draft-ietf-ippm-multimetrics-01.txt   draft-ietf-ippm-multimetrics-02.txt 
Network Working Group E. Stephan Network Working Group E. Stephan
Internet-Draft France Telecom Internet-Draft France Telecom
Expires: December 27, 2006 L. Liang Intended status: Informational L. Liang
University of Surrey Expires: April 25, 2007 University of Surrey
A. Morton A. Morton
AT&T Labs AT&T Labs
June 25, 2006 October 22, 2006
IP Performance Metrics (IPPM) for spatial and multicast IP Performance Metrics (IPPM) for spatial and multicast
draft-ietf-ippm-multimetrics-01 draft-ietf-ippm-multimetrics-02
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The Internet Society (2006).
Abstract Abstract
The IETF IP Performance Metrics (IPPM) working group has standardized The IETF IP Performance Metrics (IPPM) working group has standardized
metrics for measuring end-to-end performance between 2 points. This metrics for measuring end-to-end performance between 2 points. This
memo defines 2 sets of metrics to extend these end-to-end ones. It memo defines 2 sets of metrics to extend these end-to-end ones. It
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Multiparty metric . . . . . . . . . . . . . . . . . . . . 5 2.1. Multiparty metric . . . . . . . . . . . . . . . . . . . . 5
2.2. Spatial metric . . . . . . . . . . . . . . . . . . . . . . 5 2.2. Spatial metric . . . . . . . . . . . . . . . . . . . . . . 5
2.3. Spatial metric points of interest . . . . . . . . . . . . 5 2.3. Spatial metric points of interest . . . . . . . . . . . . 5
2.4. One-to-group metric . . . . . . . . . . . . . . . . . . . 5 2.4. One-to-group metric . . . . . . . . . . . . . . . . . . . 5
2.5. One-to-group metric points of interest . . . . . . . . . . 5 2.5. One-to-group metric points of interest . . . . . . . . . . 5
2.6. Reference point . . . . . . . . . . . . . . . . . . . . . 5 2.6. Reference point . . . . . . . . . . . . . . . . . . . . . 5
2.7. Group of singletons . . . . . . . . . . . . . . . . . . . 6 2.7. Vector . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Motivations for spatial and one-to-group metrics . . . . . . . 6 2.8. Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. spatial metrics . . . . . . . . . . . . . . . . . . . . . 6 3. Motivations for spatial and one-to-group metrics . . . . . . . 7
3.2. One-to-group metrics . . . . . . . . . . . . . . . . . . . 7 3.1. spatial metrics . . . . . . . . . . . . . . . . . . . . . 7
3.3. Discussion on Group-to-one and Group-to-group metrics . . 8 3.2. One-to-group metrics . . . . . . . . . . . . . . . . . . . 8
4. Spatial metrics definitions . . . . . . . . . . . . . . . . . 8 3.3. Discussion on Group-to-one and Group-to-group metrics . . 9
4.1. A Definition for Spatial One-way Delay Stream . . . . . . 8 4. Spatial metrics definitions . . . . . . . . . . . . . . . . . 9
4.2. A Definition of a sample of One-way Delay of a sub path . 11 4.1. A Definition for Spatial One-way Delay Vector . . . . . . 10
4.3. A Definition for Spatial One-way Packet Loss Stream . . . 13 4.2. A Definition of a sample of One-way Delay of a sub path . 12
4.4. A Definition for Spatial One-way Jitter Stream . . . . . . 15 4.3. A Definition for Spatial One-way Packet Loss Vector . . . 15
4.5. Pure Passive Metrics . . . . . . . . . . . . . . . . . . . 17 4.4. A Definition for Spatial One-way Jitter Vector . . . . . . 16
4.6. Discussion on spatial statistics . . . . . . . . . . . . . 19 4.5. Pure Passive Metrics . . . . . . . . . . . . . . . . . . . 18
5. One-to-group metrics definitions . . . . . . . . . . . . . . . 19 4.6. Discussion on spatial statistics . . . . . . . . . . . . . 20
5.1. A Definition for one-to-group One-way Delay Stream . . . . 19 5. One-to-group metrics definitions . . . . . . . . . . . . . . . 20
5.2. A Definition for one-to-group One-way Packet Loss 5.1. A Definition for one-to-group One-way Delay . . . . . . . 20
Stream . . . . . . . . . . . . . . . . . . . . . . . . . . 20 5.2. A Definition for one-to-group One-way Packet Loss . . . . 21
5.3. A Definition for one-to-group One-way Jitter Stream . . . 21 5.3. A Definition for one-to-group One-way Jitter . . . . . . . 21
5.4. Discussion on one-to-group statistics . . . . . . . . . . 22 5.4. Discussion on one-to-group statistics . . . . . . . . . . 23
6. Extension from one-to-one to one-to-many measurement . . . . . 24 6. Extension from one-to-one to one-to-many measurement . . . . . 26
7. Open issues . . . . . . . . . . . . . . . . . . . . . . . . . 25 7. Open issues . . . . . . . . . . . . . . . . . . . . . . . . . 27
8. Security Considerations . . . . . . . . . . . . . . . . . . . 25 8. Security Considerations . . . . . . . . . . . . . . . . . . . 27
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 27
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 28
11.1. Normative References . . . . . . . . . . . . . . . . . . . 26 11.1. Normative References . . . . . . . . . . . . . . . . . . . 28
11.2. Informative References . . . . . . . . . . . . . . . . . . 26 11.2. Informative References . . . . . . . . . . . . . . . . . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 28 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 29
Intellectual Property and Copyright Statements . . . . . . . . . . 29 Intellectual Property and Copyright Statements . . . . . . . . . . 30
1. Introduction 1. Introduction
The metrics specified in this memo are built on notions introduced The metrics specified in this memo are built on notions introduced
and discussed in the IPPM Framework document, RFC 2330 [RFC2330]. and discussed in the IPPM Framework document, RFC 2330 [RFC2330].
The reader should be familiar with these documents. The reader should be familiar with these documents.
This memo makes use of definitions of end-to-end One-way Delay This memo makes use of definitions of end-to-end One-way Delay
Metrics defined in the RFC 2679 [RFC2679] to define metrics for Metrics defined in the RFC 2679 [RFC2679] to define metrics for
decomposition of end-to-end one-way delays measurements. decomposition of end-to-end one-way delays measurements.
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o Network performance measurement for periodic streams, RFC 3432 o Network performance measurement for periodic streams, RFC 3432
[RFC3432]; [RFC3432];
o Packet Reordering Metric for IPPM [Work in progress]; o Packet Reordering Metric for IPPM [Work in progress];
Based on these works, this memo defines 2 kinds of multi party Based on these works, this memo defines 2 kinds of multi party
metrics. metrics.
Firstly it defines spatial metrics: Firstly it defines spatial metrics:
o A 'sample', called Type-P-Spatial-One-way-Delay-Stream, will be o A 'sample', called Type-P-Spatial-One-way-Delay-Vector, will be
introduced to decompose an end-to-end Type-P-One-way-Delay in a introduced to divide an end-to-end Type-P-One-way-Delay in a
spatial sequence of one-way delays. spatial sequence of one-way delays.
o A 'sample', called Type-P-Spatial-One-way-Packet-Loss-Stream, will o A 'sample', called Type-P-Spatial-One-way-Packet-Loss-Vector, will
be introduced to decompose an end-to-end Type-P-One-way-Packet- be introduced to divide an end-to-end Type-P-One-way-Packet-Loss
Loss in a spatial sequence of packet loss. in a spatial sequence of packet loss.
o Using the Type-P-Spatial-One-way-Delay-Stream metric, a 'sample', o Using the Type-P-Spatial-One-way-Delay-Vector metric, a 'sample',
called Type-P-Spatial-One-way-Jitter-Stream, will be introduced to called Type-P-Spatial-One-way-Jitter-Vector, will be introduced to
decompose an end-to-end Type-P-One-way-ipdv in a spatial sequence divide an end-to-end Type-P-One-way-ipdv in a spatial sequence of
of jitter. jitter.
o Using the Type-P-Spatial-One-way-Delay-Stream metric, a 'sample', o Using the Type-P-Spatial-One-way-Delay-Vector metric, a 'sample',
called Type-P-subpath-One-way-Delay-Stream, will be introduced to called Type-P-subpath-One-way-Delay-Stream, will be introduced to
define the one-way-delay between any host of the path. define the one-way-delay between a pair of host of the path. This
metric is similar to Type-P-One-way-Delay-Stream.
o Using Type-P-subpath-x-Stream, a 'sample' Type-P-Passive-x-Stream o Using Type-P-subpath-One-way-Delay-Stream, a 'sample' Type-P-
will be introduced to define the Passive metrics. These metrics Passive-One-way-Delay-Stream will be introduced to define passive
are designed for pure passive measurement methodology as metrics. These metrics are designed for pure passive measurement
introduced by PSAMP WG. methodology as introduced by PSAMP WG.
Then it defines one-to-group metrics. Then it defines one-to-group metrics.
o Using one test packet sent from one sender to a group of o Using one test packet sent from one sender to a group of
receivers, a 'sample', called Type-P-one-to-group-One-way-Delay- receivers, a 'sample', called Type-P-one-to-group-One-way-Delay-
Stream, will be introduced to define the list of Type-P-one-way- Vector, will be introduced to define the list of Type-P-one-way-
delay between this sender and the group of receivers. delay between this sender and the group of receivers.
o Using one test packet sent from one sender to a group of o Using one test packet sent from one sender to a group of
receivers, a 'sample', called Type-P-one-to-group-One-way-Packet- receivers, a 'sample', called Type-P-one-to-group-One-way-Packet-
Loss-Stream, will be introduced to define the list of Type-P-One- Loss-Vector, will be introduced to define the list of Type-P-One-
way-Packet-Loss between this sender and the group of receivers way-Packet-Loss between this sender and the group of receivers
o Using one test packet sent from one sender to a group of o Using one test packet sent from one sender to a group of
receivers, a 'sample', called Type-P-one-to-group-One-way-Jitter- receivers, a 'sample', called Type-P-one-to-group-One-way-Jitter-
Stream, will be introduced to define the list of Type-P-One-way- Vector, will be introduced to define the list of Type-P-One-way-
ipdv between this sender and the group of receivers ipdv between this sender and the group of receivers
o Then a discussion section presents the set of statistics that may o Then a discussion section presents the set of statistics that may
be computed on the top of these metrics to present the QoS in a be computed on the top of these metrics to present the QoS in a
view of a group of users as well as the requirements of relative view of a group of users as well as the requirements of relative
QoS on multiparty communications. QoS on multiparty communications.
2. Terminology 2. Terminology
2.1. Multiparty metric 2.1. Multiparty metric
A metric is said to be multiparty if the definition involved more A metric is said to be multiparty if the definition involved more
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Points of interest of One-to-group metrics are the set of host Points of interest of One-to-group metrics are the set of host
destinations receiving packets from the source (in addition to the destinations receiving packets from the source (in addition to the
source itself). source itself).
2.6. Reference point 2.6. Reference point
The centre/server in the one-to-group measurement that is controlled The centre/server in the one-to-group measurement that is controlled
by network operators can be a very good reference point where by network operators can be a very good reference point where
measurement data can be collected for further processing although the measurement data can be collected for further processing although the
actual measurements have to be carried out at all points of interest. actual measurements have to be carried out at all points of interest.
I.e., the measurement points will be all clients/receivers while the I.e., the measurement points will be all clients/receivers while the
reference point acts as source for the one-to-group metric. Thus, we reference point acts as source for the one-to-group metric. Thus, we
can define the reference point as the host while the statistic can define the reference point as the host while the statistic
calculation will be carried out. calculation will be carried out.
2.7. Group of singletons 2.7. Vector
A group of singletons is the set of results of the observation of the A group of singletons is the set of results of the observation of the
behaviour of the same packet at different places of a network. behaviour of the same packet at different places of a network.
A Vector is a set of singletons, which are a set of results of the
observation of the behaviour of the same packet at different places
of a network at different time. For instance, if One-way delay
singletons abserved at N receivers for Packet P sent by the source
Src are dT1, dT2,..., dTN, it can be say that a vector V with N
elements can be orgnized as {dT1, dT2,..., dTN}. The elements in one
vector are singletons distinct with each other in terms of both
measurement point and time. Given the vector V as an example, the
element dT1 is distinct from the rest by measured at receiver 1 at
time T1. Additional to a singleton, Vector gives information over a
space dimension.
2.8. Matrix
Several vectors can orgnize form up a Matrix, which contains results
observed in a sampling interval at different place of a network at
different time. For instance, given One-way delay vectors V1={dT11,
dT12,..., dT1N}, V2={dT21, dT22,..., dT2N},..., Vm={dTm1, dTm2,...,
dTmN} for Packet P1, P2,...,Pm, we can have a One-way delay Matrix
{V1, V2,...,Vm}. Additional to the information given by a Vector, a
Matrix is more powerful to present network performance in both space
and time dimensions. It normally corresponding to a sample.
The relation among Singleton, Vector and Matrix can be shown in the
following Fig 1.
one to group Singleton
/ Sample
Src Rcvr ..............................
..................R1dT1 R1dT2 R1dT3 R1dT4
`:=-.._
T `._ ``-..__
`. `- R2dT1 R2dT2 R2dT3 R2dT4
`-.
`-.
`._R3dT1 R3dT2 R3dT3 R3dT4
Vector Matrix
(space) (time)
Figure 1.
3. Motivations for spatial and one-to-group metrics 3. Motivations for spatial and one-to-group metrics
All IPPM metrics are defined for end-to-end measurement. These All IPPM metrics are defined for end-to-end measurement. These
metrics provide very good guides for measurement in the pair metrics provide very good guides for measurement in the pair
communications. However, further efforts should be put to define communications. However, further efforts should be put to define
metrics for multiparty measurements such as one to one trajectory metrics for multiparty measurements such as one to one trajectory
metrics and one to multipoint metrics. metrics and one to multipoint metrics.
3.1. spatial metrics 3.1. spatial metrics
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4. Spatial metrics definitions 4. Spatial metrics definitions
Spatial decomposition metrics are based on standard end-to-end Spatial decomposition metrics are based on standard end-to-end
metrics. metrics.
The definition of a spatial metric is coupled with the corresponding The definition of a spatial metric is coupled with the corresponding
end-to-end metric. The methodoly is based on the measure of the same end-to-end metric. The methodoly is based on the measure of the same
test packet and parameters of the corresponding end-to-end metric. test packet and parameters of the corresponding end-to-end metric.
4.1. A Definition for Spatial One-way Delay Stream 4.1. A Definition for Spatial One-way Delay Vector
This section is coupled with the definition of Type-P-One-way-Delay. This section is coupled with the definition of Type-P-One-way-Delay.
When a parameter from section 3 of [RFC2679] is first used in this When a parameter from section 3 of [RFC2679] is first used in this
section, it will be tagged with a trailing asterisk. section, it will be tagged with a trailing asterisk.
Sections 3.5 to 3.8 of [RFC2679] give requirements and applicability Sections 3.5 to 3.8 of [RFC2679] give requirements and applicability
statements for end-to-end one-way-delay measurements. They are statements for end-to-end one-way-delay measurements. They are
applicable to each point of interest Hi involved in the measure. applicable to each point of interest Hi involved in the measure.
Spatial one-way-delay measurement SHOULD be respectful of them, Spatial one-way-delay measurement SHOULD be respectful of them,
especially those related to methodology, clock, uncertainties and especially those related to methodology, clock, uncertainties and
reporting. reporting.
Following we adapt some of them and introduce points specific to Following we adapt some of them and introduce points specific to
spatial measurement. spatial measurement.
4.1.1. Metric Name 4.1.1. Metric Name
Type-P-Spatial-One-way-Delay-Stream Type-P-Spatial-One-way-Delay-Vector
4.1.2. Metric Parameters 4.1.2. Metric Parameters
+ Src*, the IP address of the sender. + Src*, the IP address of the sender.
+ Dst*, the IP address of the receiver. + Dst*, the IP address of the receiver.
+ i, An integer which ordered the hosts in the path. + i, An integer which ordered the hosts in the path.
+ Hi, exchange points of the path digest. + Hi, exchange points of the path digest.
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4.1.4. Definition 4.1.4. Definition
Given a Type-P packet sent by the sender Src at wire-time (first bit) Given a Type-P packet sent by the sender Src at wire-time (first bit)
T to the receiver Dst in the path <H1, H2,..., Hn>. Given the T to the receiver Dst in the path <H1, H2,..., Hn>. Given the
sequence of values <T+dT1,T+dT2,...,T+dTn,T+dT> such that dT is the sequence of values <T+dT1,T+dT2,...,T+dTn,T+dT> such that dT is the
Type-P-One-way-Delay from Src to Dst and such that for each Hi of the Type-P-One-way-Delay from Src to Dst and such that for each Hi of the
path, T+dTi is either a real number corresponding to the wire-time path, T+dTi is either a real number corresponding to the wire-time
the packet passes (last bit received) Hi, or undefined if the packet the packet passes (last bit received) Hi, or undefined if the packet
never passes Hi. never passes Hi.
Type-P-Spatial-One-way-Delay-Stream metric is defined for the path Type-P-Spatial-One-way-Delay-Vector metric is defined for the path
<Src, H1, H2,..., Hn, Dst> as the sequence of values <Src, H1, H2,..., Hn, Dst> as the sequence of values
<T,dT1,dT2,...,dTn,dT>. <T,dT1,dT2,...,dTn,dT>.
4.1.5. Discussion 4.1.5. Discussion
Following are specific issues which may occur: Following are specific issues which may occur:
o the delay looks to decrease: dTi > DTi+1. this seem typically du o the delay looks to decrease: dTi > DTi+1. this seem typically du
to some clock synchronisation issue. this point is discussed in to some clock synchronisation issue. this point is discussed in
the section 3.7.1. "Errors or uncertainties related to Clocks" of the section 3.7.1. "Errors or uncertainties related to Clocks" of
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proceed as follows: proceed as follows:
o At each Hi, prepare to capture the packet sent a time T, take a o At each Hi, prepare to capture the packet sent a time T, take a
timestamp Ti', determine the internal delay correction dTi', timestamp Ti', determine the internal delay correction dTi',
extract the timestamp T from the packet, then compute the one-way- extract the timestamp T from the packet, then compute the one-way-
delay from Src to Hi: dTi = Ti' - dTi' - T. The one-way delay is delay from Src to Hi: dTi = Ti' - dTi' - T. The one-way delay is
undefined (infinite) if the packet is not detected after the 'loss undefined (infinite) if the packet is not detected after the 'loss
threshold' duration; threshold' duration;
o Gather the set of dTi of each Hi and order them according to the o Gather the set of dTi of each Hi and order them according to the
path to build the Type-P-Spatial-One-way-Delay-Stream metric path to build the Type-P-Spatial-One-way-Delay-Vector metric
<T,dT1,dT2,...,dTn,dT> over the path <H1, H2,..., Hn>. <T,dT1,dT2,...,dTn,dT> over the path <H1, H2,..., Hn>.
It is out of the scope of this document to define how each Hi detects It is out of the scope of this document to define how each Hi detects
the packet. the packet.
4.1.9. Reporting the metric 4.1.9. Reporting the metric
Section 3.6 of [RFC2679] indicates the items to report. Section 3.6 of [RFC2679] indicates the items to report.
4.1.10. Path 4.1.10. Path
It is clear that a end-to-end Type-P-One-way-Delay can't determine It is clear that a end-to-end Type-P-One-way-Delay can't determine
the list of hosts the packet passes throught. Section 3.8.4 of the list of hosts the packet passes throught. Section 3.8.4 of
[RFC2679] says that the path traversed by the packet SHOULD be [RFC2679] says that the path traversed by the packet SHOULD be
reported but is practically impossible to determine. reported but is practically impossible to determine.
This part of the job is provide by Type-P-Spatial-One-way-Delay- This part of the job is provide by Type-P-Spatial-One-way-Delay-
Stream metric because each points of interest Hi which capture the Vector metric because each points of interest Hi which capture the
packet is part of the path. packet is part of the path.
4.2. A Definition of a sample of One-way Delay of a sub path 4.2. A Definition of a sample of One-way Delay of a sub path
This metric is similar to the metric Type-P-One-way-Delay-Poisson- This metric is similar to the metric Type-P-One-way-Delay-Poisson-
stream defined in [RFC2679] and to the metric Type-P-One-way-Delay- stream defined in [RFC2679] and to the metric Type-P-One-way-Delay-
Periodic-Stream defined in [RFC3432]. Periodic-Stream defined in [RFC3432].
Nevertheless its definition differs because it is based of the Nevertheless its definition differs because it is based of the
decomposition of end-to-end One-way delay using the metric Type-P- division of end-to-end One-way delay using the metric Type-P-Spatial-
Spatial-One-way-Delay-Stream defined above. One-way-Delay-Vector defined above.
It aims is to define a sample of One-way-Delay between a pair of It aims is to define a sample of One-way-Delay between a pair of
hosts of a path usable by active and passive measurements. hosts of a path usable by active and passive measurements.
Sections 3.5 to 3.8 of [RFC2679] give requirements and applicability Sections 3.5 to 3.8 of [RFC2679] give requirements and applicability
statements for end-to-end one-way-delay measurements. They are statements for end-to-end one-way-delay measurements. They are
applicable to each point of interest Hi involved in the measure. applicable to each point of interest Hi involved in the measure.
Subpath one-way-delay measurement SHOULD be respectful of them, Subpath one-way-delay measurement SHOULD be respectful of them,
especially those related to methodology, clock, uncertainties and especially those related to methodology, clock, uncertainties and
reporting. reporting.
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+ dT1,..., dTn a list of delay. + dT1,..., dTn a list of delay.
+ P*, the specification of the packet type. + P*, the specification of the packet type.
4.2.3. Metric Units 4.2.3. Metric Units
A sequence of pairs <Tk,dt>. A sequence of pairs <Tk,dt>.
T is one of time of the sequence T1...Tn; T is one of time of the sequence T1...Tn;
dT is a delay. dt is a delay.
4.2.4. Definition 4.2.4. Definition
Given 2 hosts Ha and Hb of the path <Src, H1, H2,..., Hn, Dst>, given Given 2 hosts Ha and Hb of the path <Src, H1, H2,..., Hn, Dst>, given
a flow of packets of Type-P sent from Src to Dst at the times T1, a flow of packets of Type-P sent from Src to Dst at the times T1,
T2... Tn. At each of these times, we obtain a Type-P-Spatial-One- T2... Tn. At each of these times, we obtain a Type-P-Spatial-One-
way-Delay-Stream <T1,dT1.1, dT1.2,..., dT1.n,dT1>. We define the way-Delay-Vector <T1,dT1.1, dT1.2,..., dT1.n,dT1>. We define the
value of the sample Type-P-subpath-One-way-Delay-Stream as the value of the sample Type-P-subpath-One-way-Delay-Stream as the
sequence made up of the couples <Tk,dTk.b - dTk.a>. dTk.a is the sequence made up of the couples <Tk,dTk.b - dTk.a>. dTk.a is the
delay between Src and Ha. dTk.b is the delay between Src and Hb. delay between Src and Ha. dTk.b is the delay between Src and Hb.
'dTk.b - dTk.a' is the one-way delay experienced by the packet sent 'dTk.b - dTk.a' is the one-way delay experienced by the packet sent
at the time Tk by Src when going from Ha to Hb. at the time Tk by Src when going from Ha to Hb.
4.2.5. Discussion 4.2.5. Discussion
Following are specific issues which may occur: Following are specific issues which may occur:
o The definition permits the measure of <Tk,dTk.b - dTk.a> when a is o When a is Src <Tk,dTk.b - dTk.a> is the measure of the first hop.
Src.
o The definition permits the measure of <Tk,dTk.b - dTk.a> when b is o When b is Dst <Tk,dTk.b - dTk.a> is the measure of the last hop.
Dst.
o the delay looks to decrease: dTi > DTi+1. this seem typically du o the delay looks to decrease: dTi > DTi+1:
to some clock synchronisation issue. this point is discussed in
the section 3.7.1. "Errors or uncertainties related to Clocks" of * This is typically du to clock synchronisation issue. this point
of [RFC2679];. is discussed in the section 3.7.1. "Errors or uncertainties
related to Clocks" of of [RFC2679];
* This may occurs too when the clock resolution of one probe is
bigger than the minimun delay of a path. As an example this
happen when measuring the delay of a path which is 500 km long
with one probe synchronized using NTP having a clock resolution
of 8ms.
o The location of the point of interest in the device influences the o The location of the point of interest in the device influences the
result (see [I-D.quittek-ipfix-middlebox]). If the packet is not result (see [I-D.quittek-ipfix-middlebox]). If the packet is not
observed on the input interface the delay includes buffering time observed on the input interface the delay includes buffering time
and consequently an uncertainty due to the difference between and consequently an uncertainty due to the difference between
'wire time' and 'host time'; 'wire time' and 'host time';
o dTk.b may be observed and not dTk.a. o dTk.b may be observed and not dTk.a.
o Tk is unknown if the flow is made of end user packets, that is o Tk is unknown if the flow is made of end user packets, that is
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4.2.8. Methodologies 4.2.8. Methodologies
Both active and passive method should discussed. Both active and passive method should discussed.
4.2.9. Reporting the metric 4.2.9. Reporting the metric
Section 3.6 of [RFC2679] indicates the items to report. Section 3.6 of [RFC2679] indicates the items to report.
4.2.10. Path 4.2.10. Path
4.3. A Definition for Spatial One-way Packet Loss Stream 4.3. A Definition for Spatial One-way Packet Loss Vector
This section is coupled with the definition of Type-P-One-way-Packet- This section is coupled with the definition of Type-P-One-way-Packet-
Loss. Then when a parameter from the section 2 of [RFC2680] is first Loss. Then when a parameter from the section 2 of [RFC2680] is first
used in this section, it will be tagged with a trailing asterisk. used in this section, it will be tagged with a trailing asterisk.
Sections 2.5 to 2.8 of [RFC2680] give requirements and applicability Sections 2.5 to 2.8 of [RFC2680] give requirements and applicability
statements for end-to-end one-way-Packet-Loss measurements. They are statements for end-to-end one-way-Packet-Loss measurements. They are
applicable to each point of interest Hi involved in the measure. applicable to each point of interest Hi involved in the measure.
Spatial packet loss measurement SHOULD be respectful of them, Spatial packet loss measurement SHOULD be respectful of them,
especially those related to methodology, clock, uncertainities and especially those related to methodology, clock, uncertainities and
reporting. reporting.
Following we define the spatial metric, then we adapt some of the Following we define the spatial metric, then we adapt some of the
points above and introduce points specific to spatial measurement. points above and introduce points specific to spatial measurement.
4.3.1. Metric Name 4.3.1. Metric Name
Type-P-Spatial-One-way-Packet-Loss-Stream Type-P-Spatial-One-way-Packet-Loss-Vector
4.3.2. Metric Parameters 4.3.2. Metric Parameters
+ Src*, the IP address of the sender. + Src*, the IP address of the sender.
+ Dst*, the IP address of the receiver. + Dst*, the IP address of the receiver.
+ i, An integer which ordered the hosts in the path. + i, An integer which ordered the hosts in the path.
+ Hi, exchange points of the path digest. + Hi, exchange points of the path digest.
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4.3.3. Metric Units 4.3.3. Metric Units
A sequence of boolean values. A sequence of boolean values.
4.3.4. Definition 4.3.4. Definition
Given a Type-P packet sent by the sender Src at time T to the Given a Type-P packet sent by the sender Src at time T to the
receiver Dst in the path <H1, H2, ..., Hn>. Given the sequence of receiver Dst in the path <H1, H2, ..., Hn>. Given the sequence of
times <T+dT1,T+dT2,...,T+dTn,T+dT> the packet passes <H1, H2 ..., Hn, times <T+dT1,T+dT2,...,T+dTn,T+dT> the packet passes <H1, H2 ..., Hn,
Dst>, Dst>,
Type-P-One-way-Packet-Lost-Stream metric is defined as the sequence
Type-P-One-way-Packet-Lost-Vector metric is defined as the sequence
of values <B1, B2, ..., Bn> such that for each Hi of the path, a of values <B1, B2, ..., Bn> such that for each Hi of the path, a
value of Bi of 0 means that dTi is a finite value, and a value of 1 value of Bi of 0 means that dTi is a finite value, and a value of 1
means that dTi is undefined. means that dTi is undefined.
4.3.5. Discussion 4.3.5. Discussion
Following are specific issues wich may occur: Following are specific issues wich may occur:
o the result includes the sequence 1,0. This case means that the o the result includes the sequence 1,0. This case means that the
packet was seen by a host but not by it successor on the path; packet was seen by a host but not by it successor on the path;
skipping to change at page 15, line 27 skipping to change at page 16, line 39
The location of the meter in the device influences the result: The location of the meter in the device influences the result:
o Even if the packet is received by a device, it may be not observed o Even if the packet is received by a device, it may be not observed
by a meter located after a buffer; by a meter located after a buffer;
4.3.6. Reporting 4.3.6. Reporting
Section in progress. Section in progress.
4.4. A Definition for Spatial One-way Jitter Stream 4.4. A Definition for Spatial One-way Jitter Vector
This section uses parameters from the definition of Type-P-One-way- This section uses parameters from the definition of Type-P-One-way-
ipdv. When a parameter from section 2 of [RFC3393] is first used in ipdv. When a parameter from section 2 of [RFC3393] is first used in
this section, it will be tagged with a trailing asterisk. this section, it will be tagged with a trailing asterisk.
Sections 3.5 to 3.7 of [RFC3393] give requirements and applicability Sections 3.5 to 3.7 of [RFC3393] give requirements and applicability
statements for end-to-end one-way-ipdv measurements. They are statements for end-to-end one-way-ipdv measurements. They are
applicable to each point of interest Hi involved in the measure. applicable to each point of interest Hi involved in the measure.
Spatial one-way-ipdv measurement SHOULD be respectful of them, Spatial one-way-ipdv measurement SHOULD be respectful of them,
especially those related to methodology, clock, uncertainities and especially those related to methodology, clock, uncertainities and
reporting. reporting.
Following we adapt some of them and introduce points specific to Following we adapt some of them and introduce points specific to
spatial measurement. spatial measurement.
4.4.1. Metric Name 4.4.1. Metric Name
Type-P-Spatial-One-way-Jitter-Stream Type-P-Spatial-One-way-Jitter-Vector
4.4.2. Metric Parameters 4.4.2. Metric Parameters
+ Src*, the IP address of the sender. + Src*, the IP address of the sender.
+ Dst*, the IP address of the receiver. + Dst*, the IP address of the receiver.
+ i, An integer which ordered the hosts in the path. + i, An integer which ordered the hosts in the path.
+ Hi, exchange points of the path digest. + Hi, exchange points of the path digest.
skipping to change at page 16, line 28 skipping to change at page 17, line 33
+ P, the specification of the packet type. + P, the specification of the packet type.
+ P1, the first packet sent at time T1. + P1, the first packet sent at time T1.
+ P2, the second packet sent at time T2. + P2, the second packet sent at time T2.
+ <Src, H1, H2,..., Hn, Dst>, a path digest. + <Src, H1, H2,..., Hn, Dst>, a path digest.
+ <T1,dT1.1, dT1.2,..., dT1.n,dT1>, + <T1,dT1.1, dT1.2,..., dT1.n,dT1>,
the Type-P-Spatial-One-way-Delay-Stream for packet sent at the Type-P-Spatial-One-way-Delay-Vector for packet sent at
time T1; time T1;
+ <T2,dT2.1, dT2.2,..., dT2.n,dT2>, + <T2,dT2.1, dT2.2,..., dT2.n,dT2>,
the Type-P-Spatial-One-way-Delay-Stream for packet sent at the Type-P-Spatial-One-way-Delay-Vector for packet sent at
time T2; time T2;
+ L*, a packet length in bits. The packets of a Type P + L*, a packet length in bits. The packets of a Type P
packet stream from which the packet stream from which the
Type-P-Spatial-One-way-Delay-Stream metric is taken MUST Type-P-Spatial-One-way-Delay-Vector metric is taken MUST
all be of the same length. all be of the same length.
4.4.3. Metric Units 4.4.3. Metric Units
A sequence of times. A sequence of times.
4.4.4. Definition 4.4.4. Definition
Given the Type-P packet having the size L and sent by the sender Src Given the Type-P packet having the size L and sent by the sender Src
at wire-time (first bit) T1 to the receiver Dst in the path <H1, at wire-time (first bit) T1 to the receiver Dst in the path <H1,
H2,..., Hn>. H2,..., Hn>.
Given the Type-P packet having the size L and sent by the sender Src Given the Type-P packet having the size L and sent by the sender Src
at wire-time (first bit) T2 to the receiver Dst in the same path. at wire-time (first bit) T2 to the receiver Dst in the same path.
Given the Type-P-Spatial-One-way-Delay-Stream <T1,dT1.1, dT1.2,..., Given the Type-P-Spatial-One-way-Delay-Vector <T1,dT1.1, dT1.2,...,
dT1,n,dT1> of the packet P1. dT1,n,dT1> of the packet P1.
Given the Type-P-Spatial-One-way-Delay-Stream <T2,dT2.1, dT2.2,..., Given the Type-P-Spatial-One-way-Delay-Vector <T2,dT2.1, dT2.2,...,
dT2,n,dT2> of the packet P2. dT2,n,dT2> of the packet P2.
Type-P-Spatial-One-way-Jitter-Stream metric is defined as the Type-P-Spatial-One-way-Jitter-Vector metric is defined as the
sequence of values <T2-T1,dT2.1-dT1.1,dT2.2-dT1.2,...,dT2.n- sequence of values <T2-T1,dT2.1-dT1.1,dT2.2-dT1.2,...,dT2.n-
dT1.n,dT2-dT1> Such that for each Hi of the path <H1, H2,..., Hn>, dT1.n,dT2-dT1> Such that for each Hi of the path <H1, H2,..., Hn>,
dT2.i-dT1.i is either a real number if the packets P1 and P2 passes dT2.i-dT1.i is either a real number if the packets P1 and P2 passes
Hi at wire-time (last bit) dT1.i, respectively dT2.i, or undefined if Hi at wire-time (last bit) dT1.i, respectively dT2.i, or undefined if
at least one of them never passes Hi. T2-T1 is the inter-packet at least one of them never passes Hi. T2-T1 is the inter-packet
emission interval and dT2-dT1 is ddT* the Type-P-One-way-ipdv at emission interval and dT2-dT1 is ddT* the Type-P-One-way-ipdv at
T1,T2*. T1,T2*.
4.4.5. Sections in progress 4.4.5. Sections in progress
skipping to change at page 18, line 36 skipping to change at page 19, line 43
of method of detection (expecting Seq++); because of the difference of method of detection (expecting Seq++); because of the difference
of source of time (H1 vs Src) and because of the difference of of source of time (H1 vs Src) and because of the difference of
behavior of the source (Poisson/unknown). behavior of the source (Poisson/unknown).
4.5.3. naming and registry 4.5.3. naming and registry
Having distinct metrics identifiers for spatial metrics and passive Having distinct metrics identifiers for spatial metrics and passive
spatial metrics in the [RFC4148] will avoid interoperabily issues spatial metrics in the [RFC4148] will avoid interoperabily issues
especially during composition of metrics. especially during composition of metrics.
They may be named
o Type-P-Passive-One-way-delay-Stream
o Type-P-Passive-One-way-Packet-Loss-Stream
o Type-P-Passive-One-way-jitter-Stream
In the same way sample should be registred too. they may be named
o Type-P-Passive-One-way-delay-Sample
o Type-P-Passive-One-way-Packet-Loss-Sample
o Type-P-Passive-One-way-jitter-Sample
4.5.4. Passive One way delay metrics 4.5.4. Passive One way delay metrics
4.5.5. Passive One way PacketLoss metrics 4.5.5. Passive One way PacketLoss metrics
4.5.6. Passive One way jitter metrics 4.5.6. Passive One way jitter metrics
4.6. Discussion on spatial statistics 4.6. Discussion on spatial statistics
Do we define min, max, avg of spatial metrics ? Do we define min, max, avg of spatial metrics ?
having the maximum loss metric value could be interesting. Say, having the maximum loss metric value could be interesting. Say,
the segment between router A and B always contributes loss metric the segment between router A and B always contributes loss metric
value of "1" means it could be the potential problem segment. value of "1" means it could be the potential problem segment.
Uploading dTi of each Hi consume a lot of bandwidth. Computing Uploading dTi of each Hi consume a lot of bandwidth. Computing
statistics (min, max and avg) of dTi locally in each Hi reduce the statistics (min, max and avg) of dTi locally in each Hi reduce the
bandwidth consumption. bandwidth consumption.
5. One-to-group metrics definitions 5. One-to-group metrics definitions
5.1. A Definition for one-to-group One-way Delay Stream 5.1. A Definition for one-to-group One-way Delay
5.1.1. Metric Name 5.1.1. Metric Name
Type-P-one-to-group-One-way-Delay-Stream Type-P-one-to-group-One-way-Delay-Vector
5.1.2. Metric Parameters 5.1.2. Metric Parameters
o Src, the IP address of a host acting as the source. o Src, the IP address of a host acting as the source.
o Recv1,..., RecvN, the IP addresses of the N hosts acting as o Recv1,..., RecvN, the IP addresses of the N hosts acting as
receivers. receivers.
o T, a time. o T, a time.
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o Gr, the multicast group address (optional). The parameter Gr is o Gr, the multicast group address (optional). The parameter Gr is
the multicast group address if the measured packets are the multicast group address if the measured packets are
transmitted by multicast. This parameter is to identify the transmitted by multicast. This parameter is to identify the
measured traffic from other unicast and multicast traffic. It is measured traffic from other unicast and multicast traffic. It is
set to be optional in the metric to avoid losing any generality, set to be optional in the metric to avoid losing any generality,
i.e. to make the metric also applicable to unicast measurement i.e. to make the metric also applicable to unicast measurement
where there is only one receivers. where there is only one receivers.
5.1.3. Metric Units 5.1.3. Metric Units
The value of a Type-P-one-to-group-One-way-Delay-Stream is a set of The value of a Type-P-one-to-group-One-way-Delay-Vector is a set of
singletons metrics Type-P-One-way-Delay [RFC2679]. singletons metrics Type-P-One-way-Delay [RFC2679].
5.1.4. Definition 5.1.4. Definition
Given a Type P packet sent by the source Src at Time T, given the N Given a Type P packet sent by the source Src at Time T, given the N
hosts { Recv1,...,RecvN } which receive the packet at the time { hosts { Recv1,...,RecvN } which receive the packet at the time {
T+dT1,...,T+dTn }, a Type-P-one-to-group-One-way-Delay-Stream is T+dT1,...,T+dTn }, a Type-P-one-to-group-One-way-Delay-Vector is
defined as the set of the Type-P-One-way-Delay singleton between Src defined as the set of the Type-P-One-way-Delay singleton between Src
and each receiver with value of { dT1, dT2,...,dTn }. and each receiver with value of { dT1, dT2,...,dTn }.
5.2. A Definition for one-to-group One-way Packet Loss Stream 5.2. A Definition for one-to-group One-way Packet Loss
5.2.1. Metric Name 5.2.1. Metric Name
Type-P-one-to-group-One-way-Packet-Loss-Stream Type-P-one-to-group-One-way-Packet-Loss-Vector
5.2.2. Metric Parameters 5.2.2. Metric Parameters
o Src, the IP address of a host acting as the source. o Src, the IP address of a host acting as the source.
o Recv1,..., RecvN, the IP addresses of the N hosts acting as o Recv1,..., RecvN, the IP addresses of the N hosts acting as
receivers. receivers.
o T, a time. o T, a time.
o T1,...,Tn a list of time. o T1,...,Tn a list of time.
o P, the specification of the packet type. o P, the specification of the packet type.
o Gr, the multicast group address (optional). o Gr, the multicast group address (optional).
5.2.3. Metric Units 5.2.3. Metric Units
The value of a Type-P-one-to-group-One-way-Packet-Loss-Stream is a The value of a Type-P-one-to-group-One-way-Packet-Loss-Vector is a
set of singletons metrics Type-P-One-way-Packet-Loss [RFC2680]. set of singletons metrics Type-P-One-way-Packet-Loss [RFC2680].
5.2.4. Definition 5.2.4. Definition
Given a Type P packet sent by the source Src at T and the N hosts, Given a Type P packet sent by the source Src at T and the N hosts,
Recv1,...,RecvN, which should receive the packet at T1,...,Tn, a Recv1,...,RecvN, which should receive the packet at T1,...,Tn, a
Type-P-one-to-group-One-way-Packet-Loss-Stream is defined as a set of Type-P-one-to-group-One-way-Packet-Loss-Vector is defined as a set of
the Type-P-One-way-Packet-Loss singleton between Src and each of the the Type-P-One-way-Packet-Loss singleton between Src and each of the
receivers {<T1,0|1>,<T2,0|1>,..., <Tn,0|1>}. receivers {<T1,0|1>,<T2,0|1>,..., <Tn,0|1>}.
5.3. A Definition for one-to-group One-way Jitter Stream 5.3. A Definition for one-to-group One-way Jitter
5.3.1. Metric Name 5.3.1. Metric Name
Type-P-one-to-group-One-way-Jitter-Stream Type-P-one-to-group-One-way-Jitter-Vector
5.3.2. Metric Parameters 5.3.2. Metric Parameters
+ Src, the IP address of a host acting as the source. + Src, the IP address of a host acting as the source.
+ Recv1,..., RecvN, the IP addresses of the N hosts acting as + Recv1,..., RecvN, the IP addresses of the N hosts acting as
receivers. receivers.
+ T1, a time. + T1, a time.
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+ P, the specification of the packet type. + P, the specification of the packet type.
+ F, a selection function defining unambiguously the two + F, a selection function defining unambiguously the two
packets from the stream selected for the metric. packets from the stream selected for the metric.
+ Gr, the multicast group address (optional) + Gr, the multicast group address (optional)
5.3.3. Metric Units 5.3.3. Metric Units
The value of a Type-P-one-to-group-One-way-Jitter-Stream is a set of The value of a Type-P-one-to-group-One-way-Jitter-Vector is a set of
singletons metrics Type-P-One-way-ipdv [RFC3393]. singletons metrics Type-P-One-way-ipdv [RFC3393].
5.3.4. Definition 5.3.4. Definition
Given a Type P packet stream, Type-P-one-to-group-One-way- Jitter- Given a Type P packet stream, Type-P-one-to-group-One-way- Jitter-
Stream is defined for two packets from the source Src to the N hosts Vector is defined for two packets from the source Src to the N hosts
{Recv1,...,RecvN },which are selected by the selection function F, as {Recv1,...,RecvN },which are selected by the selection function F, as
the difference between the value of the Type-P-one-to-group-One-way- the difference between the value of the Type-P-one-to-group-One-way-
Delay-Stream from Src to { Recv1,..., RecvN } at time T1 and the Delay-Vector from Src to { Recv1,..., RecvN } at time T1 and the
value of the Type-P-one-to-group- One-way-Delay-Stream from Src to { value of the Type-P-one-to-group- One-way-Delay-Vector from Src to {
Recv1,...,RecvN } at time T2. T1 is the wire-time at which Scr sent Recv1,...,RecvN } at time T2. T1 is the wire-time at which Scr sent
the first bit of the first packet, and T2 is the wire-time at which the first bit of the first packet, and T2 is the wire-time at which
Src sent the first bit of the second packet. This metric is derived Src sent the first bit of the second packet. This metric is derived
from the Type-P-one-to- group-One-way-Delay-Stream metric. from the Type-P-one-to- group-One-way-Delay-Vector metric.
Therefore, for a set of real number {ddT1,...,ddTn},Type-P-one- to- Therefore, for a set of real number {ddT1,...,ddTn},Type-P-one- to-
group-One-way-Jitter-Stream from Src to { Recv1,...,RecvN } at T1, T2 group-One-way-Jitter-Vector from Src to { Recv1,...,RecvN } at T1, T2
is {ddT1,...,ddTn} means that Src sent two packets, the first at is {ddT1,...,ddTn} means that Src sent two packets, the first at
wire-time T1 (first bit), and the second at wire-time T2 (first bit) wire-time T1 (first bit), and the second at wire-time T2 (first bit)
and the packets were received by { Recv1,...,RecvN } at wire-time and the packets were received by { Recv1,...,RecvN } at wire-time
{dT1+T1,...,dTn+T1}(last bit of the first packet), and at wire-time {dT1+T1,...,dTn+T1}(last bit of the first packet), and at wire-time
{dT'1+T2,...,dT'n+T2} (last bit of the second packet), and that {dT'1+T2,...,dT'n+T2} (last bit of the second packet), and that
{dT'1-dT1,...,dT'n-dTn} ={ddT1,...,ddTn}. {dT'1-dT1,...,dT'n-dTn} ={ddT1,...,ddTn}.
5.4. Discussion on one-to-group statistics 5.4. Discussion on one-to-group statistics
The defined one-to-group metrics above can all be directly achieved The defined one-to-group metrics above can all be directly achieved
from the relevant unicast one-way metrics. They managed to collect from the relevant unicast one-way metrics. They managed to collect
all unicast measurement results of one-way metrics together in one all unicast measurement results of one-way metrics together in one
profile and sort them by receivers and packets in a multicast group. profile and sort them by receivers and packets in a multicast group.
They can provide sufficient information regarding the network They can provide sufficient information regarding the network
performance in terms of each receiver and guide engineers to identify performance in terms of each receiver and guide engineers to identify
potential problem happened on each branch of a multicast routing potential problem happened on each branch of a multicast routing
tree. However, these metrics can not be directly used to tree. However, these metrics can not be directly used to
conveniently present the performance in terms of a group and neither conveniently present the performance in terms of a group and neither
to identify the relative QoS situation. to identify the relative performance situation.
One may say that no matter how many people join the communication, One may say that no matter how many people join the communication,
the connections can still be treated as a set of one-to-one the connections can still be treated as a set of one-to-one
connection. However, we might not describe a multiparty connection. However, we might not describe a multiparty
communication by a set of one-way measurement metrics because of the communication by a set of one-way measurement metrics because of the
difficulty for understanding and the lack of convenience. For difficulty for understanding and the lack of convenience. For
instance, an engineer might not describe the connections of a instance, an engineer might not describe the connections of a
multiparty online conference in terms of one-to-group one-way delay multiparty online conference in terms of one-to-group one-way delay
for user A and B, B and C, and C and A because people might be for user A and B, B and C, and C and A because people might be
confused. If there are more users in the same communication, the confused. If there are more users in the same communication, the
description might be very long. And he might use the one-way metrics description might be very long. And he might use the one-way metrics
with worst and the best value to give users an idea of the QoS range with worst and the best value to give users an idea of the
of the service they are providing. But it is not clear enough and performance range of the service they are providing. But it is not
might not be accurate in a large multiparty communication scenario. clear enough and might not be accurate in a large multiparty
communication scenario.
From the QoS point of view, the multiparty communication services not From the performance point of view, the multiparty communication
only require the absolute QoS support but also the relative QoS. The services not only require the absolute performance support but also
relative QoS means the difference between absolute QoS of all users. the relative performance. The relative performance means the
Directly using the one-way metrics cannot present the relative QoS difference between absolute performance of all users. Directly using
the one-way metrics cannot present the relative performance
situation. However, if we use the variations of all users one-way situation. However, if we use the variations of all users one-way
parameters, we can have new metrics to measure the difference of the parameters, we can have new metrics to measure the difference of the
absolute QoS and hence provide the threshold value of relative QoS absolute performance and hence provide the threshold value of
that a multiparty service might demand. A very good example of the relative performance that a multiparty service might demand. A very
high relative QoS requirement is the online gaming. A very light good example of the high relative performance requirement is the
worse delay will result in failure in the game. We have to use the online gaming. A very light worse delay will result in failure in
new statistic metrics to define exactly how small the relative delay the game. We have to use the new statistic metrics to define exactly
the online gaming requires. There are many other services, e.g. how small the relative delay the online gaming requires. There are
online biding, online stock market, etc., need a rule to judge the many other services, e.g. online biding, online stock market, etc.,
relative QoS requirement. Therefore, we can see the importance of need a rule to judge the relative performance requirement.
new statistic metrics to feed this need. Therefore, we can see the importance of new statistic metrics to feed
this need.
We might use some one-to-group statistic conceptions to present the We might use some one-to-group statistic conceptions to present and
group performance and relative QoS. In this stage, we define one-to- report the group performance and relative performance to save the
group mean stream and one-to-group variation stream. These report transmission bandwidth. Statistics have been defined for One-
statistics are offered mostly to be illustrative of what could be way metrics in corresponding FRCs. They provide the foundation of
done. definition for performance statistics. For instance, there are
definitions for minimum and maximum One-way delay in [RFC2679] and
One-way delay mean in [I-D.ietf-ippm-spatial-composition]. However,
there is a dramatic difference between the statistics for one-to-one
communications and for one-to-many communications. The former one
only has statistics over the time dimension while the later one can
have statistics over both time dimension and space dimention. This
space dimension is introduced by the Matrix concept. For a Matrix M
shown in the Fig. 2, each row is a set of One-way singletons
spreading over the space dimension and each colume is another set of
One-way singletons spreading over the time dimension.
One-to-group mean streams are trying to measure the overall QoS for a (preamble)
/ \
| dT11, dT12,..., dT1N |
| dT21, dT22,..., dT2N |
| : |
| : |
| dTm1, dTm2,..., dTmN |
\ /
Fig. 2 Matrix M (m*N)
In Matrix M, each element is a One-way delay singleton. Each row is
a delay vector contains the One-way delays of the same packet
observed at N points of interest. It implies the geographical factor
of the performance within a group. Each colume is a set of One-way
delays observed during a sampling interval at one of the points of
interest. It presents the delay performance at a receiver over the
time dimension.
Therefore, one can either calculate statistics by rows over the space
dimension or by columes over the time dimension. It's up to the
operators or service provides which dimension they are interested in.
For example, a TV broadcast service provider might want to know the
statistical performance of each user in a long term run to make sure
their services are acceptable and stable. While for an online gaming
service provider, he might be more interested to know if all users
are served farely by calculating the statistics over the space
dimension. This memo does not intent to recommend which of the
statistics are better than the other.
To save the report transmission bandwidth, each point of interest can
send statistics in a pre-defined time interval to the reference point
rather than sending every One-way singleton it observed. As long as
an appropriate time interval is decided, appropriate stantistics can
represent the performance in a certain accurate scale. How to decide
the time interval and how to bootstrap all points of interest and the
reference point depend on applications. For instance, applications
with lower transmission rate can have the time interval longer and
ones with higher transmission rate can have the time interval
shorter. However, this is out of the scope of this memo.
Moreover, after knowing the statistics over the time dimension, one
might want to know how this statistics distributed over the space
dimension. For instance, a TV broadcast service provider had the
performance Matrix M and calculated the One-way delay mean over the
time dimension to obtain a delay Vector as {V1,V2,..., VN}. He then
calculated the mean of all the elements in the Vector to see what
level of delay he has served to all N users. This new delay mean
gives information on how good the service has been delivered to a
group of users during a sampling interval in terms of delay. It
needs twice calculation to have this statistic over both time and
space dimensions. We name this kind of statistics 2-level statistics
to distinct with those 1-level statistics calculated over either
space or time dimension. It can be easily prove that no matter over
which dimension a 2-level statistic is calculated first, the results
are the same. I.e. one can calculate the 2-level delay mean using
the Matrix M by having the 1-level delay mean over the time dimension
first and then calculate the mean of the obtained vector to find out
the 2-level delay mean. Or, he can do the 1-level statistic
calculation over the space dimention first and then have the 2-level
delay mean. Both two results will be exactly the same. Therefore,
when define a 2-level statistic, it is no need to specify in which
procedure the calculation should follow.
There are many statistics can be defined for the proposed one-to-
group metrics over either the space dimension or the time dimension
or both. In this memo, we define one-to-group mean and one-to-group
variation over the space dimension. These statistics are offered
mostly to be illustrative of what could be done.
One-to-group mean are trying to measure the overall performance for a
multicast group associated to one source. It is a reflection of the multicast group associated to one source. It is a reflection of the
absolute QoS of a multiparty communication service when we treat all absolute performance of a multiparty communication service when we
receivers as one customer. It can also present the trend of the treat all receivers as one customer. It can also present the trend
absolute QoS of all receivers, i.e., it shows that most of the of the absolute performance of all receivers, i.e., it shows that
receivers in the multiparty communication service trend to receive an most of the receivers in the multiparty communication service trend
absolute QoS close to the mean. to receive an absolute performance close to the mean.
One-to-group variation streams are trying to measure how the QoS One-to-group variation streams are trying to measure how the
varies among all of the users in a multicast group associated to one performance varies among all of the users in a multicast group
source. The word "variation" in this memo is the population standard associated to one source. The word "variation" in this memo is the
deviation. It reflects the relative QoS situation in a multiparty population standard deviation. It reflects the relative
communication service, i.e., the level of the difference between the performancesituation in a multiparty communication service, i.e., the
absolute QoS of each receivers. level of the difference between the absolute performanceof each
receivers.
Using the one-to-group mean and one-to-group variation concepts, we Using the one-to-group mean and one-to-group variation concepts, we
can have a much clear understand on the QoS of a multiparty can have a much clear understand on the performanceof a multiparty
communication service in terms of its trend and range. There can be communication service in terms of its trend and range. There can be
mean and variation stream definitions for each of the three one-to- mean and variation stream definitions for each of the three one-to-
group metrics defined above. We only present the definition of Type- group metrics defined above. We only present the definition of Type-
P-one-to-group-One-way- Delay-Mean-Stream and Type-P-one-to-group- P-one-to-group-One-way-Delay-Space-Mean and Type-P-one-to-group- One-
One-way-Delay-Variation-Stream as examples in this memo. way-Delay-Space-Variation as examples in this memo.
5.4.1. Type-P-one-to-group-One-way-Delay-Mean-Stream 5.4.1. Type-P-one-to-group-One-way-Delay-Space-Mean
Given a Type-P-one-to-group-One-way-Delay-Stream, the mean stream of Given a Type-P-one-to-group-One-way-Delay-Vector, the mean { dT1,
all { dT1, dT2,...,dTn } for the packet from Src at time T to { dT2,...,dTN } for the packet from Src at time T to { Recv1,...,RecvN
Recv1,...,RecvN }. }.
For example, suppose we take a sample and the results are: For example, suppose we take a delay vector and the results is:
Delay_Stream = < Delay_Vector = {dT1,...,dTN}
{T1,...,Tn}
{T'1,...,T'n}
{T''1,...T''n}
>
Then the mean stream would be: Then the mean over space dimension would be:
Delay_Mean_Stream = < Delay_Space_Mean = DsM = sum{dT1,...,dTN}/N
DM1
DM2
DM3
>
= <
sum{T1,...,Tn}/n
sum{T'1,...,T'n}/n
sum{T''1,...T''n}/n
>
5.4.2. Type-P-one-to-group-One-way-Delay-Variation-Stream 5.4.2. Type-P-one-to-group-One-way-Delay-Variation-Stream
Given a Type-P-one-to-group-One-way-Delay-Stream, the variation Given a Type-P-one-to-group-One-way-Delay-Vector, the variation {
stream of all { dT1, dT2,...,dTn } for the packet from Src at time T dT1, dT2,...,dTN } for the packet from Src at time T to {
to { Recv1,...,RecvN }. Recv1,...,RecvN }.
We still take the above Delay_Stream as a sample and the variation We still take the above Delay_Vector as an sample and the variation
stream would be: would be:
Delay_Variation_Stream = < Delay_Variation_Stream = {SUM[(dT1-DsM)^2,...,(dTN-
DV1 DsM)^2)}/N)^(1/2)
DV2
DV3
>
=<
(SUM{(T1-DM1)^2,...,(Tn-DM1)^2)}/n)^(1/2)
(SUM{(T'1-DM2)^2,...,(T'n-DM2)^2)}/n)^(1/2)
(SUM{(T''1-DM3)^2,...,(T''n-DM3)^2)}/n)^(1/2)
>
6. Extension from one-to-one to one-to-many measurement 6. Extension from one-to-one to one-to-many measurement
The above one-to-group metrics were defined to compose measurement The above one-to-group metrics were defined to compose measurement
results of a group of users who receive the same data from one results of a group of users who receive the same data from one
source. Moreover, this is one of efforts to introducing the one-to- source. Moreover, this is one of efforts to introducing the one-to-
many concern to the IPPM working group with respect to the fact that many concern to the IPPM working group with respect to the fact that
all existing documents in the group are unicast oriented, which talk all existing documents in the group are unicast oriented, which talk
about only one-to-one single "path" in measurements. This concept about only one-to-one single "path" in measurements. This concept
can be extended from the "path" to "path tree" to cover both one-to- can be extended from the "path" to "path tree" to cover both one-to-
skipping to change at page 25, line 27 skipping to change at page 27, line 24
statistic metrics for one-to-one communications are exactly the one- statistic metrics for one-to-one communications are exactly the one-
to-group metrics themselves when calculated using the methods given. to-group metrics themselves when calculated using the methods given.
7. Open issues 7. Open issues
8. Security Considerations 8. Security Considerations
Active measumrement: see security section in owd pl, jitter rfcs Active measumrement: see security section in owd pl, jitter rfcs
(editor notes: add references). (editor notes: add references).
passive measurement: The rate of packet sampling is controled by hash passive measurement:
funcion. The analysis of such a function to generate packets that
match the hash funcion may lead to a DoS attack toward the collector. The generation of packets which match systematically the hash
function may lead to a DoS attack toward the collector.
The generation of packets with spoofing adresses may corrupt the The generation of packets with spoofing adresses may corrupt the
results without any possibility to detect the spoofing. results without any possibility to detect the spoofing.
TODO: one-to-group metrics defined here are not intrusive: they rely one-to-group metrics require collection of singletons which may
on measures of owd... nevertheless they require collection of overload the network the measurement controller is attach to.
singletons which may overload the network the measurement controller
is attach to.
The one-to-group metrics are derived from one-way metrics and
therefore, they have very close relationship.
9. Acknowledgments 9. Acknowledgments
Lei would like to acknowledge Zhili Sun from CCSR, University of Lei would like to acknowledge Zhili Sun from CCSR, University of
Surrey, for his instruction and helpful comments on this work. Surrey, for his instruction and helpful comments on this work.
10. IANA Considerations 10. IANA Considerations
Metrics defined in this memo will be registered in the IANA IPPM Metrics defined in this memo will be registered in the IANA IPPM
METRICS REGISTRY as described in initial version of the registry METRICS REGISTRY as described in initial version of the registry
[RFC4148]. [RFC4148].
11. References 11. References
11.1. Normative References 11.1. Normative References
[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, "Framework for IP Performance Metrics", RFC 2330,
skipping to change at page 26, line 32 skipping to change at page 28, line 27
[RFC3393] Demichelis, C. and P. Chimento, "IP Packet Delay Variation [RFC3393] Demichelis, C. and P. Chimento, "IP Packet Delay Variation
Metric for IP Performance Metrics (IPPM)", RFC 3393, Metric for IP Performance Metrics (IPPM)", RFC 3393,
November 2002. November 2002.
[RFC4148] Stephan, E., "IP Performance Metrics (IPPM) Metrics [RFC4148] Stephan, E., "IP Performance Metrics (IPPM) Metrics
Registry", BCP 108, RFC 4148, August 2005. Registry", BCP 108, RFC 4148, August 2005.
11.2. Informative References 11.2. Informative References
[I-D.boschi-ipfix-reducing-redundancy] [I-D.boschi-ipfix-reducing-redundancy]
Boschi, E. and L. Mark, "Reducing redundancy in IPFIX and Boschi, E., "Reducing redundancy in IPFIX and PSAMP
PSAMP reports", draft-boschi-ipfix-reducing-redundancy-01 reports", draft-boschi-ipfix-reducing-redundancy-02 (work
(work in progress), March 2006. in progress), June 2006.
[I-D.ietf-ippm-spatial-composition] [I-D.ietf-ippm-spatial-composition]
Morton, A. and E. Stephan, "Spatial Composition of Morton, A. and E. Stephan, "Spatial Composition of
Metrics", draft-ietf-ippm-spatial-composition-00 (work in Metrics", draft-ietf-ippm-spatial-composition-01 (work in
progress), February 2006. progress), June 2006.
[I-D.quittek-ipfix-middlebox] [I-D.quittek-ipfix-middlebox]
Quittek, J., "Guidelines for IPFIX Implementations on Quittek, J., "Guidelines for IPFIX Implementations on
Middleboxes", draft-quittek-ipfix-middlebox-00 (work in Middleboxes", draft-quittek-ipfix-middlebox-00 (work in
progress), February 2004. progress), February 2004.
[RFC2678] Mahdavi, J. and V. Paxson, "IPPM Metrics for Measuring [RFC2678] Mahdavi, J. and V. Paxson, "IPPM Metrics for Measuring
Connectivity", RFC 2678, September 1999. Connectivity", RFC 2678, September 1999.
[RFC2681] Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip [RFC2681] Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip
skipping to change at page 28, line 13 skipping to change at page 29, line 21
April 2004. April 2004.
Authors' Addresses Authors' Addresses
Stephan Emile Stephan Emile
France Telecom Division R&D France Telecom Division R&D
2 avenue Pierre Marzin 2 avenue Pierre Marzin
Lannion, F-22307 Lannion, F-22307
Fax: +33 2 96 05 18 52 Fax: +33 2 96 05 18 52
Email: emile.stephan@francetelecom.com Email: emile.stephan@orange-ft.com
Lei Liang Lei Liang
CCSR, University of Surrey CCSR, University of Surrey
Guildford Guildford
Surrey, GU2 7XH Surrey, GU2 7XH
Fax: +44 1483 683641 Fax: +44 1483 683641
Email: L.Liang@surrey.ac.uk Email: L.Liang@surrey.ac.uk
Al Morton Al Morton
200 Laurel Ave. South 200 Laurel Ave. South
Middletown, NJ 07748 Middletown, NJ 07748
USA USA
Phone: +1 732 420 1571 Phone: +1 732 420 1571
Email: acmorton@att.com Email: acmorton@att.com
Intellectual Property Statement Full Copyright Statement
Copyright (C) The Internet Society (2006).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
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WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
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skipping to change at page 29, line 29 skipping to change at page 30, line 45
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This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The Internet Society (2006). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is provided by the IETF
Internet Society. Administrative Support Activity (IASA).
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