Max Allocation with Reservation Bandwidth Constraints Model for Diffserv-aware MPLS Traffic Engineering & Performance Comparisons
RFC 4126

Document Type RFC - Experimental (June 2005; No errata)
Last updated 2015-10-14
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Network Working Group                                             J. Ash
Request for Comments: 4126                                          AT&T
Category: Experimental                                         June 2005

    Max Allocation with Reservation Bandwidth Constraints Model for
   Diffserv-aware MPLS Traffic Engineering & Performance Comparisons

Status of This Memo

   This memo defines an Experimental Protocol for the Internet
   community.  It does not specify an Internet standard of any kind.
   Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This document complements the Diffserv-aware MPLS Traffic Engineering
   (DS-TE) requirements document by giving a functional specification
   for the Maximum Allocation with Reservation (MAR) Bandwidth
   Constraints Model.  Assumptions, applicability, and examples of the
   operation of the MAR Bandwidth Constraints Model are presented.  MAR
   performance is analyzed relative to the criteria for selecting a
   Bandwidth Constraints Model, in order to provide guidance to user
   implementation of the model in their networks.

Table of Contents

   1. Introduction ....................................................2
      1.1. Specification of Requirements ..............................3
   2. Definitions .....................................................3
   3. Assumptions & Applicability .....................................5
   4. Functional Specification of the MAR Bandwidth
      Constraints Model ...............................................6
   5. Setting Bandwidth Constraints ...................................7
   6. Example of MAR Operation ........................................8
   7. Summary .........................................................9
   8. Security Considerations ........................................10
   9. IANA Considerations ............................................10
   10. Acknowledgements ..............................................10
   A. MAR Operation & Performance Analysis  ..........................11
   B. Bandwidth Prediction for Path Computation ......................19
   Normative References ..............................................20
   Informative References ............................................20

Ash                           Experimental                      [Page 1]
RFC 4126       MAR Bandwidth Constraints Model for DS-TE       June 2005

1.  Introduction

   Diffserv-aware MPLS traffic engineering (DS-TE) requirements and
   protocol extensions are specified in [DSTE-REQ, DSTE-PROTO].  A
   requirement for DS-TE implementation is the specification of
   Bandwidth Constraints Models for use with DS-TE.  The Bandwidth
   Constraints Model provides the 'rules' to support the allocation of
   bandwidth to individual class types (CTs).  CTs are groupings of
   service classes in the DS-TE model, which are provided separate
   bandwidth allocations, priorities, and QoS objectives.  Several CTs
   can share a common bandwidth pool on an integrated, multiservice
   MPLS/Diffserv network.

   This document is intended to complement the DS-TE requirements
   document [DSTE-REQ] by giving a functional specification for the
   Maximum Allocation with Reservation (MAR) Bandwidth Constraints
   Model.  Examples of the operation of the MAR Bandwidth Constraints
   Model are presented.  MAR performance is analyzed relative to the
   criteria for selecting a Bandwidth Constraints Model, in order to
   provide guidance to user implementation of the model in their
   networks.

   Two other Bandwidth Constraints Models are being specified for use in
   DS-TE:

   1. Maximum Allocation Model (MAM) [MAM] - the maximum allowable
      bandwidth usage of each CT is explicitly specified.

   2. Russian Doll Model (RDM) [RDM] - the maximum allowable bandwidth
      usage is done cumulatively by grouping successive CTs according to
      priority classes.

   MAR is similar to MAM in that a maximum bandwidth allocation is given
   to each CT.  However, through the use of bandwidth reservation and
   protection mechanisms, CTs are allowed to exceed their bandwidth
   allocations under conditions of no congestion but revert to their
   allocated bandwidths when overload and congestion occurs.

   All Bandwidth Constraints Models should meet these objectives:

   1. applies equally when preemption is either enabled or disabled
      (when preemption is disabled, the model still works 'reasonably'
      well),

   2. bandwidth efficiency, i.e., good bandwidth sharing among CTs under
      both normal and overload conditions,

Ash                           Experimental                      [Page 2]
RFC 4126       MAR Bandwidth Constraints Model for DS-TE       June 2005

   3. bandwidth isolation, i.e., a CT cannot hog the bandwidth of
      another CT under overload conditions,
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