FF05:0:0:0:0:0:0:43 means all NTP servers at the same site as
the sender.
FF0E:0:0:0:0:0:0:43 means all NTP servers in the internet.
Non-permanently-assigned multicast addresses are meaningful only
within a given scope. For example, a group identified by the non-
permanent, site-local multicast address FF15:0:0:0:0:0:0:43 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 ID
with different scope, nor to a permanent group with the same group
ID.
Multicast addresses must not be used as source addresses in IPv6
datagrams or appear in any routing header.
2.7.1 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
FF03:0:0:0:0:0:0:0
FF04:0:0:0:0:0:0:0
FF05:0:0:0:0:0:0:0
FF06:0:0:0:0:0:0:0
FF07:0:0:0:0:0:0:0
FF08:0:0:0:0:0:0:0
FF09:0:0:0:0:0:0:0
FF0A:0:0:0:0:0:0:0
FF0B:0:0:0:0:0:0:0
FF0C:0:0:0:0:0:0:0
FF0D:0:0:0:0:0:0:0
FF0E:0:0:0:0:0:0:0
FF0F:0:0:0:0:0:0:0
The above multicast addresses are reserved and shall never be
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 16]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
assigned to any multicast group.
All Nodes Addresses: FF01:0:0:0:0:0:0:1
FF02:0:0:0:0:0:0:1
The above multicast addresses identify the group of all IPv6 nodes,
within scope 1 (node-local) or 2 (link-local).
All Routers Addresses: FF01:0:0:0:0:0:0:2
FF02:0:0:0:0:0:0:2
FF05:0:0:0:0:0:0:2
The above multicast addresses identify the group of all IPv6 routers,
within scope 1 (node-local), 2 (link-local), or 5 (site-local).
Solicited-Node Address: FF02:0:0:0:0:1:FFXX:XXXX
The above multicast address is computed as a function of a node's
unicast and anycast addresses. The solicited-node multicast address
is formed by taking the low-order 24 bits of the address (unicast or
anycast) and appending those bits to the prefix
FF02:0:0:0:0:1:FF00::/104 resulting in a multicast address in the
range
FF02:0:0:0:0:1:FF00:0000
to
FF02:0:0:0:0:1:FFFF:FFFF
For example, the solicited 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
multiple high-order prefixes associated with different aggregations,
will map to the same solicited-node address thereby reducing the
number of multicast addresses a node must join.
A node is required to compute and support a Solicited-Node multicast
addresses for every unicast and anycast address it is assigned.
Additional IPv6 multicast addresses are defined and registered by the
IANA [MASGN].
2.8 A Node's Required Addresses
A host is required to recognize the following addresses as
identifying itself:
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 17]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
o Its Link-Local Address for each interface
o Assigned Unicast Addresses
o Loopback Address
o All-Nodes Multicast Address
o Solicited-Node Multicast Address for each of its assigned
unicast and anycast addresses
o Multicast Addresses of all other groups which the host belongs.
A router is required to recognize the following addresses as
identifying itself:
o Its Link-Local Address for each interface
o Assigned Unicast Addresses
o Loopback Address
o The Subnet-Router anycast addresses for the links it has
interfaces.
o All other Anycast addresses with which the router has been
configured.
o All-Nodes Multicast Address
o All-Router Multicast Address
o Solicited-Node Multicast Address for each of its assigned
unicast and anycast addresses
o Multicast Addresses of all other groups which the router
belongs.
The only address prefixes which should be predefined in an
implementation are the:
o Unspecified Address
o Loopback Address
o Multicast Prefix (FF)
o Local-Use Prefixes (Link-Local and Site-Local)
o Pre-Defined Multicast Addresses
o IPv4-Compatible Prefixes
Implementations should assume all other addresses are unicast unless
specifically configured (e.g., anycast addresses).
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 18]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
REFERENCES
[AGGR] Hinden, R., Deering, S., O'Dell, M., "An Aggregatable
Global Unicast Address Format", internet draft, <draft-
ietf-ipngwg-unicast-aggr-00.txt>, May 1997.
[ALLOC] Rekhter, Y., Li, T., "An Architecture for IPv6 Unicast
Address Allocation", RFC1887, December 1995.
[ANYCST]C. Partridge, T. Mendez, and W. Milliken, "Host Anycasting
Service", RFC1546, November 1993.
[CIDR] V. Fuller, T. Li, K. Varadhan, J. Yu, "Supernetting: an
Address Assignment and Aggregation Strategy", RFC1338.
[ETHER] M. Crawford, "Transmission of IPv6 Packets over Ethernet
Networks", Internet Draft, <draft-ietf-ipngwg-trans-
ethernet-00.txt>, March 1997.
[EUI64] IEEE, "Guidelines for 64-bit Global Identifier (EUI-64)
Registration Authority",
http://standards.ieee.org/db/oui/tutorials/EUI64.html,
March 1997.
[FDDI] M. Crawford, "Transmission of IPv6 Packets over FDDI
Networks", Internet Draft, <draft-ietf-ipngwg-trans-
fddi-00.txt>, March 1997.
[IPV6] S. Deering, R. Hinden, Editors, "Internet Protocol, Version
6 (IPv6) Specification", RFC1883, December 1995.
[MASGN] R. Hinden, "IPv6 Multicast Address Assignments", Internet
Draft, <draft-ietf-ipngwg-multicast-assgn-02.txt>, May
1997.
[MULT] S. Deering, "Host Extensions for IP multicasting", RFC
1112.
[NSAP] J. Bound, B. Carpenter, D. Harrington, J. Houldsworth, A.
Lloyd, "OSI NSAPs and IPv6", RFC1888, August 1996.
[RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", RFC2119, BCP14, March 1997.
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 19]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
SECURITY CONSIDERATIONS
Documents of this type do not directly impact the security of the
Internet infrastructure or its applications.
AUTHOR'S ADDRESSES
Robert M. Hinden Stephen E. Deering
Ipsilon Networks, Inc. Cisco Systems, Inc.
232 Java Drive 170 West Tasman Drive
Sunnyvale, CA 94089 San Jose, CA 95134-1706
USA USA
phone: +1 408 990-2004 phone: +1 408 527-8213
fax: +1 408 743-5677 fax: +1 408 527-8254
email: hinden@ipsilon.com email: deering@cisco.com
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 20]
INTERNET-DRAFT IPv6 Addressing Architecture May 1997
CHANGES FROM RFC-1884
This draft has the following changes from RFC-1884.
- Added notation for defining IPv6 prefixes.
- Changed solicited node multicast definition to use a longer
prefix.
- Added site scope all routers multicast address.
- Defined Aggregatable Global Unicast Addresses to use "001" Format
Prefix.
- Changed "010" (Provider-Based Unicast) and "100" (Reserved for
Geographic) Format Prefixes to Unassigned.
- Added section on Interface ID definition for unicast addresses.
Requires use of EUI-64 in range of format prefixes and rules for
setting global/local scope bit in EUI-64.
- Updated NSAP text to reflect working in RFC1888.
- Removed protocol specific IPv6 multicast addresses (e.g., DHCP)
and referenced the IANA definitions.
- Removed section "Unicast Address Example". Had become OBE.
- Added new references.
- Minor text clarifications and improvements.
draft-ietf-ipngwg-addr-arch-v2-00.txt [Page 21]
