rfc9097v7.txt   rfc9097.txt 
Internet Engineering Task Force (IETF) A. Morton Internet Engineering Task Force (IETF) A. Morton
Request for Comments: 9097 AT&T Labs Request for Comments: 9097 AT&T Labs
Category: Standards Track R. Geib Category: Standards Track R. Geib
ISSN: 2070-1721 Deutsche Telekom ISSN: 2070-1721 Deutsche Telekom
L. Ciavattone L. Ciavattone
AT&T Labs AT&T Labs
October 2021 November 2021
Metrics and Methods for One-Way IP Capacity Metrics and Methods for One-Way IP Capacity
Abstract Abstract
This memo revisits the problem of Network Capacity Metrics first This memo revisits the problem of Network Capacity Metrics first
examined in RFC 5136. This memo specifies a more practical Maximum examined in RFC 5136. This memo specifies a more practical Maximum
IP-Layer Capacity Metric definition catering to measurement and IP-Layer Capacity Metric definition catering to measurement and
outlines the corresponding Methods of Measurement. outlines the corresponding Methods of Measurement.
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Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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publication of this document. Please review these documents publication of this document. Please review these documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Revised BSD License text as described in Section 4.e of the
the Trust Legal Provisions and are provided without warranty as Trust Legal Provisions and are provided without warranty as described
described in the Simplified BSD License. in the Revised BSD License.
Table of Contents Table of Contents
1. Introduction 1. Introduction
1.1. Requirements Language 1.1. Requirements Language
2. Scope, Goals, and Applicability 2. Scope, Goals, and Applicability
3. Motivation 3. Motivation
4. General Parameters and Definitions 4. General Parameters and Definitions
5. IP-Layer Capacity Singleton Metric Definitions 5. IP-Layer Capacity Singleton Metric Definitions
5.1. Formal Name 5.1. Formal Name
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12.2. Informative References 12.2. Informative References
Appendix A. Load Rate Adjustment Pseudocode Appendix A. Load Rate Adjustment Pseudocode
Appendix B. RFC 8085 UDP Guidelines Check Appendix B. RFC 8085 UDP Guidelines Check
B.1. Assessment of Mandatory Requirements B.1. Assessment of Mandatory Requirements
B.2. Assessment of Recommendations B.2. Assessment of Recommendations
Acknowledgments Acknowledgments
Authors' Addresses Authors' Addresses
1. Introduction 1. Introduction
The IETF's efforts to define Network and Bulk Transport Capacity have The IETF's efforts to define Network Capacity and Bulk Transport
been chartered and progressed for over twenty years. Over that time, Capacity (BTC) have been chartered and progressed for over twenty
the performance community has seen the development of Informative years. Over that time, the performance community has seen the
definitions in [RFC3148] for the Framework for Bulk Transport development of Informative definitions in [RFC3148] for the Framework
Capacity (BTC), [RFC5136] for Network Capacity and Maximum IP-Layer for Bulk Transport Capacity, [RFC5136] for Network Capacity and
Capacity, and the Experimental metric definitions and methods in Maximum IP-Layer Capacity, and the Experimental metric definitions
"Model-Based Metrics for Bulk Transport Capacity" [RFC8337]. and methods in "Model-Based Metrics for Bulk Transport Capacity"
[RFC8337].
This memo revisits the problem of Network Capacity Metrics examined This memo revisits the problem of Network Capacity Metrics examined
first in [RFC3148] and later in [RFC5136]. Maximum IP-Layer Capacity first in [RFC3148] and later in [RFC5136]. Maximum IP-Layer Capacity
and Bulk Transfer Capacity [RFC3148] (goodput) are different metrics. and Bulk Transfer Capacity [RFC3148] (goodput) are different metrics.
Maximum IP-Layer Capacity is like the theoretical goal for goodput. Maximum IP-Layer Capacity is like the theoretical goal for goodput.
There are many metrics in [RFC5136], such as Available Capacity. There are many metrics in [RFC5136], such as Available Capacity.
Measurements depend on the network path under test and the use case. Measurements depend on the network path under test and the use case.
Here, the main use case is to assess the Maximum Capacity of one or Here, the main use case is to assess the Maximum Capacity of one or
more networks where the subscriber receives specific performance more networks where the subscriber receives specific performance
assurances, sometimes referred to as Internet access, or where a assurances, sometimes referred to as Internet access, or where a
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Some effects of compression on measurement are discussed in Section 6 Some effects of compression on measurement are discussed in Section 6
of [RFC8468]. of [RFC8468].
5.4. Related Round-Trip Delay and One-Way Loss Definitions 5.4. Related Round-Trip Delay and One-Way Loss Definitions
RTD[dtn,dtn+1] is defined as a Sample of the Round-Trip Delay RTD[dtn,dtn+1] is defined as a Sample of the Round-Trip Delay
[RFC2681] between the Src host and the Dst host during the interval [RFC2681] between the Src host and the Dst host during the interval
[T,T+I] (that contains equal non-overlapping intervals of dt). The [T,T+I] (that contains equal non-overlapping intervals of dt). The
"reasonable period of time" mentioned in [RFC2681] is the Parameter "reasonable period of time" mentioned in [RFC2681] is the Parameter
Tmax in this memo. The statistics used to summarize RTD[dtn,dtn+1] Tmax in this memo. The statistics used to summarize RTD[dtn,dtn+1]
MAY include the minimum, maximum, median, and mean, and the range = MAY include the minimum, maximum, median, mean, and the range =
(maximum - minimum) are referred to below for load adjustment (maximum - minimum). Some of these statistics are needed for load
purposes; see Section 8.1. adjustment purposes (Section 8.1), measurement qualification
(Section 8.2), and reporting (Section 9).
OWL[dtn,dtn+1] is defined as a Sample of the One-Way Loss [RFC7680] OWL[dtn,dtn+1] is defined as a Sample of the One-Way Loss [RFC7680]
between the Src host and the Dst host during the interval [T,T+I] between the Src host and the Dst host during the interval [T,T+I]
(that contains equal non-overlapping intervals of dt). The (that contains equal non-overlapping intervals of dt). The
statistics used to summarize OWL[dtn,dtn+1] MAY include the count of statistics used to summarize OWL[dtn,dtn+1] MAY include the count of
lost packets and the ratio of lost packets. lost packets and the ratio of lost packets.
Other metrics MAY be measured: one-way reordering, duplication, and Other metrics MAY be measured: one-way reordering, duplication, and
delay variation. delay variation.
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Metrics, and Measurements", Broadband Forum TR-471, July Metrics, and Measurements", Broadband Forum TR-471, July
2020, <https://www.broadband-forum.org/technical/download/ 2020, <https://www.broadband-forum.org/technical/download/
TR-471.pdf>. TR-471.pdf>.
[Y.1540] ITU-T, "Internet protocol data communication service - IP [Y.1540] ITU-T, "Internet protocol data communication service - IP
packet transfer and availability performance parameters", packet transfer and availability performance parameters",
ITU-T Recommendation Y.1540, December 2019, ITU-T Recommendation Y.1540, December 2019,
<https://www.itu.int/rec/T-REC-Y.1540-201912-I/en>. <https://www.itu.int/rec/T-REC-Y.1540-201912-I/en>.
[Y.Sup60] ITU-T, "Interpreting ITU-T Y.1540 maximum IP-layer [Y.Sup60] ITU-T, "Interpreting ITU-T Y.1540 maximum IP-layer
capacity measurements", ITU-T Recommendation Y.Sup60, May capacity measurements", ITU-T Recommendation Y.Sup60,
2021, <https://www.itu.int/rec/T-REC-Y.Sup60/en>. October 2021, <https://www.itu.int/rec/T-REC-Y.Sup60/en>.
Appendix A. Load Rate Adjustment Pseudocode Appendix A. Load Rate Adjustment Pseudocode
This appendix provides a pseudocode implementation of the algorithm This appendix provides a pseudocode implementation of the algorithm
described in Section 8.1. described in Section 8.1.
Rx = 0 # The current sending rate (equivalent to a row Rx = 0 # The current sending rate (equivalent to a row
# of the table) # of the table)
seqErr = 0 # Measured count that includes Loss or Reordering seqErr = 0 # Measured count that includes Loss or Reordering
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maxLoadRates = 2000 # Maximum table index (rows) maxLoadRates = 2000 # Maximum table index (rows)
if ( seqErr <= seqErrThresh && delay < lowThresh ) { if ( seqErr <= seqErrThresh && delay < lowThresh ) {
if ( Rx < hSpeedThresh && slowAdjCount < slowAdjThresh ) { if ( Rx < hSpeedThresh && slowAdjCount < slowAdjThresh ) {
Rx += highSpeedDelta; Rx += highSpeedDelta;
slowAdjCount = 0; slowAdjCount = 0;
} else { } else {
if ( Rx < maxLoadRates - 1 ) if ( Rx < maxLoadRates - 1 )
Rx++; Rx++;
} }
} else if ( seqErr > seqErrorThresh || delay > upperThresh ) { } else if ( seqErr > seqErrThresh || delay > upperThresh ) {
slowAdjCount++; slowAdjCount++;
if ( Rx < hSpeedThresh && slowAdjCount == slowAdjThresh ) { if ( Rx < hSpeedThresh && slowAdjCount == slowAdjThresh ) {
if ( Rx > highSpeedDelta * 3 ) if ( Rx > highSpeedDelta * 3 )
Rx -= highSpeedDelta * 3; Rx -= highSpeedDelta * 3;
else else
Rx = 0; Rx = 0;
} else { } else {
if ( Rx > 0 ) if ( Rx > 0 )
Rx--; Rx--;
} }
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