Internet DRAFT - draft-bagnulo-ippm-new-registry-independent
draft-bagnulo-ippm-new-registry-independent
Network Working Group M. Bagnulo
Internet-Draft UC3M
Intended status: Standards Track T. Burbridge
Expires: January 13, 2014 BT
S. Crawford
SamKnows
P. Eardley
BT
A. Morton
AT&T Labs
July 12, 2013
A registry for commonly used metrics. Independent registries
draft-bagnulo-ippm-new-registry-independent-01
Abstract
This document creates a registry for commonly used metrics, defines
the rules for assignments in the new registry and performs initial
allocations. This document proposes one particular registry
structure with independent registries for each of the fields
involved. A companion document draft-bagnulo-ippm-new-registry
explores an alternative structure with a single registry with
multiple sub-registries.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 13, 2014.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. The commonly used metrics registry . . . . . . . . . . . . . . 5
2.1. The metrics registry . . . . . . . . . . . . . . . . . . . 5
2.2. The Scheduling registry . . . . . . . . . . . . . . . . . 6
2.3. The Environment registry . . . . . . . . . . . . . . . . . 7
2.4. The Output type registry . . . . . . . . . . . . . . . . . 7
3. Initial assignment for the Scheduling registry . . . . . . . . 7
3.1. Common parameter definitions . . . . . . . . . . . . . . . 7
3.2. Poisson scheduling . . . . . . . . . . . . . . . . . . . . 8
3.3. Periodic scheduling . . . . . . . . . . . . . . . . . . . 8
3.4. Singleton scheduling . . . . . . . . . . . . . . . . . . . 9
4. Initial assignments for the Output Type registry . . . . . . . 9
4.1. Raw . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.2. Xth percentile interval . . . . . . . . . . . . . . . . . 9
4.3. Xth percentile mean . . . . . . . . . . . . . . . . . . . 10
5. Initial assignments for the Environment registry . . . . . . . 10
5.1. Undefined . . . . . . . . . . . . . . . . . . . . . . . . 10
5.2. No cross traffic . . . . . . . . . . . . . . . . . . . . . 10
6. Initial assignments for the Metric registry . . . . . . . . . 12
6.1. Comment . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.2. UDP related metrics . . . . . . . . . . . . . . . . . . . 12
6.2.1. Parameters for UDP metrics . . . . . . . . . . . . . . 12
6.2.2. Round-trip UDP latency metric . . . . . . . . . . . . 12
6.2.3. Round-trip UDP packet-loss metric . . . . . . . . . . 13
7. ICMP related metrics . . . . . . . . . . . . . . . . . . . . . 13
7.1. ICMP Parameters . . . . . . . . . . . . . . . . . . . . . 13
7.2. ICMP packet-loss metric . . . . . . . . . . . . . . . . . 14
8. DNS related metrics . . . . . . . . . . . . . . . . . . . . . 14
8.1. DNS parameters . . . . . . . . . . . . . . . . . . . . . . 14
8.2. DNS latency metric . . . . . . . . . . . . . . . . . . . . 15
9. Some examples of measurement plans . . . . . . . . . . . . . . 16
10. Security considerations . . . . . . . . . . . . . . . . . . . 17
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
13.1. Normative References . . . . . . . . . . . . . . . . . . . 17
13.2. Informative References . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
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1. Introduction
This document creates a registry for commonly used metrics. In order
to do that, it creates a number of namespaces whose values will be
recorded by the registry and will uniquely and precisely identify
metrics.
The motivation for having such registry is to allow a controller to
request a measurement agent to execute a measurement using a specific
metric. Such request can be performed using any control protocol
that refers to the value assigned to the specific metric in the
registry. Similarly, the measurement agent can report the results of
the measurement and by referring to the metric value it can
unequivocally identify the metric that the results correspond to.
There was a previous attempt to define a metric registry RFC 4148
[RFC4148]. However, it was obsoleted by RFC 6248 [RFC6248] because
it was "found to be insufficiently detailed to uniquely identify IPPM
metrics... [there was too much] variability possible when
characterizing a metric exactly" which led to the RFC4148 registry
having "very few users, if any".
Our approach learns from this, by tightly defining each entry in the
registry with only a few parameters open for each. The idea is that
the entries in the registry represent different measurement tests,
whilst the parameters set things like source and destination
addresses that don't change the fundamental nature of the test. The
downside of this approach is that it could result in an explosion in
the number of entries in the registry. We believe that less is more
in this context - it is better to have a reduced set of useful
metrics rather than a large set of metrics with questionable
usefulness. Therefore this document defines that the registry only
includes commonly used metrics that are well defined; hence we
require both specification required AND expert review policies for
the assignment of values in the registry.
There are a couple of side benefits of having such registry. First
the registry could serve as an inventory of useful and used metrics,
that are normally supported by different implementations of
measurement agents. Second, the results of the metrics would be
comparable even if they are performed by different implementations
and in different networks, as the metric is properly defined.
This version of the document defines a set of independent registries,
that limits the explosion of registry entries by allowing arbitrary
combinations of entries in the different entries. The downside is
that the list of useful metrics is less defined, as any combination
would be defined. Which approach is better is up for discussion.
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The registry forms part of an Instruction {as defined in the proposed
terminology memo, draft-eardley-lmap-terminology-02}. It describes
various factors that need to be set by the party controlling the
measurements, for example: specific values for the parameters
associated with the selected registry entry (for instance, source and
destination addresses); and how often the measurement is made. The
Instruction might look something like: "Dear measurement agent:
Please start test DNS(example.com) and RTT(server.com,150) every day
at 2000 GMT. Run the DNS test 5 times and the RTT test 50 times. Do
that when the network is idle. Generate both raw results and 99th
percentile mean. Send measurement results to collector.com in IPFIX
format". The Instruction depends on the requirements of the
controlling party. For instance the broadband consumer might want a
one-off measurement made immediately to one specific server; a
regulator might want the same measurement made once a day until
further notice to the 'top 10' servers; whilst an operator might want
a varying series of tests (some of which will be beyond those defined
in the registry) as determined from time to time by their operational
support system. While the registries defined in this document help
to define the Instruction its full specification falls outside the
scope of this document.
2. The commonly used metrics registry
In this section we define the registry for commonly used metrics. It
is composed by the following sub-registries:
o Scheduling registry
o Environment registry
o Output-type registry
o Metric registry
The rationale for the registry structure is to allow flexibility but
yet precise definition of metrics. The metric registry defines the
metric itself while the other registries define additional aspects
that are needed for the measurement plan and that are needed to fully
specify a measurement request from a controller to a measurement
agent.
2.1. The metrics registry
The metrics registry contains two categories of metrics:
1. Where a relevant metric specification exists, the Registry relies
on a reference to one or more specifications where the required
information can be found.
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2. Where the Registry defines new metrics, the specifications
provided follow the format defined in RFC 6390 [RFC6390] (with
some exceptions noted below). Also, if the Registry relies on
specifications that contain rich options or non-specific
concepts, then the Registry will define a very tight
specification, essentially a new metric.
Each Registry entry for new metrics (as described above contain the
following information, based on the Normative sections recommended in
RFC 6390 [RFC6390]:
o Metric Name: A text string that uniquely identifies the metric.
o Metric Definition: The concise specification of the quantity
assessed by the metric.
o Method of Measurement or calculation:
o Units of Measurement.
o Measurement Accuracy: Required accuracy, including calibration and
identification of errors and uncertainties.
o Discussion: Any additional information, such as the recommended
range of measurement intervals or sample sizes, restrictions on
measurement points if applicable, and other specific guidance.
Ideally, metrics can be applied at any relevant test point, so the
Registry leaves measurement points as an open parameter (omitting the
"Measurement Point(s) with potential Measurement Domain" section from
RFC 6390 [RFC6390]). A canonical reference path is defined in
[I-D.ietf-ippm-lmap-path].
The policy for the assignments in the metric registry is both
specification required AND expert review. This means that in order
to create an entry for the metric value a specification defining the
metric is required and when that happens, the request for allocation
will be reviewed by an expert.
The specification must define the input parameters for the metric as
well as the output of the metric. The metric must be well defined,
in the sense that two independent implementations must produce
uniform and comparable results.
The expert review must make sure that the proposed metric is
operationally useful. This means that the metric has proven to be
useful in operational/real scenarios.
2.2. The Scheduling registry
Each entry for the scheduling registry contain the following
information:
o Value: The name of the scheduling
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o Reference: the specification where the scheduling is defined
The scheduling defines the scheduling strategy for the metric.
Simplest is Singleton scheduling, where an atomic measurement is
made. Other strategies make a series of atomic measurements in a
"sample" or "stream", with the schedule defining the timing between
each distinct measurement. Each atomic measurement could consist of
sending a single packet (such as a DNS request) or sending several
packets (for example a webpage). A scheduling strategy requires
input parameter(s). Assignment in this registry follows the
specification required policy.
2.3. The Environment registry
Each entry for the environment registry contain the following
information:
o Value: The name of the environment
o Reference: the specification where the environment is defined
The environment defines the conditions where the metric is expected
to be used. It does not define the metric itself, but the context
where the metric is executed. Assignment in this registry follows
the specification required policy.
2.4. The Output type registry
Each entry for the output type registry contain the following
information:
o Value: The name of the output type
o Reference: the specification where the output type is defined
The output type define the type of output that the metric produces.
It can be the raw results or it can be some form of statistic.
Assignment in this registry follows the specification required
policy. The specification of the output type must define the format
of the output.
3. Initial assignment for the Scheduling registry
3.1. Common parameter definitions
Although each IPPM RFC defines individual parameters and uses them
consistently, the parameter names are not completely consistent
across the RFC set. For example, the variable "dT" is used in
several different ways. This memo uses one set of parameter names,
and the reader is cautioned to map the names according to their
definitions.
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We define some parameters that are used by several types of
scheduling:
o T0: time to begin a test
o Tf: time to end a test
T0 and Tf are both in seconds and use the date (yyyy-mm-dd) and NTP
64 bit timestamp. T0 includes any control handshaking before the
test stream or singleton. Tf is the time the last test data is sent.
As a result, we have:
o Time when test devices may close the test socket: Tf + Waiting
Time (the time to wait before declaring a packet lost is fixed for
each metric)
o Total duration of the test: Tf - T0 + Waiting Time
3.2. Poisson scheduling
The values for this entry are as follows:
o Value: Poisson
o Reference: draft-bagnulo-ippm-new-registry
The Poisson scheduling is defined in section 11.1.1 of RFC 2330
[RFC2330] and needs input parameters:
o T0 and Tf: defined above
o lambda: the parameter defining the Poisson distribution. Lambda
is the mean number of distinct measurements per second in the
sample.
3.3. Periodic scheduling
The values for this entry are as follows:
o Value: Periodic
o Reference: draft-bagnulo-ippm-new-registry
The Periodic sampling is defined in RFC 3432 [RFC3432]. The
additional input parameters for the metric required by Periodic
scheduling are:
o T0 and Tf: defined above
* Note that with Periodic sampling, T0 MUST NOT be strictly
periodic with other tests of the same type. RFC 3432 [RFC3432]
requires randomized start times and describes one way to
accomplish this. Also, the duration of the test MUST be
limited.
o incT: the time in seconds between one distinct event and the next,
where events typically result in repeating singleton measurements
of various types (illustrated below).
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* for a periodic stream this is the time between packets in the
sample, first bit to first bit
* for measurements on a process this is the time between the
first packets of the process, for example first bit to first
bit of the SYN in a TCP 3-way handshake
3.4. Singleton scheduling
The values for this entry are as follows:
o Value: singleton
o Reference: draft-bagnulo-ippm-new-registry
The singleton scheduling covers the case when an atomic metric is
performed as per RFC 2330 [RFC2330]. The additional input parameter
for the metric required by Singleton scheduling is:
o T0: defined above
4. Initial assignments for the Output Type registry
4.1. Raw
The values for this entry are as follows:
o Value: Raw
o Reference: draft-bagnulo-ippm-new-registry
The results of the metric are delivered in the exact way they are
produced by the measurements without any further processing or
filtering.
4.2. Xth percentile interval
The values for this entry are as follows:
o Value: Xth-percentile
o Reference: draft-bagnulo-ippm-new-registry
The additional input parameter for the metric is:
o X: the percentile (e.g, if the X input parameter is 99, then the
output will be the 99th percentile interval.)
The output when using this Output type will be a couple of values,
expressed in the same units as the raw output, that is the Xth
percentile interval, as defined in section 1.3 of RFC 2330 [RFC2330].
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4.3. Xth percentile mean
The values for this entry are as follows:
o Value: Xth-percentile-mean
o Reference: draft-bagnulo-ippm-new-registry
The additional input parameter for the metric is
o X: the percentile (e.g, if the X input parameter is 99, then the
output will be the 99th percentile mean.)
The output when using this Output type will be a single value,
expressed in the same units as the raw output, that is the mean of
the sample only considering the values contained in the Xth
percentile interval, as defined in RFC 2330 [RFC2330].
5. Initial assignments for the Environment registry
5.1. Undefined
The values for this entry are as follows:
o Value: Undefined
o Reference: draft-bagnulo-ippm-new-registry
The undefined environment is the case where no additional environment
settings are defined to perform the metric.
5.2. No cross traffic
The values for this entry are as follows:
o Value: No-cross-traffic
o Reference: draft-bagnulo-ippm-new-registry
It is often important that there is no other traffic than the one
generated by the measurement itself while doing the measurement. The
reasons for this are two-folded, first, it is sometimes important
that the traffic created by the measurement doesn't impact the
experience of the users of the measured resource. Second it is
sometimes important that no other traffic interferes with the
measurement. This can be ensured by checking that the level of user
traffic is either zero or low enough to be confident that it won't
impact or be impacted by the measurement.
The "No cross traffic" condition is satisfied when, during the 5
seconds preceding measurement of the metric:
o the level of traffic flowing through the interface that will be
used to send measurement packets in either direction is less than
a threshold value of 1% of the line rate of the aforementioned
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interface.
The "cross traffic" measurement is made at the interface, associated
with the measurement agent, that user traffic flows across. For
example, if the probe is attached to the home gateway, then the
interface is the service demarcation point where the subscriber
connects their private equipment or network to the subscribed
service.
Note that the No-cross traffic condition is defined only for the link
directly attached to the measurement agent initiating the
measurement. There is nothing mentioned about cross traffic on other
parts of the path used by measurement packets. In the case the
bottleneck of the path is other link than the one directly attached
to the device running the measurement agent, it may affect and be
affected by the measurement even if the No cross traffic as defined
here holds.
DISCUSSION
o It is not clear we need a registry for this. If the only thing we
are going to define is the No cross traffic condition, we can
simply set it as an input parameter in each metric.
o clarify whether traffic for each direction is less than threshold,
or the sum
o current SamKnows probes measure cross-traffic before the
measurement of the metric. Another approach would be to measure
cross-traffic during the time the metric is measured. Or a hybrid
approach. These would either be separate environment entries, or
parameterise the existing one.
o current SamKnows probes define a fixed threshold. It could be a
parameter
o could ignore broadcast traffic (think SamKnows includes)
o It would be possible to define this a bit more precisely as
follows:
* The "No cross-traffic" condition is defined for active
measurements. The measurement agent runs in a device that has
one or more interfaces. In active measurements, the
measurement agent sends one or more packets. Lets call if0 the
interface through with the packets resulting from the
measurement are sent through. The no cross traffic condition
is fulfilled when during the 5 seconds prior sending each of
the packets of the measurement:
+ The traffic incoming through if0 that does not belong to the
measurement is lower than 1% of the line rate of if0
+ The traffic coming through the rest of the interfaces
towards if0 is less than 1% of the line rate of if0.
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6. Initial assignments for the Metric registry
6.1. Comment
Need to work through that we only define T0 and Tf (and not T, dT).
6.2. UDP related metrics
6.2.1. Parameters for UDP metrics
RFC 2681 [RFC2681] defines a Round-trip delay metric and RFC 6673
[RFC6673] defines a Round-trip packet loss metric. We build on these
two metrics by specifying several of the open parameters to precisely
define several metrics for measuring UDP latency and packet loss.
All the UDP related metrics defined in this section use the
following:
Type-P:
o IPv4 header values:
* DSCP: set to 0
* TTL set to 255
* Protocol: Set to 17 (UDP)
o UDP header values:
* Checksum: the checksum must be calculated
o Payload
* Sequence number: 8-byte integer
* Timestamp: 8 byte integer. Expressed as 64-bit NTP timestamp
as per section 6 of RFC 5905 [RFC5905]
* No padding
Timeout: 3 seconds waiting time threshold for packet arrival
6.2.2. Round-trip UDP latency metric
We define the UDP latency metric as follows:
o Metric Name: RT_UDP_Latency
o Metric Definition: The metric is defined in section 2.4 of RFC
2681 [RFC2681] with the Type-P and timeout value being the ones
defined in Section 6.2.1 of this document.
o Method of Measurement or calculation: The method is defined in
section 2.6 of RFC 2681 [RFC2681].
o Units of Measurement: Defined in section 2.3 of RFC 2681
[RFC2681].
o Measurement Accuracy: Measurement timing considerations are
described in section 2.5 of RFC 2681 [RFC2681] and section 2.7 of
RFC 2681 [RFC2681].
The input parameters for this metric are:
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o Source IP Address
o Destination IP Address
o Source UDP port
o Destination UDP port
o Measurement point nomenclature from the reference path defined in
[I-D.ietf-ippm-lmap-path]
o Time
The output of this metric is the couple of values formed by the
timestamp of the sent packet and the time when the echo was received.
They are expressed in milliseconds and use the date (yyyy-mm-dd) and
NTP 64 bit timestamp
6.2.3. Round-trip UDP packet-loss metric
We define the Round-trip UDP packet-loss metric as follows:
o Metric Name: RT_UDP_packet_loss.
o Metric Definition: This metric is defined in section 4.3 of RFC
6673 [RFC6673] using the Type-P and Timeout defined in
Section 6.2.1 of this document.
o Method of Measurement or calculation: The method is defined in
section 4.4 of RFC 6673 [RFC6673].
o Units of Measurement. The units are defined in section 4.3 of RFC
6673 [RFC6673]
o Measurement Accuracy: Timing considerations are discussed in
section 4.3 of RFC 6673 [RFC6673].
The input parameters for this metric are:
o Source IP Address
o Destination IP Address
o Source UDP port
o Destination UDP port
o Measurement point nomenclature from the reference path defined in
[I-D.ietf-ippm-lmap-path]
o Time T
The output of this metric is a single value 0 (packet was lost) or 1
(packet has arrived before timeout)
7. ICMP related metrics
7.1. ICMP Parameters
RFC 6673 [RFC6673] defines a Round-trip packet loss metric. We build
on that metrics by specifying several of the open parameters to
precisely define a metric for measuring ICMP packet loss. The ICMP
related metric defined in this document use the following:
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P-Type:
o IPv4 header values:
* DSCP: set to 0
* TTL set to 255
* Protocol: Set to 1 (ICMP)
o ICMP header values:
* Type: 8 (Echo request)
* Code: 0
Observation: reply packets will contain an ICMP type of 0 Echo reply.
Timeout: 3 seconds
7.2. ICMP packet-loss metric
We define the ICMP packet-loss metric as follows:
o Metric Name: ICMP_packet_loss.
o Metric Definition: This metric is defined in section 4.3 of RFC
6673 [RFC6673] using the Type-P and Timeout defined in Section 7.1
of this document.
o Method of Measurement or calculation: The method is defined in
section 4.4 of RFC 6673 [RFC6673].
o Units of Measurement. The units are defined in section 4.3 of RFC
6673 [RFC6673]
o Measurement Accuracy: Timing considerations are discussed in
section 4.3 of RFC 6673 [RFC6673].
The input parameters for this metric are:
o Source IP Address
o Destination IP Address
o Measurement point nomenclature from the reference path defined in
[I-D.ietf-ippm-lmap-path]
o Time T
The output of this metric is a single value 0 (packet was lost) or 1
(packet has arrived before timeout)
8. DNS related metrics
8.1. DNS parameters
RFC 2681 [RFC2681] defines a Round-trip delay metric. We build on
that metric by specifying several of the open parameters to precisely
define a metric for measuring DNS latency. The metric uses the
following parameters:
P-Type:
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o IPv4 header values:
* DSCP: set to 0
* TTL set to 255
* Protocol: Set to 17 (UDP)
o UDP header values:
* Source port: 53
* Destination port: 53
* Checksum: the checksum must be calculated
o Payload: The payload contains a DNS message as defined in RFC 1035
[RFC1035] with the following values:
* The DNS header section contains:
+ QR: set to 0 (Query)
+ OPCODE: set to 0 (standard query)
+ AA: not set
+ TC: not set
+ RD: set to one (recursion desired)
+ RA: not set
+ RCODE: not set
+ QDCOUNT: set to one (only one entry)
+ ANCOUNT: not set
+ NSCOUNT: not set
+ ARCOUNT: not set
* The Question section contains:
+ QNAME: the FQDN provided as input for the test
+ QTYPE: the query type provided as input for the test
+ QCLASS: set to IN
* The other sections do not contain any Resource Records.
Observation: reply packets will contain a DNS response and may
contain RRs.
Timeout: 3 seconds
8.2. DNS latency metric
We define the DNS latency metric as follows:
o Value: DNS_Latency
o Reference: draft-bagnulo-ippm-new-registry
o Metric Name: DNS_Latency
o Metric Definition: The metric is defined in section 2.4 of RFC
2681 [RFC2681] with the Type-P and timeout value being the ones
defined in Section 8.1 of this document.
o Method of Measurement or calculation: The method is defined in
section 2.6 of RFC 2681 [RFC2681].
o Units of Measurement: Defined in section 2.3 of RFC 2681
[RFC2681].
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o Measurement Accuracy: Measurement timing considerations are
described in section 2.5 of RFC 2681 [RFC2681].
The input parameters for this metric are:
o Source IP Address
o Destination IP Address (the address of the DNS server to be
tested)
o Measurement point nomenclature from the reference path defined in
[I-D.ietf-ippm-lmap-path]
o QTYPE: A RR
o FQDN: a valid FQDN that will be queried for.
o Time T
The output of this metric is the timestamp when the packet was sent
and the delay that it took to receive a response. Please note that
any DNS response is valid, including no records in the answer.
(Should we be more explicit about what is the output when there is no
reply packet received?)
9. Some examples of measurement plans
A measurement plan will be characterized by the following tuple:
(Metric, environment, scheduling, output format). We will next
present some measurement plans that are currently used.
A measurement plan for measuring the 99th percentile interval of the
UDP latency without cross traffics, using a Poisson stream with rate
l pkts/sec, stating at time T0 and ending at Tf seconds, between
source IP address IPs and source port Ps and destination IP address
IPd and destination port Pd would be expressed as:
(RT_UDP_Latency(IPs,Ps,IPd,Pd), No-cross-traffic,
Poisson(T0,Tf,l), Xth-percentile(99))
A measurement plan for measuring the UDP packet loss ration without
cross traffics, using a Poisson stream with rate l pkts/sec, stating
at time T0 and ending at Tf seconds, between source IP address IPs
and source port Ps and destination IP address IPd and destination
port Pd would be expressed as:
(RT_UDP_Packet_Loss(IPs,Ps,IPd,Pd), No-cross-traffic,
Poisson(T0,Tf,l), Xth-percentile-mean(100))
A measurement plan for measuring the ICMP packet loss ratio, using a
Periodic stream s second between packets, stating at time T0 and
ending at Tf seconds, between source IP address IPs and destination
IP address IPd would be expressed as:
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(ICMP_Packet_Loss(IPs,IPd), Undefined, Periodic(T0,Tf,s), Xth-
percentile-mean(100))
A measurement plan for measuring the DNS latency for resolving FQDN
foo.com between a resolver in IP address IPs and a server with
address IPd at time T would be expressed as:
(DNS_Latency(IPs,IPd,foo.com), Undefined, Singleton(T), raw)
10. Security considerations
TBD
11. IANA Considerations
TBD
12. Acknowledgments
We would like to thank Henning Schulzrinne for many constructive
comments and input on early versions of this document.
13. References
13.1. Normative References
[RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis,
"Framework for IP Performance Metrics", RFC 2330,
May 1998.
[RFC3432] Raisanen, V., Grotefeld, G., and A. Morton, "Network
performance measurement with periodic streams", RFC 3432,
November 2002.
[RFC2681] Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip
Delay Metric for IPPM", RFC 2681, September 1999.
[RFC6673] Morton, A., "Round-Trip Packet Loss Metrics", RFC 6673,
August 2012.
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.
[RFC5905] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network
Time Protocol Version 4: Protocol and Algorithms
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Specification", RFC 5905, June 2010.
[RFC2679] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way
Delay Metric for IPPM", RFC 2679, September 1999.
[RFC2680] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way
Packet Loss Metric for IPPM", RFC 2680, September 1999.
[RFC3393] Demichelis, C. and P. Chimento, "IP Packet Delay Variation
Metric for IP Performance Metrics (IPPM)", RFC 3393,
November 2002.
[RFC5481] Morton, A. and B. Claise, "Packet Delay Variation
Applicability Statement", RFC 5481, March 2009.
[RFC6390] Clark, A. and B. Claise, "Guidelines for Considering New
Performance Metric Development", BCP 170, RFC 6390,
October 2011.
[I-D.ietf-ippm-lmap-path]
Bagnulo, M., Burbridge, T., Crawford, S., Eardley, P., and
A. Morton, "A Reference Path and Measurement Points for
LMAP", draft-ietf-ippm-lmap-path-00 (work in progress),
July 2013.
13.2. Informative References
[RFC4148] Stephan, E., "IP Performance Metrics (IPPM) Metrics
Registry", BCP 108, RFC 4148, August 2005.
[RFC6248] Morton, A., "RFC 4148 and the IP Performance Metrics
(IPPM) Registry of Metrics Are Obsolete", RFC 6248,
April 2011.
Authors' Addresses
Marcelo Bagnulo
Universidad Carlos III de Madrid
Av. Universidad 30
Leganes, Madrid 28911
SPAIN
Phone: 34 91 6249500
Email: marcelo@it.uc3m.es
URI: http://www.it.uc3m.es
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Trevor Burbridge
British Telecom
Adastral Park, Martlesham Heath
Ipswich
ENGLAND
Email: trevor.burbridge@bt.com
Sam Crawford
SamKnows
Email: sam@samknows.com
Philip Eardley
British Telecom
Adastral Park, Martlesham Heath
Ipswich
ENGLAND
Email: philip.eardley@bt.com
Al Morton
AT&T Labs
200 Laurel Avenue South
Middletown, NJ
USA
Email: acmorton@att.com
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