Initial IPv6 Sub-TLA ID Assignments
Early allocations of address space to regional Internet registries.
Hinden, R., Deering, S., Fink, R., and T. Hain, "Initial IPv6 Sub-TLA ID Assignments", RFC 2928, DOI 10.17487/RFC2928, September 2000, <https://www.rfc-editor.org/info/rfc2928>.
@misc{rfc2928,
series = {Request for Comments},
number = 2928,
howpublished = {RFC 2928},
publisher = {RFC Editor},
doi = {10.17487/RFC2928},
url = {https://www.rfc-editor.org/info/rfc2928},
author = {R. Hinden and S. Deering and R. Fink and T. Hain},
title = {{Initial IPv6 Sub-TLA ID Assignments}},
pagetotal = 7,
year = 2000,
month = sep,
} RFC text
Contents
Network Working Group R. Hinden
Request for Comments: 2928 Nokia
Category: Informational S. Deering
Cisco
R. Fink
LBNL
T. Hain
Microsoft
September 2000
Initial IPv6 Sub-TLA ID Assignments
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2000). All Rights Reserved.
Abstract
This document defines initial assignments of IPv6 Sub-Top-Level
Aggregation Identifiers (Sub-TLA ID) to the Address Registries. It
is intended as technical input to the Internet Assigned Numbers
Authority (IANA) from the Internet Engineering Task Force (IETF)
Internet Protocol Next Generation (IPNG) and Next Generation
Transition (NGTRANS) working groups, as an input to the process of
developing guidelines for the allocation of IPv6 addresses.
This document was originally developed to provide advice to IANA in
the fall of 1998 and is being published at this time for the
historical record. The Internet Architecture Board (IAB)
subsequently requested that the IANA delegate these assignments to
the Address Registries. The IANA did this and the Address Registries
are now using them to assign IPv6 addresses.
1. Introduction
This document was originally developed to provide advice to IANA in
the fall of 1998 and is being published at this time for the
historical record. The IAB subsequently requested that the IANA
delegate these assignments to the Address Registries. The IANA did
this and the Address Registries are now using them to assign IPv6
addresses.
This document defines initial assignments of IPv6 Sub-TLA Aggregation
Identifiers (Sub-TLA ID) to the Address Registries. It is intended
as technical input to the IANA from the IETF IP Next Generation
(IPNG) and Next Generation Transition (NGTRANS) working groups, as an
input to the process of developing guidelines for the allocation of
IPv6 addresses.
The IAB and IESG have authorized the Internet Assigned Numbers
Authority (IANA) as the appropriate entity to have the responsibility
for the management of the IPv6 address space as defined in [ALLOC].
The proposed initial assignment described in the document is
consistent with:
- RFC 2373,"IP Version 6 Addressing Architecture" [ARCH]
- RFC 2374 "An Aggregatable Global Unicast Address Format" [AGGR]
- RFC 2450 "Proposed TLA and NLA Assignment Rules" [TLA-RULES]
2. Background
[TLA-RULES] specifies that TLA assignments will be done in two
stages. The first stage is to allocate a Sub-TLA ID. This document
specifies the initial assignments of Sub-TLA ID's to the Registries.
As defined in [TLA-RULES] Section 5.1:
"Sub-TLA ID's are assigned out of TLA ID 0x0001 as follows. Note
that use of the Reserved field to create the Sub-TLA field is
specific to TLA ID 0x0001. It does not affect any other TLA.
| 3 | 13 | 13 | 19 |
+----+----------+---------+---------------+
| FP | TLA | Sub-TLA | NLA |
| | ID | | ID |
+----+----------+---------+---------------+
where:
FP = 001 = Format Prefix
This is the Format Prefix used to identify aggregatable global
unicast addresses.
TLA ID = 0x0001 = Top-Level Aggregation Identifier
This is the TLA ID assigned by the IANA for Sub-TLA
allocation.
Sub-TLA ID = Sub-TLA Aggregation Identifier
The Sub-TLA ID field is used by the registries for initial
allocations to organizations meeting the requirements in
Section 5.2 of this document. The IANA will assign small
blocks (e.g., few hundred) of Sub-TLA ID's to registries. The
registries will assign the Sub-TLA ID's to organizations
meeting the requirements specified in Section 5.2. When the
registries have assigned all of their Sub-TLA ID's they can
request that the IANA give them another block. The blocks do
not have to be contiguous. The IANA may also assign Sub-TLA
ID's to organizations directly. This includes the temporary
TLA assignment for testing and experimental usage for
activities such as the 6bone or new approaches like exchanges.
NLA ID = Next-Level Aggregation Identifier
Next-Level Aggregation ID's are used by organizations assigned
a TLA ID to create an addressing hierarchy and to identify
sites. The organization can assign the top part of the NLA ID
in a manner to create an addressing hierarchy appropriate to
its network."
Note: In the above quote from [TLA-RULES] the references to "Section
5.2" refer to section 5.2 in [TLA-RULES].
3. Initial Assignments
As specified in [TLA-RULES], Sub-TLA ID assignments are made in
blocks. The initial Sub-TLA ID assignments to IP address registries
are in blocks of 64 Sub-TLA IDs. These assignments are listed below.
Binary Value IPv6 Prefix Range Assignment
---------------- ------------------------------- -------------------
0000 000X XXXX X 2001:0000::/29 - 2001:01F8::/29 IANA
0000 001X XXXX X 2001:0200::/29 - 2001:03F8::/29 APNIC
0000 010X XXXX X 2001:0400::/29 - 2001:05F8::/29 ARIN
0000 011X XXXX X 2001:0600::/29 - 2001:07F8::/29 RIPE NCC
0000 100X XXXX X 2001:0800::/29 - 2001:09F8::/29 (future assignment)
0000 101X XXXX X 2001:0A00::/29 - 2001:0BF8::/29 (future assignment)
0000 110X XXXX X 2001:0C00::/29 - 2001:0DF8::/29 (future assignment)
0000 111X XXXX X 2001:0E00::/29 - 2001:0FF8::/29 (future assignment)
0001 000X XXXX X 2001:1000::/29 - 2001:11F8::/29 (future assignment)
. . .
. . .
. . .
1111 111X XXXX X 2001:FE00::/29 - 2001:FFF8::/29 (future assignment)
Where "X" indicates "0" or "1".
All other Sub-TLA ID values not listed above are reserved.
When a registry has assigned all of the Sub-TLA IDs in their block
they can request that the IANA provide another block. The blocks
assigned to a registry do not have to be contiguous.
The block of Sub-TLA IDs assigned to the IANA (i.e., 2001:0000::/29 -
2001:01F8::/29) is for assignment for testing and experimental usage
to support activities such as the 6bone, and for new approaches like
exchanges.
4. Acknowledgments
The authors would like to express their thanks to Joyce K. Reynolds,
Thomas Narten, Kim Hubbard, Mirjam Kuehne, and Brian Carpenter for
their help with this document.
5. Security Considerations
IPv6 addressing documents do not have any direct impact on Internet
infrastructure security. Authentication of IPv6 packets is defined
in [AUTH]. Authentication of the ownership of prefixes to avoid
"prefix stealing" is a related security issue but is beyond the scope
of this document.
6. References
[AGGR] Hinden, R., Deering, S. and M. O'Dell, "An Aggregatable
Global Unicast Address Format", RFC 2374, July 1998.
[ALLOC] IAB and IESG, "IPv6 Address Allocation Management", RFC
1881, December 1995.
[ARCH] Hinden, R., "IP Version 6 Addressing Architecture", RFC
2373, July 1998.
[AUTH] Kent, S. and R. Atkinson, "IP Authentication Header", RFC
2402, November 1998.
[IPV6] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, October 1996.
[TLA-RULES] Hinden, R., "Proposed TLA and NLA Assignment Rules", RFC
2450, December 1998.
[TST-ALLOC] Hinden, R., Fink R. and J. Postel, "IPv6 Testing Address
Allocation", RFC 2471, December 1998.
7. Authors' Addresses
Robert M. Hinden
Nokia
313 Fairchild Drive
Mountain View, CA 94043
USA
Phone: +1 650 625-2004
EMail: hinden@iprg.nokia.com
Stephen E. Deering
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134-1706
USA
Phone: +1 408 527-8213
EMail: deering@cisco.com
Robert L. Fink
Lawrence Berkeley National Lab
1 Cyclotron Rd.
Bldg 50A, Room 3111
Berkeley, CA 94720
USA
Phone: +1 510 486-5692
EMail: rlfink@lbl.gov
Tony Hain
Microsoft
Phone: +1 425 703-6619
EMail: tonyhain@microsoft.com
8. Full Copyright Statement
Copyright (C) The Internet Society (2000). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
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followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
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Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
AI ELI5
On this page
§1Introduction
IPv6 addresses are 128 bits long, giving vastly more address space than IPv4's 32 bits. To manage this space, the IETF designed a hierarchical aggregation scheme. Addresses begin with a Format Prefix identifying the type (001 for global unicast), followed by a Top-Level Aggregation (TLA) ID, then a Sub-TLA ID.
This document was created in 1998 to advise the Internet Assigned Numbers Authority (IANA) on how to allocate the first blocks of address space to regional registries. The Internet Architecture Board later requested that IANA delegate these assignments to the registries, and that is what happened. The registries have been using them since to assign IPv6 addresses to organizations.
The document is now published as a historical record of this initial allocation strategy.
IPv6 has much more address space than IPv4. This document describes how the very first big chunks were divided up among regional offices.
§2Background
The RFC 2450 Proposed TLA and NLA Assignment Rules specified a two-stage process: first allocate Sub-TLA IDs (smaller blocks) to registries, then the registries allocate those to organizations.
Sub-TLA IDs come from the special TLA ID 0x0001. The allocation uses 13 bits for the TLA ID (0x0001) and 13 bits for the Sub-TLA ID, which together form a /29 prefix when combined with the 3-bit format prefix. This creates large address blocks suitable for regional distribution.
The two-step process lets IANA hand out blocks to registries, which then hand out smaller blocks to companies.
§3Initial Assignments
Sub-TLA ID assignments are made in blocks of 64 IDs. The initial assignments are:
IANA (2001:0000::/29 - 2001:01F8::/29): Reserved for testing and experimental use to support activities like the 6bone (an IPv6 testbed network) and new exchange points.
APNIC (2001:0200::/29 - 2001:03F8::/29): Asia-Pacific region.
ARIN (2001:0400::/29 - 2001:05F8::/29): North America.
RIPE NCC (2001:0600::/29 - 2001:07F8::/29): Europe, Middle East, and Central Asia.
Remaining blocks (2001:0800::/29 through 2001:FFF8::/29) are reserved for future assignments. When a registry has assigned all Sub-TLA IDs in its current block, it can request additional blocks from IANA. The blocks assigned to a registry do not need to be contiguous.
IANA kept some for testing. The other big regions each got their own blocks to assign to local networks.
§4Status and Legacy
These assignments were the initial IPv6 address distribution in the early 2000s. The /29 prefix size (given in the RFC) was based on the address allocation model of that era.
Over the following decades, IPv6 deployment strategy and address allocation policies evolved significantly. Today's address allocation follows updated rules that differ from this scheme, and the Sub-TLA assignment model is no longer the primary means of IPv6 address distribution. However, addresses in the 2001::/16 block (particularly 2001:db8::/32 for documentation and 2001:20::/28 for testing) remain important for specific purposes.
This RFC is now maintained as a historical record of how IPv6 address allocation began.
These were the first assignments, but IPv6 allocation rules have changed many times since then. Some of the address blocks are still used for special purposes.