## Background

Many applications are capable of adjusting their bit rate based on

network conditions and attempt to understand what bitrate is usable for

a given network UDP 4-tuple. Some networks use rate-limiters to

influence these applications. However, when networks enforce

rate-limiters, applications like video streaming or conferencing

struggle to adapt, leading to a suboptimal user experience.

## Goals

This WG aims to establish a mechanism for network elements capable of

rate-limiting a UDP 4-tuple to communicate an upper bound on achievable

bitrate termed "throughput advice" to the sender of packets matching

the UDP 4-tuple.


This mechanism will allow an application to receive notifications

containing throughput advice for both upstream and downstream traffic

from any network elements capable of dropping or delaying packets on the

path of a UDP 4-tuple.


The throughput advice serves as a guideline to enhance user experience

and represents the maximum bitrate manageable by a single network

element. It is not a strict indicator of network congestion. This

mechanism focuses on throughput advice intended for adaptive bitrate

applications and is not a replacement for congestion control algorithms

and mechanisms like BBR, ECN, and L4S.


This mechanism will allow network elements to update the throughput

advice as needed.


The working group will analyze the privacy and security implications of

the mechanism.


To achieve the goals listed above, the working group will

determine whether it is necessary for an endpoint to explicitly signal

its capability of receiving throughput advice, and whether it is

necessary for an endpoint to confirm its receipt of throughput advice.


The working group will initially focus on developing a solution for

QUIC.


## Non-Goals

This working group will not produce a solution that:


1. Looks inside a QUIC or TLS encryption envelope

2. Is appropriate for use as input to a congestion control algorithm

3. Provides information other than the throughput advice

## Program of Work

The WG is expected to:

1. Develop standard protocol to communicate an upper bound on

achievable bitrate — termed "throughput advice"— from network elements

to the endpoint.

2. Develop an Informational Applicability and Manageability

specification.


The WG will work collaboratively with the WEBTRANS, MOQ, AVTCORE, MOPS,

QUIC, TSVWG, and CCWG WGs as appropriate.


The WG will coordinate its work with owners of any APIs that use

the "throughput advice" to ensure that browser applications will be able to

use SCONE protocol effectively, but no work on APIs will be carried out in
the working group.