]> Ericsson

marcus.ihlar@ericsson.com

Ericsson

mirja.kuehlewind@ericsson.com

Web and Internet Transport Multiplexed Application Substrate over QUIC Encryption 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 the available bitrate for media traffic that is proxied through an HTTP server. This information can be used by a media application to regulate its media bitrate in accordance with a network policy, as an alternative to in-network traffic shaping. About This Document Status information for this document may be found at . Discussion of this document takes place on the Multiplexed Application Substrate over QUIC Encryption 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 a new Capsule (RFC9297) that can be used with CONNECT-UDP (RFC9298), CONNECT-IP (RFC9484), or other future CONNECT extensions to signal the available bitrate for media traffic that is proxied through an HTTP server. This information can be used by a media application to regulate its media bitrate in accordance with a network policy, as an alternative to in-network traffic shaping. The extension can be used with the HTTP CONNECT method when the :protocol pseudo header is equal to "connect-udp" or "connect-ip" and 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 Media Bitrate Signaling A client who wishes to receive media bitrate capsules can indicate support by sending a request header with the boolean-valued Item Structured Field "Media-Bitrate: ?1". The HTTP proxy indicates support by sending a response header with the boolean-valued Item Structured Field "Media-Bitrate: ?1" See for information about the boolean format. Once support has been established, a proxy MAY send MEDIA_BITRATE capsules at any time during the lifetime of the stream that originated the request.

MEDIA_BITRATE Capsule Type Format The MEDIA_BITRATE Capsule has the following format: The capsule has the following fields: Media Bitrate: Indicates the average bitrate that is supported by the network without traffic shaping. Average Window: Indicates the duration over which the bitrate is enforced. The largest allowed burst is given by Media Bitrate * Average window. This field is optional.

Client Behaviour A client that receives media bitrate capsules needs to make the information available to a media application, this is implementation specific and out of scope for this document. A media application can use the information to select a media track that conforms with the specified bitrate. How this is done and whether an application client needs to explicitly coordinate with an application server is out of scope for this document.

Proxy Behaviour A proxy that sends media bitrate capsules needs to be tightly integrated with the access network infrastructure and policy framework. A proxy that sends media bitrate capsules does so as an alternative to traffic shaping, the policies that govern shaping behaviour can be used to determine the values sent with media bitrate capsules. A proxy might still apply shaping or policing to traffic that is breaching the policy in order to ensure that the bitrate policy is respected. In this case, it is RECOMMENDED that the proxy uses an averaging window that is sufficiently long to allow data transmission bursts that make full use of the available network capacity. A proxy can SHOULD the Average Window field in the media bitrate capsule to inform the client about how it enforces bitrates.

Performance Considerations This protocol is intended to provide policy indications to applications traversing a network. Using HTTP proxying for this purpose does add overhead in terms of CPU, memory and MTU. It is RECOMMENDED that this solution is used together with QUIC-Aware proxying whenever possible.

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
MEDIA-BITRATE	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
Media-Bitrate		permanent	(This document)

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. Apple Inc. Apple Inc. Google LLC This document extends UDP Proxying over HTTP to add optimizations for proxied QUIC connections. Specifically, it allows a proxy to reuse UDP 4-tuples for multiple proxied connections, and adds a mode of proxying in which QUIC short header packets can be forwarded and transformed through a HTTP/3 proxy rather than being fully re- encapsulated and re-encrypted.

Acknowledgments TODO acknowledge.