RFC 9637

Expanding the IPv6 Documentation Space

📅 published August 2024, from ietf

📜 RFC 9637: Expanding the IPv6 Documentation Space 🦋

Internet Engineering Task Force (IETF) 💅 Request for Comments: 9637 ✨ Obsoletes: nothing 💖 Updates: RFC 3849 🌸 Category: Informational 🧚 ISSN: 2070-1721 🍓 Published: August 2024 🎀

Okay bestie, let's get the basics out of the way first 💖 This doc was written by Geoff Huston (APNIC) and Nick Buraglio (Energy Sciences Network) 🫶 It's an Informational doc, so it's not a Standards Track spec 🌈 It updates RFC 3849, which is the original doc that reserved 2001:db8::/32 for documentation 🦋 It doesn't obsolete anything, so no drama there ✨

Abstract ✨

So the vibe is this: the doc reserves an extra IPv6 prefix for documentation examples 💅 It builds on the existing 2001:db8::/32 block by adding a bigger one, a /20 😭 The whole point is that examples can look more like real, current deployments and match how big networks get allocated today 🔥 Iconic, honestly 👑

Status of This Memo 🌸

This document is not an Internet Standards Track specification 💀 It's published for informational purposes only 🧚

This doc is a product of the Internet Engineering Task Force (IETF) 🌈 It represents the consensus of the IETF community 💖 It got public review and was approved for publication by the Internet Engineering Steering Group (IESG) 🫶 Not everything the IESG approves ends up as an Internet Standard, so check out Section 2 of RFC 7841 if you're curious about that 🙈

You can find the current status, any errata, and feedback info at https://www.rfc-editor.org/info/rfc9637 🍓

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

This doc is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) as they stand on the publication date 📜 Read those carefully, because they spell out your rights and restrictions 🧐 Code extracted from this doc must include Revised BSD License text, as described in Section 4.e of the Trust Legal Provisions, and it comes without warranty as described in that license ⚠️

Table of Contents 🗺️

  1. Introduction 🌷
  2. Requirements Language 💅
  3. Current Assignment and Allocation Data 📊
  4. Filtering and Appropriate Use 🚧
  5. Security Considerations 🔐
  6. IANA Considerations 🏠
  7. References 📚 7.1. Normative References 7.2. Informative References Acknowledgments 🫶 Authors' Addresses 💌

1. Introduction 🌷

[RFC3849] introduced the IPv6 address prefix 2001:db8::/32 as a reserved prefix for documentation 🦋 The goal was to cut down on conflicts and confusion when people match documented examples to systems that are actually deployed 💖

Okay so, as IPv6 deployment keeps growing, individual networks have also gotten bigger and more varied 📈 Documentation needs to show that range too 🌈 The original 2001:db8::/32 reservation just isn't big enough to describe many realistic, current deployments 😭

Without a bigger block, documentation prefixes get pulled from address space that's already allocated or assigned to real organizations or well-known ISPs, or from the unallocated pool 🙈 That causes trouble with existing or future allocations and assignments of IPv6 address space 💀 So the doc reserves a /20 from the Global Unicast Address pool [RFC4291] for documentation, which lets those conflicts be avoided 🫶 Periodt ✨

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 📊

The Regional Internet Registries (RIRs) publish allocation and assignment data (see [NROStatsReport]) 📈 In August 2023, 25.9% of the 62,770 recorded IPv6 unicast allocations and assignments were larger than a /32 👀 The most common size was a /29, showing up in 24.8% of cases 💖

The four biggest assignments to end users were /19s 😳 But those were handed out before the RIRs stopped using a fixed /48 site address prefix in IPv6 address assignment policies ✨ Looking ahead, it's unlikely that individual networks will need more than a /20 🧚 So a /20 should cover documentation needs across the broad range of realistic network deployments 🔥

4. Filtering and Appropriate Use 🚧

Documentation prefixes are for relaying configuration and documentation examples 📝 So they MUST NOT be used for actual traffic 🚫 They MUST NOT be globally advertised 🌍 And they SHOULD NOT be used internally for routed production traffic or other connectivity 🙅‍♀️ Documentation prefixes should be treated as bogons [BOGON] and filtered in routing advertisements as appropriate 🛡️

5. Security Considerations 🔐

⚠️ This is a serious section, bestie, so pay attention!

This special-use prefix should be marked as and treated as a bogon [BOGON] 🚨 As is appropriate with bogon prefixes, packets whose source or destination falls in 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

7. References 📚

7.1. Normative References 💜

[IANA-IPv6-SPAR]
           IANA, "IANA IPv6 Special-Purpose Address Registry",
           <https://www.iana.org/assignments/iana-ipv6-special-
           registry>.

[RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
           Requirement Levels", BCP 14, RFC 2119,
           DOI 10.17487/RFC2119, March 1997,
           <https://www.rfc-editor.org/info/rfc2119>.

[RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
           2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
           May 2017, <https://www.rfc-editor.org/info/rfc8174>.

7.2. Informative References 🦋

[BOGON]    Team Cymru, "Unravelling the Mystery of Bogons: A senior
           stakeholder and IT professional guide", July 2023,
           <https://www.team-cymru.com/post/unravelling-the-mystery-
           of-bogons-a-senior-stakeholder-and-it-professional-guide>.

[NROStatsReport]
           "NRO Stats Reports",
           <https://ftp.ripe.net/pub/stats/ripencc/nro-stats>.

[RFC3849]  Huston, G., Lord, A., and P. Smith, "IPv6 Address Prefix
           Reserved for Documentation", RFC 3849,
           DOI 10.17487/RFC3849, July 2004,
           <https://www.rfc-editor.org/info/rfc3849>.

[RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
           Architecture", RFC 4291, DOI 10.17487/RFC4291, February
           2006, <https://www.rfc-editor.org/info/rfc4291>.

Acknowledgments 🫶

The authors want to give a huge shoutout to XiPeng Xiao, Chris Cummings, Russ White, Kevin Myers, Ed Horley, Tom Coffeen, and Scott Hogg 💖 Thank you, queens 👑

Authors' Addresses 💌

Geoff Huston APNIC Email: gih@apnic.net

Nick Buraglio Energy Sciences Network Email: buraglio@forwardingplane.net

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