Internet DRAFT - draft-daiya-tsvwg-udp-options-next-header
draft-daiya-tsvwg-udp-options-next-header
Internet Engineering Task Force D. Yuyama
Internet-Draft Keio University / WIDE Project
Intended status: Standards Track H. Asai
Expires: 25 April 2024 Preferred Networks / WIDE Project
23 October 2023
Next Header Option in UDP Options
draft-daiya-tsvwg-udp-options-next-header-00
Abstract
This document defines the next header option in UDP options. The
next header option specifies the protocol immediately following the
UDP header.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 25 April 2024.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
3. Transport Protocols based on UDP . . . . . . . . . . . . . . 3
4. UDP-based Protocols Extensibility . . . . . . . . . . . . . . 3
4.1. Spread of applications using UDP-based transport
protocols . . . . . . . . . . . . . . . . . . . . . . . . 3
4.2. Concerns about limited UDP-based transport
extensibility . . . . . . . . . . . . . . . . . . . . . . 4
5. Value of Next Header Option . . . . . . . . . . . . . . . . . 4
6. Option Format . . . . . . . . . . . . . . . . . . . . . . . . 4
7. Recommendation . . . . . . . . . . . . . . . . . . . . . . . 4
7.1. Next Header Options is for Transport Ends . . . . . . . . 5
7.2. TBD . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
9. Security Considerations . . . . . . . . . . . . . . . . . . . 5
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
10.1. Normative References . . . . . . . . . . . . . . . . . . 5
10.2. Informative References . . . . . . . . . . . . . . . . . 5
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
The User Datagram Protocol [RFC0768] provides only a port number and
a checksum as a minimum functional transport protocol. Because of
its simplicity and interoperability in the Internet, new transport
protocols such as QUIC [RFC9000] and SCTP [RFC6951] are implemented
over UDP. However, UDP has no field in the header that identifies
the encapsulated protocol. Typically, the IANA port number
[IANA_service_names_port_numbers] is used for that purpose, but the
port number corresponds to the service of the communication. We
argue that it is a clear misuse of the port number to indicate the
protocol on UDP. Currently, it is not possible to provide the UDP
layer with information about the transport protocols implemented on
top of UDP.
Transport Options for UDP [I-D.ietf-tsvwg-udp-options] is a proposal
for extending UDP to have an options area. This creates an options
area behind the UDP payload to allow TLV(Type-Length-Value) format
options to be added.
This document describes the next header option. This option allows
information about the protocol following the UDP header. This option
is provided as one of the UDP options.
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2. Conventions used in this document
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. Transport Protocols based on UDP
Using new IP-based transport protocols on the Internet is difficult
bacause of ossified middle boxes. Therefore, in order to maintain
affinity with the Internet, it is often used to encapsulate the
transport protocol with UDP. The following are transport protocols
used for UDP-based.
Registered in IP Protocol Numbers
* DCCP [RFC6773] - DCCP-UDP: A Datagram Congestion Control Protocol
UDP Encapsulation for NAT Traversal
* SCTP [RFC6951] - UDP Encapsulation of Stream Control Transmission
Protocol (SCTP) Packets for End-Host to End-Host Communication
Not registered in IP Protocol Numbers
* QUIC [RFC9000] - QUIC: A UDP-Based Multiplexed and Secure
Transport
4. UDP-based Protocols Extensibility
4.1. Spread of applications using UDP-based transport protocols
Transport protocols implemented based on UDP such as QUIC often are
used as transport protocols for existing applications.
The following are examples of applications that operate using UDP-
based transport protocols.
HTTP
* HTTP/3 [RFC9114] - HTTP over QUIC, uses UDP port 443.
DNS
* DNS over Datagram Transport Layer Security [RFC8094] - uses UDP
port 853.
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* DNS over Dedicated QUIC Connections [RFC9250] - uses UDP port 853,
same as DNS over DTLS.
4.2. Concerns about limited UDP-based transport extensibility
The UDP header does not have any information to identify the
encapsulated protocol. Without this information, problems may arise
when there are applications that can communicate with multiple
transport protocols using the same port number. In the case of
client-server communication, the server cannot instantly determine
which transport protocol was used to send the packet sent by the
client.
For instance, when a new transport protocol other than QUIC is
developed and used that is based on UDP and works as a transport for
HTTP, the server will not be able to instantly identify whether QUIC
is used as the transport protocol or the new one is used.
Therefore, if the next protocol after the UDP header is a transport
protocol, it should be possible to have a field in the UDP layer
information that identifies the protocol that follows the UDP header.
5. Value of Next Header Option
The next header option is a number to identify the protocol
immediately following the UDP header. This number used be the same
as IP Protocol Numbers[IANA_protocol_numbers] In many cases, the
protocol number is available, but a new protocol number is needed for
protocols that do not have a protocol number, such as QUIC.
6. Option Format
The UDP option is provided in the form of a TLV. The value of next
header option is represented by 8 bits. It is shown in Figure 1.
+---------+---------+---------+---------+
| Kind=10 | Len=4 | Nxt Hdr | Padding |
+---------+---------+---------+---------+
1 byte 1 byte 1 byte 1 byte
Figure 1: Option format
7. Recommendation
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7.1. Next Header Options is for Transport Ends
The next header option is intended to be interpreted by transport
ends. As with the original UDP Options, not intended to be
interpreted in-transit.
7.2. TBD
TBD
8. IANA Considerations
On publication, request IANA to assign one number from the Safe
Options range of the UDP Option Kind Number as Next Header (NXTHDR).
9. Security Considerations
This document should not affect the security of the Internet.
10. References
10.1. Normative References
[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>.
[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>.
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
DOI 10.17487/RFC0768, August 1980,
<https://www.rfc-editor.org/info/rfc768>.
[I-D.ietf-tsvwg-udp-options]
Touch, J. D., "Transport Options for UDP", Work in
Progress, Internet-Draft, draft-ietf-tsvwg-udp-options-23,
15 September 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-tsvwg-udp-options-23>.
10.2. Informative References
[IANA_service_names_port_numbers]
IANA, "Service Name and Transport Protocol Port Number
Registry", <http://www.iana.org/assignments/service-names-
port-numbers>.
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[IANA_protocol_numbers]
IANA, "Protocol Numbers",
<http://www.iana.org/assignments/protocol-numbers>.
[RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", RFC 9000,
DOI 10.17487/RFC9000, May 2021,
<https://www.rfc-editor.org/info/rfc9000>.
[RFC6773] Phelan, T., Fairhurst, G., and C. Perkins, "DCCP-UDP: A
Datagram Congestion Control Protocol UDP Encapsulation for
NAT Traversal", RFC 6773, DOI 10.17487/RFC6773, November
2012, <https://www.rfc-editor.org/info/rfc6773>.
[RFC6951] Tuexen, M. and R. Stewart, "UDP Encapsulation of Stream
Control Transmission Protocol (SCTP) Packets for End-Host
to End-Host Communication", RFC 6951,
DOI 10.17487/RFC6951, May 2013,
<https://www.rfc-editor.org/info/rfc6951>.
[RFC9114] Bishop, M., Ed., "HTTP/3", RFC 9114, DOI 10.17487/RFC9114,
June 2022, <https://www.rfc-editor.org/info/rfc9114>.
[RFC8094] Reddy, T., Wing, D., and P. Patil, "DNS over Datagram
Transport Layer Security (DTLS)", RFC 8094,
DOI 10.17487/RFC8094, February 2017,
<https://www.rfc-editor.org/info/rfc8094>.
[RFC9250] Huitema, C., Dickinson, S., and A. Mankin, "DNS over
Dedicated QUIC Connections", RFC 9250,
DOI 10.17487/RFC9250, May 2022,
<https://www.rfc-editor.org/info/rfc9250>.
Acknowledgements
TBD
Authors' Addresses
Daiya Yuyama
Keio University / WIDE Project
5322 Endo
Fujisawa, Kanagawa
252-0882
Japan
Email: daiya@sfc.wide.ad.jp
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Hirochika Asai
Preferred Networks / WIDE Project
1-6-1 Otemachi
Chiyoda, Tokyo
100-0004
Japan
Email: panda@wide.ad.jp
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