Internet DRAFT - draft-schinazi-masque-connect-udp-ecn
draft-schinazi-masque-connect-udp-ecn
MASQUE D. Schinazi
Internet-Draft Google LLC
Intended status: Standards Track 28 March 2022
Expires: 29 September 2022
An ECN Extension to CONNECT-UDP
draft-schinazi-masque-connect-udp-ecn-02
Abstract
CONNECT-UDP allows proxying UDP packets over HTTP. This document
describes an extension to CONNECT-UDP that allows conveying ECN
information on proxied UDP packets.
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.
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This Internet-Draft will expire on 29 September 2022.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions and Definitions . . . . . . . . . . . . . . . 2
2. Context Identifiers . . . . . . . . . . . . . . . . . . . . . 2
3. ECN Header Definition . . . . . . . . . . . . . . . . . . . . 3
4. Encoding of ECN bits . . . . . . . . . . . . . . . . . . . . 3
5. A Note about Future Extensions . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Normative References . . . . . . . . . . . . . . . . . . . . 5
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
CONNECT-UDP [CONNECT-UDP] allows proxying UDP packets over HTTP.
This document describes an extension to CONNECT-UDP that allows
conveying ECN [ECN] information on proxied UDP packets.
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.
2. Context Identifiers
The "Context Identifiers" section of [CONNECT-UDP] defines the
concept of context IDs and how they can be used to extend CONNECT-
UDP. When a client wishes to use ECN with CONNECT-UDP, it generates
an unique client-allocated context ID. In this document, we'll refer
to that context ID as the "chosen context ID". Note that, by
definition of client-allocated context IDs, the chosen context ID
will always be a non-zero even number. We also add the restriction
that the chosen context ID MUST be strictly less than 10^15. If the
client has run out of available context ID values that match this
requirement for this CONNECT-UDP request, it MUST NOT use the ECN
extension with this CONNECT-UDP request.
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3. ECN Header Definition
The "ECN" header field is an Item Structured Field, see Section 3.3
of [STRUCT-FIELD]; its value MUST be a Integer; any other value type
MUST be handled as if the field were not present by recipients (for
example, if this field is included multiple times, its type will
become a List and the field will therefore be ignored). This
document does not define any parameters for the "ECN" header field
value, but future documents might define parameters. Receivers MUST
ignore unknown parameters.
When present, the "ECN" header indicates that the sender supports
this extension, and communicates the chosen context ID as the "ECN"
field value.
For example, if the client chosen context ID is 42, it would send the
following:
ECN: 42; foo=bar
Figure 1: Example Client ECN Field
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. When indicating support for this extension, the proxy send
the client's chosen context ID as the "ECN" field value.
For example, the proxy could reply with:
ECN: 42
Figure 2: Example Proxy ECN Field
4. Encoding of ECN bits
When an HTTP Datagram [HTTP-DGRAM] associated with a CONNECT-UDP
stream uses the chosen context ID as its context ID, its "Payload"
field contains the following format (using the notation from the
"Notational Conventions" section of [QUIC]):
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CONNECT-UDP Payload with ECN {
Must be Zero (6),
ECN Bits (2),
UDP Payload (..),
}
Figure 3: CONNECT-UDP Payload with ECN
Must be Zero: 6 bits that MUST be sent as zero. Receivers MUST
validate that these bits are zero and MUST silently drop the HTTP
Datagram if they have any other value. Extensions to this
mechanism MAY relax this requirement.
ECN Bits: The ECN bits, sent in the same order as they appear in the
IP header.
UDP Payload: The UDP Payload, as defined in the "HTTP Datagram
Payload Format" section of [CONNECT-UDP].
When the proxy receives a datagram with the chosen context ID, it
sets the IP packet's ECN bits accordingly on the UDP packet it sends
to the target. Similarly, in the other direction the ECN Bits field
represents which ECN bits were seen on the UDP packets received from
the target.
5. A Note about Future Extensions
This CONNECT-UDP extension uses an HTTP field to register its chosen
context ID. Future extensions to CONNECT-UDP can use the same
strategy to register their chosen context ID(s) via another HTTP
field. This strategy is best for CONNECT-UDP extensions that only
need to register context IDs during the HTTP request and response.
Some extensions may need to register context IDs after the request
and response have been exchanged, for example an extension that
wishes to compress QUIC connection IDs [QUIC] is not aware of all
connection IDs at request time. In such cases, extensions can use
new Capsule Types (see [HTTP-DGRAM]) to perform context ID
registration.
6. Security Considerations
This document does not have additional security considerations beyond
those defined in [CONNECT-UDP].
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7. IANA Considerations
This document will request IANA to register the following entry in
the "HTTP Field Name" registry:
Field Name: ECN
Template: None
Status: provisional (permanent if this document is approved)
Reference: This document
Comments: None
8. Normative References
[CONNECT-UDP]
Schinazi, D., "UDP Proxying Support for HTTP", Work in
Progress, Internet-Draft, draft-ietf-masque-connect-udp-
08, 21 March 2022, <https://datatracker.ietf.org/doc/html/
draft-ietf-masque-connect-udp-08>.
[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/rfc/rfc3168>.
[HTTP-DGRAM]
Schinazi, D. and L. Pardue, "HTTP Datagrams and the
Capsule Protocol", Work in Progress, Internet-Draft,
draft-ietf-masque-h3-datagram-08, 28 March 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-masque-
h3-datagram-08>.
[QUIC] 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/rfc/rfc9000>.
[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/rfc/rfc2119>.
[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/rfc/rfc8174>.
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[STRUCT-FIELD]
Nottingham, M. and P-H. Kamp, "Structured Field Values for
HTTP", RFC 8941, DOI 10.17487/RFC8941, February 2021,
<https://www.rfc-editor.org/rfc/rfc8941>.
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
Mountain View, California 94043,
United States of America
Email: dschinazi.ietf@gmail.com
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