Internet DRAFT - draft-daiya-tsvwg-udp-options-protocol-number
draft-daiya-tsvwg-udp-options-protocol-number
Internet Engineering Task Force D. Yuyama
Internet-Draft Keio University / WIDE Project
Intended status: Standards Track H. Asai
Expires: 11 January 2024 Preferred Networks / WIDE Project
10 July 2023
Protocol Number Option in UDP Options
draft-daiya-tsvwg-udp-options-protocol-number-00
Abstract
This document defines the protocol number option in UDP options. The
protocol number option specifies the protocol immediately following
the UDP header.
Status of This Memo
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This Internet-Draft will expire on 11 January 2024.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
3. UDP-based Protocol Extensibility . . . . . . . . . . . . . . 3
3.1. Spread of applications using UDP-based transport
protocols . . . . . . . . . . . . . . . . . . . . . . . . 3
3.2. Concerns about limited UDP-based transport
extensibility . . . . . . . . . . . . . . . . . . . . . . 3
4. Protocol Number in UDP Options . . . . . . . . . . . . . . . 4
5. Option Format . . . . . . . . . . . . . . . . . . . . . . . . 4
6. Recommendation . . . . . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
8. Security Considerations . . . . . . . . . . . . . . . . . . . 4
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
9.1. Normative References . . . . . . . . . . . . . . . . . . 4
9.2. 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 that maps UDP to 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, using the difference
between the total length field in the IP header and the length field
in the UDP field. It allows options to be added in TLV(Type-Length-
Value) format.
This document describes the protocol number option, which allows
information about the protocol following the UDP header to be
provided in the UDP options area.
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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. UDP-based Protocol Extensibility
3.1. Spread of applications using UDP-based transport protocols
Frequently, new transport protocols are implemented based on UDP,
such as QUIC, and 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.
* DNS over Dedicated QUIC Connections [RFC9250] - uses UDP port 853,
same as DNS over DTLS.
3.2. 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.
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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.
4. Protocol Number in UDP Options
The protocol number is a number to identify the protocol immediately
following the UDP header. In many cases, the port number of the
transport layer is available for this number, but a new protocol
number is needed for protocols that do not have a port number, such
as QUIC.
5. Option Format
The UDP option is provided in the form of a TLV. The protocol number
is represented by 16 bits. It is shown in Figure 1.
+---------+---------+---------+---------+
| Kind=10 | Len=4 | Next Header Num |
+---------+---------+---------+---------+
1 byte 1 byte 2 bytes
Figure 1: Option format
6. Recommendation
TBD
7. IANA Considerations
On publication, request IANA to create a new registry for protocol
numbers. The details of the number will be described in a later
revision. Also, request IANA to assign one number from the Safe
Options range of the UDP Option Kind Number as Protocol Number
(PROTONUM).
8. Security Considerations
This document should not affect the security of the Internet.
9. References
9.1. 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>.
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[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-22,
9 June 2023, <https://datatracker.ietf.org/doc/html/draft-
ietf-tsvwg-udp-options-22>.
9.2. 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>.
[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>.
[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>.
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Acknowledgements
TBD
Authors' Addresses
Daiya Yuyama
Keio University / WIDE Project
Endo 5322
Fujisawa, Kanagawa
252-0882
Japan
Email: daiya@sfc.wide.ad.jp
Hirochika Asai
Preferred Networks / WIDE Project
1-6-1 Otemachi
Chiyoda, Tokyo
100-0004
Japan
Email: panda@wide.ad.jp
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