RFC 9330 · INFORMATIONAL · 2023

Low Latency, Low Loss, and Scalable Throughput Internet Service: Architecture

Overview

RFC 9330, “Low Latency, Low Loss, and Scalable Throughput Internet Service: Architecture”, is an Informational document published in January 2023 by B. Briscoe, K. De Schepper, M. Bagnulo, G. White. The canonical text is published by the RFC Editor.

Abstract

This document describes the L4S architecture, which enables Internet applications to achieve low queuing latency, low congestion loss, and scalable throughput control. L4S is based on the insight that the root cause of queuing delay is in the capacity-seeking congestion controllers of senders, not in the queue itself. With the L4S architecture, all Internet applications could (but do not have to) transition away from congestion control algorithms that cause substantial queuing delay and instead adopt a new class of congestion controls that can seek capacity with very little queuing. These are aided by a modified form of Explicit Congestion Notification (ECN) from the network. With this new architecture, applications can have both low latency and high throughput.

The architecture primarily concerns incremental deployment. It defines mechanisms that allow the new class of L4S congestion controls to coexist with 'Classic' congestion controls in a shared network. The aim is for L4S latency and throughput to be usually much better (and rarely worse) while typically not impacting Classic performance.

Abstract as published in the RFC, via rfc-editor.org.

What “Informational” means

Published for the general information of the community. It does not define an IETF standard and carries no standards-track status.

Read this RFC

The canonical text of RFC 9330 is hosted at rfc-editor.org. Available in HTML,TXT,PDF,XML.

Other RFCs from 2023

Who Is Online

In total there are 61 users online: 0 registered, 56 guests and 5 bots.

Most users ever online was 1,226 on 13 Jun 2026, 3:56 am.

Bots: AhrefsBot Applebot Other Bot SemrushBot Sogou

Users active in the past 15 minutes. Total registered members: 354