draft-morton-ippm-2679-bis-05.txt   draft-morton-ippm-2679-bis-06.txt 
Network Working Group G. Almes Network Working Group G. Almes
Internet-Draft Texas A&M Internet-Draft Texas A&M
Obsoletes: 2679 (if approved) S. Kalidindi Obsoletes: 2679 (if approved) S. Kalidindi
Intended status: Standards Track Ixia Intended status: Standards Track Ixia
Expires: January 5, 2015 M. Zekauskas Expires: April 9, 2015 M. Zekauskas
Internet2 Internet2
A. Morton, Ed. A. Morton, Ed.
AT&T Labs AT&T Labs
July 4, 2014 October 6, 2014
A One-Way Delay Metric for IPPM A One-Way Delay Metric for IPPM
draft-morton-ippm-2679-bis-05 draft-morton-ippm-2679-bis-06
Abstract Abstract
This memo (RFC 2679 bis) defines a metric for one-way delay of This memo (RFC 2679 bis) defines a metric for one-way delay of
packets across Internet paths. It builds on notions introduced and packets across Internet paths. It builds on notions introduced and
discussed in the IPPM Framework document, RFC 2330; the reader is discussed in the IPPM Framework document, RFC 2330; the reader is
assumed to be familiar with that document. assumed to be familiar with that document.
Requirements Language Requirements Language
skipping to change at page 1, line 44 skipping to change at page 1, line 44
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 5, 2015. This Internet-Draft will expire on April 9, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 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
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
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 Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. RFC 2679 bis . . . . . . . . . . . . . . . . . . . . . . . . 3 1. RFC 2679 bis . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 5 2.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 6
2.2. General Issues Regarding Time . . . . . . . . . . . . . . 6 2.2. General Issues Regarding Time . . . . . . . . . . . . . . 7
3. A Singleton Definition for One-way Delay . . . . . . . . . . 7 3. A Singleton Definition for One-way Delay . . . . . . . . . . 8
3.1. Metric Name: . . . . . . . . . . . . . . . . . . . . . . 7 3.1. Metric Name: . . . . . . . . . . . . . . . . . . . . . . 8
3.2. Metric Parameters: . . . . . . . . . . . . . . . . . . . 7 3.2. Metric Parameters: . . . . . . . . . . . . . . . . . . . 8
3.3. Metric Units: . . . . . . . . . . . . . . . . . . . . . . 7 3.3. Metric Units: . . . . . . . . . . . . . . . . . . . . . . 8
3.4. Definition: . . . . . . . . . . . . . . . . . . . . . . . 7 3.4. Definition: . . . . . . . . . . . . . . . . . . . . . . . 8
3.5. Discussion: . . . . . . . . . . . . . . . . . . . . . . . 8 3.5. Discussion: . . . . . . . . . . . . . . . . . . . . . . . 9
3.6. Methodologies: . . . . . . . . . . . . . . . . . . . . . 9 3.6. Methodologies: . . . . . . . . . . . . . . . . . . . . . 10
3.7. Errors and Uncertainties: . . . . . . . . . . . . . . . . 10 3.7. Errors and Uncertainties: . . . . . . . . . . . . . . . . 11
3.7.1. Errors or uncertainties related to Clocks . . . . . . 10 3.7.1. Errors or uncertainties related to Clocks . . . . . . 11
3.7.2. Errors or uncertainties related to Wire-time vs Host- 3.7.2. Errors or uncertainties related to Wire-time vs Host-
time . . . . . . . . . . . . . . . . . . . . . . . . 11 time . . . . . . . . . . . . . . . . . . . . . . . . 12
3.7.3. Calibration . . . . . . . . . . . . . . . . . . . . . 12 3.7.3. Calibration . . . . . . . . . . . . . . . . . . . . . 13
3.8. Reporting the metric: . . . . . . . . . . . . . . . . . . 14 3.8. Reporting the metric: . . . . . . . . . . . . . . . . . . 15
3.8.1. Type-P . . . . . . . . . . . . . . . . . . . . . . . 14 3.8.1. Type-P . . . . . . . . . . . . . . . . . . . . . . . 15
3.8.2. Loss Threshold . . . . . . . . . . . . . . . . . . . 14 3.8.2. Loss Threshold . . . . . . . . . . . . . . . . . . . 16
3.8.3. Calibration Results . . . . . . . . . . . . . . . . . 15 3.8.3. Calibration Results . . . . . . . . . . . . . . . . . 16
3.8.4. Path . . . . . . . . . . . . . . . . . . . . . . . . 15 3.8.4. Path . . . . . . . . . . . . . . . . . . . . . . . . 16
4. A Definition for Samples of One-way Delay . . . . . . . . . . 15 4. A Definition for Samples of One-way Delay . . . . . . . . . . 16
4.1. Metric Name: . . . . . . . . . . . . . . . . . . . . . . 16 4.1. Metric Name: . . . . . . . . . . . . . . . . . . . . . . 17
4.2. Metric Parameters: . . . . . . . . . . . . . . . . . . . 16 4.2. Metric Parameters: . . . . . . . . . . . . . . . . . . . 17
4.3. Metric Units: . . . . . . . . . . . . . . . . . . . . . . 16 4.3. Metric Units: . . . . . . . . . . . . . . . . . . . . . . 17
4.4. Definition: . . . . . . . . . . . . . . . . . . . . . . . 16 4.4. Definition: . . . . . . . . . . . . . . . . . . . . . . . 17
4.5. Discussion: . . . . . . . . . . . . . . . . . . . . . . . 17 4.5. Discussion: . . . . . . . . . . . . . . . . . . . . . . . 18
4.6. Methodologies: . . . . . . . . . . . . . . . . . . . . . 17 4.6. Methodologies: . . . . . . . . . . . . . . . . . . . . . 18
4.7. Errors and Uncertainties: . . . . . . . . . . . . . . . . 18 4.7. Errors and Uncertainties: . . . . . . . . . . . . . . . . 19
4.8. Reporting the metric: . . . . . . . . . . . . . . . . . . 18 4.8. Reporting the metric: . . . . . . . . . . . . . . . . . . 19
5. Some Statistics Definitions for One-way Delay . . . . . . . . 18 5. Some Statistics Definitions for One-way Delay . . . . . . . . 19
5.1. Type-P-One-way-Delay-Percentile . . . . . . . . . . . . . 18 5.1. Type-P-One-way-Delay-Percentile . . . . . . . . . . . . . 19
5.2. Type-P-One-way-Delay-Median . . . . . . . . . . . . . . . 19 5.2. Type-P-One-way-Delay-Median . . . . . . . . . . . . . . . 20
5.3. Type-P-One-way-Delay-Minimum . . . . . . . . . . . . . . 19 5.3. Type-P-One-way-Delay-Minimum . . . . . . . . . . . . . . 21
5.4. Type-P-One-way-Delay-Inverse-Percentile . . . . . . . . . 20 5.4. Type-P-One-way-Delay-Inverse-Percentile . . . . . . . . . 21
6. Security Considerations . . . . . . . . . . . . . . . . . . . 20 6. Security Considerations . . . . . . . . . . . . . . . . . . . 21
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 22
9. Refetrences (temporary) . . . . . . . . . . . . . . . . . . . 21 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 22
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 21 9.1. Normative References . . . . . . . . . . . . . . . . . . 22
10.1. Normative References . . . . . . . . . . . . . . . . . . 21 9.2. Informative References . . . . . . . . . . . . . . . . . 23
10.2. Informative References . . . . . . . . . . . . . . . . . 22 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. RFC 2679 bis 1. RFC 2679 bis
The following text constitutes RFC 2769 bis proposed for advancement The following text constitutes RFC 2769 bis proposed for advancement
on the IETF Standards Track. on the IETF Standards Track. This section tracks the changes from
[RFC2679].
[I-D.ietf-ippm-testplan-rfc2679] (now approved) provides the test [RFC6808] provides the test plan and results supporting [RFC2679]
plan and results supporting [RFC2679] advancement along the standards advancement along the standards track, according to the process in
track, according to the process in [RFC6576]. The conclusions of [RFC6576]. The conclusions of [RFC6808] list four minor
[I-D.ietf-ippm-testplan-rfc2679] list four minor modifications for modifications:
inclusion:
1. Section 6.2.3 of [I-D.ietf-ippm-testplan-rfc2679] asserts that 1. Section 6.2.3 of [RFC6808] asserts that the assumption of post-
the assumption of post-processing to enforce a constant waiting processing to enforce a constant waiting time threshold is
time threshold is compliant, and that the text of the RFC should compliant, and that the text of the RFC should be revised
be revised slightly to include this point (see the last list item slightly to include this point (see the last list item of section
of section 3.6, below). 3.6, below).
2. Section 6.5 of [I-D.ietf-ippm-testplan-rfc2679] indicates that 2. Section 6.5 of [RFC6808] indicates that Type-P-One-way-Delay-
Type-P-One-way-Delay-Inverse-Percentile statistic has been Inverse-Percentile statistic has been ignored in both
ignored in both implementations, so it is a candidate for removal implementations, so it is a candidate for removal or deprecation
or deprecation in RFC2679bis (this small discrepancy does not in RFC2679bis (this small discrepancy does not affect candidacy
affect candidacy for advancement) (see section 5.4, below). for advancement) (see section 5.4, below).
3. The IETF has reached consensus on guidance for reporting metrics 3. The IETF has reached consensus on guidance for reporting metrics
in [RFC6703], and this memo should be referenced in RFC2679bis to in [RFC6703], and this memo should be referenced in RFC2679bis to
incorporate recent experience where appropriate (see the last incorporate recent experience where appropriate (see the last
list item of section 3.6, section 3.8, and section 5 below). list item of section 3.6, section 3.8, and section 5 below).
4. There is currently one erratum with status "Held for document 4. There is currently one erratum with status "Held for document
update" for [RFC2679], and it appears this minor revision and update" for [RFC2679], and it appears this minor revision and
additional text should be incorporated in RFC2679bis (see section additional text should be incorporated in RFC2679bis (see section
5.1). 5.1).
A small number of updates to the [RFC2679] text have been proposed A number of updates to the [RFC2679] text have been implemented in
(by the current Editor) in the text below, principally to reference the text below, to reference key IPPM RFCs that were approved after
key IPPM RFCs that were approved after [RFC2679].
Section 5.4.4 of RFC 6390 suggests a common template for performance [RFC2679], and to address comments on the IPPM mailing list
describing current conditions and experience.
1. Near the end of section 2.1, update of a network example using
ATM and clarification of TCP's affect on queue occupation and
importance of one-way delay measurement.
2. Explicit inclusion of the maximum waiting time input parameter
in section 3.2 and 4.2, reflecting recognition of this parameter
in more recent RFCs and ITU-T Recommendation Y.1540.
3. Addition of reference to RFC6703 in the discussion of packet
life time and application timeouts in section 3.5.
4. Addition of reference to the default requirement (that packets
be standard-formed) from RFC2330 as a new list item in section
3.5.
5. GPS-based NTP experience replaces "to be tested" in section 3.5.
6. Added parenthetical guidance on minimizing interval between
timestamp placement to send time in section 3.6.
7. Added text recognizing the impending deployment of transport
layer encryption in section 3.6.
8. Section 3.7.2 notes that some current systems perform host time
stamping on the network interface hardware.
9. "instrument" replaced by the defined term "host" in sections
3.7.3 and 3.8.3.
10. Added reference to RFC 3432 Periodic sampling alongside Poisson
sampling in section 4, and also noting that a truncated Poisson
distribution may be needed with modern networks as described in
the IPPM Framework update, RFC7312.
11. Add reference to RFC 4737 Reordering metric in the related
discussion of section 4.6, Methodologies.
12. Clarifying the conclusions on two related points on harm to
measurements (recognition of measurement traffic for unexpected
priority treatment and attacker traffic which emulates
measurement) in section 6, Security Considerations.
Section 5.4.4 of [RFC6390] suggests a common template for performance
metrics partially derived from previous IPPM and BMWG RFCs, but also metrics partially derived from previous IPPM and BMWG RFCs, but also
some new items. All of the RFC 6390 Normative points are covered, contains some new items. All of the [RFC6390] Normative points are
but not quite in the same section names or orientation. Several of covered, but not quite in the same section names or orientation.
the Informative points are covered. It is proposed to "grandfather- Several of the Informative points are covered. Maintaining the
in" bis RFCs w.r.t. RFC 6390 (keeping the familiar outline and familiar outline of IPPM literature has both value and minimizes
minimizing unnecessary differences), and focus efforts on applying unnecessary differences between this revised RFC and current/future
the template with new metric memos instead. IPPM RFCs.
The publication of RFC 6921 suggests an area where this memo might be The publication of RFC 6921 suggested an area where this memo might
updated. Packet transfer on Faster-Than-Light (FTL) networks could need updating. Packet transfer on Faster-Than-Light (FTL) networks
result in negative delays and packet reordering, and both are covered could result in negative delays and packet reordering, however both
as possibilities in the current text (we note that this is an April are covered as possibilities in the current text and no revisions are
1st RFC). deemed necessary (we also note that this is an April 1st RFC).
2. Introduction 2. Introduction
This memo defines a metric for one-way delay of packets across This memo defines a metric for one-way delay of packets across
Internet paths. It builds on notions introduced and discussed in the Internet paths. It builds on notions introduced and discussed in the
IPPM Framework document, RFC 2330 [1]; the reader is assumed to be IPPM Framework document, [RFC2330]; the reader is assumed to be
familiar with that document. familiar with that document.
This memo is intended to be parallel in structure to a companion This memo is intended to be parallel in structure to a companion
document for Packet Loss ("A One-way Packet Loss Metric for IPPM") document for Packet Loss ("A One-way Packet Loss Metric for IPPM")
[2]. [RFC2680].
Although RFC 2119 was written with protocols in mind, the key words Although [RFC2119] was written with protocols in mind, the key words
are used in this document for similar reasons. They are used to are used in this document for similar reasons. They are used to
ensure the results of measurements from two different implementations ensure the results of measurements from two different implementations
are comparable, and to note instances when an implementation could are comparable, and to note instances when an implementation could
perturb the network. perturb the network.
The structure of the memo is as follows: The structure of the memo is as follows:
+ A 'singleton' analytic metric, called Type-P-One-way-Delay, will be + A 'singleton' analytic metric, called Type-P-One-way-Delay, will be
introduced to measure a single observation of one-way delay. introduced to measure a single observation of one-way delay.
+ Using this singleton metric, a 'sample', called Type-P-One-way- + Using this singleton metric, a 'sample', called Type-P-One-way-
Delay-Poisson-Stream, will be introduced to measure a sequence of Delay-Poisson-Stream, will be introduced to measure a sequence of
singleton delays measured at times taken from a Poisson process. singleton delays sent at times taken from a Poisson process.
+ Using this sample, several 'statistics' of the sample will be + Using this sample, several 'statistics' of the sample will be
defined and discussed. This progression from singleton to sample to defined and discussed. This progression from singleton to sample to
statistics, with clear separation among them, is important. statistics, with clear separation among them, is important.
Whenever a technical term from the IPPM Framework document is first Whenever a technical term from the IPPM Framework document is first
used in this memo, it will be tagged with a trailing asterisk. For used in this memo, it will be tagged with a trailing asterisk. For
example, "term*" indicates that "term" is defined in the Framework. example, "term*" indicates that "term" is defined in the Framework.
2.1. Motivation 2.1. Motivation
skipping to change at page 5, line 45 skipping to change at page 6, line 41
+ In today's Internet, the path from a source to a destination may be + In today's Internet, the path from a source to a destination may be
different than the path from the destination back to the source different than the path from the destination back to the source
("asymmetric paths"), such that different sequences of routers are ("asymmetric paths"), such that different sequences of routers are
used for the forward and reverse paths. Therefore round-trip used for the forward and reverse paths. Therefore round-trip
measurements actually measure the performance of two distinct paths measurements actually measure the performance of two distinct paths
together. Measuring each path independently highlights the together. Measuring each path independently highlights the
performance difference between the two paths which may traverse performance difference between the two paths which may traverse
different Internet service providers, and even radically different different Internet service providers, and even radically different
types of networks (for example, research versus commodity networks, types of networks (for example, research versus commodity networks,
or ATM versus packet-over-SONET). or networks with asymmetric link capacities, or wireless vs. wireline
access).
+ Even when the two paths are symmetric, they may have radically + Even when the two paths are symmetric, they may have radically
different performance characteristics due to asymmetric queueing. different performance characteristics due to asymmetric queueing.
+ Performance of an application may depend mostly on the performance + Performance of an application may depend mostly on the performance
in one direction. For example, a file transfer using TCP may depend in one direction. For example, a TCP-based communication may
more on the performance in the direction that data flows (queue experience reduced throughput if congestion occurs in one direction
occupation tends to grow in this direction, possibly dominating the of its communication. Trouble shooting may be simplified if the
round-trip delay), rather than the direction in which congested direction of TCP transmission can be identified.
acknowledgements travel.
+ In quality-of-service (QoS) enabled networks, provisioning in one + In quality-of-service (QoS) enabled networks, provisioning in one
direction may be radically different than provisioning in the reverse direction may be radically different than provisioning in the reverse
direction, and thus the QoS guarantees differ. Measuring the paths direction, and thus the QoS guarantees differ. Measuring the paths
independently allows the verification of both guarantees. independently allows the verification of both guarantees.
It is outside the scope of this document to say precisely how delay It is outside the scope of this document to say precisely how delay
metrics would be applied to specific problems. metrics would be applied to specific problems.
2.2. General Issues Regarding Time 2.2. General Issues Regarding Time
skipping to change at page 8, line 30 skipping to change at page 9, line 30
values. values.
+ Since delay values will often be as low as the 100 usec to 10 msec + Since delay values will often be as low as the 100 usec to 10 msec
range, it will be important for Src and Dst to synchronize very range, it will be important for Src and Dst to synchronize very
closely. GPS systems afford one way to achieve synchronization to closely. GPS systems afford one way to achieve synchronization to
within several 10s of usec. Ordinary application of NTP may allow within several 10s of usec. Ordinary application of NTP may allow
synchronization to within several msec, but this depends on the synchronization to within several msec, but this depends on the
stability and symmetry of delay properties among those NTP agents stability and symmetry of delay properties among those NTP agents
used, and this delay is what we are trying to measure. A combination used, and this delay is what we are trying to measure. A combination
of some GPS-based NTP servers and a conservatively designed and of some GPS-based NTP servers and a conservatively designed and
deployed set of other NTP servers should yield good results, but this deployed set of other NTP servers should yield good results. This
is yet to be tested. was tested in [RFC6808], where a GPS measurement system's results
compared well with a GPS-based NTP synchronized system for the same
intercontinental path.
+ A given methodology will have to include a way to determine whether + A given methodology will have to include a way to determine whether
a delay value is infinite or whether it is merely very large (and the a delay value is infinite or whether it is merely very large (and the
packet is yet to arrive at Dst). As noted by Mahdavi and Paxson [4], packet is yet to arrive at Dst). As noted by Mahdavi and Paxson
simple upper bounds (such as the 255 seconds theoretical upper bound [RFC2678], simple upper bounds (such as the 255 seconds theoretical
on the lifetimes of IP packets [5]) could be used, but good upper bound on the lifetimes of IP packets [RFC0791]) could be used,
engineering, including an understanding of packet lifetimes, will be but good engineering, including an understanding of packet lifetimes,
needed in practice. {Comment: Note that, for many applications of will be needed in practice. {Comment: Note that, for many
these metrics, the harm in treating a large delay as infinite might applications of these metrics, the harm in treating a large delay as
be zero or very small. A TCP data packet, for example, that arrives infinite might be zero or very small. A TCP data packet, for
only after several multiples of the RTT may as well have been lost.} example, that arrives only after several multiples of the RTT may as
well have been lost. See section 4.1.1 of [RFC6703] for examination
of unusual packet delays and application performance estimation.}
+ If the packet is duplicated along the path (or paths) so that + If the packet is duplicated along the path (or paths) so that
multiple non-corrupt copies arrive at the destination, then the multiple non-corrupt copies arrive at the destination, then the
packet is counted as received, and the first copy to arrive packet is counted as received, and the first copy to arrive
determines the packet's one-way delay. determines the packet's one-way delay.
+ If the packet is fragmented and if, for whatever reason, reassembly + If the packet is fragmented and if, for whatever reason, reassembly
does not occur, then the packet will be deemed lost. does not occur, then the packet will be deemed lost.
+ The packet is standard-formed, the default criteria for all metric
definitions defined in Section 15 of [RFC2330], otherwise the packet
will be deemed lost.
3.6. Methodologies: 3.6. Methodologies:
As with other Type-P-* metrics, the detailed methodology will depend As with other Type-P-* metrics, the detailed methodology will depend
on the Type-P (e.g., protocol number, UDP/TCP port number, size, on the Type-P (e.g., protocol number, UDP/TCP port number, size,
precedence). precedence).
Generally, for a given Type-P, the methodology would proceed as Generally, for a given Type-P, the methodology would proceed as
follows: follows:
+ Arrange that Src and Dst are synchronized; that is, that they have + Arrange that Src and Dst are synchronized; that is, that they have
skipping to change at page 9, line 31 skipping to change at page 10, line 38
filled with randomized bits to avoid a situation in which the filled with randomized bits to avoid a situation in which the
measured delay is lower than it would otherwise be due to compression measured delay is lower than it would otherwise be due to compression
techniques along the path. Note that use of transport layer techniques along the path. Note that use of transport layer
encryption will counteract the deployment of network-based analysis encryption will counteract the deployment of network-based analysis
and may reduce the adoption of payload optimizations like and may reduce the adoption of payload optimizations like
compression. compression.
+ At the Dst host, arrange to receive the packet. + At the Dst host, arrange to receive the packet.
+ At the Src host, place a timestamp in the prepared Type-P packet, + At the Src host, place a timestamp in the prepared Type-P packet,
and send it towards Dst. and send it towards Dst (ideally minimizing time before sending).
+ If the packet arrives within a reasonable period of time, take a + If the packet arrives within a reasonable period of time, take a
timestamp as soon as possible upon the receipt of the packet. By timestamp as soon as possible upon the receipt of the packet. By
subtracting the two timestamps, an estimate of one-way delay can be subtracting the two timestamps, an estimate of one-way delay can be
computed. Error analysis of a given implementation of the method computed. Error analysis of a given implementation of the method
must take into account the closeness of synchronization between Src must take into account the closeness of synchronization between Src
and Dst. If the delay between Src's timestamp and the actual sending and Dst. If the delay between Src's timestamp and the actual sending
of the packet is known, then the estimate could be adjusted by of the packet is known, then the estimate could be adjusted by
subtracting this amount; uncertainty in this value must be taken into subtracting this amount; uncertainty in this value must be taken into
account in error analysis. Similarly, if the delay between the account in error analysis. Similarly, if the delay between the
actual receipt of the packet and Dst's timestamp is known, then the actual receipt of the packet and Dst's timestamp is known, then the
estimate could be adjusted by subtracting this amount; uncertainty in estimate could be adjusted by subtracting this amount; uncertainty in
this value must be taken into account in error analysis. See the this value must be taken into account in error analysis. See the
next section, "Errors and Uncertainties", for a more detailed next section, "Errors and Uncertainties", for a more detailed
discussion. discussion.
+ If the packet fails to arrive within a reasonable period of time, + If the packet fails to arrive within a reasonable period of time,
the one-way delay is taken to be undefined (informally, infinite). Tmax, the one-way delay is taken to be undefined (informally,
Note that the threshold of 'reasonable' is a parameter of the infinite). Note that the threshold of 'reasonable' is a parameter of
methodology. These points are examined in detail in [RFC6703], the metric. These points are examined in detail in [RFC6703],
including analysis preferences to assign undefined delay to packets including analysis preferences to assign undefined delay to packets
that fail to arrive with the difficulties emerging from the informal that fail to arrive with the difficulties emerging from the informal
"infinite delay" assignment, and an estimation of an upper bound on "infinite delay" assignment, and an estimation of an upper bound on
waiting time for packets in transit. Further, enforcing a specific waiting time for packets in transit. Further, enforcing a specific
constant waiting time on stored singletons of one-way delay is constant waiting time on stored singletons of one-way delay is
compliant with this specification and may allow the results to serve compliant with this specification and may allow the results to serve
more than one reporting audience. more than one reporting audience.
Issues such as the packet format, the means by which Dst knows when Issues such as the packet format, the means by which Dst knows when
to expect the test packet, and the means by which Src and Dst are to expect the test packet, and the means by which Src and Dst are
skipping to change at page 12, line 40 skipping to change at page 13, line 46
If the systematic error (the constant bias in measured values) can be If the systematic error (the constant bias in measured values) can be
determined, it can be compensated for in the reported results. determined, it can be compensated for in the reported results.
reported value = measured value - systematic error reported value = measured value - systematic error
therefore therefore
reported value = true value + random error reported value = true value + random error
The goal of calibration is to determine the systematic and random The goal of calibration is to determine the systematic and random
error generated by the instruments themselves in as much detail as error generated by the hosts themselves in as much detail as
possible. At a minimum, a bound ("e") should be found such that the possible. At a minimum, a bound ("e") should be found such that the
reported value is in the range (true value - e) to (true value + e) reported value is in the range (true value - e) to (true value + e)
at least 95 percent of the time. We call "e" the calibration error at least 95 percent of the time. We call "e" the calibration error
for the measurements. It represents the degree to which the values for the measurements. It represents the degree to which the values
produced by the measurement instrument are repeatable; that is, how produced by the measurement host are repeatable; that is, how closely
closely an actual delay of 30 ms is reported as 30 ms. {Comment: 95 an actual delay of 30 ms is reported as 30 ms. {Comment: 95 percent
percent was chosen because (1) some confidence level is desirable to was chosen because (1) some confidence level is desirable to be able
be able to remove outliers, which will be found in measuring any to remove outliers, which will be found in measuring any physical
physical property; (2) a particular confidence level should be property; (2) a particular confidence level should be specified so
specified so that the results of independent implementations can be that the results of independent implementations can be compared; and
compared; and (3) even with a prototype user-level implementation, (3) even with a prototype user-level implementation, 95% was loose
95% was loose enough to exclude outliers.} enough to exclude outliers.}
From the discussion in the previous two sections, the error in From the discussion in the previous two sections, the error in
measurements could be bounded by determining all the individual measurements could be bounded by determining all the individual
uncertainties, and adding them together to form uncertainties, and adding them together to form
Esynch(t) + Rsource + Rdest + Hsource + Hdest. Esynch(t) + Rsource + Rdest + Hsource + Hdest.
However, reasonable bounds on both the clock-related uncertainty However, reasonable bounds on both the clock-related uncertainty
captured by the first three terms and the host-related uncertainty captured by the first three terms and the host-related uncertainty
captured by the last two terms should be possible by careful design captured by the last two terms should be possible by careful design
techniques and calibrating the instruments using a known, isolated, techniques and calibrating the hosts using a known, isolated, network
network in a lab. in a lab.
For example, the clock-related uncertainties are greatly reduced For example, the clock-related uncertainties are greatly reduced
through the use of a GPS time source. The sum of Esynch(t) + Rsource through the use of a GPS time source. The sum of Esynch(t) + Rsource
+ Rdest is small, and is also bounded for the duration of the + Rdest is small, and is also bounded for the duration of the
measurement because of the global time source. measurement because of the global time source.
The host-related uncertainties, Hsource + Hdest, could be bounded by The host-related uncertainties, Hsource + Hdest, could be bounded by
connecting two instruments back-to-back with a high-speed serial link connecting two hosts back-to-back with a high-speed serial link or
or isolated LAN segment. In this case, repeated measurements are isolated LAN segment. In this case, repeated measurements are
measuring the same one-way delay. measuring the same one-way delay.
If the test packets are small, such a network connection has a If the test packets are small, such a network connection has a
minimal delay that may be approximated by zero. The measured delay minimal delay that may be approximated by zero. The measured delay
therefore contains only systematic and random error in the therefore contains only systematic and random error in the
instrumentation. The "average value" of repeated measurements is the measurement hosts. The "average value" of repeated measurements is
systematic error, and the variation is the random error. the systematic error, and the variation is the random error.
One way to compute the systematic error, and the random error to a One way to compute the systematic error, and the random error to a
95% confidence is to repeat the experiment many times - at least 95% confidence is to repeat the experiment many times - at least
hundreds of tests. The systematic error would then be the median. hundreds of tests. The systematic error would then be the median.
The random error could then be found by removing the systematic error The random error could then be found by removing the systematic error
from the measured values. The 95% confidence interval would be the from the measured values. The 95% confidence interval would be the
range from the 2.5th percentile to the 97.5th percentile of these range from the 2.5th percentile to the 97.5th percentile of these
deviations from the true value. The calibration error "e" could then deviations from the true value. The calibration error "e" could then
be taken to be the largest absolute value of these two numbers, plus be taken to be the largest absolute value of these two numbers, plus
the clock-related uncertainty. {Comment: as described, this bound is the clock-related uncertainty. {Comment: as described, this bound is
relatively loose since the uncertainties are added, and the absolute relatively loose since the uncertainties are added, and the absolute
value of the largest deviation is used. As long as the resulting value of the largest deviation is used. As long as the resulting
value is not a significant fraction of the measured values, it is a value is not a significant fraction of the measured values, it is a
reasonable bound. If the resulting value is a significant fraction reasonable bound. If the resulting value is a significant fraction
of the measured values, then more exact methods will be needed to of the measured values, then more exact methods will be needed to
compute the calibration error.} compute the calibration error.}
Note that random error is a function of measurement load. For Note that random error is a function of measurement load. For
example, if many paths will be measured by one instrument, this might example, if many paths will be measured by one host, this might
increase interrupts, process scheduling, and disk I/O (for example, increase interrupts, process scheduling, and disk I/O (for example,
recording the measurements), all of which may increase the random recording the measurements), all of which may increase the random
error in measured singletons. Therefore, in addition to minimal load error in measured singletons. Therefore, in addition to minimal load
measurements to find the systematic error, calibration measurements measurements to find the systematic error, calibration measurements
should be performed with the same measurement load that the should be performed with the same measurement load that the hosts
instruments will see in the field. will see in the field.
We wish to reiterate that this statistical treatment refers to the We wish to reiterate that this statistical treatment refers to the
calibration of the instrument; it is used to "calibrate the meter calibration of the host; it is used to "calibrate the meter stick"
stick" and say how well the meter stick reflects reality. and say how well the meter stick reflects reality.
In addition to calibrating the instruments for finite one-way delay, In addition to calibrating the hosts for finite one-way delay, two
two checks should be made to ensure that packets reported as losses checks should be made to ensure that packets reported as losses were
were really lost. First, the threshold for loss should be verified. really lost. First, the threshold for loss should be verified. In
In particular, ensure the "reasonable" threshold is reasonable: that particular, ensure the "reasonable" threshold is reasonable: that it
it is very unlikely a packet will arrive after the threshold value, is very unlikely a packet will arrive after the threshold value, and
and therefore the number of packets lost over an interval is not therefore the number of packets lost over an interval is not
sensitive to the error bound on measurements. Second, consider the sensitive to the error bound on measurements. Second, consider the
possibility that a packet arrives at the network interface, but is possibility that a packet arrives at the network interface, but is
lost due to congestion on that interface or to other resource lost due to congestion on that interface or to other resource
exhaustion (e.g. buffers) in the instrument. exhaustion (e.g. buffers) in the host.
3.8. Reporting the metric: 3.8. Reporting the metric:
The calibration and context in which the metric is measured MUST be The calibration and context in which the metric is measured MUST be
carefully considered, and SHOULD always be reported along with metric carefully considered, and SHOULD always be reported along with metric
results. We now present four items to consider: the Type-P of test results. We now present four items to consider: the Type-P of test
packets, the threshold of infinite delay (if any), error calibration, packets, the threshold of infinite delay (if any), error calibration,
and the path traversed by the test packets. This list is not and the path traversed by the test packets. This list is not
exhaustive; any additional information that could be useful in exhaustive; any additional information that could be useful in
interpreting applications of the metrics should also be reported (see interpreting applications of the metrics should also be reported (see
[RFC6703] for extensive discussion of reporting considerations for [RFC6703] for extensive discussion of reporting considerations for
different audiences). different audiences).
3.8.1. Type-P 3.8.1. Type-P
As noted in the Framework document [1], the value of the metric may As noted in the Framework document [RFC2330], the value of the metric
depend on the type of IP packets used to make the measurement, or may depend on the type of IP packets used to make the measurement, or
"type-P". The value of Type-P-One-way-Delay could change if the "type-P". The value of Type-P-One-way-Delay could change if the
protocol (UDP or TCP), port number, size, or arrangement for special protocol (UDP or TCP), port number, size, or arrangement for special
treatment (e.g., IP precedence or RSVP) changes. The exact Type-P treatment (e.g., IP precedence or RSVP) changes. The exact Type-P
used to make the measurements MUST be accurately reported. used to make the measurements MUST be accurately reported.
3.8.2. Loss Threshold 3.8.2. Loss Threshold
In addition, the threshold (or methodology to distinguish) between a In addition, the threshold (or methodology to distinguish) between a
large finite delay and loss MUST be reported. large finite delay and loss MUST be reported.
skipping to change at page 15, line 16 skipping to change at page 16, line 21
+ If the systematic error can be determined, it SHOULD be removed + If the systematic error can be determined, it SHOULD be removed
from the measured values. from the measured values.
+ You SHOULD also report the calibration error, e, such that the true + You SHOULD also report the calibration error, e, such that the true
value is the reported value plus or minus e, with 95% confidence (see value is the reported value plus or minus e, with 95% confidence (see
the last section.) the last section.)
+ If possible, the conditions under which a test packet with finite + If possible, the conditions under which a test packet with finite
delay is reported as lost due to resource exhaustion on the delay is reported as lost due to resource exhaustion on the
measurement instrument SHOULD be reported. measurement host SHOULD be reported.
3.8.4. Path 3.8.4. Path
Finally, the path traversed by the packet SHOULD be reported, if Finally, the path traversed by the packet SHOULD be reported, if
possible. In general it is impractical to know the precise path a possible. In general it is impractical to know the precise path a
given packet takes through the network. The precise path may be given packet takes through the network. The precise path may be
known for certain Type-P on short or stable paths. If Type-P known for certain Type-P on short or stable paths. If Type-P
includes the record route (or loose-source route) option in the IP includes the record route (or loose-source route) option in the IP
header, and the path is short enough, and all routers* on the path header, and the path is short enough, and all routers* on the path
support record (or loose-source) route, then the path will be support record (or loose-source) route, then the path will be
skipping to change at page 15, line 47 skipping to change at page 17, line 4
4. A Definition for Samples of One-way Delay 4. A Definition for Samples of One-way Delay
Given the singleton metric Type-P-One-way-Delay, we now define one Given the singleton metric Type-P-One-way-Delay, we now define one
particular sample of such singletons. The idea of the sample is to particular sample of such singletons. The idea of the sample is to
select a particular binding of the parameters Src, Dst, and Type-P, select a particular binding of the parameters Src, Dst, and Type-P,
then define a sample of values of parameter T. The means for then define a sample of values of parameter T. The means for
defining the values of T is to select a beginning time T0, a final defining the values of T is to select a beginning time T0, a final
time Tf, and an average rate lambda, then define a pseudo-random time Tf, and an average rate lambda, then define a pseudo-random
Poisson process of rate lambda, whose values fall between T0 and Tf. Poisson process of rate lambda, whose values fall between T0 and Tf.
The time interval between successive values of T will then average 1/ The time interval between successive values of T will then average 1/
lambda. lambda.
{Comment: Note that Poisson sampling is only one way of defining a Note that Poisson sampling is only one way of defining a sample.
sample. Poisson has the advantage of limiting bias, but other Poisson has the advantage of limiting bias, but other methods of
methods of sampling might be appropriate for different situations. sampling will be appropriate for different situations. For example,
a truncated Poisson distribution may be needed to avoid reactive
We encourage others who find such appropriate cases to use this network state changes during intervals of inactivity, see section 4.6
general framework and submit their sampling method for of [RFC7321]. Sometimes, the goal is sampling with a known bias, and
standardization.} [RFC3432] describes a method for periodic sampling with random start
times.
>>> Editor proposal: Add ref to RFC 3432 Periodic sampling above.
4.1. Metric Name: 4.1. Metric Name:
Type-P-One-way-Delay-Poisson-Stream Type-P-One-way-Delay-Poisson-Stream
4.2. Metric Parameters: 4.2. Metric Parameters:
+ Src, the IP address of a host + Src, the IP address of a host
+ Dst, the IP address of a host + Dst, the IP address of a host
+ T0, a time + T0, a time
+ Tf, a time + Tf, a time
+ lambda, a rate in reciprocal seconds + Tmax, a loss threshold waiting time
+ lambda, a rate in reciprocal seconds (or parameters for another
distribution)
4.3. Metric Units: 4.3. Metric Units:
A sequence of pairs; the elements of each pair are: A sequence of pairs; the elements of each pair are:
+ T, a time, and + T, a time, and
+ dT, either a real number or an undefined number of seconds. + dT, either a real number or an undefined number of seconds.
The values of T in the sequence are monotonic increasing. Note that The values of T in the sequence are monotonic increasing. Note that
skipping to change at page 17, line 8 skipping to change at page 18, line 13
ending at or after Tf. Those time values greater than or equal to T0 ending at or after Tf. Those time values greater than or equal to T0
and less than or equal to Tf are then selected. At each of the times and less than or equal to Tf are then selected. At each of the times
in this process, we obtain the value of Type-P-One-way-Delay at this in this process, we obtain the value of Type-P-One-way-Delay at this
time. The value of the sample is the sequence made up of the time. The value of the sample is the sequence made up of the
resulting <time, delay> pairs. If there are no such pairs, the resulting <time, delay> pairs. If there are no such pairs, the
sequence is of length zero and the sample is said to be empty. sequence is of length zero and the sample is said to be empty.
4.5. Discussion: 4.5. Discussion:
The reader should be familiar with the in-depth discussion of Poisson The reader should be familiar with the in-depth discussion of Poisson
sampling in the Framework document [1], which includes methods to sampling in the Framework document [RFC2330], which includes methods
compute and verify the pseudo-random Poisson process. to compute and verify the pseudo-random Poisson process.
We specifically do not constrain the value of lambda, except to note We specifically do not constrain the value of lambda, except to note
the extremes. If the rate is too large, then the measurement traffic the extremes. If the rate is too large, then the measurement traffic
will perturb the network, and itself cause congestion. If the rate will perturb the network, and itself cause congestion. If the rate
is too small, then you might not capture interesting network is too small, then you might not capture interesting network
behavior. {Comment: We expect to document our experiences with, and behavior. {Comment: We expect to document our experiences with, and
suggestions for, lambda elsewhere, culminating in a "best current suggestions for, lambda elsewhere, culminating in a "best current
practices" document.} practices" document.}
Since a pseudo-random number sequence is employed, the sequence of Since a pseudo-random number sequence is employed, the sequence of
skipping to change at page 17, line 47 skipping to change at page 19, line 4
new time values T0' and Tf' such that T0 <= T0' <= Tf' <= Tf, the new time values T0' and Tf' such that T0 <= T0' <= Tf' <= Tf, the
subsequence of the given sample whose time values fall between T0' subsequence of the given sample whose time values fall between T0'
and Tf' are also a valid Type-P-One-way-Delay-Poisson-Stream sample. and Tf' are also a valid Type-P-One-way-Delay-Poisson-Stream sample.
4.6. Methodologies: 4.6. Methodologies:
The methodologies follow directly from: The methodologies follow directly from:
+ the selection of specific times, using the specified Poisson + the selection of specific times, using the specified Poisson
arrival process, and arrival process, and
+ the methodologies discussion already given for the singleton Type- + the methodologies discussion already given for the singleton Type-
P-One-way-Delay metric. P-One-way-Delay metric.
Care must, of course, be given to correctly handle out-of-order Care must, of course, be given to correctly handle out-of-order
arrival of test packets; it is possible that the Src could send one arrival of test packets; it is possible that the Src could send one
test packet at TS[i], then send a second one (later) at TS[i+1], test packet at TS[i], then send a second one (later) at TS[i+1],
while the Dst could receive the second test packet at TR[i+1], and while the Dst could receive the second test packet at TR[i+1], and
then receive the first one (later) at TR[i]. then receive the first one (later) at TR[i]. Metrics for reordering
may be found in [RFC4737].
>>> Editor proposal: Add ref to RFC 4737 Reordering metric above.
4.7. Errors and Uncertainties: 4.7. Errors and Uncertainties:
In addition to sources of errors and uncertainties associated with In addition to sources of errors and uncertainties associated with
methods employed to measure the singleton values that make up the methods employed to measure the singleton values that make up the
sample, care must be given to analyze the accuracy of the Poisson sample, care must be given to analyze the accuracy of the Poisson
process with respect to the wire-times of the sending of the test process with respect to the wire-times of the sending of the test
packets. Problems with this process could be caused by several packets. Problems with this process could be caused by several
things, including problems with the pseudo-random number techniques things, including problems with the pseudo-random number techniques
used to generate the Poisson arrival process, or with jitter in the used to generate the Poisson arrival process, or with jitter in the
skipping to change at page 19, line 18 skipping to change at page 20, line 23
<T3, undefined> <T3, undefined>
<T4, 90 msec> <T4, 90 msec>
<T5, 500 msec> <T5, 500 msec>
> >
Then the 50th percentile would be 110 msec, since 90 msec and 100 Then the 50th percentile would be 110 msec, since 90 msec and 100
msec are smaller and 500 msec and 'undefined' are larger. See msec are smaller and 500 msec and 'undefined' are larger. See
Section 11.3 of [1] for computing percentiles. Section 11.3 of [RFC2330] for computing percentiles.
Note that if the possibility that a packet with finite delay is Note that if the possibility that a packet with finite delay is
reported as lost is significant, then a high percentile (90th or reported as lost is significant, then a high percentile (90th or
95th) might be reported as infinite instead of finite. 95th) might be reported as infinite instead of finite.
5.2. Type-P-One-way-Delay-Median 5.2. Type-P-One-way-Delay-Median
Given a Type-P-One-way-Delay-Poisson-Stream, the median of all the dT Given a Type-P-One-way-Delay-Poisson-Stream, the median of all the dT
values in the Stream. In computing the median, undefined values are values in the Stream. In computing the median, undefined values are
treated as infinitely large. As with Type-P-One-way-Delay- treated as infinitely large. As with Type-P-One-way-Delay-
skipping to change at page 20, line 43 skipping to change at page 21, line 52
packets into the network. The measurement parameters MUST be packets into the network. The measurement parameters MUST be
carefully selected so that the measurements inject trivial amounts of carefully selected so that the measurements inject trivial amounts of
additional traffic into the networks they measure. If they inject additional traffic into the networks they measure. If they inject
"too much" traffic, they can skew the results of the measurement, and "too much" traffic, they can skew the results of the measurement, and
in extreme cases cause congestion and denial of service. in extreme cases cause congestion and denial of service.
The measurements themselves could be harmed by routers giving The measurements themselves could be harmed by routers giving
measurement traffic a different priority than "normal" traffic, or by measurement traffic a different priority than "normal" traffic, or by
an attacker injecting artificial measurement traffic. If routers can an attacker injecting artificial measurement traffic. If routers can
recognize measurement traffic and treat it separately, the recognize measurement traffic and treat it separately, the
measurements will not reflect actual user traffic. If an attacker measurements will not reflect actual user traffic. Therefore, the
injects artificial traffic that is accepted as legitimate, the loss measurement methodologies SHOULD include appropriate techniques to
rate will be artificially lowered. Therefore, the measurement reduce the probability measurement traffic can be distinguished from
methodologies SHOULD include appropriate techniques to reduce the "normal" traffic.
probability measurement traffic can be distinguished from "normal"
traffic. Authentication techniques, such as digital signatures, may If an attacker injects packets emulating traffic that are accepted as
be used where appropriate to guard against injected traffic attacks. legitimate, the loss ratio or other measured values could be
corrupted. Authentication techniques, such as digital signatures,
may be used where appropriate to guard against injected traffic
attacks.
The privacy concerns of network measurement are limited by the active The privacy concerns of network measurement are limited by the active
measurements described in this memo. Unlike passive measurements, measurements described in this memo. Unlike passive measurements,
there can be no release of existing user data. there can be no release of existing user data.
7. IANA Considerations 7. IANA Considerations
This memo makes no requests of IANA. This memo makes no requests of IANA.
8. Acknowledgements 8. Acknowledgements
Special thanks are due to Vern Paxson of Lawrence Berkeley Labs for Special thanks are due to Vern Paxson of Lawrence Berkeley Labs for
his helpful comments on issues of clock uncertainty and statistics. his helpful comments on issues of clock uncertainty and statistics.
Thanks also to Garry Couch, Will Leland, Andy Scherrer, Sean Shapira, Thanks also to Garry Couch, Will Leland, Andy Scherrer, Sean Shapira,
and Roland Wittig for several useful suggestions. and Roland Wittig for several useful suggestions.
9. Refetrences (temporary) 9. References
[1] Paxson, V., Almes, G., Mahdavi, J. and M. Mathis, "Framework for
IP Performance Metrics", RFC 2330, May 1998.
[2] Almes, G., Kalidindi, S. and M. Zekauskas, "A One-way Packet
Loss Metric for IPPM", RFC 2680, September 1999.
[3] Mills, D., "Network Time Protocol (v3)", RFC 1305, April 1992.
[4] Mahdavi J. and V. Paxson, "IPPM Metrics for Measuring
Connectivity", RFC 2678, September 1999.
[5] Postel, J., "Internet Protocol", STD 5, RFC 791, September 1981.
[6] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[7] Bradner, S., "The Internet Standards Process -- Revision 3", BCP
9, RFC 2026, October 1996.
10. References 9.1. Normative References
10.1. Normative References [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, September
1981.
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision [RFC2026] Bradner, S., "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, October 1996. 3", BCP 9, RFC 2026, October 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis, [RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis,
"Framework for IP Performance Metrics", RFC 2330, May "Framework for IP Performance Metrics", RFC 2330, May
1998. 1998.
[RFC2678] Mahdavi, J. and V. Paxson, "IPPM Metrics for Measuring
Connectivity", RFC 2678, September 1999.
[RFC2679] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way [RFC2679] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way
Delay Metric for IPPM", RFC 2679, September 1999. Delay Metric for IPPM", RFC 2679, September 1999.
[RFC2680] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way [RFC2680] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way
Packet Loss Metric for IPPM", RFC 2680, September 1999. Packet Loss Metric for IPPM", RFC 2680, September 1999.
[RFC3432] Raisanen, V., Grotefeld, G., and A. Morton, "Network [RFC3432] Raisanen, V., Grotefeld, G., and A. Morton, "Network
performance measurement with periodic streams", RFC 3432, performance measurement with periodic streams", RFC 3432,
November 2002. November 2002.
skipping to change at page 22, line 34 skipping to change at page 23, line 27
Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
RFC 5357, October 2008. RFC 5357, October 2008.
[RFC5657] Dusseault, L. and R. Sparks, "Guidance on Interoperation [RFC5657] Dusseault, L. and R. Sparks, "Guidance on Interoperation
and Implementation Reports for Advancement to Draft and Implementation Reports for Advancement to Draft
Standard", BCP 9, RFC 5657, September 2009. Standard", BCP 9, RFC 5657, September 2009.
[RFC5835] Morton, A. and S. Van den Berghe, "Framework for Metric [RFC5835] Morton, A. and S. Van den Berghe, "Framework for Metric
Composition", RFC 5835, April 2010. Composition", RFC 5835, April 2010.
[RFC5905] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network
Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, June 2010.
[RFC6049] Morton, A. and E. Stephan, "Spatial Composition of [RFC6049] Morton, A. and E. Stephan, "Spatial Composition of
Metrics", RFC 6049, January 2011. Metrics", RFC 6049, January 2011.
[RFC6576] Geib, R., Morton, A., Fardid, R., and A. Steinmitz, "IP [RFC6576] Geib, R., Morton, A., Fardid, R., and A. Steinmitz, "IP
Performance Metrics (IPPM) Standard Advancement Testing", Performance Metrics (IPPM) Standard Advancement Testing",
BCP 176, RFC 6576, March 2012. BCP 176, RFC 6576, March 2012.
[RFC6703] Morton, A., Ramachandran, G., and G. Maguluri, "Reporting [RFC6703] Morton, A., Ramachandran, G., and G. Maguluri, "Reporting
IP Network Performance Metrics: Different Points of View", IP Network Performance Metrics: Different Points of View",
RFC 6703, August 2012. RFC 6703, August 2012.
10.2. Informative References [RFC7321] McGrew, D. and P. Hoffman, "Cryptographic Algorithm
Implementation Requirements and Usage Guidance for
Encapsulating Security Payload (ESP) and Authentication
Header (AH)", RFC 7321, August 2014.
9.2. Informative References
[ADK] Scholz, F. and M. Stephens, "K-sample Anderson-Darling [ADK] Scholz, F. and M. Stephens, "K-sample Anderson-Darling
Tests of fit, for continuous and discrete cases", Tests of fit, for continuous and discrete cases",
University of Washington, Technical Report No. 81, May University of Washington, Technical Report No. 81, May
1986. 1986.
[I-D.ietf-ippm-testplan-rfc2679] [I-D.ietf-ippm-testplan-rfc2679]
Ciavattone, L., Geib, R., Morton, A., and M. Wieser, "Test Ciavattone, L., Geib, R., Morton, A., and M. Wieser, "Test
Plan and Results Supporting Advancement of RFC 2679 on the Plan and Results Supporting Advancement of RFC 2679 on the
Standards Track", draft-ietf-ippm-testplan-rfc2679-03 Standards Track", draft-ietf-ippm-testplan-rfc2679-03
(work in progress), September 2012. (work in progress), September 2012.
[RFC3931] Lau, J., Townsley, M., and I. Goyret, "Layer Two Tunneling [RFC3931] Lau, J., Townsley, M., and I. Goyret, "Layer Two Tunneling
Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005. Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005.
[RFC4737] Morton, A., Ciavattone, L., Ramachandran, G., Shalunov,
S., and J. Perser, "Packet Reordering Metrics", RFC 4737,
November 2006.
[RFC6390] Clark, A. and B. Claise, "Guidelines for Considering New
Performance Metric Development", BCP 170, RFC 6390,
October 2011.
[RFC6808] Ciavattone, L., Geib, R., Morton, A., and M. Wieser, "Test
Plan and Results Supporting Advancement of RFC 2679 on the
Standards Track", RFC 6808, December 2012.
Authors' Addresses Authors' Addresses
Guy Almes Guy Almes
Texas A&M Texas A&M
Email: galmes@tamu.edu
Sunil Kalidindi Sunil Kalidindi
Ixia Ixia
Email: skalidindi@ixiacom.com
Matt Zekauskas Matt Zekauskas
Internet2 Internet2
Email: matt@internet2.edu Email: matt@internet2.edu
Al Morton (editor) Al Morton (editor)
AT&T Labs AT&T Labs
200 Laurel Avenue South 200 Laurel Avenue South
Middletown, NJ 07748 Middletown, NJ 07748
USA USA
 End of changes. 54 change blocks. 
177 lines changed or deleted 243 lines changed or added

This html diff was produced by rfcdiff 1.41. The latest version is available from http://tools.ietf.org/tools/rfcdiff/