[Docs] [txt|pdf] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   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.




Bagnulo, et al.         Expires January 13, 2014                [Page 1]


Internet-Draft       Metrics Registry - Independent            July 2013


   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.










































Bagnulo, et al.         Expires January 13, 2014                [Page 2]


Internet-Draft       Metrics Registry - Independent            July 2013


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











Bagnulo, et al.         Expires January 13, 2014                [Page 3]


Internet-Draft       Metrics Registry - Independent            July 2013


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.



Bagnulo, et al.         Expires January 13, 2014                [Page 4]


Internet-Draft       Metrics Registry - Independent            July 2013


   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.





Bagnulo, et al.         Expires January 13, 2014                [Page 5]


Internet-Draft       Metrics Registry - Independent            July 2013


   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





Bagnulo, et al.         Expires January 13, 2014                [Page 6]


Internet-Draft       Metrics Registry - Independent            July 2013


   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.



Bagnulo, et al.         Expires January 13, 2014                [Page 7]


Internet-Draft       Metrics Registry - Independent            July 2013


   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).



Bagnulo, et al.         Expires January 13, 2014                [Page 8]


Internet-Draft       Metrics Registry - Independent            July 2013


      *  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].







Bagnulo, et al.         Expires January 13, 2014                [Page 9]


Internet-Draft       Metrics Registry - Independent            July 2013


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



Bagnulo, et al.         Expires January 13, 2014               [Page 10]


Internet-Draft       Metrics Registry - Independent            July 2013


      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.




Bagnulo, et al.         Expires January 13, 2014               [Page 11]


Internet-Draft       Metrics Registry - Independent            July 2013


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:



Bagnulo, et al.         Expires January 13, 2014               [Page 12]


Internet-Draft       Metrics Registry - Independent            July 2013


   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:



Bagnulo, et al.         Expires January 13, 2014               [Page 13]


Internet-Draft       Metrics Registry - Independent            July 2013


   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:



Bagnulo, et al.         Expires January 13, 2014               [Page 14]


Internet-Draft       Metrics Registry - Independent            July 2013


   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].





Bagnulo, et al.         Expires January 13, 2014               [Page 15]


Internet-Draft       Metrics Registry - Independent            July 2013


   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:





Bagnulo, et al.         Expires January 13, 2014               [Page 16]


Internet-Draft       Metrics Registry - Independent            July 2013


      (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



Bagnulo, et al.         Expires January 13, 2014               [Page 17]


Internet-Draft       Metrics Registry - Independent            July 2013


              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





Bagnulo, et al.         Expires January 13, 2014               [Page 18]


Internet-Draft       Metrics Registry - Independent            July 2013


   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




















Bagnulo, et al.         Expires January 13, 2014               [Page 19]


Html markup produced by rfcmarkup 1.129b, available from https://tools.ietf.org/tools/rfcmarkup/