Status of This Memo

This document is not an Internet Standards Track specification; it is published for informational purposes.¶

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are candidates for any level of Internet Standard; see Section 2 of RFC 7841.¶

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained athttps://www.rfc-editor.org/info/rfc9637.¶

Copyright Notice

Copyright (c) 2024 IETF Trust and the persons identified as the document authors. All rights reserved.¶

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶

Table of Contents

1.Introduction

[RFC3849] introduced the IPv6 address prefix 2001:db8::/32 as a reserved prefix for use in documentation. The rationale for this reservation was to reduce the likelihood of conflict and confusion when relating documented examples to deployed systems.¶

As the global deployment of IPv6 expands and evolves, individual IPv6network deployment scenarios have also increased in size and diversity, andthere is a requirement for documentation to reflect this increased diversityand scope. The original 2001:db8::/32 reservation is inadequate to describemany realistic, current deployment scenarios.¶

Without this additional address allocation, documentation prefixesare drawn from address blocks already allocated or assigned to existingorganizations or well-known ISPs, or they are drawn from the currently unallocatedaddress pool. Such use conflicts with existing or future allocations orassignments of IPv6 address space. The reservation of a /20 IPv6address prefix from the Global Unicast Address pool[RFC4291] fordocumentation purposes allows such conflicts to be avoided.¶

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 be interpreted as described in BCP 14[RFC2119][RFC8174] when, and only when, they appear in all capitals, as shown here.¶

3.Current Assignment and Allocation Data

According to the allocation and assignment data published by the RegionalInternet Registries (RIRs) (see[NROStatsReport]),in August 2023, 25.9% of the 62,770 recorded IPv6 unicast allocations andassignments were larger than a /32 in size. The most common allocation orassignment size was a /29, used in 24.8% of cases.¶

The four largest assignments made to end users have been /19s, but theseallocations were made before the RIRs moved away from the use of a fixed /48site address prefix in IPv6 address assignment policies, and in theforeseeable future, it is unlikely that individual networks will require morethan a /20. It is believed that reservation of a /20 will cover thedocumentation needs as they relate to the broad range of realistic networkdeployments.¶

4.Filtering and Appropriate Use

Documentation prefixes are for the use of relaying configuration and documentation examples, and as such, theyMUST NOT be used for actual traffic,MUST NOT be globally advertised, andSHOULD NOT be used internally for routed production traffic or other connectivity. Documentation prefixes should be considered bogon[BOGON] and filtered in routing advertisements as appropriate.¶

5.Security Considerations

This special-use prefix should be marked as and considered bogon[BOGON]. As is appropriate with bogon prefixes, packets whose source or destination belongs to this prefix should be dropped and disallowed over the public Internet.¶

6.IANA Considerations

IANA has registered the following in the "IANA IPv6 Special-Purpose Address Registry"[IANA-IPv6-SPAR].¶

Address Block:

3fff::/20¶

Name:

Documentation¶

RFC:

RFC 9637¶

Allocation Date

2024-07¶

Termination Date:

N/A¶

Source:

False¶

Destination:

False¶

Forwardable:

False¶

Globally Reachable :

False¶

Reserved-by-Protocol:

False¶

Acknowledgments

The authors would like to acknowledge the valuable input fromXiPeng Xiao,Chris Cummings,Russ White,Kevin Myers,Ed Horley,Tom Coffeen, andScott Hogg.¶

Authors' Addresses