Internet DRAFT - draft-ietf-intarea-schc-protocol-numbers
draft-ietf-intarea-schc-protocol-numbers
INTAREA R. Moskowitz
Internet-Draft HTT Consulting
Intended status: Standards Track S. Card
Expires: 14 April 2024 A. Wiethuechter
AX Enterprize, LLC
P. Thubert
Cisco Systems
12 October 2023
Protocol Numbers for SCHC
draft-ietf-intarea-schc-protocol-numbers-01
Abstract
This document requests an Internet Protocol Number, an Ethertype, and
UDP port assignment for SCHC. The Internet Protocol Number request
is so that SCHC can be used for IP independent SCHC of other
transports such as UDP and ESP. The Ethertype is to support generic
use of native SCHC over any IEEE 802 technology for IP and non-IP
protocols. The UDP port request is to support End-to-End SCHC
through potentially blocking firewalls.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Basic use case for SCHC as an Internet Protocol Number . 3
1.2. Basic use case for SCHC as an Ethertype . . . . . . . . . 4
1.3. Basic use case for SCHC as a UDP port number . . . . . . 5
2. Terms and Definitions . . . . . . . . . . . . . . . . . . . . 5
2.1. Requirements Terminology . . . . . . . . . . . . . . . . 5
3. Internet Protocol Number for SCHC . . . . . . . . . . . . . . 5
4. Ethertype for SCHC . . . . . . . . . . . . . . . . . . . . . 6
5. UDP Port Number for SCHC . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6.1. IANA Internet Protocol Number Registry Update . . . . . . 6
6.2. IANA Ethertype Request . . . . . . . . . . . . . . . . . 6
6.3. IANA SCHC Ethertype Registry . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 7
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
The Static Context Header Compression (SCHC) Architecture
[schc-architecture] originally envisioned SCHC used at the Network
layer to enable IPv6 over selected Low-Power Wide Area Networking
(LPWAN) radio technologies, encompassing IP and Transport, by the
network provider. Then SCHC would be used by the application; this
would include any security envelope.
This approach brakes down when dealing with Diet ESP [diet-esp].
When Next Header is ESP, it is challenging for the ESP process to
determine if an incoming ESP payload is regular ESP [RFC4303] or a
diet ESP payload. Careful allocation of the incoming SPI
[ikev2-diet-esp] can mitigate this and have an implicit SCHC header,
but it is not sound protocol design. If the Next Header in the IP
header were SCHC, not ESP, a clear segregation of incoming traffic is
directly supportable.
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Additionally, SCHC can then be the Next Header within the ESP header
with 'regular' SCHC rules for processing this content. This approach
will greatly simplify [diet-esp].
DTLS 1.3 [RFC9147] adds further complications. DTLS 1.3 headers
themselves are typically already very compressed and SCHC would not
provide much value. But the UDP header in front of DTLS would
benefit of a separate compression from the IP Header compression.
Where it is possible with ESP's SPI to mitigate inbound packet
processing challenges implicit SCHC would generate, DTLS header does
not safely even provide this and a SCHC IP number is necessary to
separate traffic.
New IETF work has started with the SCHC WH that is chartered to:
| provide specifications for the application of SCHC over underlying
| layers, where underlying layers include but are not limited to UDP
| tunnels, IP, PPP, and Ethernet, as well as the use of SCHC by
| upper-layer protocols.
To achieve its charter, the SCHC working group needs the allocations
that are requested in this document.
These issues carry over to IP Header compression if SCHC were
available as an Ethertype (for 802 networking) and if SCHC were
available as a TCP/UDP port number (for firewall traversal
challenges). At each layer, SCHC solves a problem that protocol
designers, using constrained networks, currently have to design
around.
1.1. Basic use case for SCHC as an Internet Protocol Number
A mobile node, or network, may use different links over a period of
time. In some cases the node has the multiple interfaces and, in
theory, could tune the compression to each interface. In other
cases, it is the whole network that is mobile and individual nodes
have no "knowledge" of which link with what characteristics is
actively handling the traffic. In either case, the node
administrator is aware that some links are constrained and use of
SCHC compression is highly recommended.
One example is an UA that uses different links over the duration of
an operation (i.e. flight).
* Operation starts using Veriport's WiFi service.
* On gaining altitude, UA transitions to a Cellular service.
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* On gaining more altitude, UA transitions to a constrained 700MHz
UHF service.
* On approach to destination vertiport, link transition is reversed.
The UA could use SCHC compression only on the UHF link, but this may
complicate the implementation.
A more complex example is an Unmanned Cargo Aircraft that has
multiple avionics systems, all Ethernet connected to an onboard
router that has the multiple interfaces. Here the nodes each manage
their own secure path to their ground-based server, but have no
knowledge of which link is in use to intelligently use compression.
1.2. Basic use case for SCHC as an Ethertype
In the case of a classical LPWAN link such as LoRa [RFC9011], the use
of SCHC to compress the transported protocol, as well as the SCHC
session (called instance) to use, are implicit. The MAC-Layer
endpoints are preconfigured so there can be only one session, and
there can be only SCHC. When extended to Ethernet and more powerful
endpoint, this model is way too restrictive, and it is necessary to
signal both the use of SCHC and the SCHC session to be used. While
the SCHC WG is charterd to produce the latter, the Ethertype defined
in this document will be used to signal SCHC as the upper* layer
protocol.
As an example that will leverage this, Aircraft-to-anything (A2X)
[drip-a2x-adhoc-session] and Aircraft-to-Ground
[drip-efficient-a2g-comm] protocols are specific cases that can
benefit from SCHC as an Ethertype. These can use IEEE 802 wireless
technology and lessen spectrum contention in high traffic or long-
range situations by minimizing the datagram size via SCHC.
In the above uses, SCHC compresses the IPv6 header completely (all 40
bytes), leaving only destination address (32 bytes, source address
calcuated from content), or only 8 bytes (needs both addresses) at
the cost of the 1-byte SCHC RuleID. The 2-byte payload length may be
needed in some cases (as in Section 4).
Since the whole point of SCHC is to reduce payload size, SCHC
directly over an 802 technology cannot be addressed via the Ethernet
Protocol Assignment under the IANA OUI. A distinct Ethertype is
needed by SCHC to actually reduce payload overhead.
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1.3. Basic use case for SCHC as a UDP port number
TBD
2. Terms and Definitions
2.1. Requirements Terminology
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. Internet Protocol Number for SCHC
SCHC as the IP payload SHOULD be indicated in the IPv4 "Protocol"
field or the IPv6 "Next Header" field with a value of TBD1
(recommended: 145) as shown below:
+=========+=========+================+================+===========+
| Decimal | Keyword | Protocol | IPv6 Extension | Reference |
| | | | Header | |
+=========+=========+================+================+===========+
| TBD1 | SCHC | Static Context | | This RFC |
| (145) | | Header | | |
| | | Compression | | |
+---------+---------+----------------+----------------+-----------+
Table 1: Internet Protocol Numbers
The SCHC compressed header with payload is shown below. The size of
the SCHC RuleID is variable as described in [RFC8724]. An
implementation should have a table of source IP address and RuleID
size. The addresses should be represented in prefix format to allow
for groups of addresses having the same RuleID size.
|------- Compressed Header -------|
+---------------------------------+--------------------+
| RuleID | Compression Residue | Payload |
+---------------------------------+--------------------+
Figure 1: SCHC Packet
The RuleID may be statically configured per [RFC8724], or may be
negotiated within a protocol as in IKE [ikev2-diet-esp].
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4. Ethertype for SCHC
The use of SCHC as an Ethertype is similar to that as in Section 3,
above. Immediately after the SCHC Ethertype is the RuleID as in
Figure 1. If the rules for the RuleID does not provide the datagram
length, the datagram length MUST be explicit in the Compression
Residue, as the 802 header may not provide the needed length
information to properly process the datagram.
5. UDP Port Number for SCHC
TBD
6. IANA Considerations
6.1. IANA Internet Protocol Number Registry Update
This document requests IANA to make the following change to the
"Assigned Internet Protocol Numbers" [IANA-IPN] registry:
Internet Protocol Number:
This document defines the new Internet Protocol Number value TBD1
(suggested: 145) (Section 3) in the "Assigned Internet Protocol
Numbers" registry.
+=========+=========+================+================+===========+
| Decimal | Keyword | Protocol | IPv6 Extension | Reference |
| | | | Header | |
+=========+=========+================+================+===========+
| TBD1 | SCHC | Static Context | | This RFC |
| (145) | | Header | | |
| | | Compression | | |
+---------+---------+----------------+----------------+-----------+
Table 2
6.2. IANA Ethertype Request
IANA is requested using the process in Section 5.5 of
[intarea-rfc7042bis], to request the Ethertype for SCHC.
6.3. IANA SCHC Ethertype Registry
A registry of SCHC RuleIDs for SCHC as an Ethertype may be needed.
More discussion is needed to resolve this. For example, split a
1-byte RuleID in half. The top half of 1-14 assigned to different
domains of use, like for aviation. A value of 15 designates that a
2-byte RuleID is used.
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7. Security Considerations
TBD
8. References
8.1. 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>.
8.2. Informative References
[diet-esp] Migault, D., Guggemos, T., Bormann, C., and D. Schinazi,
"ESP Header Compression Profile", Work in Progress,
Internet-Draft, draft-mglt-ipsecme-diet-esp-10, 29 June
2023, <https://datatracker.ietf.org/doc/html/draft-mglt-
ipsecme-diet-esp-10>.
[drip-a2x-adhoc-session]
Moskowitz, R., Card, S. W., and A. Gurtov, "Aircraft to
Anything AdHoc Broadcasts and Session", Work in Progress,
Internet-Draft, draft-moskowitz-drip-a2x-adhoc-session-02,
23 July 2023, <https://datatracker.ietf.org/doc/html/
draft-moskowitz-drip-a2x-adhoc-session-02>.
[drip-efficient-a2g-comm]
Moskowitz, R., Card, S. W., and A. Gurtov, "Efficient Air-
Ground Communications", Work in Progress, Internet-Draft,
draft-moskowitz-drip-efficient-a2g-comm-01, 28 September
2023, <https://datatracker.ietf.org/doc/html/draft-
moskowitz-drip-efficient-a2g-comm-01>.
[IANA-IPN] IANA, "Assigned Internet Protocol Numbers",
<https://www.iana.org/assignments/protocol-numbers/
protocol-numbers.xhtml>.
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[ikev2-diet-esp]
Migault, D., Guggemos, T., and D. Schinazi, "Internet Key
Exchange version 2 (IKEv2) extension for the ESP Header
Compression (EHC)", Work in Progress, Internet-Draft,
draft-mglt-ipsecme-ikev2-diet-esp-extension-03, 28 June
2023, <https://datatracker.ietf.org/doc/html/draft-mglt-
ipsecme-ikev2-diet-esp-extension-03>.
[intarea-rfc7042bis]
Eastlake, D. E., Abley, J., and Y. Li, "IANA
Considerations and IETF Protocol and Documentation Usage
for IEEE 802 Parameters", Work in Progress, Internet-
Draft, draft-ietf-intarea-rfc7042bis-10, 9 October 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-intarea-
rfc7042bis-10>.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, DOI 10.17487/RFC4303, December 2005,
<https://www.rfc-editor.org/info/rfc4303>.
[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>.
[RFC9011] Gimenez, O., Ed. and I. Petrov, Ed., "Static Context
Header Compression and Fragmentation (SCHC) over LoRaWAN",
RFC 9011, DOI 10.17487/RFC9011, April 2021,
<https://www.rfc-editor.org/info/rfc9011>.
[RFC9147] Rescorla, E., Tschofenig, H., and N. Modadugu, "The
Datagram Transport Layer Security (DTLS) Protocol Version
1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022,
<https://www.rfc-editor.org/info/rfc9147>.
[schc-architecture]
Pelov, A., Thubert, P., and A. Minaburo, "Static Context
Header Compression (SCHC) Architecture", Work in Progress,
Internet-Draft, draft-ietf-schc-architecture-01, 6 October
2023, <https://datatracker.ietf.org/doc/html/draft-ietf-
schc-architecture-01>.
Acknowledgments
Discussions with Pascal Thubert, lpwan co-chair, helped develop this
approach of using SCHC E2E below the current Transport Layers.
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Authors' Addresses
Robert Moskowitz
HTT Consulting
Oak Park, MI 48237
United States of America
Email: rgm@labs.htt-consult.com
Stuart W. Card
AX Enterprize, LLC
4947 Commercial Drive
Yorkville, NY 13495
United States of America
Email: stu.card@axenterprize.com
Adam Wiethuechter
AX Enterprize, LLC
4947 Commercial Drive
Yorkville, NY 13495
United States of America
Email: adam.wiethuechter@axenterprize.com
Pascal Thubert
Cisco Systems, Inc
Emerald Square, Batiment C
rue Evariste Galois
06410 BIOT - Sophia Antipolis
France
Phone: +33 497 23 26 34
Email: pthubert@cisco.com
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