RFC 8093

Okay bestie, let's talk about RFC 8093 💖 The title is "Deprecation of BGP Path Attribute Values 30, 31, 129, 241, 242, and 243," written by J. Snijders at NTT. It's a Standards Track doc dated February 2017, with ISSN 2070-1721. The header doesn't have any Obsoletes or Updates lines, so it doesn't replace or change any other RFC 🎀

Abstract

So the big ask 🔥 This doc requests that IANA mark BGP path attribute values 30, 31, 129, 241, 242, and 243 as "Deprecated" 💅

Status of This Memo

This is an Internet Standards Track document ✨

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). Further information on Internet Standards is available in 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 at http://www.rfc-editor.org/info/rfc8093 🦋

Copyright Notice

Copyright (c) 2017 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 (http://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 Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License 🫶

Table of Contents

1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
2.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   2
3.  Security Considerations . . . . . . . . . . . . . . . . . . .   2
4.  Informative References  . . . . . . . . . . . . . . . . . . .   3
Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   3
Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   3

1. Introduction ✨

Okay so, it turns out some BGP path attribute values have been showing up in BGP implementations out in the wild even though IANA never assigned them for that purpose 😭 Unregistered usage of BGP path attribute values can cause deployment problems for new technologies, and that's the drama we're here to fix 💀

The problem was spotted when IANA assigned value 30 to the BGP Large Communities attribute [RFC8092]. Then it was discovered that a widely deployed BGP-4 [RFC4271] implementation had shipped code using path attribute 30. That code applied a "Treat-as-withdraw" [RFC7606] strategy to any route carrying a valid Large Community attribute, because it was expecting a different data structure. So those routes got dropped, and early adopters of Large Communities became unreachable from parts of the Internet 😱 As a workaround, a new Early IANA Allocation was requested 🩹

The squatting of values 30, 31, 129, 241, 242, and 243 has been confirmed by the involved vendors or through source code review 🔍

2. IANA Considerations

IANA has marked values 30, 31, 129, 241, 242, and 243 as "Deprecated" in the "BGP Path Attributes" subregistry under the "Border Gateway Protocol (BGP) Parameters" registry 🎀 The marking "Deprecated" means "use is not recommended" ([IANA-GUIDELINES]) 🙈

3. Security Considerations

Okay, here's the serious part 🚨 There are no meaningful security consequences arising from this registry update 💅

4. Informative References

[IANA-GUIDELINES]
           Cotton, M., Leiba, B., and T. Narten, "Guidelines for
           Writing an IANA Considerations Section in RFCs", Work in
           Progress, draft-leiba-cotton-iana-5226bis-18, September
           2016.

[RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
           Border Gateway Protocol 4 (BGP-4)", RFC 4271,
           DOI 10.17487/RFC4271, January 2006,
           <http://www.rfc-editor.org/info/rfc4271>.

[RFC7606]  Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
           Patel, "Revised Error Handling for BGP UPDATE Messages",
           RFC 7606, DOI 10.17487/RFC7606, August 2015,
           <http://www.rfc-editor.org/info/rfc7606>.

[RFC8092]  Heitz, J., Ed., Snijders, J., Ed., Patel, K., Bagdonas,
           I., and N. Hilliard, "BGP Large Communities Attribute",
           RFC 8092, DOI 10.17487/RFC8092, February 2017,
           <http://www.rfc-editor.org/info/rfc8092>.

Acknowledgements

Huge thanks to Marlien Vijfhuizen, who helped discover the squatting of value 30, and to Nick Hilliard for editorial feedback 🌈🫶

Author's Address

Job Snijders
NTT Communications
Theodorus Majofskistraat 100
Amsterdam  1065 SZ
The Netherlands

Email: job@ntt.net