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