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Next Header Option in UDP Options
draft-daiya-tsvwg-udp-options-next-header-00

Document Type Active Internet-Draft (individual)
Authors Daiya Yuyama , Hirochika Asai
Last updated 2023-10-23
Replaces draft-daiya-tsvwg-udp-options-protocol-number
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draft-daiya-tsvwg-udp-options-next-header-00
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

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 25 April 2024.

Copyright Notice

   Copyright (c) 2023 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

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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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