## 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.

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

The solution produced by the working group,

- must not require looking inside an encryption envelope.
- need not be a congestion signal appropriate to be used as input to a congestion control algorithm.
- need not provide 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.

No work on APIs related to the use the "throughput advice" will 
be carried out in the working group.