A Queuing Mechanism with Multiple Cyclic Buffers
draft-dang-queuing-with-multiple-cyclic-buffers-00

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Network Working Group                                             B. Liu
Internet-Draft                                              J. Dang, Ed.
Intended status: Standards Track                                  Huawei
Expires: August 26, 2021                               February 22, 2021

            A Queuing Mechanism with Multiple Cyclic Buffers
           draft-dang-queuing-with-multiple-cyclic-buffers-00

Abstract

   This document presents a queuing mechanism with multiple cyclic
   buffers.

Status of This Memo

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   This Internet-Draft will expire on August 26, 2021.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   2
   3.  Terminology & Abbreviations . . . . . . . . . . . . . . . . .   2
   4.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   2
   5.  Queuing with Multiple Cyclic Buffers  . . . . . . . . . . . .   3
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   Network forwarding with bounded latency and zero congestion loss is
   important for various industrial applications.  The DetNet working
   group draft "DetNet Bounded
   Latency"[draft-ietf-detnet-bounded-latency] describes requirements
   for queuing mechanisms.  Among the referenced queuing mechanisms,
   Cyclic Queuing and Forwarding (CQF) requires no per-flow dynamic
   state at core nodes, which is scalable when the number of flows
   grows.  To cope with long link delay, more than two cyclic buffers
   can be used.

   This document discusses the details of the cyclic queuing mechanisms.
   We propose a queuing model and mechanism with multiple cyclic
   buffers, which can improve bandwidth utilization without sacrificing
   latency and jitter.

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119.

3.  Terminology & Abbreviations

   CQF: Cyclic Queuing and Forwarding

   T_c: the length of a cycle

4.  Problem Statement

   IEEE 802.1Q[IEEE8021TSN] defines CQF.  As described in "DetNet
   Bounded Latency"[draft-ietf-detnet-bounded-latency], CQF with two
   synchronized buffers works as follows.  All nodes keep a same cycle
   starting time.  In a cycle x, Node A sends all packets in a buffer to

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Internet-Draft                                             February 2021

   Node B.  In the same cycle x, Node B uses a buffer to accumulate all
   packets from A, and at the same time sends out the packets that have
   already been buffered in cycle x-1.  In the next cycle x+1, Node B
   sends out all the packets that are received from Node A in cycle x.
   If a packet traverses h hops, the maximum latency is (h+1)T_c, and
   the minimum latency is (h-1)T_c.  The jitter (latency variation)
   bound is 2T_c.

                            |  cycle x  | cycle x+1 |
                     Node A +-----------+-----------+
                               \
                                \packet