Low Latency DOCSIS - Technology Overview

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Last updated 2019-07-29 (latest revision 2019-03-11)
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Transport Area Working Group                                    G. White
Internet-Draft                                             K. Sundaresan
Intended status: Informational                                B. Briscoe
Expires: September 12, 2019                                    CableLabs
                                                          March 11, 2019

                Low Latency DOCSIS - Technology Overview


   NOTE: This document is a reformatted version of [LLD-white-paper].

   The evolution of the bandwidth capabilities - from kilobits per
   second to gigabits - across generations of DOCSIS cable broadband
   technology has paved the way for the applications that today form our
   digital lives.  Along with increased bandwidth, or "speed", the
   latency performance of DOCSIS technology has also improved in recent
   years.  Although it often gets less attention, latency performance
   contributes as much or more to the broadband experience and the
   feasibility of future applications as does speed.

   Low Latency DOCSIS technology (LLD) is a specification developed by
   CableLabs in collaboration with DOCSIS vendors and cable operators
   that tackles the two main causes of latency in the network: queuing
   delay and media acquisition delay.  LLD introduces an approach
   wherein data traffic from applications that aren't causing latency
   can take a different logical path through the DOCSIS network without
   getting hung up behind data from applications that are causing
   latency, as is the case in today's Internet architectures.  This
   mechanism doesn't interfere with the way applications share the total
   bandwidth of the connection, and it doesn't reduce one application's
   latency at the expense of others.  In addition, LLD improves the
   DOCSIS upstream media acquisition delay with a faster request-grant
   loop and a new proactive scheduling mechanism.  LLD makes the
   internet experience better for latency sensitive applications without
   any negative impact on other applications.

   The latest generation of DOCSIS equipment that has been deployed in
   the field - DOCSIS 3.1 - experiences typical latency performance of
   around 10 milliseconds (ms) on the Access Network link.  However,
   under heavy load, the link can experience delay spikes of 100 ms or
   more.  LLD systems can deliver a consistent 1 ms delay on the DOCSIS
   network for traffic that isn't causing latency, imperceptible for
   nearly all applications.  The experience will be more consistent with
   much smaller delay variation.

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   LLD can be deployed by field-upgrading DOCSIS 3.1 cable modem and
   cable modem termination system devices with new software.  The
   technology includes tools that enable automatic provisioning of these
   new services, and it also introduces new tools to report statistics
   of latency performance to the operator.

   Cable operators, DOCSIS equipment manufacturers, and application
   providers will all have to act in order to take advantage of LLD.
   This white paper explains the technology and describes the role that
   each of these parties plays in making LLD a reality.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on September 12, 2019.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
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