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Network Working Group                                        D. Schinazi
Internet-Draft                                                Google LLC
Intended status: Standards Track                          5 January 2021
Expires: 9 July 2021


                    An ECN Extension to CONNECT-UDP
                draft-schinazi-masque-connect-udp-ecn-01

Abstract

   The CONNECT-UDP method allows proxying UDP packets over HTTP.  This
   document describes an extension to CONNECT-UDP that allows conveying
   ECN information on proxied UDP packets.

   Discussion of this work is encouraged to happen on the MASQUE IETF
   mailing list (masque@ietf.org (mailto:masque@ietf.org)) or on the
   GitHub repository which contains the draft:
   https://github.com/DavidSchinazi/draft-connect-udp-ecn.

Discussion Venues

   This note is to be removed before publishing as an RFC.

   Source for this draft and an issue tracker can be found at
   https://github.com/DavidSchinazi/draft-connect-udp-ecn.

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 9 July 2021.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.



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   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 Simplified BSD License text
   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions and Definitions . . . . . . . . . . . . . . .   2
   2.  ECN Header Definition . . . . . . . . . . . . . . . . . . . .   3
   3.  Datagram Encoding of Proxied UDP Packets  . . . . . . . . . .   3
   4.  Stream Encoding of Proxied UDP Packets  . . . . . . . . . . .   4
   5.  HTTP Intermediaries . . . . . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
     7.1.  HTTP Header . . . . . . . . . . . . . . . . . . . . . . .   5
     7.2.  Flow Identifier Parameters  . . . . . . . . . . . . . . .   5
     7.3.  Stream Chunk Type Registration  . . . . . . . . . . . . .   5
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   The CONNECT-UDP [CONNECT-UDP] method allows proxying UDP packets over
   HTTP.  This document describes an extension to CONNECT-UDP that
   allows conveying ECN [ECN] information on proxied UDP packets.

   Discussion of this work is encouraged to happen on the MASQUE IETF
   mailing list (masque@ietf.org (mailto:masque@ietf.org)) or on the
   GitHub repository which contains the draft:
   https://github.com/DavidSchinazi/draft-connect-udp-ecn.

1.1.  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.







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2.  ECN Header Definition

   "ECN" is a Item Structured Header [STRUCT-HDR].  Its value MUST be a
   Boolean.  Its ABNF is:

     ECN = sf-boolean

   The "ECN" header indicates whether the sender supports this
   extension.  A value of 1 indicates support whereas a value of 0 (or
   the absence of the header) indicates lack of support.

   Clients MUST NOT indicate support for this extension unless they know
   that the protocol running over UDP that is being proxied supports
   ECN, and will react appropriately to Congestion Experienced (CE)
   markings.

   Proxies MUST NOT indicate support for this extension unless they know
   they have the ability to read and write the IP ECN bits on its
   target-bound UDP sockets.

   This extension is said to have been negotiated when both client and
   proxy indicated support for it in their CONNECT-UDP request and
   response.

3.  Datagram Encoding of Proxied UDP Packets

   If a client supports this extension and HTTP/3 datagrams [H3DGRAM],
   it can attempt to use datagrams for ECN information.  This is done by
   allocating four datagram flow identifiers (as opposed to one in
   traditional CONNECT-UDP) and communicating them to the proxy using
   named elements on the "Datagram-Flow-Id" header.  These names are
   "ecn-ect0", "ecn-ect1", and "ecn-ce".  For example:

     Datagram-Flow-Id = 42, 44; ecn-ect0, 46; ecn-ect1, 48; ecn-ce

   If the proxy wishes to support datagram encoding of this extension,
   it echoes those named elements in its CONNECT-UDP response.  The
   unnamed element now represents Not-ECT, whereas the one in "ecn-ect0"
   represents ECT(0), "ecn-ect1" represents ECT(1) and "ecn-ce"
   represents CE; see Section 5 of [ECN] for the definition of these IP
   header fields.

   When the proxy receives a datagram from the given flow identifier, it
   sets the IP packet's ECN bits accordingly on the UDP packet it sends
   to the target.  Similarly, in the other direction the flow identifier
   represents which ECN bits were seen on the UDP packets received from
   the target.




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4.  Stream Encoding of Proxied UDP Packets

   If HTTP/3 datagrams are not supported, the stream is used to convey
   UDP payloads, and the CONNECT-UDP Stream Chunk Type is used to
   indicate the values of the ECN bits, as defined below:

     +-------+-----------------+-----------+
     | Value |      Type       | ECN Field |
     +-------+-----------------+-----------+
     | 0x00  | UDP_PACKET      |  Not-ECT  |
     +-------+-----------------+-----------+
     | 0x31  | UDP_PACKET_ECT0 |  ECT(0)   |
     +-------+-----------------+-----------+
     | 0x32  | UDP_PACKET_ECT1 |  ECT(1)   |
     +-------+-----------------+-----------+
     | 0x33  | UDP_PACKET_CE   |  CE       |
     +-------+-----------------+-----------+

   The proxy then uses the the CONNECT-UDP Stream Chunk Type on received
   UDP payloads to set the ECN bits on the IP packets it sends to the
   target, and in the reverse direction to indicate which ECN bits
   received from the target.

5.  HTTP Intermediaries

   HTTP/3 DATAGRAM flow identifiers are specific to a given HTTP/3
   connection.  However, in some cases, an HTTP request may travel
   across multiple HTTP connections if there are HTTP intermediaries
   involved; see Section 2.3 of [RFC7230].

   Intermediaries that support this extension and HTTP/3 datagrams MUST
   negotiate all four flow identifiers separately on the client-facing
   and server-facing connections.  This is accomplished by having the
   intermediary parse the unnamed element and the "ecn-ect0", "ecn-
   ect1", and "ecn-ce" named elements in the "Datagram-Flow-Id" header
   on all CONNECT-UDP requests it receives, and sending the same four
   flow identifiers in the "Datagram-Flow-Id" header on the response.

   Intermediaries MUST NOT send the "ECN" header with a value of 1 to
   the client on its response unless it has received that same value in
   the response it received from the server.

6.  Security Considerations

   This document does not have additional security considerations beyond
   those defined in [CONNECT-UDP].





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7.  IANA Considerations

7.1.  HTTP Header

   This document will request IANA to register the "ECN" header in the
   "Permanent Message Header Field Names" registry maintained at
   <https://www.iana.org/assignments/message-headers>.

     +-------------------+----------+--------+---------------+
     | Header Field Name | Protocol | Status |   Reference   |
     +-------------------+----------+--------+---------------+
     |        ECN        |   http   |  std   | This document |
     +-------------------+----------+--------+---------------+

7.2.  Flow Identifier Parameters

   This document will request IANA to register the "ecn-ect0", "ecn-
   ect1", and "ecn-ce" flow identifier parameters in the "HTTP Datagram
   Flow Identifier Parameters" registry (see [H3DGRAM]):

     +----------+-------------------------+---------+---------------+
     |   Key    |       Description       | Is Name |   Reference   |
     +----------+-------------------------+---------+---------------+
     | ecn-ect0 | UDP payload with ECT(0) |   Yes   | This document |
     +----------+-------------------------+---------+---------------+
     | ecn-ect1 | UDP payload with ECT(1) |   Yes   | This document |
     +----------+-------------------------+---------+---------------+
     | ecn-ce   | UDP payload with CE     |   Yes   | This document |
     +----------+-------------------------+---------+---------------+

7.3.  Stream Chunk Type Registration

   This document will request IANA to register the following entry in
   the "CONNECT-UDP Stream Chunk Type" registry [CONNECT-UDP]:

   +-------+-----------------+-------------------------+---------------+
   | Value |      Type       |       Description       |   Reference   |
   +-------+-----------------+-------------------------+---------------+
   | 0x31  | UDP_PACKET_ECT0 | UDP payload with ECT(0) | This document |
   +-------+-----------------+-------------------------+---------------+
   | 0x32  | UDP_PACKET_ECT1 | UDP payload with ECT(1) | This document |
   +-------+-----------------+-------------------------+---------------+
   | 0x33  | UDP_PACKET_CE   | UDP payload with CE     | This document |
   +-------+-----------------+-------------------------+---------------+

8.  Normative References





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   [CONNECT-UDP]
              Schinazi, D., "The CONNECT-UDP HTTP Method", Work in
              Progress, Internet-Draft, draft-ietf-masque-connect-udp-
              02, 30 December 2020, <http://www.ietf.org/internet-
              drafts/draft-ietf-masque-connect-udp-02.txt>.

   [ECN]      Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
              of Explicit Congestion Notification (ECN) to IP",
              RFC 3168, DOI 10.17487/RFC3168, September 2001,
              <https://www.rfc-editor.org/info/rfc3168>.

   [H3DGRAM]  Schinazi, D., "Using QUIC Datagrams with HTTP/3", Work in
              Progress, Internet-Draft, draft-schinazi-quic-h3-datagram-
              05, 12 October 2020, <http://www.ietf.org/internet-drafts/
              draft-schinazi-quic-h3-datagram-05.txt>.

   [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>.

   [RFC7230]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Message Syntax and Routing",
              RFC 7230, DOI 10.17487/RFC7230, June 2014,
              <https://www.rfc-editor.org/info/rfc7230>.

   [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>.

   [STRUCT-HDR]
              Nottingham, M. and P. Kamp, "Structured Field Values for
              HTTP", Work in Progress, Internet-Draft, draft-ietf-
              httpbis-header-structure-19, 3 June 2020,
              <http://www.ietf.org/internet-drafts/draft-ietf-httpbis-
              header-structure-19.txt>.

Acknowledgments

   This proposal was inspired directly or indirectly by prior work from
   many people.  The author would like to thank contributors the MASQUE
   working group.

Author's Address

   David Schinazi
   Google LLC
   1600 Amphitheatre Parkway



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   Mountain View, California 94043,
   United States of America

   Email: dschinazi.ietf@gmail.com















































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