Internet DRAFT - draft-minaburo-schc-flow-compression
draft-minaburo-schc-flow-compression
SCHC Working Group L. Toutain
Internet-Draft Institut MINES TELECOM; IMT-Atlantique
Intended status: Standards Track A. Minaburo
Expires: 14 April 2024 Consultant
12 October 2023
Static Context Header Compression and Fragmentation for packets
establishing a flow
draft-minaburo-schc-flow-compression-00
Abstract
This document describes how to compress the header of packets
belonging to a flow using Static Context Header Compression and
Fragmentation (SCHC) specifications.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 2
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
4. Flow Compression . . . . . . . . . . . . . . . . . . . . . . 3
4.1. ## Action Derivable . . . . . . . . . . . . . . . . . . . 3
4.2. Type of Rules . . . . . . . . . . . . . . . . . . . . . . 4
4.2.1. Based-Rule. . . . . . . . . . . . . . . . . . . . . . 4
4.2.2. Derived-Rule. . . . . . . . . . . . . . . . . . . . . 5
5. IANA considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Security considerations . . . . . . . . . . . . . . . . . . . 5
7. Normative References . . . . . . . . . . . . . . . . . . . . 5
Appendix A. Appendix A . . . . . . . . . . . . . . . . . . . . . 6
Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
This document defines how to use Static Context Header Compression
and fragmentation (SCHC) [RFC8724] and [RFC8824] for compressing the
headers of packets in a flow.
SCHC compresses headers of individual packets without any dependency
among them, it does not have the notion of flow. In a flow, some
information on the header change in each packet. When using SCHC,
the information described in the Rule MAY change to consider this
dependency. This document solves the possibility of optimizing the
use of SCHC while compressing the flow packet headers.
2. Conventions and Definitions
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. Terminology
This document will follow the terms defined in [RFC8724] and in
[RFC8824].
* Rule. Part of the Context that describes how a packet is
Compressed/Decompressed or Fragmented/Reassembled.
* Rule Manager (RM). It is in charge of handling data derived from
the YANG Data Model and apply changes to the rules context.
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* Action. Indication in the Rule to perform some operations. *
* To Do
4. Flow Compression
This document does not change the way SCHC compresses and chooses a
Rule. The behavior defined in [RFC8724] is respected. SCHC
compressor compresses each packet separately and MAY select the best
behavior Rule for each packet. For instance, an action in the Rule
indicates that the description compresses the header of a flow, and
the compressor will process the packets using the action Derivable
behavior.
4.1. ## Action Derivable
This Action identifies those Rules describing protocol headers using
flows to transmit payloads such as TCP, RTP, SCTP, or any other
protocol. When SCHC compresses a packet belonging to a flow, it MUST
first identify whether it belongs to a flow. SCHC will check the IP
addresses and the ports and keep a reference value for the sequence
number, the timestamp, and any other field that maintain the flow
description. The fields describing a flow are out of the scope of
this document. Each protocol MUST define the corresponding fields.
The following packets belonging to a flow will use a Derived Rule
which updates the fields changing on each flow packet. The Derived
Rule is NOT limited to a number. SCHC C/D Rule Manager decides when
to create a new Derived Rule or delete it. At the end of the flow,
SCHC MUST delete all the Derived Rules.
Figure 1 Shows the format of a Rule with Derivable Action.
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Rule 1000
Action: Derivable
+----------------+--+--+--+--------+--------+-----------++------+
| FID |FL|FP|DI| TV | MO | CDA || Sent |
| | | | | | | ||[bits]|
+----------------+--+--+--+--------+--------------------++------+
|IPv6 Version |4 |1 |Bi|6 | ignore | not-sent || |
| ... || |
|IPv6 AppIID |64|1 |Bi|::1 | equal | not-sent || |
| ... | | | | | | || |
|TCP Seq-Num. |32|1 |Up| 234 | LSB | MSB || XXX |
+================+==+==+==+========+========+===========++======+
Rule 1001
Action: Derivable
+----------------+--+--+--+--------+--------+-----------++------+
| FID |FL|FP|DI| TV | MO | CDA || Sent |
| | | | | | | ||[bits]|
+----------------+--+--+--+--------+--------------------++------+
|IPv6 Version |4 |1 |Bi|6 | ignore | not-sent || |
| ... || |
|IPv6 AppIID |64|1 |Bi|::1 | equal | not-sent || |
| ... | | | | | | || |
|TCP Seq-Num. |32|1 |Up| 235 | LSB | MSB || X |
+================+==+==+==+========+========+===========++======+
Figure 1: Rule with Derivable Action
4.2. Type of Rules
The [RFC8724] defines the format of the Rule and its content. But it
does not specify the different types of Rules. This document
specifies two kinds of Rules for compressing the headers of a flow
packet. Based-Rule and Derived-Rule.
4.2.1. Based-Rule.
A Based-Rule is a Rule as described in section 7.1 of RFC8724. These
Rules are charged at run-time and contain the first values of the
flow headers. But it will have the action Derivable.
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4.2.2. Derived-Rule.
A Derived-Rule is a short-life updated copy of a Based-Rule. This
new Derived Rule has updated TV values of those fields that define
the flow as Sequence Number, Timestamp, and any other field
describing the flow. The compressor/decompressor will prioritize the
last Derived Rule to compress the packet. And when needed, it can
create another Derived Rule with new TV values or delete the oldest.
The Rule ID used to identify the Derived Rules is a complementary
number of the Based Rule, so if the Based Rule has a 1000 RuleID, the
Derived Rule will use 1001, ..., 1020,...
At the end of the flow transmission, SCHC must delete all the Derived
Rules.
5. IANA considerations
This document has no IANA actions.
6. Security considerations
This document does not add any security considerations and follows
the [RFC8724].
7. Normative References
[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>.
[RFC8724] Minaburo, A., Toutain, L., Gomez, C., Barthel, D., and JC.
Zuniga, "SCHC: Generic Framework for Static Context Header
Compression and Fragmentation", RFC 8724,
DOI 10.17487/RFC8724, April 2020,
<https://www.rfc-editor.org/info/rfc8724>.
[RFC8824] Minaburo, A., Toutain, L., and R. Andreasen, "Static
Context Header Compression (SCHC) for the Constrained
Application Protocol (CoAP)", RFC 8824,
DOI 10.17487/RFC8824, June 2021,
<https://www.rfc-editor.org/info/rfc8824>.
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Appendix A. Appendix A
To Do, examples.
Appendix B. Acknowledgements
The authors would like to thank (in alphabetic order): ToDo
Authors' Addresses
Laurent Toutain
Institut MINES TELECOM; IMT-Atlantique
2 rue de la Chataigneraie
35576 Cesson-Sevigne Cedex
France
Email: Laurent.Toutain@imt-atlantique.fr
Ana Minaburo
Consultant
Rue de Rennes
35510 Cesson-Sevigne Cedex
France
Email: anaminaburo@gmail.com
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