RFC 5396

RFC 5396: Textual Representation of Autonomous System (AS) Numbers 🎀

Okay bestie, here's the title block tea ☕. It's from the Network Working Group, written by Geoff Huston and George Michaelson (both at APNIC), and it's a Standards Track doc dated December 2008. Main character energy 💅.

Status of This Memo ✨

Okay so this doc is an Internet standards track protocol for the Internet community, and it's basically asking everyone to talk about it and suggest improvements 🗣️. For the standardization state and status of this protocol, check the current edition of "Internet Official Protocol Standards" (STD 1) 📚. Distribution of this memo is unlimited 🌈.

Copyright Notice 🔐

Copyright (c) 2008 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 (http://trustee.ietf.org/license-info), which were in effect on the publication date. Please read these carefully, bestie 🙏. They explain your rights and restrictions for this document, and that stuff matters!!

Abstract 🦋

So the big idea is this: AS numbers get a textual representation that's just their decimal value 🔢. Everyone (documents, systems, user interfaces, all of it) is supposed to use this same format whenever they mention AS numbers 🫶.

Table of Contents 📑

1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.  Taxonomy of Representation Formats  . . . . . . . . . . . . . . 2
3.  Representation of AS Number Values  . . . . . . . . . . . . . . 2
4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 3
5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 3
6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 3
7.  Informative References  . . . . . . . . . . . . . . . . . . . . 3

1. Introduction 🌸

Okay, the intro basically repeats the abstract: AS numbers get a textual representation that's their decimal value 💖, and every document, system, and user interface that talks about AS numbers should use it 🙌.

This doc also lists a bunch of possible representation formats. It proposes decimal value notation for AS numbers, which it calls "asplain", and it sorts it into the taxonomy you'll see in the next section 🧚.

2. Taxonomy of Representation Formats 🍓

Here's the full family tree of formats, lowkey my favourite part 🤭:

asplain is a syntax scheme where every AS number is written as a decimal integer 🔢. So an AS number with value 65526 is the string "65526", and one with value 65546 is the string "65546" ✨.

asdot+ is a syntax scheme where every AS number is written as two integers joined by a period 🦋. The first is the high order 16-bit value in decimal, and the second is the low order 16-bit value in decimal, like this: <high order 16-bit value in decimal>.<low order 16-bit value in decimal>. So 65526 becomes "0.65526" and 65546 becomes "1.10" 💅.

asdot is a mix 🎀. AS number values below 65536 use asplain, and values of 65536 or higher use asdot+. So 65526 is "65526" and 65546 is "1.10" 🫶.

3. Representation of AS Number Values 💜

To avoid confusion 🙈, one single textual notation is useful for documentation, configuration systems, reports, external tools, and information repositories. The decimal value representation, which is "asplain", is the one proposed as the textual notation for AS numbers 🔥.

The "asplain" representation is just the decimal value, with no field delimiter. That matches the fact that AS numbers don't need any internal structure when they're used in inter-domain routing 🧠.

4. IANA Considerations 🌈

IANA Registries should use decimal representation ("asplain") for AS numbers ✨.

5. Security Considerations 🔒

This doc doesn't touch security of routing systems at all 🙃. Not gonna lie, it's a lil plot twist that there's nothing here, but that's the truth 💀.

6. Acknowledgments 🧚‍♀️

Shoutout to Juergen Kammer, who originally came up with and described the terms "asplain", "asdot", and "asdot+" back in January 2007 🫶 [KAMMER2007]. Iconic.

7. Informative References 📚

[KAMMER2007]  Kammer, J., "AS Number Formats", Jan 2007,
              <http://quagga.ncc.eurodata.de/asnumformat.html>.

Authors' Addresses 🦋

Geoff Huston
Asia Pacific Network Information Centre

EMail: gih@apnic.net


George Michaelson
Asia Pacific Network Information Centre

EMail: ggm@apnic.net

---

That's the whole RFC, bestie!! 🌈💖 Thanks for reading with me 🫶✨