The DOCSIS Queue Protection Algorithm to Preserve Low Latency

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Publisher: IETF
Doc Type: Informational
Pages: 28
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.
Publication Date: 2026-05-01
Status Note: Informational
DOI: 10.17487/RFC9957
Link: https://doi.org/10.17487/RFC9957
Author(s): Bob Briscoe
Greg White
Keyword(s): Independent Submission Stream, ISE, Latency, Policing

Latest version of IETF RFC 9957

Document Versions — IETF RFC 9957

▶ IETF RFC 9957 (2026-05-01)

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Normative Reference(s)

Bibliographic Reference(s)

10.48550-arXiv.1904.07605 — ScalingCC EXTERNAL
IETF.draft-briscoe-iccrg-prague-congestion-control-04 — I-D.briscoe-iccrg-prague-congestion-control EXTERNAL
"SCReAM", commit 0208f59, 10 November 2025, <https://github.com/EricssonResearch/scream/blob/master/README.md>. EXTERNAL
"TCP BBR v3 Release", commit 90210de, 18 March 2025, <https://github.com/google/bbr/blob/v3/README.md>. EXTERNAL
White, G., Sundaresan, K., and B. Briscoe, "Low Latency DOCSIS: Technology Overview", CableLabs White Paper, February 2019, <https://cablela.bs/low-latency-docsis-technology-overview-february-2019>. EXTERNAL
IETF RFC 4303 [Active*]
IETF RFC 5681 [Active*]
IETF RFC 6789 [Active*]
IETF RFC 7713 [Active*]
IETF RFC 8257 [Active*]
IETF RFC 8298 [Active*]
IETF RFC 9330 [Active*]
IETF RFC 9332 [Active*]
IETF RFC 9438 [Active*]

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IETF RFC 9957, The DOCSIS Queue Protection Algorithm to Preserve Low Latency. Available at https://doi.org/10.17487/RFC9957

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<span class="citation"><cite>IETF RFC 9957</cite>, The DOCSIS Queue Protection Algorithm to Preserve Low Latency. Available at <a href="https://doi.org/10.17487/RFC9957" target="_blank" rel="noopener">https://doi.org/10.17487/RFC9957</a></span>

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IETF RFC 9957, The DOCSIS Queue Protection Algorithm to Preserve Low Latency
doi: 10.17487/RFC9957
url: https://doi.org/10.17487/RFC9957

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<cite id="bib-rfc9957">IETF RFC 9957</cite>, The DOCSIS Queue Protection Algorithm to Preserve Low Latency
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IETF RFC 9956 [Active*]