draft-ietf-ippm-multimetrics-11.txt   draft-ietf-ippm-multimetrics-12.txt 
Network Working Group E. Stephan Network Working Group E. Stephan
Internet-Draft France Telecom Internet-Draft France Telecom
Intended status: Standards Track L. Liang Intended status: Standards Track L. Liang
Expires: October 30, 2009 University of Surrey Expires: March 5, 2010 University of Surrey
A. Morton A. Morton
AT&T Labs AT&T Labs
April 28, 2009 September 1, 2009
IP Performance Metrics (IPPM) for spatial and multicast IP Performance Metrics (IPPM) for spatial and multicast
draft-ietf-ippm-multimetrics-11 draft-ietf-ippm-multimetrics-12
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. This document may contain material provisions of BCP 78 and BCP 79. This document may contain material
from IETF Documents or IETF Contributions published or made publicly from IETF Documents or IETF Contributions published or made publicly
available before November 10, 2008. The person(s) controlling the available before November 10, 2008. The person(s) controlling the
copyright in some of this material may not have granted the IETF copyright in some of this material may not have granted the IETF
Trust the right to allow modifications of such material outside the Trust the right to allow modifications of such material outside the
IETF Standards Process. Without obtaining an adequate license from IETF Standards Process. Without obtaining an adequate license from
skipping to change at page 1, line 45 skipping to change at page 1, line 45
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."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on October 30, 2009. This Internet-Draft will expire on March 5, 2010.
Copyright Notice Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the Copyright (c) 2009 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 in effect on the date of Provisions Relating to IETF Documents in effect on the date of
publication of this document (http://trustee.ietf.org/license-info). publication of this document (http://trustee.ietf.org/license-info).
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
skipping to change at page 3, line 14 skipping to change at page 3, line 14
Table of Contents Table of Contents
1. Introduction and Scope . . . . . . . . . . . . . . . . . . . . 4 1. Introduction and Scope . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Brief Metric Descriptions . . . . . . . . . . . . . . . . . . 8 3. Brief Metric Descriptions . . . . . . . . . . . . . . . . . . 8
4. Motivations . . . . . . . . . . . . . . . . . . . . . . . . . 10 4. Motivations . . . . . . . . . . . . . . . . . . . . . . . . . 10
5. Spatial vector metrics definitions . . . . . . . . . . . . . . 12 5. Spatial vector metrics definitions . . . . . . . . . . . . . . 12
6. Spatial Segment Metrics Definitions . . . . . . . . . . . . . 19 6. Spatial Segment Metrics Definitions . . . . . . . . . . . . . 19
7. One-to-group metrics definitions . . . . . . . . . . . . . . . 24 7. One-to-group metrics definitions . . . . . . . . . . . . . . . 24
8. One-to-group Sample Statistics . . . . . . . . . . . . . . . . 27 8. One-to-group Sample Statistics . . . . . . . . . . . . . . . . 28
9. Measurement Methods: Scalability and Reporting . . . . . . . . 37 9. Measurement Methods: Scalability and Reporting . . . . . . . . 37
10. Manageability Considerations . . . . . . . . . . . . . . . . . 40 10. Manageability Considerations . . . . . . . . . . . . . . . . . 41
11. Security Considerations . . . . . . . . . . . . . . . . . . . 45 11. Security Considerations . . . . . . . . . . . . . . . . . . . 45
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 46 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 47
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 46 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 47
14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 50 14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 51
14.1. Normative References . . . . . . . . . . . . . . . . . . 50 14.1. Normative References . . . . . . . . . . . . . . . . . . 51
14.2. Informative References . . . . . . . . . . . . . . . . . 51 14.2. Informative References . . . . . . . . . . . . . . . . . 52
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 51 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 52
1. Introduction and Scope 1. Introduction and Scope
IETF has standardized IP Performance Metrics (IPPM) for measuring IETF has standardized IP Performance Metrics (IPPM) for measuring
end-to-end performance between two points. This memo defines two new end-to-end performance between two points. This memo defines two new
categories of metrics that extend the coverage to multiple categories of metrics that extend the coverage to multiple
measurement points. It defines spatial metrics for measuring the measurement points. It defines spatial metrics for measuring the
performance of segments of a source to destination path, and metrics performance of segments of a source to destination path, and metrics
for measuring the performance between a source and many destinations for measuring the performance between a source and many destinations
in multiparty communications (e.g., a multicast tree). in multiparty communications (e.g., a multicast tree).
skipping to change at page 5, line 9 skipping to change at page 5, line 9
2.1. Naming of the metrics 2.1. Naming of the metrics
The names of the metrics, including capitalization letters, are as The names of the metrics, including capitalization letters, are as
close as possible of the names of the one-way end-to-end metrics they close as possible of the names of the one-way end-to-end metrics they
are derived from. are derived from.
2.2. Terms Defined Elsewhere 2.2. Terms Defined Elsewhere
host: section 5 of RFC 2330 host: section 5 of RFC 2330
router: section 5 of RFC 2330
loss threshold: section 2.8.2 of RFC 2680 loss threshold: section 2.8.2 of RFC 2680
path: section 5 of RFC 2330 path: section 5 of RFC 2330
path digest: section 5 of RFC 2330
sample: section 11 of RFC 2330 sample: section 11 of RFC 2330
singleton: section 11 of RFC 2330 singleton: section 11 of RFC 2330
2.3. Path Digest Hosts 2.3. Routers Digest
The list of the hosts on a path from the source to the destination, The list of the routers on the path from the source to the
also referred to as the host path digest. destination which act as points of interest, also referred to as the
routers digest.
2.4. Multiparty metric 2.4. Multiparty metric
A metric is said to be multiparty if the topology involves more than A metric is said to be multiparty if the topology involves more than
one measurement collection point. All multiparty metrics designate a one measurement collection point. All multiparty metrics designate a
set of hosts as "points of interest", where one host is the source set of hosts as "points of interest", where one host is the source
and other hosts are the measurement collection points. For example, and other hosts are the measurement collection points. For example,
if the set of points of interest is < ha, hb, hc, ..., hn >, where ha if the set of points of interest is < ha, hb, hc, ..., hn >, where ha
is the source and < hb, hc, ..., hn > are the destinations, then is the source and < hb, hc, ..., hn > are the destinations, then
measurements may be conducted between < ha, hb>, < ha, hc>, ..., <ha, measurements may be conducted between < ha, hb>, < ha, hc>, ..., <ha,
hn >. hn >.
For the purposes of this memo (reflecting the scope of a single For the purposes of this memo (reflecting the scope of a single
source), the only multiparty metrics are one-to-group metrics. source), the only multiparty metrics are one-to-group metrics.
2.5. Spatial metric 2.5. Spatial metric
A metric is said to be spatial if one of the hosts (measurement A metric is said to be spatial if one of the hosts (measurement
collection points) involved is neither the source nor a destination collection points) involved is neither the source nor a destination
of the measured packet(s). Such measurement hosts will usually be of the measured packet(s). Such measurement hosts will usually be
members of the path digest. routers member of the routers digest.
2.6. One-to-group metric 2.6. One-to-group metric
A metric is said to be one-to-group if the measured packet is sent by A metric is said to be one-to-group if the measured packet is sent by
one source and (potentially) received by more than one destination. one source and (potentially) received by more than one destination.
Thus, the topology of the communication group can be viewed as a Thus, the topology of the communication group can be viewed as a
center-distributed or server-client topology with the source as the center-distributed or server-client topology with the source as the
center/server in the topology. center/server in the topology.
2.7. Points of interest 2.7. Points of interest
Points of interest are the hosts (as per the RFC 2330 definition, Points of interest are the hosts (as per the RFC 2330 definition,
"hosts" include routing nodes) that are measurement collection "hosts" include routing nodes) that are measurement collection
points, a sub-set of the set of hosts involved in the delivery of the points, a sub-set of the set of hosts involved in the delivery of the
packets (in addition to the source itself). packets (in addition to the source itself).
For spatial metrics, points of interest are a (possibly arbitrary) For spatial metrics, points of interest are a (possibly arbitrary)
sub-set of all the hosts involved in the path. sub-set of all the routers involved in the path.
Points of interest of one-to-group metrics are the intended Points of interest of one-to-group metrics are the intended
destination hosts for packets from the source (in addition to the destination hosts for packets from the source (in addition to the
source itself). source itself).
Src Dst Src Dst
`. ,-. `. ,-.
`. ,' `...... 1 `. ,' `...... 1
`. ; : `. ; :
`. ; : `. ; :
; :... 2 ; :... 2
| | | |
: ; : ;
: ;.... 3 : ;.... 3
: ; : ;
`. ,' `. ,'
`-'....... I `-'....... I
Figure 1: One-to-group points of interest Figure 1: One-to-group points of interest
A candidate point of interest for spatial metrics is a host from the A candidate point of interest for spatial metrics is a router from
set of hosts involved in the delivery of the packets from source to the set of routers involved in the delivery of the packets from
destination. source to destination.
Src ------. Hosts Src ------. Hosts
\ \
`---X ... 1 `---X --- 1
\ \
x x
/ /
.---------X .... 2 .---------X ---- 2
/ /
x x
\ ...
`---X .... 3 `---X ---- ...
\ \
\ \
\ \
X .... J X ---- J
\ \
\ \
\ \
`---- Dst `---- Dst
Note: 'x' are nodes which are not points of interest Note: 'X' are nodes which are points of interest,
'x' are nodes which are not points of interest
Figure 2: Spatial points of interest Figure 2: Spatial points of interest
2.8. Reference point 2.8. Reference point
A reference point is defined as the server where the statistical A reference point is defined as the server where the statistical
calculations will be carried out. It is usually a centralized server calculations will be carried out. It is usually a centralized server
in the measurement architecture that is controlled by a network in the measurement architecture that is controlled by a network
operator, where measurement data can be collected for further operator, where measurement data can be collected for further
processing. The reference point is distinctly different from hosts processing. The reference point is distinctly different from hosts
skipping to change at page 8, line 48 skipping to change at page 8, line 50
vector matrix vector matrix
(space) (time and space) (space) (time and space)
Figure 3: Relationship between singletons, samples, vectors and Figure 3: Relationship between singletons, samples, vectors and
matrix matrix
3. Brief Metric Descriptions 3. Brief Metric Descriptions
The metrics for spatial and one-to-group measurement are based on the The metrics for spatial and one-to-group measurement are based on the
source-to-destination, or end-to-end metrics defined by IETF in source-to-destination, or end-to-end metrics defined by IETF in
[[RFC2679], [RFC2680], [RFC3393], [RFC3432]. [RFC2679], [RFC2680], [RFC3393], [RFC3432].
This memo defines seven new spatial metrics using the [RFC2330] This memo defines seven new spatial metrics using the [RFC2330]
framework of parameters, units of measure, and measurement framework of parameters, units of measure, and measurement
methodologies. Each definition includes a section that describes methodologies. Each definition includes a section that describes
measurements constraints and issues, and provides guidance to measurements constraints and issues, and provides guidance to
increase the accuracy of the results. increase the accuracy of the results.
The spatial metrics are: The spatial metrics are:
o Type-P-Spatial-One-way-Delay-Vector divides the end-to-end Type-P- o Type-P-Spatial-One-way-Delay-Vector divides the end-to-end Type-P-
One-way-Delay [RFC2679] into a spatial vector of one-way delay One-way-Delay [RFC2679] into a spatial vector of one-way delay
singletons. singletons.
o Type-P-Spatial-One-way-Packet-Loss-Vector divides an end-to-end o Type-P-Spatial-One-way-Packet-Loss-Vector divides an end-to-end
Type-P-One-way-Packet-Loss [RFC2680] into a spatial vector of Type-P-One-way-Packet-Loss [RFC2680] into a spatial vector of
packet loss singletons. packet loss singletons.
o Type-P-Spatial-One-way-ipdv-Vector divides an end-to-end Type-P- o Type-P-Spatial-One-way-ipdv-Vector divides an end-to-end Type-P-
One-way-ipdv into a spatial vector of ipdv singletons. One-way-ipdv into a spatial vector of ipdv (IP Packet Delay
Variation) singletons.
o Using elements of the Type-P-Spatial-One-way-Delay-Vector metric, o Using elements of the Type-P-Spatial-One-way-Delay-Vector metric,
a sample called Type-P-Segment-One-way-Delay-Stream collects one- a sample called Type-P-Segment-One-way-Delay-Stream collects one-
way delay metrics between two points of interest on the path over way delay metrics between two points of interest on the path over
time. time.
o Likewise, using elements of the Type-P-Spatial-Packet-Loss-Vector o Likewise, using elements of the Type-P-Spatial-Packet-Loss-Vector
metric, a sample called Type-P-Segment-Packet-Loss-Stream collects metric, a sample called Type-P-Segment-Packet-Loss-Stream collects
one-way delay metrics between two points of interest on the path one-way delay metrics between two points of interest on the path
over time. over time.
o Using the Type-P-Spatial-One-way-Delay-Vector metric, a sample o Using the Type-P-Spatial-One-way-Delay-Vector metric, a sample
called Type-P-Segment-ipdv-prev-Stream, will be introduced to called Type-P-Segment-ipdv-prev-Stream, will be introduced to
skipping to change at page 10, line 46 skipping to change at page 11, line 4
metrics and one to multipoint metrics. metrics and one to multipoint metrics.
4.1. Motivations for spatial metrics 4.1. Motivations for spatial metrics
Spatial metrics are needed for: Spatial metrics are needed for:
o Decomposing the performance of an inter-domain path to quantify o Decomposing the performance of an inter-domain path to quantify
the per-AS contribution to the end-to-end performance. the per-AS contribution to the end-to-end performance.
o Traffic engineering and troubleshooting, which benefit from o Traffic engineering and troubleshooting, which benefit from
spatial views of one-way delay and ipdv consumption, or spatial views of one-way delay and ipdv consumption, or
identification of the path segment where packets were lost. identification of the path segment where packets were lost.
o Monitoring the decomposed performance of a multicast tree based on o Monitoring the decomposed performance of a multicast tree based on
of MPLS point-to-multipoint communications. MPLS point-to-multipoint communications.
o Dividing end-to-end metrics, so that some segment measurements can o Dividing end-to-end metrics, so that some segment measurements can
be re-used and help measurement systems reach large-scale be re-used and help measurement systems reach large-scale
coverage. Spatial measures could characterize the performance of coverage. Spatial measures could characterize the performance of
an intra-domain segment and provide an elementary piece of an intra-domain segment and provide an elementary piece of
information needed to estimate inter-domain performance to another information needed to estimate inter-domain performance to another
destination using Spatial Composition metrics destination using Spatial Composition metrics
[I-D.ietf-ippm-spatial-composition]. [I-D.ietf-ippm-spatial-composition].
4.2. Motivations for One-to-group metrics 4.2. Motivations for One-to-group metrics
skipping to change at page 13, line 19 skipping to change at page 13, line 19
related to methodology, clock, uncertainties and reporting. related to methodology, clock, uncertainties and reporting.
5.1.1. Metric Name 5.1.1. Metric Name
Type-P-Spatial-One-way-Delay-Vector Type-P-Spatial-One-way-Delay-Vector
5.1.2. Metric Parameters 5.1.2. Metric Parameters
o Src*, the IP address of the sender. o Src*, the IP address of the sender.
o Dst*, the IP address of the receiver. o Dst*, the IP address of the receiver.
o i, an integer in the ordered list <1,2,...,n> of hosts in the o i, an integer in the ordered list <1,2,...,n> of routers in the
path. path.
o Hi, a host in the path digest. o Hi, a router of the routers digest.
o T*, a time, the sending (or initial observation) time for a o T*, a time, the sending (or initial observation) time for a
measured packet. measured packet.
o dT*, a delay, the one-way delay for a measured packet. o dT*, a delay, the one-way delay for a measured packet.
o dTi, a delay, the one-way delay for a measured packet from the o dTi, a delay, the one-way delay for a measured packet from the
source to host Hi. source to router Hi.
o <dT1,... dTi,... dTn> a list of n delay singletons. o <dT1,... dTi,... dTn> a list of n delay singletons.
o Type-P*, the specification of the packet type. o Type-P*, the specification of the packet type.
o <H1, H2,..., Hn>, a path host digest. o <H1, H2,..., Hn> the routers digest.
5.1.3. Metric Units 5.1.3. Metric Units
The value of Type-P-Spatial-One-way-Delay-Vector is a sequence of The value of Type-P-Spatial-One-way-Delay-Vector is a sequence of
times (a real number in the dimension of seconds with sufficient times (a real number in the dimension of seconds with sufficient
resolution to convey the results). resolution to convey the results).
5.1.4. Definition 5.1.4. Definition
Given a Type-P packet sent by the Src at wire-time (first bit) T to Given a Type-P packet sent by the Src at wire-time (first bit) T to
skipping to change at page 14, line 8 skipping to change at page 14, line 8
(last bit received) Hi, or undefined if the packet does not pass Hi (last bit received) Hi, or undefined if the packet does not pass Hi
within a specified loss threshold* time. within a specified loss threshold* time.
Type-P-Spatial-One-way-Delay-Vector 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>.
5.1.5. Discussion 5.1.5. Discussion
Some specific issues that may occur are as follows: Some specific issues that may occur are as follows:
o the delay singletons "appear" to decrease: dTi > DTi+1. This may o the delay singletons "appear" to decrease: dTi > dTi+1. This may
occur despite being physically impossible with the definition occur despite being physically impossible with the definition
used. used.
* This is frequently due to a measurement clock synchronization * This is frequently due to a measurement clock synchronization
issue. This point is discussed in the section 3.7.1. "Errors issue. This point is discussed in the section 3.7.1. "Errors
or uncertainties related to Clocks" of [RFC2679]. or uncertainties related to Clocks" of [RFC2679].
Consequently, the values of delays measured at multiple hosts Consequently, the values of delays measured at multiple routers
may not match the order of those hosts on the path. may not match the order of those routers on the path.
* The actual order of hosts on the path may change due to * The actual order of routers on the path may change due to
reconvergence (e.g., recovery from a link failure). reconvergence (e.g., recovery from a link failure).
* The location of the measurement collection point in the device * The location of the measurement collection point in the device
influences the result. If the packet is not observed directly influences the result. If the packet is not observed directly
on the input interface the delay includes buffering time and on the input interface the delay includes buffering time and
consequently an uncertainty due to the difference between 'wire consequently an uncertainty due to the difference between 'wire
time' and 'host time'. time' and 'host time'.
5.2. A Definition for Spatial Packet Loss Vector 5.2. A Definition for Spatial 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. When a parameter from the section 2 of [RFC2680] is used in Loss. When a parameter from section 2 of [RFC2680] is used in this
this section, the first instance will be tagged with a trailing section, the first instance will be tagged with a trailing asterisk.
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 MUST respect them, especially those Spatial packet loss measurement MUST respect them, especially those
related to methodology, clock, uncertainties and reporting. related to methodology, clock, uncertainties and reporting.
The following sections define the spatial loss vector, adapt some of The following sections define the spatial loss vector, adapt some of
the points above, and introduce points specific to spatial loss the points above, and introduce points specific to spatial loss
measurement. measurement.
5.2.1. Metric Name 5.2.1. Metric Name
Type-P-Spatial-Packet-Loss-Vector Type-P-Spatial-Packet-Loss-Vector
5.2.2. Metric Parameters 5.2.2. Metric Parameters
o Src*, the IP address of the sender. o Src*, the IP address of the sender.
o Dst*, the IP address of the receiver. o Dst*, the IP address of the receiver.
o i, an integer in the ordered list <1,2,...,n> of hosts in the o i, an integer in the ordered list <1,2,...,n> of routers in the
path. path.
o Hi, a router of the routers digest.
o Hi, points of interest from the path digest.
o T*, a time, the sending time for a measured packet. o T*, a time, the sending time for a measured packet.
o dTi, a delay, the one-way delay for a measured packet from the o dTi, a delay, the one-way delay for a measured packet from the
source to host Hi. source to host Hi.
o <dT1,..., dTn>, list of n delay singletons. o <dT1,..., dTn>, list of n delay singletons.
o Type-P*, the specification of packet type. o Type-P*, the specification of packet type.
o <H1, H2,..., Hn>, a host path digest. o <H1, H2,..., Hn>, the routers digest.
o <L1, L2, ...,Ln>, a list of Boolean values. o <L1, L2, ...,Ln>, a list of Boolean values.
5.2.3. Metric Units 5.2.3. Metric Units
The value of Type-P-Spatial-Packet-Loss-Vector is a sequence of The value of Type-P-Spatial-Packet-Loss-Vector is a sequence of
Boolean values. Boolean values.
5.2.4. Definition 5.2.4. Definition
Given a Type-P packet sent by the Src at time T to the receiver Dst Given a Type-P packet sent by the Src at time T to the receiver Dst
skipping to change at page 15, line 35 skipping to change at page 15, line 34
of values <T, L1, L2, ..., Ln> such that for each Hi of the path, a of values <T, L1, L2, ..., Ln> such that for each Hi of the path, a
value of 0 for Li means that dTi is a finite value, and a value of 1 value of 0 for Li means that dTi is a finite value, and a value of 1
means that dTi is undefined. means that dTi is undefined.
5.2.5. Discussion 5.2.5. Discussion
Some specific issues that may occur are as follows: Some specific issues that may occur are as follows:
o The result might include the sequence of values 1,0. Although o The result might include the sequence of values 1,0. Although
this appears physically impossible (a packet is lost, then re- this appears physically impossible (a packet is lost, then re-
appears later on the path): appears later on the path):
* The actual hosts on the path may change due to reconvergence * The actual routers on the path may change due to reconvergence
(e.g., recovery from a link failure). (e.g., recovery from a link failure).
* The order of hosts on the path may change due to reconvergence. * The order of routers on the path may change due to
* A packet may not be observed in a host due to some buffer or reconvergence.
* A packet may not be observed in a router due to some buffer or
CPU overflow at the measurement collection point. CPU overflow at the measurement collection point.
5.3. A Definition for Spatial One-way Ipdv Vector 5.3. A Definition for Spatial One-way Ipdv Vector
When a parameter from section 2 of [RFC3393] (the definition of Type- When a parameter from section 2 of [RFC3393] (the definition of Type-
P-One-way-ipdv) is used in this section, the first instance will be P-One-way-ipdv) is used in this section, the first instance will be
tagged with a trailing asterisk. tagged with a trailing asterisk.
The following sections define the spatial ipdv vector, adapt some of The following sections define the spatial ipdv vector, adapt some of
the points above, and introduce points specific to spatial ipdv the points above, and introduce points specific to spatial ipdv
measurement. measurement.
5.3.1. Metric Name 5.3.1. Metric Name
Type-P-Spatial-One-way-ipdv-Vector Type-P-Spatial-One-way-ipdv-Vector
5.3.2. Metric Parameters 5.3.2. Metric Parameters
o Src*, the IP address of the sender. o Src*, the IP address of the sender.
o Dst*, the IP address of the receiver. o Dst*, the IP address of the receiver.
o i, an integer in the ordered list <1,2,...,n> of hosts in the o i, an integer in the ordered list <1,2,...,n> of routers in the
path. path.
o Hi, a host of the path digest. o Hi, a router of the routers digest.
o T1*, a time, the sending time for a first measured packet. o T1*, a time, the sending time for a first measured packet.
o T2*, a time, the sending time for a second measured packet. o T2*, a time, the sending time for a second measured packet.
o dT*, a delay, the one-way delay for a measured packet. o dT*, a delay, the one-way delay for a measured packet.
o dTi, a delay, the one-way delay for a measured packet from the o dTi, a delay, the one-way delay for a measured packet from the
source to host Hi. source to router Hi.
o Type-P*, the specification of the packets type. o Type-P*, the specification of the packets type.
o P1, the first packet sent at time T1. o P1, the first packet sent at time T1.
o P2, the second packet sent at time T2. o P2, the second packet sent at time T2.
o <H1, H2,..., Hn>, a host path digest. o <H1, H2,..., Hn>, the routers digest.
o <T1,dT1.1, dT1.2,..., dT1.n,dT1>, the Type-P-Spatial-One-way- o <T1,dT1.1, dT1.2,..., dT1.n,dT1>, the Type-P-Spatial-One-way-
Delay-Vector for packet sent at time T1. Delay-Vector for packet sent at time T1.
o <T2,dT2.1, dT2.2,..., dT2.n,dT2>, the Type-P-Spatial-One-way- o <T2,dT2.1, dT2.2,..., dT2.n,dT2>, the Type-P-Spatial-One-way-
Delay-Vector for packet sent at time T2. Delay-Vector for packet sent at time T2.
o L*, a packet length in bits. The packets of a Type P packet o L*, a packet length in bits. The packets of a Type P packet
stream from which the Type-P-Spatial-One-way-Delay-Vector metric stream from which the Type-P-Spatial-One-way-Delay-Vector metric
is taken MUST all be of the same length. is taken MUST all be of the same length.
5.3.3. Metric Units 5.3.3. Metric Units
The value of Type-P-Spatial-One-way-ipdv-Vector is a sequence of The value of Type-P-Spatial-One-way-ipdv-Vector is a sequence of
times (a real number in the dimension of seconds with sufficient times (a real number in the dimension of seconds with sufficient
resolution to convey the results). resolution to convey the results).
5.3.4. Definition 5.3.4. Definition
Given P1 the Type-P packet sent by the sender Src at wire-time (first Given P1 the Type-P packet sent by the sender Src at wire-time (first
bit) T1 to the receiver Dst and <T1, dT1.1, dT1.2,..., dT1.n, dT1> bit) T1 to the receiver Dst and <T1, dT1.1, dT1.2,..., dT1.n, dT1>
its Type-P-Spatial-One-way-Delay-Vector over the path <H1, H2,..., its Type-P-Spatial-One-way-Delay-Vector over the sequence of routers
Hn>. <H1, H2,..., Hn>.
Given P2 the Type-P packet sent by the sender Src at wire-time (first Given P2 the Type-P packet sent by the sender Src at wire-time (first
bit) T2 to the receiver Dst and <T2, dT2.1, dT2.2,..., dT2.n, dT2> bit) T2 to the receiver Dst and <T2, dT2.1, dT2.2,..., dT2.n, dT2>
its Type-P-Spatial-One-way-Delay-Vector over the same path. its Type-P-Spatial-One-way-Delay-Vector over the same path.
Type-P-Spatial-One-way-ipdv-Vector metric is defined as the sequence Type-P-Spatial-One-way-ipdv-Vector metric is defined as the sequence
of values <T1, T2, dT2.1-dT1.1, dT2.2-dT1.2 ,..., dT2.n-dT1.n, dT2- of values <T1, T2, 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>, dT2.i-dT1.i dT1> such that for each Hi of the sequence of routers <H1, H2,...,
is either a real number if the packets P1 and P2 pass Hi at wire-time Hn>, dT2.i-dT1.i is either a real number if the packets P1 and P2
(last bit) dT1.i and dT2.i respectively, or undefined if at least one pass Hi at wire-time (last bit) dT1.i and dT2.i respectively, or
of them never passes Hi (and the respective one-way delay is undefined if at least one of them never passes Hi (and the respective
undefined). The T1,T2* pair indicates the inter-packet emission one-way delay is undefined). The T1,T2* pair indicates the inter-
interval and dT2-dT1 is ddT* the Type-P-One-way-ipdv. packet emission interval and dT2-dT1 is ddT* the Type-P-One-way-ipdv.
5.4. Spatial Methodology 5.4. Spatial Methodology
The methodology, reporting specifications, and uncertainties The methodology, reporting specifications, and uncertainties
specified in section 3 of [RFC2679] apply to each point of interest specified in section 3 of [RFC2679] apply to each point of interest
(or measurement collection point), Hi, measuring an element of a (or measurement collection point), Hi, measuring an element of a
spatial delay vector. spatial delay vector.
Likewise, the methodology, reporting specifications, and Likewise, the methodology, reporting specifications, and
uncertainties specified in section 2 of [RFC2680] apply to each point uncertainties specified in section 2 of [RFC2680] apply to each point
skipping to change at page 18, line 32 skipping to change at page 18, line 32
may be computed as infinite by one observation point but as a real may be computed as infinite by one observation point but as a real
value by another one, or may be measured as a real value by the last value by another one, or may be measured as a real value by the last
observation point of the path but designated as undefined by Dst. observation point of the path but designated as undefined by Dst.
The observation/measurement collection points and the destination The observation/measurement collection points and the destination
SHOULD use consistent methods to detect packets losses. The methods SHOULD use consistent methods to detect packets losses. The methods
and parameters must be systematically reported to permit careful and parameters must be systematically reported to permit careful
comparison and to avoid introducing any confounding factors in the comparison and to avoid introducing any confounding factors in the
analysis. analysis.
5.4.2. Host Path Digest 5.4.2. Routers Digest
The methodology given above relies on knowing the order of the hosts/ The methodology given above relies on knowing the order of the
measurement collection points on the path [RFC2330]. router/measurement collection points on the path [RFC2330].
Path instability might cause a test packet to be observed more than Path instability might cause a test packet to be observed more than
once by the same host, resulting in the repetition of one or more once by the same router, resulting in the repetition of one or more
hosts in the Path Digest. routers in the routers digest.
For example, repeated observations may occur during rerouting phases For example, repeated observations may occur during rerouting phases
which introduce temporary micro loops. During such an event the host which introduce temporary micro loops. During such an event the
path digest for a packet crossing Ha and Hb may include the pattern routers digest for a packet crossing Ha and Hb may include the
<Hb, Ha, Hb, Ha, Hb> meaning that Ha ended the computation of the new pattern <Hb, Ha, Hb, Ha, Hb> meaning that Ha ended the computation of
path before Hb and that the initial path was from Ha to Hb and that the new path before Hb and that the initial path was from Ha to Hb
the new path is from Hb to Ha. and that the new path is from Hb to Ha.
Consequently, duplication of hosts in the path digest of a vector Consequently, duplication of routers in the routers digest of a
MUST be identified before computation of statistics to avoid vector MUST be identified before computation of statistics to avoid
producing corrupted information. producing corrupted information.
6. Spatial Segment Metrics Definitions 6. Spatial Segment Metrics Definitions
This section defines samples to measure the performance of a segment This section defines samples to measure the performance of a segment
of a path over time. The definitions rely on the matrix of the of a path over time. The definitions rely on the matrix of the
spatial vector metrics defined above. spatial vector metrics defined above.
Firstly this section defines a sample of one-way delay, Type-P- Firstly this section defines a sample of one-way delay, Type-P-
Segment-One-way-Delay-Stream, and a sample of packet loss, Type-P- Segment-One-way-Delay-Stream, and a sample of packet loss, Type-P-
segment-Packet-Loss-Stream. segment-Packet-Loss-Stream.
Then it defines 2 different samples of ipdv: Type-P-Segment-ipdv- Then it defines 2 different samples of ipdv: Type-P-Segment-ipdv-
prev-Stream uses the current and previous packets as the selection prev-Stream uses the current and previous packets as the selection
function, and Type-P-Segment-ipdv-min-Stream, uses the minimum delay function, and Type-P-Segment-ipdv-min-Stream, uses the minimum delay
as one of the selected packets in every pair. as one of the selected packets in every pair.
6.1. A Definition of a Sample of One-way Delay of a Segment of the Path 6.1. A Definition of a Sample of One-way Delay of a Segment of the Path
This metric defines a sample of One-way delays over time between a This metric defines a sample of One-way delays over time between a
pair of hosts on a path. Since it is very close semantically to the pair of routers on a path. Since it is very close semantically to
metric Type-P-One-way-Delay-Poisson-Stream defined in section 4 of the metric Type-P-One-way-Delay-Poisson-Stream defined in section 4
[RFC2679], sections 4.5 to 4.8 of [RFC2679] are integral parts of the of [RFC2679], sections 4.5 to 4.8 of [RFC2679] are integral parts of
definition text below. the definition text below.
6.1.1. Metric Name 6.1.1. Metric Name
Type-P-Segment-One-way-Delay-Stream Type-P-Segment-One-way-Delay-Stream
6.1.2. Metric Parameters 6.1.2. Metric Parameters
o Src, the IP address of the sender. o Src, the IP address of the sender.
o Dst, the IP address of the receiver. o Dst, the IP address of the receiver.
o Type-P, the specification of the packet type. o Type-P, the specification of the packet type.
o i, an integer in the ordered list <1,2,...,n> of hosts in the o i, an integer in the ordered list <1,2,...,n> of routers in the
path. path.
o k, an integer which orders the packets sent. o k, an integer which orders the packets sent.
o a and b, two integers where b > a. o a and b, two integers where b > a.
o Hi, a host of the path digest. o Hi, a router of the routers digest.
o <H1,..., Ha, ..., Hb, ...., Hn>, a host path digest. o <H1,..., Ha, ..., Hb, ...., Hn>, the routers digest.
o <T1, T2, ..., Tm>, a list of times. o <T1, T2, ..., Tm>, a list of times.
6.1.3. Metric Units 6.1.3. Metric Units
The value of a Type-P-Segment-One-way-Delay-Stream is a pair of: The value of a Type-P-Segment-One-way-Delay-Stream is a pair of:
A list of times <T1, T2, ..., Tm>; A list of times <T1, T2, ..., Tm>;
A sequence of delays. A sequence of delays.
6.1.4. Definition 6.1.4. Definition
Given 2 hosts, Ha and Hb, of the path <H1, H2,..., Ha, ..., Hb, ..., Given two routers, Ha and Hb, of the the path <H1, H2,..., Ha, ...,
Hn>, and the matrix of Type-P-Spatial-One-way-Delay-Vector for the Hb, ..., Hn>, and the matrix of Type-P-Spatial-One-way-Delay-Vector
packets sent from Src to Dst at times <T1, T2, ..., Tm-1, Tm> : for the packets sent from Src to Dst at times <T1, T2, ..., Tm-1, Tm>
:
<T1, dT1.1, dT1.2, ..., dT1.a, ..., dT1.b,..., dT1.n, dT1>; <T1, dT1.1, dT1.2, ..., dT1.a, ..., dT1.b,..., dT1.n, dT1>;
<T2, dT2.1, dT2.2, ..., dT2.a, ..., dT2.b,..., dT2.n, dT2>; <T2, dT2.1, dT2.2, ..., dT2.a, ..., dT2.b,..., dT2.n, dT2>;
... ...
<Tm, dTm.1, dTm.2, ..., dTm.a, ..., dTm.b,..., dTm.n, dTm>. <Tm, dTm.1, dTm.2, ..., dTm.a, ..., dTm.b,..., dTm.n, dTm>.
We define the sample Type-P-segment-One-way-Delay-Stream as the We define the sample Type-P-segment-One-way-Delay-Stream as the
sequence <dT1.ab, dT2.ab, ..., dTk.ab, ..., dTm.ab> such that for sequence <dT1.ab, dT2.ab, ..., dTk.ab, ..., dTm.ab> such that for
each time Tk, 'dTk.ab' is either the real number 'dTk.b - dTk.a' if each time Tk, 'dTk.ab' is either the real number 'dTk.b - dTk.a' if
the packet sent at time Tk passes Ha and Hb or undefined if this the packet sent at time Tk passes Ha and Hb or undefined if this
packet never passes Ha or (inclusive) never passes Hb. packet never passes Ha or (inclusive) never passes Hb.
skipping to change at page 20, line 39 skipping to change at page 20, line 40
through optical fiber facilities is 2.5ms, but the measurement through optical fiber facilities is 2.5ms, but the measurement
collection point has a clock resolution of 8ms. collection point has a clock resolution of 8ms.
The metric SHALL be invalid for times < T1 , T2, ..., Tm-1, Tm> if The metric SHALL be invalid for times < T1 , T2, ..., Tm-1, Tm> if
the following conditions occur: the following conditions occur:
o Ha or Hb disappears from the path due to some routing change. o Ha or Hb disappears from the path due to some routing change.
o The order of Ha and Hb changes in the path. o The order of Ha and Hb changes in the path.
6.2. A Definition of a Sample of Packet Loss of a Segment of the Path 6.2. A Definition of a Sample of Packet Loss of a Segment of the Path
This metric defines a sample of packet loss over time between a pair This metric defines a sample of packet loss over time between a pair
of hosts of a path. Since it is very close semantically to the of routers of a path. Since it is very close semantically to the
metric Type-P-Packet-loss-Stream defined in section 3 of [RFC2680], metric Type-P-Packet-loss-Stream defined in section 3 of [RFC2680],
sections 3.5 to 3.8 of [RFC2680] are integral parts of the definition sections 3.5 to 3.8 of [RFC2680] are integral parts of the definition
text below. text below.
6.2.1. Metric Name 6.2.1. Metric Name
Type-P-segment-Packet-Loss-Stream Type-P-segment-Packet-Loss-Stream
6.2.2. Metric Parameters 6.2.2. Metric Parameters
o Src, the IP address of the sender. o Src, the IP address of the sender.
o Dst, the IP address of the receiver. o Dst, the IP address of the receiver.
o Type-P, the specification of the packet type. o Type-P, the specification of the packet type.
o k, an integer which orders the packets sent. o k, an integer which orders the packets sent.
o n, an integer which orders the hosts on the path. o n, an integer which orders the routers on the path.
o a and b, two integers where b > a. o a and b, two integers where b > a.
o <H1, H2, ..., Ha, ..., Hb, ...,Hn>, a host path digest. o <H1, H2, ..., Ha, ..., Hb, ...,Hn>, the routers digest.
o Hi, exchange points of the path digest. o Hi, a router of the routers digest.
o <T1, T2, ..., Tm>, a list of times. o <T1, T2, ..., Tm>, a list of times.
o <L1, L2, ..., Ln>, a list of Boolean values. o <L1, L2, ..., Ln>, a list of Boolean values.
6.2.3. Metric Units 6.2.3. Metric Units
The value of a Type-P-segment-Packet-Loss-Stream is a pair of: The value of a Type-P-segment-Packet-Loss-Stream is a pair of:
A The list of times <T1, T2, ..., Tm>; A The list of times <T1, T2, ..., Tm>;
A sequence of Boolean values. A sequence of Boolean values.
6.2.4. Definition 6.2.4. Definition
Given two hosts, Ha and Hb, of the path <H1, H2,..., Ha, ..., Hb, Given two routers, Ha and Hb, of the the path <H1, H2,..., Ha, ...,
..., Hn>, and the matrix of Type-P-Spatial-Packet-Loss-Vector for the Hb, ..., Hn>, and the matrix of Type-P-Spatial-Packet-Loss-Vector for
packets sent from Src to Dst at times <T1, T2, ..., Tm-1, Tm> : the packets sent from Src to Dst at times <T1, T2, ..., Tm-1, Tm> :
<T1, L1.1, L1.2,..., L1.a, ..., L1.b, ..., L1.n, L>, <T1, L1.1, L1.2,..., L1.a, ..., L1.b, ..., L1.n, L>,
<T2, L2.1, L2.2,..., L2.a, ..., L2.b, ..., L2.n, L>, <T2, L2.1, L2.2,..., L2.a, ..., L2.b, ..., L2.n, L>,
..., ...,
<Tm, Lm.1, Lm.2,..., Lma, ..., Lm.b, ..., Lm.n, L>. <Tm, Lm.1, Lm.2,..., Lma, ..., Lm.b, ..., Lm.n, L>.
We define the value of the sample Type-P-segment-Packet-Lost-Stream We define the value of the sample Type-P-segment-Packet-Loss-Stream
from Ha to Hb as the sequence of Booleans <L1.ab, L2.ab,..., Lk.ab, from Ha to Hb as the sequence of Booleans <L1.ab, L2.ab,..., Lk.ab,
..., Lm.ab> such that for each Tk: ..., Lm.ab> such that for each Tk:
o A value of Lk of 0 means that Ha and Hb observed the packet sent o A value of Lk of 0 means that Ha and Hb observed the packet sent
at time Tk (both Lk.a and Lk.b have a value of 0). at time Tk (both Lk.a and Lk.b have a value of 0).
o A value of Lk of 1 means that Ha observed the packet sent at time o A value of Lk of 1 means that Ha observed the packet sent at time
Tk (Lk.a has a value of 0) and that Hb did not observe the packet Tk (Lk.a has a value of 0) and that Hb did not observe the packet
sent at time Tk (Lk.b has a value of 1). sent at time Tk (Lk.b has a value of 1).
o The value of Lk is undefined when neither Ha nor Hb observed the o The value of Lk is undefined when neither Ha nor Hb observed the
packet (both Lk.a and Lk.b have a value of 1). packet (both Lk.a and Lk.b have a value of 1).
6.2.5. Discussion 6.2.5. Discussion
Unlike Type-P-Packet-loss-Stream, Type-P-Segment-Packet-Loss-Stream Unlike Type-P-Packet-loss-Stream, Type-P-Segment-Packet-Loss-Stream
relies on the stability of the host path digest. The metric SHALL be relies on the stability of the routers digest. The metric SHALL be
invalid for times < T1 , T2, ..., Tm-1, Tm> if the following invalid for times < T1 , T2, ..., Tm-1, Tm> if the following
conditions occur: conditions occur:
o Ha or Hb disappears from the path due to some routing change. o Ha or Hb disappears from the path due to some routing change.
o The order of Ha and Hb changes in the path. o The order of Ha and Hb changes in the path.
o Lk.a or Lk.b is undefined.
o Lk.a or Lk.b is undefined.
o Lk.a has the value 1 (not observed) and Lk.b has the value 0 o Lk.a has the value 1 (not observed) and Lk.b has the value 0
(observed); (observed);
o L has the value 0 (the packet was received by Dst) and Lk.ab has o L has the value 0 (the packet was received by Dst) and Lk.ab has
the value 1 (the packet was lost between Ha and Hb). the value 1 (the packet was lost between Ha and Hb).
6.3. A Definition of a Sample of ipdv of a Segment using the Previous 6.3. A Definition of a Sample of ipdv of a Segment using the Previous
Packet Selection Function Packet Selection Function
This metric defines a sample of ipdv [RFC3393] over time between a This metric defines a sample of ipdv [RFC3393] over time between a
pair of hosts using the previous packet as the selection function. pair of routers using the previous packet as the selection function.
6.3.1. Metric Name 6.3.1. Metric Name
Type-P-Segment-ipdv-prev-Stream Type-P-Segment-ipdv-prev-Stream
6.3.2. Metric Parameters 6.3.2. Metric Parameters
o Src, the IP address of the sender. o Src, the IP address of the sender.
o Dst, the IP address of the receiver. o Dst, the IP address of the receiver.
o Type-P, the specification of the packet type. o Type-P, the specification of the packet type.
o k, an integer which orders the packets sent. o k, an integer which orders the packets sent.
o n, an integer which orders the hosts on the path. o n, an integer which orders the routers on the path.
o a and b, two integers where b > a. o a and b, two integers where b > a.
o <H1, H2, ..., Ha, ..., Hb, ...,Hn>, the hosts path digest. o <H1, H2, ..., Ha, ..., Hb, ...,Hn>, the routers digest.
o <T1, T2, ..., Tm-1, Tm>, a list of times. o <T1, T2, ..., Tm-1, Tm>, a list of times.
o <Tk, dTk.1, dTk.2, ..., dTk.a, ..., dTk.b,..., dTk.n, dTk>, a o <Tk, dTk.1, dTk.2, ..., dTk.a, ..., dTk.b,..., dTk.n, dTk>, a
Type-P-Spatial-One-way-Delay-Vector. Type-P-Spatial-One-way-Delay-Vector.
6.3.3. Metric Units 6.3.3. Metric Units
The value of a Type-P-Segment-ipdv-prev-Stream is a pair of: The value of a Type-P-Segment-ipdv-prev-Stream is a pair of:
The list of <T1, T2, ..., Tm-1, Tm>; The list of <T1, T2, ..., Tm-1, Tm>;
A list of pairs of interval of times and delays; A list of pairs of interval of times and delays;
6.3.4. Definition 6.3.4. Definition
Given two hosts, Ha and Hb, of the path <H1, H2,..., Ha, ..., Hb, Given two routers, Ha and Hb, of the path <H1, H2,..., Ha, ..., Hb,
..., Hn>, and the matrix of Type-P-Spatial-One-way-Delay-Vector for ..., Hn>, and the matrix of Type-P-Spatial-One-way-Delay-Vector for
the packets sent from Src to Dst at times <T1, T2, ..., Tm-1, Tm> : the packets sent from Src to Dst at times <T1, T2, ..., Tm-1, Tm> :
<T1, dT1.1, dT1.2, ..., dT1.a, ..., dT1.b,..., dT1.n, dT1>, <T1, dT1.1, dT1.2, ..., dT1.a, ..., dT1.b,..., dT1.n, dT1>,
<T2, dT2.1, dT2.2, ..., dT2.a, ..., dT2.b,..., dT2.n, dT2>, <T2, dT2.1, dT2.2, ..., dT2.a, ..., dT2.b,..., dT2.n, dT2>,
... ...
<Tm, dTm.1, dTm.2, ..., dTm.a, ..., dTm.b,..., dTm.n, dTm>. <Tm, dTm.1, dTm.2, ..., dTm.a, ..., dTm.b,..., dTm.n, dTm>.
We define the Type-P-Segment-ipdv-prev-Stream as the sequence of We define the Type-P-Segment-ipdv-prev-Stream as the sequence of
packet time pairs and delay variations packet time pairs and delay variations
<(T1, T2 , dT2.ab - dT1.ab) ,..., <(T1, T2 , dT2.ab - dT1.ab) ,...,
(Tk-1, Tk, dTk.ab - dTk-1.ab), ..., (Tk-1, Tk, dTk.ab - dTk-1.ab), ...,
(Tm-1, Tm, dTm.ab - dTm-1.ab)> (Tm-1, Tm, dTm.ab - dTm-1.ab)>
For any pair, Tk, Tk-1 in k=1 through m, the difference dTk.ab - dTk- For any pair, Tk, Tk-1 in k=1 through m, the difference dTk.ab - dTk-
1.ab is undefined if: 1.ab is undefined if:
o the delay dTk.a or the delay dTk-1.a is undefined, OR o the delay dTk.a or the delay dTk-1.a is undefined, OR
o the delay dTk.b or the delay dTk-1.b is undefined. o the delay dTk.b or the delay dTk-1.b is undefined.
6.3.5. Discussion 6.3.5. Discussion
skipping to change at page 23, line 32 skipping to change at page 23, line 34
control the ingress point of interest of the measure, Ha. The control the ingress point of interest of the measure, Ha. The
interval will certainly vary if there is delay variation between the interval will certainly vary if there is delay variation between the
Source and Ha. Therefore, the ingress inter-packet interval must be Source and Ha. Therefore, the ingress inter-packet interval must be
known at Ha in order to fully comprehend the delay variation between known at Ha in order to fully comprehend the delay variation between
Ha and Hb. Ha and Hb.
6.4. A Definition of a Sample of ipdv of a Segment using the Minimum 6.4. A Definition of a Sample of ipdv of a Segment using the Minimum
Delay Selection Function Delay Selection Function
This metric defines a sample of ipdv [RFC3393] over time between a This metric defines a sample of ipdv [RFC3393] over time between a
pair of hosts on a path using the minimum delay as one of the pair of routers on a path using the minimum delay as one of the
selected packets in every pair. selected packets in every pair.
6.4.1. Metric Name 6.4.1. Metric Name
Type-P-Segment-One-way-ipdv-min-Stream Type-P-Segment-One-way-ipdv-min-Stream
6.4.2. Metric Parameters 6.4.2. Metric Parameters
o Src, the IP address of the sender. o Src, the IP address of the sender.
o Dst, the IP address of the receiver. o Dst, the IP address of the receiver.
o Type-P, the specification of the packet type. o Type-P, the specification of the packet type.
o k, an integer which orders the packets sent. o k, an integer which orders the packets sent.
o i, an integer which identifies a packet sent. o i, an integer which identifies a packet sent.
o n, an integer which orders the hosts on the path. o n, an integer which orders the routers on the path.
o a and b, two integers where b > a. o a and b, two integers where b > a.
o <H1, H2, ..., Ha, ..., Hb, ...,Hn>, the host path digest.
o <T1, T2, ..., Tm-1, Tm>, a list of times.
o <H1, H2, ..., Ha, ..., Hb, ...,Hn>, the routers digest.
o <T1, T2, ..., Tm-1, Tm>, a list of times.
o <Tk, dTk.1, dTk.2, ..., dTk.a, ..., dTk.b,..., dTk.n, dTk>, a o <Tk, dTk.1, dTk.2, ..., dTk.a, ..., dTk.b,..., dTk.n, dTk>, a
Type-P-Spatial-One-way-Delay-Vector. Type-P-Spatial-One-way-Delay-Vector.
6.4.3. Metric Units 6.4.3. Metric Units
The value of a Type-P-Segment-One-way-ipdv-min-Stream is a pair of: The value of a Type-P-Segment-One-way-ipdv-min-Stream is a pair of:
The list of <T1, T2, ..., Tm-1, Tm>; The list of <T1, T2, ..., Tm-1, Tm>;
A list of times. A list of times.
6.4.4. Definition 6.4.4. Definition
Given two hosts, Ha and Hb, of the path <H1, H2,..., Ha, ..., Hb, Given two routers, Ha and Hb, of the path <H1, H2,..., Ha, ..., Hb,
..., Hn>, and the matrix of Type-P-Spatial-One-way-Delay-Vector for ..., Hn>, and the matrix of Type-P-Spatial-One-way-Delay-Vector for
the packets sent from Src to Dst at times <T1, T2, ..., Tm-1, Tm> : the packets sent from Src to Dst at times <T1, T2, ..., Tm-1, Tm> :
<T1, dT1.1, dT1.2, ..., dT1.a, ..., dT1.b,..., dT1.n, dT1>, <T1, dT1.1, dT1.2, ..., dT1.a, ..., dT1.b,..., dT1.n, dT1>,
<T2, dT2.1, dT2.2, ..., dT2.a, ..., dT2.b,..., dT2.n, dT2>, <T2, dT2.1, dT2.2, ..., dT2.a, ..., dT2.b,..., dT2.n, dT2>,
... ...
<Tm, dTm.1, dTm.2, ..., dTm.a, ..., dTm.b,..., dTm.n, dTm>. <Tm, dTm.1, dTm.2, ..., dTm.a, ..., dTm.b,..., dTm.n, dTm>.
We define the Type-P-Segment-One-way-ipdv-min-Stream as the sequence We define the Type-P-Segment-One-way-ipdv-min-Stream as the sequence
of times <dT1.ab - min(dTi.ab) ,..., dTk.ab - min(dTi.ab), ..., of times <dT1.ab - min(dTi.ab) ,..., dTk.ab - min(dTi.ab), ...,
dTm.ab - min(dTi.ab)> where: dTm.ab - min(dTi.ab)> where:
skipping to change at page 29, line 8 skipping to change at page 29, line 9
former one only has statistics over the time dimension while the former one only has statistics over the time dimension while the
later one can have statistics over both time and space dimensions. later one can have statistics over both time and space dimensions.
This space dimension is introduced by the Matrix concept as This space dimension is introduced by the Matrix concept as
illustrated in Figure 4. For a Matrix M each row is a set of One-way illustrated in Figure 4. For a Matrix M each row is a set of One-way
singletons spreading over the time dimension and each column is singletons spreading over the time dimension and each column is
another set of One-way singletons spreading over the space dimension. another set of One-way singletons spreading over the space dimension.
Receivers Receivers
Space Space
^ ^
1 | / R1dT1 R1dT2 R1dT3 ... R3dTk \ 1 | / R1dT1 R1dT2 R1dT3 ... R1dTk \
| | | | | |
2 | | R2dT1 R2dT2 R2dT3 ... R3dTk | 2 | | R2dT1 R2dT2 R2dT3 ... R2dTk |
| | | | | |
3 | | R3dT1 R3dT2 R3dT3 ... R3dTk | 3 | | R3dT1 R3dT2 R3dT3 ... R3dTk |
. | | | . | | |
. | | | . | | |
. | | | . | | |
n | \ RndT1 RndT2 RndT3 ... RndTk / n | \ RndT1 RndT2 RndT3 ... RndTk /
+--------------------------------------------> time +--------------------------------------------> time
T0 T0
Figure 4: Matrix M (n*m) Figure 4: Matrix M (n*m)
In Matrix M, each element is a one-way delay singleton. Each column In Matrix M, each element is a one-way delay singleton. Each column
is a delay vector contains the One-way delays of the same packet is a delay vector. It contains the One-way delays of the same packet
observed at M points of interest. It implies the geographical factor observed at n points of interest. It implies the geographical factor
of the performance within a group. Each row is a set of One-way of the performance within a group. Each row is a set of One-way
delays observed during a sampling interval at one of the points of delays observed during a sampling interval at one of the points of
interest. It presents the delay performance at a receiver over the interest. It presents the delay performance at a receiver over the
time dimension. time dimension.
Therefore, one can either calculate statistics by rows over the space Therefore, one can either calculate statistics by rows over the space
dimension or by columns over the time dimension. It's up to the dimension or by columns over the time dimension. It's up to the
operators or service provides which dimension they are interested in. operators or service provides which dimension they are interested in.
For example, a TV broadcast service provider might want to know the 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 statistical performance of each user in a long term run to make sure
skipping to change at page 30, line 13 skipping to change at page 30, line 16
Moreover, after knowing the statistics over the time dimension, one Moreover, after knowing the statistics over the time dimension, one
might want to know how these statistics are distributed over the might want to know how these statistics are distributed over the
space dimension. For instance, a TV broadcast service provider had space dimension. For instance, a TV broadcast service provider had
the performance Matrix M and calculated the One-way delay mean over 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 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 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 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 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 a group of users during a sampling interval in terms of delay. It
requires twice as much calculation to have this statistic over both requires twice as much calculation to have this statistic over both
time and space dimensions. This kind of statistics is referred to as time and space dimensions. These kinds of statistics are referred to
2-level statistics to distinguish them from 1-level statistics as 2-level statistics to distinguish them from 1-level statistics
calculated over either space or time dimension. It can be easily calculated over either space or time dimension. It can be easily
proven that no matter over which dimension a 2-level statistic is proven that no matter over which dimension a 2-level statistic is
calculated first, the results are the same. I.e. one can calculate 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 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 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 obtained vector to find out the 2-level delay mean. Or, he can do
the 1-level statistic calculation over the space dimension first and the 1-level statistic calculation over the space dimension first and
then have the 2-level delay mean. Both two results will be exactly then have the 2-level delay mean. Both two results will be exactly
the same. Therefore, when defining a 2-level statistic there is no the same. Therefore, when defining a 2-level statistic there is no
need to specify the order in which the calculation is executed. need to specify the order in which the calculation is executed.
skipping to change at page 30, line 37 skipping to change at page 30, line 40
over either the space dimension or the time dimension or both. This over either the space dimension or the time dimension or both. This
memo treats the case where a stream of packets from the Source memo treats the case where a stream of packets from the Source
results in a sample at each of the Receivers in the Group, and these results in a sample at each of the Receivers in the Group, and these
samples are each summarized with the usual statistics employed in samples are each summarized with the usual statistics employed in
one-to-one communication. New statistic definitions are presented, one-to-one communication. New statistic definitions are presented,
which summarize the one-to-one statistics over all the Receivers in which summarize the one-to-one statistics over all the Receivers in
the Group. the Group.
8.1. Discussion on the Impact of packet loss on statistics 8.1. Discussion on the Impact of packet loss on statistics
The packet loss does have effects on one-way metrics and their Packet loss does have effects on one-way metrics and their
statistics. For example, a lost packet can result in an infinite statistics. For example, a lost packet can result in an infinite
one-way delay. It is easy to handle the problem by simply ignoring one-way delay. It is easy to handle the problem by simply ignoring
the infinite value in the metrics and in the calculation of the the infinite value in the metrics and in the calculation of the
corresponding statistics. However, the packet loss has such a strong corresponding statistics. However, the packet loss has such a strong
impact on the statistics calculation for the one-to-group metrics impact on the statistics calculation for the one-to-group metrics
that it can not be solved by the same method used for one-way that it can not be solved by the same method used for one-way
metrics. This is due to the complexity of building a matrix, which metrics. This is due to the complexity of building a matrix, which
is needed for calculation of the statistics proposed in this memo. is needed for calculation of the statistics proposed in this memo.
The situation is that measurement results obtained by different end The situation is that measurement results obtained by different end
skipping to change at page 32, line 51 skipping to change at page 33, line 8
Statistics are computed on the finite One-way delays of the matrix Statistics are computed on the finite One-way delays of the matrix
above. above.
All One-to-group delay statistics are expressed in seconds with All One-to-group delay statistics are expressed in seconds with
sufficient resolution to convey 3 significant digits. sufficient resolution to convey 3 significant digits.
8.3.1. Type-P-One-to-group-Receiver-n-Mean-Delay 8.3.1. Type-P-One-to-group-Receiver-n-Mean-Delay
This section defines Type-P-One-to-group-Receiver-n-Mean-Delay the This section defines Type-P-One-to-group-Receiver-n-Mean-Delay the
Delay Mean at each Receiver N, also named RnDM. Delay Mean at each Receiver N, also named RnMD.
We obtain the value of Type-P-One-way-Delay singleton for all packets We obtain the value of Type-P-One-way-Delay singleton for all packets
sent during the test interval at each Receiver (Destination), as per sent during the test interval at each Receiver (Destination), as per
[RFC2679]. For each packet that arrives within Tmax of its sending [RFC2679]. For each packet that arrives within Tmax of its sending
time, TstampSrc, the one-way delay singleton (dT) will be the finite time, TstampSrc, the one-way delay singleton (dT) will be the finite
value TstampRecv[i] - TstampSrc[i] in units of seconds. Otherwise, value TstampRecv[i] - TstampSrc[i] in units of seconds. Otherwise,
the value of the singleton is Undefined. the value of the singleton is Undefined.
J[n] J[n]
--- ---
1 \ 1 \
RnMD = --- * > TstampRecv[i] - TstampSrc[i] RnMD = --- * > TstampRecv[i] - TstampSrc[i]
J[n] / J[n] /
--- ---
i = 1 i = 1
Note: RnMD value is Undefined when J[n] = 0 for all n.
Figure 6: Type-P-One-to-group-Receiver-N-Mean-Delay Figure 6: Type-P-One-to-group-Receiver-N-Mean-Delay
where all packets i= 1 through J[n] have finite singleton delays. where all packets i= 1 through J[n] have finite singleton delays.
8.3.2. Type-P-One-to-group-Mean-Delay 8.3.2. Type-P-One-to-group-Mean-Delay
This section defines Type-P-One-to-group-Mean-Delay, the Mean One-way This section defines Type-P-One-to-group-Mean-Delay, the Mean One-way
delay calculated over the entire Group, also named GMD. delay calculated over the entire Group, also named GMD.
N N
--- ---
1 \ 1 \
GMD = - * > RnDM GMD = - * > RnMD
N / N /
--- ---
n = 1 n = 1
Figure 7: Type-P-One-to-group-Mean-Delay Figure 7: Type-P-One-to-group-Mean-Delay
Note that the Group Mean Delay can also be calculated by summing the Note that the Group Mean Delay can also be calculated by summing the
Finite one-way Delay singletons in the Matrix, and dividing by the Finite one-way Delay singletons in the Matrix, and dividing by the
number of Finite One-way Delay singletons. number of Finite One-way Delay singletons.
8.3.3. Type-P-One-to-group-Range-Mean-Delay 8.3.3. Type-P-One-to-group-Range-Mean-Delay
This section defines a metric for the range of mean delays over all N This section defines a metric for the range of mean delays over all N
receivers in the group (R1DM, R2DM,...RnDM). receivers in the group (R1MD, R2MD...RnMD).
Type-P-One-to-group-Range-Mean-Delay = GRMD = max(RnDM) - min(RnDM) Type-P-One-to-group-Range-Mean-Delay = GRMD = max(RnMD) - min(RnMD)
8.3.4. Type-P-One-to-group-Max-Mean-Delay 8.3.4. Type-P-One-to-group-Max-Mean-Delay
This section defines a metric for the maximum of mean delays over all This section defines a metric for the maximum of mean delays over all
N receivers in the group (R1DM, R2DM,...RnDM). N receivers in the group (R1MD, R2MD,...RnMD).
Type-P-One-to-group-Max-Mean-Delay = GMMD = max(RnDM) Type-P-One-to-group-Max-Mean-Delay = GMMD = max(RnMD)
8.4. One-to-group Packet Loss Statistics 8.4. One-to-group Packet Loss Statistics
This section defines the overall one-way loss statistics for a This section defines the overall one-way loss statistics for a
receiver and for an entire group as illustrated by the matrix below. receiver and for an entire group as illustrated by the matrix below.
Recv /----------- Sample ----------\ Stats Group Stat Recv /----------- Sample ----------\ Stats Group Stat
1 R1L1 R1L2 R1L3 ... R1Lk R1LR \ 1 R1L1 R1L2 R1L3 ... R1Lk R1LR \
| |
skipping to change at page 35, line 19 skipping to change at page 35, line 22
--- ---
k = 1 k = 1
Figure 9: Type-P-One-to-group-Receiver-n-Loss-Ratio Figure 9: Type-P-One-to-group-Receiver-n-Loss-Ratio
8.4.2. Type-P-One-to-group-Receiver-n-Comp-Loss-Ratio 8.4.2. Type-P-One-to-group-Receiver-n-Comp-Loss-Ratio
Usually, the number of packets sent is used in the denominator of Usually, the number of packets sent is used in the denominator of
packet loss ratio metrics. For the comparative metrics defined here, packet loss ratio metrics. For the comparative metrics defined here,
the denominator is the maximum number of packets received at any the denominator is the maximum number of packets received at any
receiver for the sample and test interval of interest. receiver for the sample and test interval of interest. The numerator
is the sum of the losses at receiver n.
The Comparative Loss Ratio, also named, RnCLR, is defined as The Comparative Loss Ratio, also named, RnCLR, is defined as
K K
--- ---
\ \
> Ln(k) > Ln(k)
/ /
--- ---
k=1 k=1
RnCLR = ----------------------------- RnCLR = -----------------------------
/ K \ / K \
| --- | | --- |
| \ | | \ |
K - Min | > Ln(k) | K - Min | > Ln(k) |
| / | | / |
| --- | | --- |
\ k=1 / N \ k=1 / N
Note: Ln is a set of one-way loss values at receiver n.
There is one value for each of the K packets sent.
Figure 10: Type-P-One-to-group-Receiver-n-Comp-Loss-Ratio Figure 10: Type-P-One-to-group-Receiver-n-Comp-Loss-Ratio
8.4.3. Type-P-One-to-group-Loss-Ratio 8.4.3. Type-P-One-to-group-Loss-Ratio
Type-P-One-to-group-Loss-Ratio, the overall Group loss ratio, also Type-P-One-to-group-Loss-Ratio, the overall Group loss ratio, also
named GLR, is defined as named GLR, is defined as
K,N K,N
--- ---
1 \ 1 \
GLR = --- * > L(k,n) GLR = --- * > Ln(k)
K*N / K*N /
--- ---
k,n = 1 k,n = 1
Figure 11: Type-P-One-to-group-Loss-Ratio Figure 11: Type-P-One-to-group-Loss-Ratio
Where the sum includes all of the Loss singletons, Ln(k), over the N
receivers and K packets sent, in a ratio with the total packets over
all receivers.
8.4.4. Type-P-One-to-group-Range-Loss-Ratio 8.4.4. Type-P-One-to-group-Range-Loss-Ratio
The One-to-group Loss Ratio Range is defined as: The One-to-group Loss Ratio Range is defined as:
Type-P-One-to-group-Range-Loss-Ratio = max(RnLR) - min(RnLR) Type-P-One-to-group-Range-Loss-Ratio = max(RnLR) - min(RnLR)
It is most effective to indicate the range by giving both the max and It is most effective to indicate the range by giving both the max and
minimum loss ratios for the Group, rather than only reporting the minimum loss ratios for the Group, rather than only reporting the
difference between them. difference between them.
skipping to change at page 38, line 37 skipping to change at page 38, line 46
the sample session, and so on. Apparently, the centralized the sample session, and so on. Apparently, the centralized
calculation method can require much more bandwidth than the calculation method can require much more bandwidth than the
distributed calculation method when the sample size is big. This is distributed calculation method when the sample size is big. This is
especially true when the measurement has a very large number of the especially true when the measurement has a very large number of the
points of interest. It can lead to a scalability issue at the points of interest. It can lead to a scalability issue at the
reference point by overloading the network resources. reference point by overloading the network resources.
The distributed calculation method can save much more bandwidth and The distributed calculation method can save much more bandwidth and
mitigate issues arising from scalability at the reference point side. mitigate issues arising from scalability at the reference point side.
However, it may result in a lost of information. As all measured However, it may result in a loss of information. As not all measured
singletons are not available for building up the group matrix, the singletons are available for building up the group matrix, the real
real performance over time can be hidden from the result. For performance over time can be hidden from the result. For example,
example, the loss pattern can be missed by simply accepting the loss the loss pattern can be missed by simply accepting the loss ratio.
ratio. This tradeoff between bandwidth consumption and information This tradeoff between bandwidth consumption and information
acquisition has to be taken into account when designing the acquisition has to be taken into account when designing the
measurement approach. measurement approach.
One possible solution could be to transit the statistic parameters to One possible solution could be to transmit the statistic parameters
the reference point first to obtain the general information of the to the reference point first to obtain the general information of the
group performance. If detailed results are required, the reference group performance. If detailed results are required, the reference
point should send the requests to the points of interest, which could point should send the requests to the points of interest, which could
be particular ones or the whole group. This procedure can happen in be particular ones or the whole group. This procedure can happen in
the off peak time and can be well scheduled to avoid delivery of too the off peak time and can be well scheduled to avoid delivery of too
many points of interest at the same time. Compression techniques can many points of interest at the same time. Compression techniques can
also be used to minimize the bandwidth required by the transmission. also be used to minimize the bandwidth required by the transmission.
This could be a measurement protocol to report the measurement This could be a measurement protocol to report the measurement
results. However, this is out of the scope of this memo. results. However, this is out of the scope of this memo.
9.2. Measurement 9.2. Measurement
To prevent any bias in the result, the configuration of a one-to-many To prevent any bias in the result, the configuration of a one-to-many
measure must take in consideration that intrically more packets will measure must take in consideration that more packets will to be
to be routed than sent (copies of a packet sent are expected to routed than sent (copies of a packet sent are expected to arrive at
arrive at many destination points) and selects a test packets rate many destination points) and selects a test packets rate that will
that will not impact the network performance. not impact the network performance.
9.3. Effect of Time and Space Aggregation Order on Stats 9.3. Effect of Time and Space Aggregation Order on Stats
This section presents the impact of the aggregation order on the This section presents the impact of the aggregation order on the
scalability of the reporting and of the computation. It makes the scalability of the reporting and of the computation. It makes the
hypothesis that receivers are not co-located and that results are hypothesis that receivers are not co-located and that results are
gathered in a point of reference for further usages. gathered in a point of reference for further usages.
Multimetrics samples are represented in a matrix as illustrated below Multimetrics samples are represented in a matrix as illustrated below
Point of Point of
interest interest
1 R1S1 R1S1 R1S1 ... R1Sk \ 1 R1S1 R1S1 R1S1 ... R1Sk \
| |
2 R2S1 R2S2 R2S3 ... R2Sk | 2 R2S1 R2S2 R2S3 ... R2Sk |
| |
3 R3S1 R3S2 R3S3 ... R3Sk > sample over space 3 R3S1 R3S2 R3S3 ... R3Sk > sample over space
. | . |
. | . |
. | . |
skipping to change at page 40, line 50 skipping to change at page 41, line 30
Two methods are available to compute group statistics: Two methods are available to compute group statistics:
o Method1: Figure 5 and Figure 8 illustrate the method chosen: the o Method1: Figure 5 and Figure 8 illustrate the method chosen: the
one-to-one statistic is computed per interval of time before the one-to-one statistic is computed per interval of time before the
computation of the mean over the group of receivers; computation of the mean over the group of receivers;
o Method2: Figure 13 presents the second one, metric is computed o Method2: Figure 13 presents the second one, metric is computed
over space and then over time. over space and then over time.
10. Manageability Considerations 10. Manageability Considerations
Usually IPPM WG documents defines each metric reporting within its This section defines the reporting of all the metrics introduced in
definition. This document defines the reporting of all the metrics the document.
introduced in a single section to provide consistent information, to
avoid repetitions and to conform to IESG recommendation of gathering
manageability considerations in a dedicated section.
Information models of spatial metrics and of one-to-group metrics are Information models of spatial metrics and of one-to-group metrics are
similar excepted that points of interests of spatial vectors must be similar excepted that points of interests of spatial vectors MUST be
ordered. ordered.
The complexity of the reporting relies on the number of points of The complexity of the reporting relies on the number of points of
interests. interests.
10.1. Reporting spatial metric 10.1. Reporting spatial metric
The reporting of spatial metrics shares a lot of aspects with The reporting of spatial metrics shares a lot of aspects with
RFC2679-80. New ones are common to all the definitions and are RFC2679-80. New ones are common to all the definitions and are
mostly related to the reporting of the path and of methodology mostly related to the reporting of the path and of methodology
parameters that may bias raw results analysis. This section presents parameters that may bias raw results analysis. This section presents
these specific parameters and then lists exhaustively the parameters these specific parameters and then lists exhaustively the parameters
that shall be reported. that SHOULD be reported.
10.1.1. Path 10.1.1. Path
End-to-end metrics can't determine the path of the measure despite End-to-end metrics can't determine the path of the measure despite
IPPM RFCs recommend it to be reported (See Section 3.8.4 of IPPM RFCs recommend it to be reported (See Section 3.8.4 of
[RFC2679]). Spatial metrics vectors provide this path. The report [RFC2679]). Spatial metrics vectors provide this path. The report
of a spatial vector must include the points of interests involved: of a spatial vector MUST include the points of interests involved:
the sub set of the hosts of the path participating to the the sub set of the routers of the path participating to the
instantaneous measure. instantaneous measure.
10.1.2. Host order 10.1.2. Host order
A spatial vector must order the points of interest according to their A spatial vector MUST order the points of interest according to their
order in the path. It is highly suggested to use the TTL in IPv4, order in the path. The ordering MAY be based on information from the
the Hop Limit in IPv6 or the corresponding information in MPLS. TTL in IPv4, the Hop Limit in IPv6 or the corresponding information
in MPLS.
The report of a spatial vector must include the ordered list of the The report of a spatial vector MUST include the ordered list of the
hosts involved in the instantaneous measure. hosts involved in the instantaneous measure.
10.1.3. Timestamping bias 10.1.3. Timestamping bias
The location of the point of interest inside a node influences the The location of the point of interest inside a node influences the
timestamping skew and accuracy. As an example, consider that some timestamping skew and accuracy. As an example, consider that some
internal machinery delays the timestamping up to 3 milliseconds then internal machinery delays the timestamping up to 3 milliseconds then
the minimal uncertainty reported be 3 ms if the internal delay is the minimal uncertainty reported be 3 ms if the internal delay is
unknown at the time of the timestamping. unknown at the time of the timestamping.
The report of a spatial vector must include the uncertainty of the The report of a spatial vector MUST include the uncertainty of the
timestamping compared to wire time. timestamping compared to wire time.
10.1.4. Reporting spatial One-way Delay 10.1.4. Reporting spatial One-way Delay
The reporting includes information to report for one-way-delay as the The reporting includes information to report for one-way-delay as the
Section 3.6 of [RFC2679]. The same apply for packet loss and ipdv. Section 3.6 of [RFC2679]. The same apply for packet loss and ipdv.
10.2. Reporting One-to-group metric 10.2. Reporting One-to-group metric
All reporting rules described in [RFC2679] and [RFC2680] apply to the All reporting rules described in [RFC2679] and [RFC2680] apply to the
corresponding One-to-group metrics. Following are specific corresponding One-to-group metrics. Following are specific
parameters that should be reported. parameters that SHOULD be reported.
10.2.1. Path 10.2.1. Path
As suggested by the [RFC2679] and [RFC2680], the path traversed by As suggested by the [RFC2679] and [RFC2680], the path traversed by
the packet SHOULD be reported, if possible. For One-to-group the packet SHOULD be reported, if possible. For One-to-group
metrics, the path tree between the source and the destinations or the metrics, the path tree between the source and the destinations or the
set of paths between the source and each destination SHOULD be set of paths between the source and each destination SHOULD be
reported. reported.
Path tree might not be as valuable as individual paths because an Path tree might not be as valuable as individual paths because an
incomplete path might be difficult to identify in the path tree. For incomplete path might be difficult to identify in the path tree. For
example, how many points of interest are reached by a packet example, how many points of interest are reached by a packet
travelling along an incomplete path? travelling along an incomplete path?
10.2.2. Group size 10.2.2. Group size
The group size should be reported as one of the critical management The group size SHOULD be reported as one of the critical management
parameters. One-to-group metrics, unlike spatial metrics, don't parameters. One-to-group metrics, unlike spatial metrics, don't
require the ordering of the points of interests because group members require the ordering of the points of interests because group members
receive the packets in parallel. receive the packets in parallel.
10.2.3. Timestamping bias 10.2.3. Timestamping bias
It is the same as described in section 10.1.3. It is the same as described in section 10.1.3.
10.2.4. Reporting One-to-group One-way Delay 10.2.4. Reporting One-to-group One-way Delay
It is the same as described in section 10.1.4. It is the same as described in section 10.1.4.
10.2.5. Measurement method 10.2.5. Measurement method
As explained in section 9, the measurement method will have impact on As explained in section 9, the measurement method will have impact on
the analysis of the measurement result. Therefore, it should be the analysis of the measurement result. Therefore, it SHOULD be
reported. reported.
10.3. Metric identification 10.3. Metric identification
IANA assigns each metric defined by the IPPM WG with a unique IANA assigns each metric defined by the IPPM WG with a unique
identifier as per [RFC4148] in the IANA-IPPM-METRICS-REGISTRY-MIB. identifier as per [RFC4148] in the IANA-IPPM-METRICS-REGISTRY-MIB.
10.4. Information model 10.4. Information model
This section presents the elements of information and the usage of This section presents the elements of information and the usage of
skipping to change at page 43, line 32 skipping to change at page 44, line 9
Uncertainties". Uncertainties".
Following are the elements of information taken from end-to-end Following are the elements of information taken from end-to-end
metrics definitions referred in this memo and from spatial and metrics definitions referred in this memo and from spatial and
multicast metrics it defines: multicast metrics it defines:
o Packet_type, The Type-P of test packets (Type-P); o Packet_type, The Type-P of test packets (Type-P);
o Packet_length, a packet length in bits (L); o Packet_length, a packet length in bits (L);
o Src_host, the IP address of the sender; o Src_host, the IP address of the sender;
o Dst_host, the IP address of the receiver; o Dst_host, the IP address of the receiver;
o Hosts_serie: <H1, H2,..., Hn>, a list of points of interest; o Hosts_serie: <H1, H2,..., Hn>, a list of points of interest
participating to the instantaneous measure. They are routers in
the case of spatial metrics or receivers in the case of one-to-
group metrics;
o Loss_threshold: The threshold of infinite delay; o Loss_threshold: The threshold of infinite delay;
o Systematic_error: constant delay between wire time and o Systematic_error: constant delay between wire time and
timestamping; timestamping;
o Calibration_error: maximal uncertainty; o Calibration_error: maximal uncertainty;
o Src_time, the sending time for a measured packet; o Src_time, the sending time for a measured packet;
o Dst_time, the receiving time for a measured packet; o Dst_time, the receiving time for a measured packet;
o Result_status : an indicator of usability of a result 'Resource o Result_status : an indicator of usability of a result 'Resource
exhaustion' 'infinite', 'lost'; exhaustion' 'infinite', 'lost';
o Delays_serie: <dT1,..., dTn> a list of delays; o Delays_serie: <dT1,..., dTn> a list of delays;
o Losses_serie: <B1, B2, ..., Bi, ..., Bn>, a list of Boolean values o Losses_serie: <B1, B2, ..., Bi, ..., Bn>, a list of Boolean values
(spatial) or a set of Boolean values (one-to-group); (spatial) or a set of Boolean values (one-to-group);
o Result_status_serie: a list of results status; o Result_status_serie: a list of results status;
o dT: a delay; o dT: a delay;
o Singleton_number: a number of singletons; o Singleton_number: a number of singletons;
o Observation_duration: An observation duration; o Observation_duration: An observation duration;
o metric_identifier. o metric_identifier.
Following is the information of each vector that should be available Following is the information of each vector that SHOULD be available
to compute samples: to compute samples:
o Packet_type; o Packet_type;
o Packet_length; o Packet_length;
o Src_host, the sender of the packet; o Src_host, the sender of the packet;
o Dst_host, the receiver of the packet, apply only for spatial o Dst_host, the receiver of the packet, apply only for spatial
vectors; vectors;
o Hosts_serie: not ordered for one-to-group; o Hosts_serie: not ordered for one-to-group;
o Src_time, the sending time for the measured packet; o Src_time, the sending time for the measured packet;
o dT, the end-to-end one-way delay for the measured packet, apply o dT, the end-to-end one-way delay for the measured packet, apply
only for spatial vectors; only for spatial vectors;
o Delays_serie: apply only for delays and ipdv vector, not ordered o Delays_serie: apply only for delays and ipdv vector, not ordered
for one-to-group; for one-to-group;
o Losses_serie: apply only for packets loss vector, not ordered for o Losses_serie: apply only for packets loss vector, not ordered for
one-to-group; one-to-group;
o Result_status_serie; o Result_status_serie;
o Observation_duration: the difference between the time of the last o Observation_duration: the difference between the time of the last
singleton and the time of the first singleton. singleton and the time of the first singleton.
o Following is the context information (measure, points of o Following is the context information (measure, points of
interests) that should be available to compute samples : interests) that SHOULD be available to compute samples :
* Loss threshold; * Loss threshold;
* Systematic error: constant delay between wire time and * Systematic error: constant delay between wire time and
timestamping; timestamping;
* Calibration error: maximal uncertainty; * Calibration error: maximal uncertainty;
A spatial or a one-to-group sample is a collection of singletons A spatial or a one-to-group sample is a collection of singletons
giving the performance from the sender to a single point of interest. giving the performance from the sender to a single point of interest.
Following is the information that should be available for each sample Following is the information that SHOULD be available for each sample
to compute statistics: to compute statistics:
o Packet_type; o Packet_type;
o Packet_length; o Packet_length;
o Src_host, the sender of the packet; o Src_host, the sender of the packet;
o Dst_host, the receiver of the packet; o Dst_host, the receiver of the packet;
o Start_time, the sending time of the first packet; o Start_time, the sending time of the first packet;
o Delays_serie: apply only for delays and ipdv samples; o Delays_serie: apply only for delays and ipdv samples;
o Losses_serie: apply only for packets loss samples; o Losses_serie: apply only for packets loss samples;
o Result_status_serie; o Result_status_serie;
o Observation_duration: the difference between the time of the last o Observation_duration: the difference between the time of the last
singleton of the last sample and the time of the first singleton singleton of the last sample and the time of the first singleton
of the first sample. of the first sample.
o Following is the context information (measure, points of o Following is the context information (measure, points of
interests) that should be available to compute statistics : interests) that SHOULD be available to compute statistics :
* Loss threshold; * Loss threshold;
* Systematic error: constant delay between wire time and * Systematic error: constant delay between wire time and
timestamping; timestamping;
* Calibration error: maximal uncertainty; * Calibration error: maximal uncertainty;
Following is the information of each statistic that should be Following is the information of each statistic that SHOULD be
reported: reported:
o Result; o Result;
o Start_time; o Start_time;
o Duration; o Duration;
o Result_status; o Result_status;
o Singleton_number, the number of singletons the statistic is o Singleton_number, the number of singletons the statistic is
computed on; computed on;
11. Security Considerations 11. Security Considerations
Spatial and one-to-group metrics are defined on the top of end-to-end Spatial and one-to-group metrics are defined on the top of end-to-end
metrics. Security considerations discussed in One-way delay metrics metrics. Security considerations discussed in One-way delay metrics
definitions of [RFC2679] , in packet loss metrics definitions of definitions of [RFC2679] , in packet loss metrics definitions of
[RFC2680] and in IPDV metrics definitions of[RFC3393] and [RFC3432] [RFC2680] and in IPDV metrics definitions of[RFC3393] and [RFC3432]
apply to metrics defined in this memo. apply to metrics defined in this memo.
11.1. Spatial metrics Someone may spoof the identity of a Point of interest identity and
intentionally send corrupt results in order to remotely orient the
traffic engineering decisions.
Malicious generation of packets with spoofing addresses may corrupt A point of interest could intentionally corrupt its results in order
the results without any possibility to detect the spoofing. to remotely orient the traffic engineering decisions.
11.1. Spatial metrics
Malicious generation of packets which match systematically the hash Malicious generation of packets which match systematically the hash
function used to detect the packets may lead to a DoS attack toward function used to detect the packets may lead to a DoS attack toward
the point of reference. the point of reference.
Spatial measurement results carry the performance of individual
segments of the path and the identity of nodes. An attacker may
infer from this information the points of weakness of a network (e.g.
congested node) which would require the least amount of additional
attacking traffic to exploit. Therefore, monitoring information
should be carried in a way which prevents unintended recipients from
inspecting the measurement reports. A straight forward solution is
to restrict access to the reports using encrypted sessions or secured
networks.
11.2. One-to-group metrics 11.2. One-to-group metrics
Reporting of measurement results from a huge number of probes may Reporting of measurement results from a huge number of probes may
overload reference point resources (network, network interfaces, overload reference point resources (network, network interfaces,
computation capacities ...). computation capacities ...).
The configuration of a measurement must take in consideration that The configuration of a measurement must take in consideration that
implicitly more packets will be routed than sent and selects a test implicitly more packets will be routed than sent and selects a test
packets rate accordingly. Collecting statistics from a huge number packets rate accordingly. Collecting statistics from a huge number
of probes may overload any combination of the network where the of probes may overload any combination of the network where the
measurement controller is attached to, measurement controller network measurement controller is attached to, measurement controller network
interfaces and measurement controller computation capacities. interfaces and measurement controller computation capacities.
One-to-group metrics measurement should consider using source One-to-group metrics measurement should consider using source
authentication protocols, standardized in the MSEC group, to avoid authentication protocols, standardized in the MSEC group, to avoid
fraud packet in the sampling interval. The test packet rate could be fraud packet in the sampling interval. The test packet rate could be
negotiated before any measurement session to avoid deny of service negotiated before any measurement session to avoid deny of service
attacks. attacks.
A point of interest could intentionally degrade its results in order
to remotely increase the quality of the network on the branches of
the multicast tree it is connected to.
12. Acknowledgments 12. Acknowledgments
Lei would like to acknowledge Prof. Zhili Sun from CCSR, University Lei would like to acknowledge Prof. Zhili Sun from CCSR, University
of Surrey, for his instruction and helpful comments on this work. of Surrey, for his instruction and helpful comments on this work.
13. IANA Considerations 13. IANA Considerations
Metrics defined in this memo Metrics defined in this memo are Metrics defined in this memo are designed to be registered in the
designed to be registered in the IANA IPPM METRICS REGISTRY as IANA IPPM METRICS REGISTRY as described in initial version of the
described in initial version of the registry [RFC4148] : registry [RFC4148] :
IANA is asked to register the following metrics in the IANA-IPPM- IANA is asked to register the following metrics in the IANA-IPPM-
METRICS-REGISTRY-MIB : METRICS-REGISTRY-MIB :
ietfSpatialOneWayDelayVector OBJECT-IDENTITY ietfSpatialOneWayDelayVector OBJECT-IDENTITY
STATUS current STATUS current
DESCRIPTION DESCRIPTION
"Type-P-Spatial-One-way-Delay-Vector" "Type-P-Spatial-One-way-Delay-Vector"
REFERENCE REFERENCE
"Reference "RFCyyyy, section 5.1." "Reference "RFCyyyy, section 5.1."
skipping to change at page 51, line 9 skipping to change at page 52, line 9
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.
14.2. Informative References 14.2. Informative References
[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-08 (work in Metrics", draft-ietf-ippm-spatial-composition-09 (work in
progress), March 2009. progress), June 2009.
[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,
May 1998. May 1998.
[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.
Authors' Addresses Authors' Addresses
 End of changes. 116 change blocks. 
163 lines changed or deleted 195 lines changed or added

This html diff was produced by rfcdiff 1.35. The latest version is available from http://tools.ietf.org/tools/rfcdiff/