RFC 8066

IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) ESC Dispatch Code Points and Guidelines

📅 published February 2017, from ietf

RFC 8066: IPv6 over Low-Power Wireless Personal Area Network (6LoWPAN) ESC Dispatch Code Points and Guidelines ✨

Okay bestie, the title block first 💅 This is RFC 8066, published by the IETF in February 2017. The authors are S. Chakrabarti, G. Montenegro, and R. Droms from Microsoft, plus J. Woodyatt from Google 🫶 It's a Standards Track doc with ISSN: 2070-1721, and it updates RFC 4944 and RFC 6282 🔥

Abstract

So [RFC4944] added the ESC dispatch type so the 6LoWPAN header could carry extra dispatch octets 🎀 Then RFC 6282 changed the value of that ESC type, but neither doc ever said what the octets after it are supposed to do 😭 This doc fixes that by defining the ESC extension octet code points, and it lists the registration entries for known use cases at the time it was written 🦋

Status of This Memo

This is an Internet Standards Track document 🌈

This doc is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community, it went through public review, and the Internet Engineering Steering Group (IESG) approved it for publication 👑 If you want more on Internet Standards, check out Section 2 of RFC 7841 ✨

For the current status, any errata, and how to send feedback, go to http://www.rfc-editor.org/info/rfc8066 💖

Copyright Notice

This doc is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents, which you can find at http://trustee.ietf.org/license-info, as they were in effect when it was published 📜 Please read those carefully, because they spell out your rights and restrictions for this doc 🙈 If you pull any Code Components out of this document, they must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions, and they come with no warranty, same as the Simplified BSD License says 💅

1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
3.  Usage of ESC Dispatch Octets  . . . . . . . . . . . . . . . .   3
  3.1.  Interaction with Other RFC 4944 Implementations . . . . .   4
  3.2.  ESC Extension Octets Typical Sequence . . . . . . . . . .   5
  3.3.  ITU-T G.9903 ESC Type Usage . . . . . . . . . . . . . . .   6
  3.4.  NALP and ESC Dispatch Types . . . . . . . . . . . . . . .   6
4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
5.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
  6.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
  6.2.  Informative References  . . . . . . . . . . . . . . . . .   8
Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   8
Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1. Introduction 🦋

Okay so Section 5.1 of [RFC4944] is where the dispatch header and its types are defined 🧚 The ESC type is the one that uses extra dispatch octets in the 6LoWPAN header. RFC 6282 changed the value of the ESC dispatch type, and that value is recorded in the IANA registry [IANA-6LoWPAN]. BUT the octets and usage after the ESC dispatch type are not defined in either [RFC4944] or [RFC6282] 🙈 Lately, 6LoWPAN deployments, implementations, and standards organizations have started using the ESC extension octets anyway, so we really need an updated IANA registration policy 💀

This doc creates the new "ESC Extension Types" registry and defines the ESC extension octets for future applications 🌸 It also records the ITU-T specification for ESC dispatch octet code points as an existing known usage ✨

2. Terminology 💜

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 📖

3. Usage of ESC Dispatch Octets 🎀

RFC 4944 [RFC4944] was the first to bring in this "ESC" dispatch header type for extending dispatch octets 🌈 After that, RFC 6282 [RFC6282] changed its value to [01 000000] ✨

This doc says the first octet after the ESC dispatch type is used for the extension type, which is the extended dispatch value 💖 The octets after that are left unstructured, so the extension type can use them however it wants 🫶

 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|     ESC       | ESC EXT Type  | Extended Dispatch Payload
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Figure 1: Frame Format with ESC Dispatch Type

ESC: The left-most octet is the ESC dispatch type, and it contains '01000000' 🍓

ESC Extension Type (EET): This is the first octet after the ESC dispatch type. The extension type decides what the additional dispatch octets carry. The values run from 0 to 255. Values 0 and 255 are reserved for future use 🔮 The remaining values, 1 to 254, are assigned by IANA 🧁 EET values work a lot like the dispatch values in the 6LoWPAN header, except they come after the ESC dispatch type. So ESC extension types and dispatch values use orthogonal code spaces, meaning they don't overlap 🦄 It's not desirable, but multiple ESC dispatch types MAY appear in a 6LoWPAN header. Section 3.1 explains how to handle an unknown ESC dispatch type 🙃

Extended Dispatch Payload (EDP): This part of the frame format must be defined by the corresponding extension type. A specification is required to define how each extension type is used and what its corresponding Extension Payload looks like. For interoperability's sake, specifications of extension octets MUST NOT redefine the existing ESC Extension Type codes 🚫

Section 5.1 of RFC 4944 says the Extension Type field may contain additional dispatch values larger than 63, as corrected by [Err4359] 🤓 For interoperability's sake, the new dispatch type (EET) MUST NOT modify the behavior of existing dispatch types [RFC4944] 💅

3.1. Interaction with Other RFC 4944 Implementations 🌸

It's expected that existing RFC 4944 implementations can't process ESC extension data octets the way this doc defines them 😭 Still, implementers have to assume that an existing implementation which tries to process an EET it doesn't know will just drop the packet or ignore the ESC dispatch octets 👀

If an implementation following this document hits an ESC dispatch type during processing and doesn't understand its ESC Extension Type (EET) octets, it MUST drop that packet 🚫 But it's important to note that a router node SHOULD forward a 6LoWPAN packet with EET octets as long as it doesn't try to process any unknown ESC extension octets 🦋

Multiple ESC extension octets may show up in one packet. ESC dispatch types can appear as the first, last, or middle dispatch octets ✨ However, any node that doesn't understand the EET at the beginning of the packet will drop the whole packet 💀 Putting an EET near the front has a higher chance of getting the packet dropped than putting that same EET later on 🥺 When the EET sits later in the packet, a legacy device has a better shot at recognizing and successfully processing some dispatch type [RFC4944] before it reaches the EET. In that case the legacy device ignores the EET instead of dropping the entire packet 🫶

3.2. ESC Extension Octets Typical Sequence 🧚

Here's the order of ESC extension octets relative to the 6LoWPAN Mesh header and the LOWPAN_IPHC header 🗺️ When the LOWPAN_IPHC dispatch type is present, ESC dispatch types MUST appear before the LOWPAN_IPHC dispatch type, so it stays backward compatible with Section 3.2 of RFC 6282 💖 The diagrams below show examples of ESC extension octet usages 🎀

A LoWPAN encapsulated IPv6 Header compressed packet:

+-------+------+--------+--------+-----------------+--------+
|   ESC | EET  | EDP    |Dispatch| LOWPAN_IPHC hdr | Payld  |
+-------+------+--------+--------+-----------------+--------+

A LoWPAN_IPHC Header, Mesh header and an ESC extension octet:

+-----+-----+-----+----+------+-------+---------------+------+
|M typ| Mhdr| ESC | EET|EDP   |Disptch|LOWPAN_IPHC hdr| Payld|
+-----+-----+-----+----+------+-------+---------------+------+

A Mesh header with ESC dispatch types:

+-------+-------+-----+-----+-------+
| M Typ | M Hdr | ESC | EET |EDP    |
+-------+-------+-----+-----+-------+

With Fragment header:

+-------+-------+--------+------+-----+-----+-------+
| M Typ | M Hdr | F Typ  | F hdr|ESC  | EET |  EDP  |
+-------+-------+--------+------+-----+-----+-------+

ESC dispatch type as a LowPAN encapsulation:

+--------+--------+--------+
| ESC    | EET    | EDP    |
+--------+--------+--------+

 Figure 2: A 6LoWPAN Packet with ESC Dispatch Types

3.3. ITU-T G.9903 ESC Type Usage 🌈

Okay this one's a fun one 🤩 The ESC dispatch type is used in [G3-PLC] to provide native mesh routing and bootstrapping functionalities ⚡ The ITU-T recommendation [G3-PLC] (see Section 9.4.2.3) defines commands that are formatted like ESC Extension Type fields 🎀 The command ID values run from 0x01 to 0x1F 🍓

The frame format goes like this:

 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 1| ESC       |  Command ID   | Command Payload
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

        Figure 3: G.9903 Frame Format with ESC Dispatch Type

3.4. NALP and ESC Dispatch Types 🦢

According to Section 5.1 of RFC 4944 [RFC4944], NALP dispatch octets are reserved for use as a kind of escape code for identifying non-6LoWPAN payloads 🔍 Since ESC dispatch types are part of the (extended) 6LoWPAN dispatch types, they're orthogonal to NALP octets 💜

This doc clarifies that NALP dispatch codes only act as an escape method for non-6LoWPAN payloads when they show up as the initial octet of a LoWPAN encapsulation 🎯 Anywhere else they appear, their potential meaning is reserved for future use 🌷

4. IANA Considerations 🎀

okay bestie, so IANA registered the 'ESC Extension Types' values under the policy 'Specification Required' [RFC5226] 📋✨, following the same policy as the IANA Considerations section of [RFC4944] 🦋. For each Extension Type (except the Reserved values), the specification MUST define corresponding Extended Dispatch Payload frame octets so the receiver implementation can read the ESC dispatch types in an interoperable way 💖. No vibes-based parsing, periodt 💅.

Section 4.1 of [RFC5226] says that "Specification Required" calls for a Designated Expert review of the public specification that requests registration of the ESC Extension Type values 🧚.

The allocation of code points should follow the guidelines in "Usage of ESC Dispatch Octets" (Section 3) and the typical example (Section 3.2) 🌸. ESC Extension Type code points MUST be used in conjunction with 6lo protocols following [RFC4944] or its derivatives 🫶. The requesting document MUST specify how the ESC dispatch octets will be used along with 6LoWPAN headers in their use cases 👑. Non-negotiable, bestie 😭.

The initial values for the 'ESC Extension Type' fields are as follows 🌈:

+-------+---------------------------------+---------------+
| Value | Description                     | Reference     |
+-------+---------------------------------+---------------+
|  0    | Reserved                        | This document |
|       |                                 |               |
| 1-31  | Used by ITU-T G.9903 and G.9905 | ITU-T G.9903 &|
|       |     Command IDs                 | ITU-T G.9905  |
|       |                                 |               |
| 32-254| Unassigned                      |               |
|       |                                 |               |
| 255   | Reserved                        | This document |
+-------+---------------------------------+---------------+

Figure 4: Initial Values for the ESC Extension Types Registry

5. Security Considerations ⚠️

There are no additional security threats due to the assignments of ESC dispatch type usage described in this document. 🙈

Furthermore, this document forbids defining any extended dispatch values or extension types that modify the behavior of existing dispatch types. Nobody gets to rewrite how the existing dispatch types behave, not even with a cute new extension, so don't even try it 🚫💀.

6. References 📚

6.1. Normative References 💜

[Err4359] RFC Errata, Erratum ID 4359, RFC 4944, <https://www.rfc-editor.org/errata_search.php?eid=4359>.

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

[RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, "Transmission of IPv6 Packets over IEEE 802.15.4 Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, <http://www.rfc-editor.org/info/rfc4944>.

[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, DOI 10.17487/RFC6282, September 2011, <http://www.rfc-editor.org/info/rfc6282>.

6.2. Informative References 🧚

[G3-PLC] International Telecommunications Union, "G.9903 : Narrowband orthogonal frequency division multiplexing power line communication transceivers for G3-PLC networks", February 2014, <http://www.itu.int/rec/T-REC-G.9903-201402-I>.

[IANA-6LoWPAN] IANA, "IPv6 Low Power Personal Area Network Parameters", <https://www.iana.org/assignments/_6lowpan-parameters>.

[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, DOI 10.17487/RFC5226, May 2008, <http://www.rfc-editor.org/info/rfc5226>.

Acknowledgements 🫶

The authors would like to thank the members of the 6lo WG for their comments. Many thanks to Carsten Bormann, Ralph Droms, Thierry Lys, Cedric Lavenu, and Pascal Thubert for discussions regarding the bits allocation issues, which led to this document 🌸. Jonathan Hui and Robert Cragie provided extensive reviews and guidance for interoperability ✨. The authors acknowledge the comments from the following people that helped shape this document: Paul Duffy, Don Sturek, Michael Richardson, Xavier Vilajosana, Scott Mansfield, Dale Worley, and Russ Housley 💖. Thanks to Brian Haberman, our document shepherd, for guidance in the IANA Considerations section 👑.

Authors' Addresses 🦋

Samita Chakrabarti San Jose, CA United States of America

Email: samitac.ietf@gmail.com

Gabriel Montenegro Microsoft United States of America

Email: gabriel.montenegro@microsoft.com

Ralph Droms United States of America

Email: rdroms.ietf@gmail.com

James Woodyatt Google Mountain View, CA United States of America

Email: jhw@google.com

📦 where this page comes from

ietf: rfc8066 2017-02
💖 girlified by claude-haiku-5-5 on 2026-10-18: a language model's rewrite of the original, under its terms