The DOCSIS Queue Protection Algorithm to Preserve Low Latency
RFC 9957, “The DOCSIS Queue Protection Algorithm to Preserve Low Latency”, is an Informational document published in May 2026 by B. Briscoe, G. White. The canonical text is published by the RFC Editor.
Abstract
This Informational RFC explains the specification of the queue protection algorithm introduced into Data-Over-Cable Service Interface Specification (DOCSIS) technology at version 3.1. A shared low-latency queue relies on the non-queue-building behaviour of every traffic flow using it. However, some flows might not take such care, either accidentally or maliciously. If a queue is about to exceed a threshold level of delay, the Queue Protection algorithm can rapidly detect the flows most likely to be responsible. It can then prevent harm to other traffic in the low-latency queue by ejecting selected packets (or all packets) of these flows. This document is designed for four audiences: a) congestion control designers who need to understand how to keep on the "good" side of the algorithm; b) implementers of the algorithm who want to understand it in more depth; c) designers of algorithms with similar goals, perhaps for non-DOCSIS scenarios; and d) researchers interested in evaluating the algorithm.
What “Informational” means
Published for the general information of the community. It does not define an IETF standard and carries no standards-track status.
The canonical text of RFC 9957 is hosted at rfc-editor.org. Available in HTML,TXT,PDF,XML.
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