Internet-Draft Reserving Additional IPv6 Address Prefix January 2022
Horley, et al. Expires 30 July 2022 [Page]
Network Working Group
Intended Status:
E. Horley
T. Coffeen
S. Hogg
N. Buraglio
Energy Sciences Network
C. Cummings
Energy Sciences Network
K. Myers
IP ArchiTechs
R. White
Juniper Networks

Reserving Additional IPv6 Address Prefixes for Use in Documentation


To reduce the likelihood of conflict and confusion when relating documented examples to deployed systems, the IPv6 unicast address prefix 2001:db8::/32 is reserved for use in examples in documentation including RFCs, books, articles, vendor manuals, etc. This document proposes the reservation of additional IPv6 prefixes for this purpose; specifically, 3ffe::/16 (formerly 6bone) and fec0::/10 (formerly site-local).

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at

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."

This Internet-Draft will expire on 30 July 2022.

Table of Contents

1. Introduction

The address architecture for IPv6 [RFC4291] does not specifically allocate any IPv6 address prefixes for documentation purposes. The current IPv6 documentation prefix of 2001:db8::/32 defined in [RFC6890] is not large enough for many design and documentation requirements. No additional documentation prefix(es) were allocated in the most recent IPv6 Specification [RFC8200].

These are example use cases that require a documentation IPv6 prefix larger than a /32:

The following existing criteria are beneficially extended to the additional documentation prefixes:

2. Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to are to be interpreted as described in BCP 14 [RFC2119] when, and only when, they appear in all capitals, as shown here.

3. Documentation IPv6 Address Prefixes

The additional IPv6 address prefixes allocated for documentation purposes are 3ffe::/16 (formerly 6bone - [RFC3701]) and fec0::/10 (formerly site-local - [RFC3879]), resulting in the following prefixes for use in documentation:

4. Operational Implications

The addition of IPv6 address prefixes for documentation implies that IPv6 network operators should add these address prefixes to their lists of non-routable/bogon IPv6 address space. If packet filters are deployed in live networks, these address prefixes should be added to those filters intended to prevent any public routing of such address space.

Because the 3ffe::/16 address prefix was previously used for the subsequently decommissioned 6bone network, this address prefix is included in many existing non-routable prefix filters and lists. Its precedence value per [RFC6724] is 1, which limits its usability in production networks. In addition, the 3ffe::/16 address prefix was returned to IANA and is available to be reserved for documentation purposes.

Similarly the fec0::/10 address prefix was previously used for site-local addressing, and thus is already included in many non-routable prefix filters and lists. Its precedence value per [RFC6724] is 1, which limits its usability in production networks. In addition, the fec0::/10 address prefix was returned to IANA and is available to be reserved for documentation purposes.

As a documentation prefix, the former site-local scope of fec0::/10 is considered deprecated and filters may be required and used with any scope.

5. IANA Considerations

These documentation prefixes have limited impact on IANA and no impact on any RIRs.

IANA is to record the allocation of the IPv6 global unicast address prefix 3ffe::/16 and fec0::/10 as documentation-only prefixes in the IPv6 address registry. No end-user or service provider/LIR is to be assigned these addresses.

6. Security Considerations

IPv6 addressing documentation has no direct impact on Internet security.

However, the assignment of a new address space for documentation purposes does mean, as indicated above, that these addresses SHOULD be added to any filters required by individual operators to prevent their use for globally routed destinations.

7. Acknowledgements

The authors acknowledge the work of Geoff Huston, assisted by Anne Lord, and Philip Smith, in authoring the previous proposal for the IPv6 documentation prefix.

8. References

8.1. Normative References

Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Fink, R. and R. Hinden, "6bone (IPv6 Testing Address Allocation) Phaseout", RFC 3701, DOI 10.17487/RFC3701, , <>.
Huitema, C. and B. Carpenter, "Deprecating Site Local Addresses", RFC 3879, DOI 10.17487/RFC3879, , <>.
Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", STD 86, RFC 8200, DOI 10.17487/RFC8200, , <>.

8.2. Informative References

Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, DOI 10.17487/RFC4291, , <>.
Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown, "Default Address Selection for Internet Protocol Version 6 (IPv6)", RFC 6724, DOI 10.17487/RFC6724, , <>.
Cotton, M., Vegoda, L., Bonica, R., Ed., and B. Haberman, "Special-Purpose IP Address Registries", BCP 153, RFC 6890, DOI 10.17487/RFC6890, , <>.

Authors' Addresses

Ed Horley
Tom Coffeen
Scott Hogg
Nick Buraglio
Energy Sciences Network
Chris Cummings
Energy Sciences Network
Kevin Myers
IP ArchiTechs
Russ White
Juniper Networks