MASQUE extension for signaling throughput advice

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Table of Contents

1. Introduction

This document specifies an HTTP Capsule (RFC9297) that can be used with CONNECT-UDP (RFC9298), CONNECT-IP (RFC9484), or other future CONNECT extensions to signal throughput advice for traffic proxied through an HTTP server.¶

The extension can be used with the HTTP CONNECT method when the :protocol pseudo-header is equal to "connect-udp" or "connect-ip", as well as with future CONNECT protocols that use the Capsule Protocol.¶

2. 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.¶

3. Indicating Support for Throughput Advice Signaling

A client that wishes to receive throughput advice capsules can indicate support by sending a request header with the boolean-valued Item Structured Field: "Throughput-Advice: ?1". The HTTP proxy can indicate support by sending a response header with the same boolean-valued Item Structured Field: "Throughput-Advice: ?1". See Section 3.3.6 of [RFC8941] for information about the boolean format.¶

Once support has been established, a proxy MAY send THROUGHPUT_ADVICE capsules at any time during the lifetime of the stream that originated the request.¶

4. THROUGHPUT_ADVICE Capsule Type Format

The THROUGHPUT_ADVICE Capsule has the following format:¶

THROUGHPUT_ADVICE Capsule {
  Type (i) = 0xTBD,
  Length (i)
  Bitrate (i)
  [Average Window (i)]
}

The capsule has the following fields:¶

Bitrate: The maximum sustainable throughput that the client can expect for proxied traffic, expressed in kilobits per second.¶

Average Window: Indicates the duration over which the bitrate is enforced, expressed in milliseconds. This field is optional.¶

5. Applicability

If the sole purpose of the communication between a client endpoint and a network element is the exchange of throughput advice, it is RECOMMENDED to use more lightweight approaches than HTTP proxying, such as [SCONE] or [TRAIN].¶

However, in cases where clients connect to the Internet via MASQUE proxies and also want to receive throughput advice from the MASQUE proxy, it can be beneficial to communicate directly with the proxy using the already established communication channel.¶

6. Security Considerations

TODO Security¶

7. IANA Considerations

8. References

Acknowledgments

TODO acknowledge.¶

Authors' Addresses