]> Ericsson

marcus.ihlar@ericsson.com

Ericsson

mirja.kuehlewind@ericsson.com

Web and Internet Transport Standard Communication with Network Elements media bitrate This document specifies a new Capsule (RFC9297) that can be used with CONNECT-UDP (RFC9298), CONNECT-IP (RFC9484), or other future CONNECT extensions to signal throughput advice for traffic that is proxied through an HTTP server. About This Document Status information for this document may be found at . Discussion of this document takes place on the Standard Communication with Network Elements Working Group mailing list (), which is archived at . Subscribe at . Source for this draft and an issue tracker can be found at .

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.

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 when, and only when, they appear in all capitals, as shown here.

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 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.

THROUGHPUT_ADVICE Capsule Type Format The THROUGHPUT_ADVICE Capsule has the following format: The capsule has the following fields: Rate Limit: 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.

Applicability A proxy that intends to rate limit proxied traffic can notify clients using the THROUGHPUT_ADVICE capsule. Reasons for rate limiting traffic through a proxy include enforcement of access network policies, proxy resource management and proxy service differentiation. 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 .

Security Considerations TODO Security

IANA Considerations

Capsule types This document adds following entries to the "HTTP Capsule Types" registry: New Capsule Type to register

Capsule Type	Value	Specification
THROUGHPUT_ADVICE	TBD	(This document)

HTTP headers This document adds following entry to the "Hypertext Transfer Protocol (HTTP) Field Name Registry": HTTP Field Name to register

Field Name	Template	Status	Reference	Comments
Throughput-Advice		permanent	(This document)

References Normative References In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. This document describes a set of data types and associated algorithms that are intended to make it easier and safer to define and handle HTTP header and trailer fields, known as "Structured Fields", "Structured Headers", or "Structured Trailers". It is intended for use by specifications of new HTTP fields that wish to use a common syntax that is more restrictive than traditional HTTP field values. Informative References Mozilla Private Octopus Inc. Fastly Meta Ericsson On-path network elements can sometimes be configured to apply rate limits to flows that pass them. This document describes a method for signaling to endpoints that rate limiting policies are in force and what that rate limit is.

Acknowledgments TODO acknowledge.