Technical Committee
`
`Traffic Management Specification
`
`Version 4.0
`
`af-tm-0056.000
`
`April 1996
`
`GUEST TEK EXHIBIT 1016
`Guest Tek v. Nomadix, IPR2019-00211
`
`

`

`af-tm-0056.000 Traffic Management Specification Version 4.0
`
`ª 1996 The ATM Forum. All Rights Reserved. No part of this publication may be
`reproduced in any form or by any means.
`
`The information in this publication is believed to be accurate as of its publication date.
`Such information is subject to change without notice and the ATM Forum is not
`responsible for any errors. The ATM Forum does not assume any responsibility to update
`or correct any information in this publication. Notwithstanding anything to the contrary,
`neither The ATM Forum nor the publisher make any representation or warranty,
`expressed or implied, concerning the completeness, accuracy, or applicability of any
`information contained in this publication. No liability of any kind shall be assumed by
`The ATM Forum or the publisher as a result of reliance upon any information contained
`in this publication.
`
`The receipt or any use of this document or its contents does not in any way create by
`implication or otherwise:
`
`• Any express or implied license or right to or under any ATM Forum member
`company’s patent, copyright, trademark or trade secret rights which are or may be
`associated with the ideas, techniques, concepts or expressions contained herein; nor
`
`• Any warranty or representation that any ATM Forum member companies will
`announce any product(s) and/or service(s) related thereto, or if such announcements are
`made, that such announced product(s) and/or service(s) embody any or all of the ideas,
`technologies, or concepts contained herein; nor
`
`• Any form of relationship between any ATM Forum member companies and the
`recipient or user of this document.
`
`Implementation or use of specific ATM standards or recommendations and ATM Forum
`specifications will be voluntary, and no company shall agree or be obliged to implement
`them by virtue of participation in the ATM Forum.
`The ATM Forum is a non-profit international organization accelerating industry
`cooperation on ATM technology. The ATM Forum does not, expressly or otherwise,
`endorse or promote any specific products or services.
`
`ii
`
` ATM Forum Technical Committee
`
`

`

`Traffic Management Specification Version 4.0 af-tm-0056.000
`
`This specification consolidates the dedication and creativity of many individuals. This
`work would not have been possible without the involvment of the numerous members of
`The ATM Forum Traffic Management Working Group who made contributions to
`enhance, analyze, challenge, discuss, and review the specification.
`
`The following individuals deserve mention for their involvment in the production of this
`specification:
`• Shirish Sathaye, Editor, Traffic Management Working Group.
`• Vijay Samalam, Vice-chair, Traffic Management Working Group.
`•
`Jim Ormord, former Vice-chair, Traffic Management Working Group
`
`This specification also includes previous Traffic Management concepts which were
`specified as part of UNI 3.1. Special thanks are extended to the following people for
`producing these parts of the specification:
`• Dave McDysan, former Chair, Traffic Management Working Group
`• Lou Wojnaroski, former Editor, Traffic Management Working Group
`
`Natalie Giroux, Chair
`The ATM Forum Traffic Management Working Group
`
`ATM Forum Technical Committee
`
`iii
`
`

`

`af-tm-0056.000 Traffic Management Specification Version 4.0
`
`CONTENTS
`PREFACE ...............................................................................................................................................1
`1. INTRODUCTION ...............................................................................................................................2
`1.1 GENERIC FUNCTIONS............................................................................................................................2
`1.2 RELATION WITH OTHER DOCUMENTS ....................................................................................................2
`2. ATM SERVICE ARCHITECTURE...................................................................................................4
`2.1 DEFINITIONS FOR SERVICE CATEGORIES ................................................................................................4
`2.1.1 Constant Bit Rate (CBR) Service Category Definition ..................................................................4
`2.1.2 Real-Time Variable Bit Rate (rt-VBR) Service Category Definition..............................................5
`2.1.3 Non-Real-Time (nrt-VBR) Service Category Definition ................................................................5
`2.1.4 Unspecified Bit Rate (UBR) Service Category Definition .............................................................5
`2.1.5 Available Bit Rate (ABR) Service Category Definition .................................................................5
`2.2 ATM SERVICE CATEGORY PARAMETERS AND ATTRIBUTES....................................................................5
`2.3 RELATIONSHIP BETWEEN NRT-VBR, UBR, AND ABR SERVICE CATEGORIES...........................................6
`2.3.1 Nature of Service Guarantees.......................................................................................................6
`2.3.2 Mechanisms .................................................................................................................................7
`2.4 FLOW CONTROL MODEL AND SERVICE MODEL FOR THE ABR SERVICE CATEGORY .................................7
`2.4.1 Flow Control Model for ABR .......................................................................................................7
`2.4.2 Detailed Service Model for ABR ..................................................................................................8
`3. ATM LAYER QUALITY OF SERVICE .........................................................................................11
`3.1 QUALITY OF SERVICE PARAMETERS.....................................................................................................11
`3.2 NATURE OF QOS COMMITMENTS ........................................................................................................11
`3.3 NEGOTIATION OF QOS PARAMETERS...................................................................................................11
`3.4 TERMINOLOGY...................................................................................................................................12
`3.4.1 Cell Events.................................................................................................................................12
`3.4.2 Cell Transfer Outcome ...............................................................................................................12
`3.5 QOS REFERENCE CONFIGURATION ......................................................................................................12
`3.6 DEFINITION OF NEGOTIATED QOS PARAMETERS..................................................................................13
`3.6.1 Delay Parameters ......................................................................................................................14
`3.6.2 Accumulation of QoS Parameters...............................................................................................16
`3.6.3 Dependability Parameters..........................................................................................................17
`3.6.4 Accumulation of Dependability Parameters ...............................................................................17
`3.7 NON-NEGOTIATED QOS PARAMETERS .................................................................................................17
`3.7.1 Dependability Parameters..........................................................................................................17
`4. TRAFFIC CONTRACT....................................................................................................................19
`4.1 TRAFFIC PARAMETERS AND DESCRIPTORS ...........................................................................................19
`4.1.1 Traffic Parameters .....................................................................................................................19
`4.1.2 Source Traffic Descriptor...........................................................................................................19
`4.1.3 Connection Traffic Descriptor....................................................................................................19
`4.2 TRAFFIC CONTRACT SPECIFICATION....................................................................................................19
`4.3 CELL CONFORMANCE AND CONNECTION COMPLIANCE.........................................................................20
`4.3.1 Compliance for CBR, rt-VBR, nrt-VBR, and UBR ......................................................................20
`4.3.2 Compliance for ABR ..................................................................................................................20
`4.4 TRAFFIC CONTRACT PARAMETERS AND RELATED ALGORITHMS ...........................................................21
`4.4.1 Cell Delay Variation Tolerance (CDVT) for PCR and SCR ........................................................21
`4.4.2 Generic Cell Rate Algorithm (GCRA).........................................................................................21
`4.4.3 Peak Cell Rate Conformance .....................................................................................................24
`4.4.4 Sustainable Cell Rate and Burst Tolerance ................................................................................25
`4.5 TRAFFIC CONTRACT AND CONFORMANCE DEFINITIONS........................................................................26
`4.5.1 Traffic Contract Conformance Definition for CBR Service.........................................................27
`4.5.2 Traffic Contract and Conformance Definition for rt-VBR and nrt-VBR ......................................27
`4.5.3 Traffic Contract and Conformance Definition for UBR Service..................................................28
`4.5.4 Summary of Conformance Definitions for CBR, rt-VBR, nrt-VBR, and UBR...............................29
`
`iv
`
` ATM Forum Technical Committee
`
`

`

`Traffic Management Specification Version 4.0 af-tm-0056.000
`
`4.5.5 Traffic Contract and Conformance Definition for ABR Service ..................................................29
`5. FUNCTIONS AND PROCEDURES FOR TRAFFIC MANAGEMENT ........................................31
`5.1 INTRODUCTION ..................................................................................................................................31
`5.2 CONNECTION ADMISSION CONTROL....................................................................................................31
`5.3 USAGE PARAMETER CONTROL ............................................................................................................32
`5.3.1 UPC Functions...........................................................................................................................32
`5.3.2 UPC Requirements.....................................................................................................................32
`5.3.3 UPC Location ............................................................................................................................33
`5.3.4 Traffic Parameters Subject to UPC Enforcement........................................................................33
`5.3.5 UPC Actions (Cell Tagging and Discard)...................................................................................34
`5.3.6 Relationship between UPC, CLP, and Network Performance......................................................34
`5.3.7 Relationship between UPC and OAM.........................................................................................34
`5.3.8 Reaction to UPC Failures ..........................................................................................................35
`5.4 SELECTIVE CELL DISCARD ..................................................................................................................35
`5.5 TRAFFIC SHAPING...............................................................................................................................35
`5.6 EXPLICIT FORWARD CONGESTION INDICATION (EFCI).........................................................................35
`5.7 RESOURCE MANAGEMENT USING VIRTUAL PATHS................................................................................36
`5.8 FRAME DISCARD ................................................................................................................................37
`5.9 GENERIC FLOW CONTROL...................................................................................................................37
`5.10 ABR FLOW CONTROL ......................................................................................................................38
`5.10.1 Introduction .............................................................................................................................38
`5.10.2 ABR Service Parameters ..........................................................................................................38
`5.10.3 RM-cell Structure.....................................................................................................................40
`5.10.4 Source Behavior.......................................................................................................................43
`5.10.5 Destination Behavior ...............................................................................................................44
`5.10.6 Switch Behavior .......................................................................................................................45
`5.10.7 Virtual Source and Virtual Destination Behavior .....................................................................45
`5.10.8 Point-to-Multipoint Behavior ...................................................................................................46
`5.10.9 Support for Virtual Paths .........................................................................................................47
`6. REFERENCES..................................................................................................................................49
`
`ATM Forum Technical Committee
`
`v
`
`

`

`af-tm-0056.000 Traffic Management Specification Version 4.0
`
`NORMATIVE ANNEX A: GLOSSARY OF ACRONYMS AND TERMS ........................................50
`NORMATIVE ANNEX B: MEASUREMENT & ANALYSIS OF QOS PARAMETERS.................53
`B.1 MEASUREMENT METHODS..................................................................................................................53
`B.1.1 Cell Error Parameters ...............................................................................................................53
`B.1.2 Cell Loss Ratio ..........................................................................................................................53
`B.1.3 Cell Misinsertion Rate ...............................................................................................................53
`B.1.4 Cell Transfer Delay ...................................................................................................................54
`B.1.5 Measuring Cell Non-Conformance Ratio ...................................................................................54
`B.1.6 Measuring of Range of Cell Transfer Delay...............................................................................55
`B.2 FACTORS AFFECTING ATM QOS PARAMETERS...................................................................................56
`B.2.1 Sources of QoS Degradation......................................................................................................57
`B.2.2 Impact of QoS Degradation on Performance Parameters...........................................................57
`B.3 QOS CLASSES....................................................................................................................................60
`B.3.1 Specified QoS Classes................................................................................................................60
`B.3.2 Unspecified QoS Class...............................................................................................................61
`NORMATIVE ANNEX C: TRAFFIC CONTRACT RELATED ALGORITHMS AND
`PROCEDURES .....................................................................................................................................62
`C.1 EQUIVALENCE OF VIRTUAL SCHEDULING AND CONTINUOUS LEAKY BUCKET ALGORITHMS ...................62
`C.2 INTERPRETATION OF THE DEFINITION OF PCR AND EQUIVALENT-TERMINAL ........................................63
`C.3 EXAMPLES OF CELL CLUMPING...........................................................................................................64
`C.4 INTERPRETATION OF SCR AND BT IN CONJUNCTION WITH PCR...........................................................65
`C.4.1 Relationship of CDVT, SCR and BT...........................................................................................66
`INFORMATIVE APPENDIX I: IMPLEMENTATION EXAMPLES ON ABR SERVICE
`CATEGORY .........................................................................................................................................68
`I.1 EXAMPLE END-SYSTEM PSEUDOCODE..................................................................................................68
`I.2 STATE MACHINE.................................................................................................................................72
`I.3 EXAMPLE FAIRNESS CRITERIA .............................................................................................................73
`I.4 MCR CHARACTERISTICS .....................................................................................................................74
`I.5 EXAMPLE SWITCH MECHANISMS..........................................................................................................75
`I.5.1 Binary Feedback Schemes ..........................................................................................................75
`I.5.2 Explicit Rate Feedback Schemes.................................................................................................76
`I.5.3 Reactive Switch Behavior ...........................................................................................................77
`I.6 GENERIC NEGOTIATING BEHAVIOR ......................................................................................................77
`I.6.1 Overview of Generic Negotiating Behavior.................................................................................77
`I.6.2 Details of Generic Negotiating Behavior ....................................................................................77
`I.6.3 Description of Generic Negotiation Algorithm............................................................................78
`I.7 TURNING RM-CELLS AROUND.............................................................................................................79
`I.7.1 Introduction................................................................................................................................79
`I.7.2 Behavior of the Non-Queuing Options ........................................................................................80
`I.7.3 ACRbck = 0................................................................................................................................83
`I.7.4 Behavior of the Queuing Options................................................................................................84
`I.7.5 Summary.....................................................................................................................................86
`I.8 END-SYSTEM CONGESTION AND OPTIONAL USE-IT-OR-LOSE-IT BEHAVIOR............................................86
`INFORMATIVE APPENDIX II: CONFORMANCE EXAMPLES IN A TRAFFIC CONTRACT...88
`II.1 INTRODUCTION..................................................................................................................................88
`II.2 EXAMPLE 1: SWITCHED MULTI-MEGABIT DATA SERVICE (SMDS) .......................................................88
`II.3 EXAMPLE 2: FRAME RELAY SERVICE (FRS) ........................................................................................89
`II.4 EXAMPLE 3: CONSTANT BIT RATE SERVICES.......................................................................................90
`II.5 EXAMPLE 4: LAN INTERCONNECTION ................................................................................................91
`INFORMATIVE APPENDIX III: EXAMPLES OF ABR CONFORMANCE AND COMPLIANCE
`DEFINITIONS ......................................................................................................................................92
`III.1 DYNAMIC GCRA: AN EXAMPLE OF A CONFORMANCE DEFINITION .....................................................92
`III.2 ALGORITHM A TO DETERMINE I(K) ...................................................................................................92
`III.3 ALGORITHM B TO DETERMINE I(K) ...................................................................................................94
`
`vi
`
` ATM Forum Technical Committee
`
`

`

`Traffic Management Specification Version 4.0 af-tm-0056.000
`
`III.4 MEASURES OF ABR RM-CELL COMPLIANCE: EXAMPLES ...................................................................96
`INFORMATIVE APPENDIX IV: APPLICATION EXAMPLES FOR ATM SERVICE
`CATEGORIES......................................................................................................................................98
`INFORMATIVE APPENDIX V: EXAMPLE OF A FUTURE CDV ACCUMULATION METHOD99
`V.1 VALUES DETERMINED DIRECTLY FROM THE DELAY DENSITY ..............................................................99
`V.2 DERIVED VALUES PRECOMPUTED AT THE SWITCH...............................................................................99
`V.3 PARAMETERS USED IN ACCUMULATION ALGORITHMS........................................................................100
`V.4 ACCUMULATION ALGORITHMS.........................................................................................................100
`
`ATM Forum Technical Committee
`
`vii
`
`

`

`

`

`Traffic Management Specification Version 4.0 af-tm-0056.000
`
`Preface
`This is Version 4.0 of the ATM Forum Traffic Management Specification. The previous version of the
`traffic management specification may be found in:
`• ATM User-Network Interface (UNI) Specification Version 3.1, September 1994, Prentice Hall PTR,
`Upper Saddle, NJ 07458, ISBN 0-13-3933828-X.
`This document uses the following three levels for indicating the degree of compliance necessary for
`specific functions/procedures/coding associated with traffic management:
`• Requirement (R): functions, procedures, and coding necessary for operational compatibility.
`• Conditional Requirement (CR): functions, procedures, and coding necessary provided the specified
`optional functional is implemented.
`• Option (O): functions, procedures, and coding that may be useful, but are not necessary for
`operational compatibility.
`When a level is not specified, the level “Requirement (R)” should be assumed to hold.
`In this specification, annexes are normative and appendices are informative. The major advances of this
`version are:
`• Definition of the ABR service category.
`• Detailed ATM service architecture.
`• Modifications to conformance definitions.
`
`ATM Forum Technical Committee
`
`1
`
`

`

`af-tm-0056.000 Traffic Management Specification Version 4.0
`
`1. Introduction
`ATM technology is intended to support a wide variety of services and applications. The control of ATM
`network traffic is fundamentally related to the ability of the network to provide appropriately differentiated
`Quality of Service (QoS) for network applications. This specification defines procedures and parameters
`related to Traffic Management and Quality of Service. A primary role of traffic management is to protect
`the network and the end-system from congestion in order to achieve network performance objectives. An
`additional role is to promote the efficient use of network resources.
`A set of five service categories are specified. For each one, a set of parameters is given to describe both the
`traffic presented to the network, and the Quality of Service (QoS) which is required of the network. A
`number of traffic control mechanisms are defined, which the network may utilize to meet the QoS
`objectives.
`
`1.1 Generic Functions
`To meet these objectives, the following functions form a framework for managing and controlling traffic
`and congestion in ATM networks and may be used in appropriate combinations depending on the service
`category.
`• Connection Admission Control (CAC) is defined as the set of actions taken by the network during the
`call set-up phase in order to determine whether a connection request can be accepted or should be
`rejected (or whether a request for re-allocation can be accommodated).
`• Feedback controls are defined as the set of actions taken by the network and by end-systems to
`regulate the traffic submitted on ATM connections according to the state of network elements.
`• Usage Parameter Control (UPC) is defined as the set of actions taken by the network to monitor and
`control traffic, in terms of traffic offered and validity of the ATM connection, at the end-system
`access. Its main purpose is to protect network resources from malicious as well as unintentional
`misbehavior, which can affect the QoS of other already established connections, by detecting
`violations of negotiated parameters and taking appropriate actions. Such actions may include cell
`discard and cell tagging.
`• Cell Loss Priority control: For some service categories the end system may generate traffic flows of
`cells with Cell Loss Priority (CLP) marking. The network may follow models which treat this
`marking as transparent or as significant. If treated as significant, the network may selectively discard
`cells marked with a low priority to protect, as far as possible, the QoS objectives of cells with high
`priority.
`• Traffic Shaping: Traffic shaping mechanisms may be used to achieve a desired modification of the
`traffic characteristics.
`• Network Resource Management (NRM): The service architecture allows logical separation of
`connections according to service characteristics. Although cell scheduling and resource provisioning
`are implementation and network specific, they can be utilized to provide appropriate isolation and
`access to resources. Virtual Paths are a useful tool for resource management.
`• Frame Discard: A congested network that needs to discard cells may discard at the frame level rather
`than at the cell level. The concept of a frame is defined in Section 5.8.
`• ABR Flow Control: The ABR flow control protocol may be used to adaptively share the available
`bandwidth among participating users.
`• Other generic functions are for further study.
`
`1.2 Relation with Other Documents
`This specification expands on some topics in ITU-T Recommendations I.371-draft, I.356, and I.150.
`Section 4 of this specification is closely related to ITU-T Recommendation I.371-draft. Some differences
`are as follows:
`
`2
`
` ATM Forum Technical Committee
`
`

`

`Traffic Management Specification Version 4.0 af-tm-0056.000
`
`•
`
`• The service categories of the ATM Forum are called ATM transfer capabilities in I.371-draft. Some
`of the ATM service categories of the ATM Forum are equivalent to some of the ATM transfer
`capabilities in I.371-draft but have different names: Constant Bit Rate (CBR) is called Deterministic
`Bit Rate (DBR) in I.371-draft and Variable Bit Rate (VBR) is called Statistical Bit Rate (SBR) in
`I.371-draft. In general, a mapping between the ATM Forum service categories and the ATM transfer
`capabilities can be made with the following discrepancies:
`• The ATM Forum distinguishes between real-time VBR and non-real-time VBR while
`I.371-draft so far specifies non-real-time SBR and leaves real-time SBR for further study.
`• The ATM Forum has a service category Unspecified Bit Rate (UBR) which has no equivalent
`ATM transfer capability in I.371-draft.
`I.371-draft partially specifies an ATM transfer capability, ATM Block Transfer (ABT),
`which has no equivalent in this specification.
`• ABR is fully specified in this specification, but the ABR transfer capability is only partially
`specified in I.371-draft and is still under study.
`• Differences from ITU-T Recommendation I.356 include:
`• This specification provides for negotiation of the following QoS parameters on a connection
`basis:
`• Peak-to-peak Cell Delay Variation,
`• Maximum Cell Transfer Delay
`• Cell Loss Ratio
`ITU-T Recommendation I.356 only defines QoS classes. However, in this specification,
`individual QoS parameters are specified and QoS classes are retained for backward
`compatibility.
`Note: ITU-T SG 13 intends to include a single end-to-end objective applicable for all
`connections for CER, SECBR, and CMR, in ITU-T Recommendation I.356.
`• The text in Section 1.5 of ITU-T Recommendation I.371-draft is not consistent with Sections 3.4.2.1
`and 3.4.2.2 of ITU-T Recommendation I.150. Moreover the text in Section 2.3.2 of ITU-T
`Recommendation I.371-draft is open to different interpretations. In an effort to provide a consistent
`interpretation of the above basic concept in this specification, the QoS classes have been divided into
`two categories: Specified QoS classes and the Unspecified QoS class (see Annex B.3). For each
`direction of an ATM layer connection, an end-system requests one QoS class at connection setup or
`subscription time. Also, differences exist in the use of RM-cell fields QL and SN defined in ITU-T
`Recommendation I.371-draft, and the source, destination and switch behaviors (not yet specified in
`ITU-T Recommendation I.371-draft).
`ITU-T Recommendation I.371-draft (Section 6.2.3) states that “The use of a UPC function is
`recommended, and the use of an NPC function is a network option.” In this specification, the UPC is
`optional.
`
`•
`
`
`
`•
`
`ATM Forum Technical Committee
`
`3
`
`

`

`af-tm-0056.000 Traffic Management Specification Version 4.0
`
`2. ATM Service Architecture
`The architecture for services provided at the ATM layer consists of the following five service categories:
`• CBR
`Constant Bit Rate
`•
`rt-VBR
`Real-Time Variable Bit Rate
`• nrt-VBR
`Non-Real-Time Variable Bit Rate
`• UBR
`Unspecified Bit Rate
`• ABR
`Available Bit Rate
`These service categories relate traffic characteristics and QoS requirements to network behavior.
`Functions such as routing, CAC, and resource allocation are, in general, structured differently for each
`service category. Service categories are distinguished as being either real-time or non-real-time. For
`real-time traffic, there are two categories, CBR and rt-VBR, distinguished by whether the traffic
`descriptor contains only the Peak Cell Rate (PCR) or both PCR and the Sustainable Cell Rate (SCR)
`parameters. The three non-real-time categories (nrt-VBR, UBR, and ABR) are compared and
`distinguished in some detail in Section 2.3. All service categories apply to both VCCs and VPCs.
`Throughout this document, the term “connection” refers to either VCCs or VPCs.
`The specification of a real-time service category that uses a feedback flow control mechanism similar or
`identica