Network Working Group                                          A. Morton
Internet-Draft                                                 AT&T Labs
Intended status: Informational                         September 6, 2021
Expires: March 10, 2022

Dream-Pipe or Pipe-Dream: What Do Users Want (and how can we assure it)?


   This memo addresses the problem of defining relevant properties and
   metrics with the goal of improving Internet access for all users.
   Where the fundamental metrics are well-defined, a framework to
   standardize new metrics exists and been used with success.  Users
   consider reliability to be important, as well as latency and
   capacity; it really depends who you ask and their current

Status of This Memo

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  What's happening with users today?  . . . . . . . . . . .   2
     1.2.  User expectations and how they can change . . . . . . . .   3
     1.3.  How fast can you go?  . . . . . . . . . . . . . . . . . .   4
   2.  Dream-Pipe/Pipe-Dream . . . . . . . . . . . . . . . . . . . .   5
   3.  Metrics to Assess Fundamental Properties  . . . . . . . . . .   7
   4.  Interpreting the Measurements . . . . . . . . . . . . . . . .  10
   5.  Work together, as always! . . . . . . . . . . . . . . . . . .  11
   6.  Displaying or Reporting Results . . . . . . . . . . . . . . .  11
   7.  Summary . . . . . . . . . . . . . . . . . . . . . . . . . . .  12
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  13
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     11.1.  References . . . . . . . . . . . . . . . . . . . . . . .  13
     11.2.  More References  . . . . . . . . . . . . . . . . . . . .  15
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

   This memo addresses the problem of defining relevant properties and
   metrics with the goal of improving Internet access for all users.
   Much has already been done, and it's important to have a common
   foundation as we move forward.  There is certainly more to understand
   about the problem and the approaches to a solution.

1.1.  What's happening with users today?

   Part of the motivation for examining metrics in greater detail at
   this time is the belief that "Internet speed" is no longer the only
   service dimension that matters to users.  A small sample of recent
   surveys follows.

   In a 2021 UK [EY-Study] EY study (Summary in Advanced Television),
   Decoding the digital home, Chapter 2, a survey of 2500 subscribers
   found that "Fifty-eight per cent of UK households believe broadband
   reliability is more important than speed".  Also, "the appetite for a
   consistent connection aligns with perceptions that broadband
   reliability declined during the pandemic - 29 per cent across all
   households, rising to 46 per cent in households with children aged up
   to 11 years."  If the family is on-line more-often, they will notice
   more outages.

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   Reliability is surely important, but other factors come into play:
   "...nearly half (47 per cent) don't think upgrading to higher-speed
   packages is worth the cost.  Meanwhile, 29 per cent say they don't
   understand what broadband speed means in practice."  [EY-Study] Price
   trade-off and knowledge about the communication details play a role
   when discussing speed.  Reliability issues are experienced by

   All the findings above are predicated on the current "speeds" being
   delivered.  For example, "Fifty-two percent of rural users are
   frustrated that the fastest speeds are not available in their area,
   and only 52 per cent believe they are getting value for money from
   their current broadband package."  [EY-Study] The proportion of Urban
   users was 10-15% higher when asked about value.  Broadband speed
   available often defines the development gap in world-wide surveys,
   and users in under-served areas are likely glad to see

   Another survey described in [DontKnow] found that 36% of Americans
   *don't* know their Internet speed.  A higher percentage of females
   did not know (47%) than males (25%).  Older Americans (55+) and those
   in lower income households are other demographics where service speed
   was an above-overall-average gap in their Internet knowledge.  Those
   who did not know their speed tended to be satisfied with the speed
   they receive, about 20% of these indicated dissatisfaction.

   Latency wasn't mentioned in [EY-Study], but "While the survey
   indicates that most households ultimately want 'the basics' to work
   well, those that do consider additional features as part of a
   broadband bundle favour privacy and security (48 per cent),
   reflecting wider anxieties and concerns relating to data protection
   experienced during the pandemic."  Many users want their service
   provider to provide all the services.

1.2.  User expectations and how they can change

   User expectations are greatly influenced by their current
   experiences, and by what is technologically feasible at the time.
   Users have a view of the levels of availability, quality, and utility
   that constitute the overall experience in their situation of use
   (e.g., stationary in their home).

   When we insert a communication network as an integral part of an
   activity (a task or form of entertainment), then the expectation
   doesn't change or make allowances without a trade-off between the new
   features and the new situation For example, take the home but add the
   ability to travel: a stretch limousine fills some of the need but

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   with reduced capabilities (the refrigerator is smaller, no beds or
   lavatory; there is less of everything).  But we have a TV!

   Let's assume the TV uses analog transmission for this discussion.
   The TV is smaller and experiences reception outages, so we are
   suddenly aware of radio characteristics like fading and multipath
   (especially with earlier analog transmissions, there is no buffering
   at all).  The limo is really nicely appointed, but it's not all we
   dreamed-of (or possibly even expected), especially the TV reception
   because we wanted to watch a play-off game on this trip!

   Where did they go wrong providing the TV in the Limo?  They made the
   communication channel a much more obvious part of the viewing
   experience.  And the first-time users didn't expect it.  They
   inserted unexpected impairments in the communication channel by
   adding mobility.  The TV designer might not have been aware of the
   moving use case; their "portable TV" means you can pick-up the TV
   easily, not watch TV at high speed, so needed features were not
   provided (a tracking antenna, to start with...).

   Since the goal of the workshop is to improve Internet Access for
   *all* users, then we have set a difficult task.  Some users might
   want a dedicated pipe to communicate in the ways they choose or
   access content that they have identified.  Other users are willing to
   share a pool of communication resources to communicate only when and
   where they want, for the potential benefits of being able to
   communicate more widely, spontaneously, and possibly for less cost
   than the dedicated pipe.  It seems that we should focus on the subset
   of performance attributes that will benefit as many users as
   possible, and over-which our constituent organizations have some

1.3.  How fast can you go?

   To some, the maximum bit rate remains the primary goal.

   The Internet Speed record previously held by the University College
   of London (178 Tbps) was topped in July 2021 by a team of researchers
   from the National Institute of Information and Communications
   Technology (NICT) in Japan.  The new world record for Internet speed,
   is 319 Tbps, using 4-core fiber [WorldRecord].

   Higher link rates and subscriber rates may not be everything to
   users, but there can be a cross-over dependency to latency
   performance.  Packet serialization time is reduced at higher link
   speeds, directly proportional to the increased rate.  Bursts of large
   packets arriving for one stream affect the buffer time for packets in
   other streams that arrive behind them in a single FIFO queue, but

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   again the problem is relieved by using higher link rates.  For
   example, early VoIP used very low bit rate codecs: 8kbps was common,
   and so were 10 Mbps LANs.  But mixing bursty and periodic traffic
   meant unreliable delivery and delay variation for the latter.  Packet
   marking, prioritization of multiple queues and queue management
   methods helped.  More rate headroom and adaptation for the network
   impairments was also welcome.

   Instead of providing more capacity for a single user, today's Gigabit
   services support more users efficiently on the same access service.
   So higher rates can improve the other important dimensions of

2.  Dream-Pipe/Pipe-Dream

   Perhaps the ideal view of point-to-point communications is a pipe
   that illustrates many fundamental communication properties.  A dream-
   pipe, so to speak.

   o  The pipe is always ready to support communications when the user

   o  Material that enters the pipe leaves the pipe in a sufficiently
      unadulterated form.

   o  The pipe has sufficient and dedicated capacity to deliver
      information at the same rate at which it entered (once the
      diameter of the pipe has been chosen).

   The apparent rigidity of the pipe model helps identify additional
   properties that are needed:

   o  The capacity requirement may change/increase over time, even from
      session to session, so a user might anticipate a growing need for
      communications or anticipate use by more than one user by choosing
      a larger capacity pipe than they currently need.

   o  When we say, "delivered in sufficiently unadulterated form", we
      could mean:

      1.  a perfect reproduction (the communication of all messages with
          the same timing and order in which they started), or

      2.  a reliable byte stream delivery, or

      3.  communication of most messages with sufficient timeliness to
          reconstruct the original messages,or

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      4.  even a perceptual interpretation of a portion of the decoded
          messages delivered in a sufficiently timely way (for human-to-
          human voice communication: the users understood what was said,
          the conversation was sufficiently interactive as though they
          were in the same room (imperceptible latency), and each user
          can identify the remote speaker's voice.  But the overall
          tolerance for imperfections in the pipe depends on the
          particular use case and many design choices.

   o  The pipe itself must be ready for use, and the systems at the
      source and destination ends of the pipe must be equally ready and
      operational; all the systems required between users are
      responsible for success.

   o  The pipe may be invisible!  Radio access has its own advantages
      and challenges.

   So, a short list of network properties that contribute to good user
   experience are:

   1.  Available always when needed

   2.  Sufficient Capacity when needed

   3.  No apparent loss

   4.  No apparent latency (which implies both low and consistent

   Networking and geographic reality tells us that we are unlikely to
   see all properties at once, for all time, AOE (anywhere on Earth);
   that's the extreme Pipe-Dream.

   But attaining a good user experience level in different communication
   activities/scenarios likely implies different demands among the four
   properties above, and places different relative importance on each of
   these properties.

   Author's Note: I'm positing a rigid pipe as the object of an
   idealistic idea, or "dream pipe".  I hope there won't be any
   confusion about the play on words with "pipe dream; the dream pipe is
   a pipe dream, especially when the dream includes zero latency between
   any two points.  I'm not talking about a hose or flexible pipe,

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3.  Metrics to Assess Fundamental Properties

   The IETF has been working the problem of standardizing metrics for
   the Internet and the communication streams it transports for well
   over 20 years.  Many other organizations have been successfully
   working in this area as well, and hopefully they will identify their
   literature and key results for review.

   The IETF's efforts to define IP-Layer and Transport-Layer performance
   metrics and methods have largely been carried-out in the IPPM working
   group (IP-Performance Metrics, and later, called IP-Performance
   Measurements).  Beginning as a somewhat joint effort with the
   performance-focused Benchmarking Methodology Working Group (BMWG),
   IPPM was chartered individually in 1997.  IPPM has extensive
   literature relevant to Internet measurement.  The IPPM working group
   has a strong foundation in its Framework [RFC2330] that has been
   updated over time, with [RFC7312] and [RFC8468].  What we can
   *standardize and measure*, we have as a basis to evaluate and
   determine whether we have made it better (or not).

   The problem that initiated the IPPM work turned-out to be the most
   difficult to solve (Bulk Transfer Capacity, BTC [RFC3148]), and has
   taken the longest.  Meanwhile, the standards for fundamental metrics
   other than BTC turned-out to be sufficiently challenging.

   Here is a list of fundamental packet transfer metrics, specified in

   o  Connectivity [RFC2678]

   o  One-Way Loss [RFC7679], STD 81

   o  One-Way Delay [RFC7680], STD 82

   o  Round-Trip Delay [RFC2681]

   o  Round-Trip Loss [RFC6673]

   o  Reordering [RFC4737]

   o  Duplication [RFC5560]

   The metrics and methods above were specified with considerable
   flexibility, so that they could be applied in a range of specific

   One of the most flexible metrics is IP Packet Delay Variation,
   [RFC3393] which is a "derived metric", in that it requires One-Way

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   Delay measurements for assessment.  The powerful feature of [RFC3393]
   is the selection function, which permits comparing the delays of any
   pair of packets in the stream.  Fortunately, the performance
   community predominantly uses one of two forms of delay variation, the
   inter-packet delay variation and the packet delay variation forms.
   These forms are defined and compared in efficacy for measurement uses
   in [RFC5481] along with many other considerations and measurement

   It is possible to create new derived metrics at the IP-layer, and to
   measure similar quantities (loss, delay, reordering) at other layers
   [ForAll] [RFC6390] [RFC6076].

   Another example of a derived metric uses loss instead of delay.  This
   metric that does not have a direct parallel in the IETF literature is
   the Stream Block metric found in ITU-T Recommendation Y.1540 [Y.1540]
   (virtually all the IP-layer metrics are found in one standard).  This
   metric assigns consecutive packets into multi-packet blocks, and
   assesses the number of lost packets in a block as a surrogate for a
   higher-layer process's ability to maintain good communication.  For
   example, a Forward Error Correction process might be able to replace
   2 lost packets in any order, but not 3.  There is a parallel to
   retransmission rate limits when attempting to maintain a continued
   loss-free ratio with buffering to allow for the retransmission time.

   Network and Bulk Transport Capacity have been chartered and
   progressed over twenty years.  The performance community has seen
   development of Informative definitions in [RFC3148] for Framework for
   Bulk Transport Capacity (BTC), [RFC5136] for Network Capacity,
   Maximum IP-layer Capacity (in RFC9097-to-be), and the Experimental
   metric definitions and methods in [RFC8337], Model-Based Metrics for

   One quantity that could be measured without too much controversy is
   the Maximum IP-Layer Capacity (judging by the adoption in standards
   bodies, RFC9097-to-be) [I-D.ietf-ippm-capacity-metric-method].  This
   is the basis for many service specifications (and there is a
   technology or configuration-limited "ground truth" for the
   measurement), and can be tested simply with minimal reliance on end
   systems.  The method deploys a feedback channel from the receiver to
   control the sender's transmission rate in near-real-time, and search
   for the maximum.

   The "invisible" radio dream pipe presents a challenge in terms of
   results variability for all metrics and adds at least one critical
   input parameter: location.  It may be that the variability with
   location and time are key metrics to help users understand radio

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   coverage (in addition to signal strength portrayed by the "number of

   A network property that is very high on the list in Section 2 is
   Availability.  There is treatment of this important property as a
   metric in IETF (Connectivity [RFC2678]) and somewhat different
   details in an alternate definition (ITU-T Point-to-Point IP Service
   Availability [Y.1540]), but not much deployment for such an important
   pre-requisite to the rest of the metrics.  Both Connectivity and
   Availability rely on packet loss measurements, in fact they can be
   considered *derived metrics*, adding time constraints and/or loss
   ratio thresholds to the fundamental loss measurements on a packet

   Sometimes the end systems decide whether the path is available or
   not.  In one on-line gaming system, reception of ICMP Destination
   Unreachable caused complete and immediate termination of the session
   with loss of all progress and resources accumulated.  Customer
   service centers sometimes experienced call-in overload from users
   seeking to restore their player environment.  But the Destination
   Unreachable condition was temporary and resolved by routing updates
   in a few seconds.  The ultimate fix was to delay the session's
   reaction to Destination Unreachable for a few seconds, and recovery
   was automatic.  So, when end systems play a role in the definition of
   connectivity or availability, they must also be cognizant that all
   automatic failure detection and restoration requires some amount of
   time.  Since failures are inevitable, the dream-pipe heals itself,
   too (and doesn't confuse end-systems or users with error messages
   that "sound final").

   Most measurement systems begin their process with a Source-
   Destination packet exchange prior to actual measurements.  If this
   pre-measurement exchange fails, then the test is not conducted (and
   re-tried later).  But the most useful information to assess
   continuous connectivity/Availability is the record of test set-up
   success or failure over time.  Measurement systems that make this
   info readily available do a more complete job of network
   characterization than others.

   We cannot leave the topic of metrics without mentioning the equally
   important topic of measurement streams for Active Metrics and
   Measurements [RFC7799].  When attempting to measure characteristics
   of VoIP streams, the IETF agreed on ways to produce periodic streams
   in an acceptable way [RFC3432].  Many measured results completely
   depend on the stream characteristics, and inter-packet delay
   variation is a great example.  If the stream contains packet bursts,
   are the bursts preserved in transit?  We would ask later-on whether
   preserving burst spacing matters to the communication quality or to

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   the user's experience.  The answer is likely a matter of degree, and
   dependent on the communications activity itself.

   When we consider the topic of new test streams in the context of
   Gigabit and higher access speeds intended to support multiple users,
   we might consider the notion of a "standard single user's stream
   set".  Then we might measure how many simultaneous standard users can
   be supported with sufficient network performance: an indicator of
   each user's experience in the "dream-pipe".  Of course, that details
   of a standard user's traffic would change over time, so we couldn't
   argue over the current year's definition for a year... The facility
   to register the new standard user test streams would be a key part of
   such a solution.

4.  Interpreting the Measurements

   If we had measured only the fundamental metrics, we might ask, "we
   saw a small proportion of packet losses; did this matter to users?
   Did losses affect their satisfaction during their activity in any
   way?  Did any users experience an outage at this loss level?"

   The likely role for derived metrics is to improve results
   interpretation by measuring a new quantity, possibly in the context
   of a newly-defined packet stream, thereby making the process of
   results-interpretation easier to perform.

   For example, Delay Variation metrics had many possible formulations,
   but two main forms emerged.  RFC 5481 [RFC5481] compared the IPDV and
   PDV forms with tasks that network and application designers were
   facing at the time.  The RFC describes measurement considerations and
   results interpretation from a purely objective point of view.  The
   most useful result interpretation was to show how PDV (a
   characterization of the delay distribution from minimum to a high
   percentile) could be used to determine the size of the de-jitter
   buffer needed for the tested path.

   For other fundamental IP-Layer metrics, there is some amount of
   discussion of best practices and interpretation in each of the IETF
   IPPM Metric RFCs.

   Many researchers (working in ITU-T Study Group 12 and elsewhere) take
   the information that can be derived from packet-layer measurements,
   plus higher layers when available, and produce objective estimates of
   user satisfaction by modeling user Mean Opinion Score (MOS) variation
   over a range of conditions.  The process determines the user MOS
   through formal subjective testing in laboratories (or more recently
   prompted by COVID-19 conditions, in crowd-sourced scenarios).  The
   corresponding objective models of user satisfaction are often

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   determined through competition among several candidates, where the
   goal is to seek the most accurate model possible at the time.  The
   modeling efforts often produce new derived metrics that facilitate
   automated interpretation.  The main drawback is that the process
   described above takes significant time when conducted in the context
   of an industry standards body.  So, user activities that are not
   particularly demanding of network performance do not receive much
   attention from researchers doing modeling; their performance is
   assumed to come-along for the ride (but in a system with multiple
   queues or other categorizations, each activities' requirements need
   to be quantified).  Nevertheless, a process to take-in network
   measurements and produce a measure of user satisfaction is well-
   understood and used.  The output of these objective models can
   rightly be called Quality of Experience (QoE), because a set of
   users' opinions is an inherent part of the result (without users, you
   don't have QoE!  That's how QoE is defined and differs from QoS and
   network performance).

5.  Work together, as always!

   "What are the best ways to communicate these properties to service
   providers and network operators?"  Work together with service
   providers and network operators.  Everyone has a stake in our future.

   There are quite a few networking professionals whose day-job is
   network operation, and who are participating now.

6.  Displaying or Reporting Results

   Whether we present a single figure of merit, or a set of relevant
   measurements on a dashboard summary, each numer requires a frame of
   reference.  This is true for everyone, not just everyday users.

   One example of a solid reference for results comes from the
   fundamental benchmarking specification, [RFC2544].  The measured
   Throughput (as defined in [RFC2544] ) must be compared to the maximum
   theoretical frame rate on the layer-2 technology (accounting for
   frame size, inter-frame gap, preamble, etc.).  Tests with small frame
   size may not achieve the maximum frame rate due to header processing
   rate limitations, and tabulating the maximum with the results makes
   this fact very clear.  Other reference levels can be made available,
   such as the capacity required to support 4k video (~25Mbps), etc.

   Some people will simply want to know whether the measurement result
   is good, bad, or somewhere in-between.  We can follow common practice
   here to use colors (green, red, yellow in-between), or present the
   numer on a gauge with suitable color cues.  But we need to know the
   use case or the service specification accurately to do this.

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   In fact, a portion of user testing is prompted by subscribing to a
   new service provider, a new level of service (higher speed?), or a
   perception that poor-performance and trouble-shooting may be
   necessary; even an apparent outage may prompt test attempts using
   alternate devices and networks.

   This last testing scenario is the most interesting: how can we help
   users when they encounter a problem?  It's usually most important to
   isolate the problem in the complex network, and when user to network
   host results are failing, can the next step remove some of the
   components and check them in isolation (while keeping in mind that
   the acceptance level for a sub-network is a part of the end-to-end
   budget for performance!).  Is it impossible to reach a particular
   far-end host?  Does the access network appear to be unavailable, or
   is the problem related to interference on the WiFi radio network?
   With test hosts placed at strategic points in the path, it may be
   possible to segment the problem a user is experiencing.

7.  Summary

   When all components that comprise a user's activity work well-
   together, then there are no surprises.  Given that a large proportion
   of user expectations are met at some point in time, then the metrics
   and performance levels that characterize the network's contribution
   to overall satisfaction are what we want to describe and maintain.
   Users consider reliability to be important, as well as latency and
   capacity; it really depends who you ask and their current
   experiences.  End-system designers have a role to play in the process
   by recognizing the realities of packet networks and compensating for
   them: the dream-pipe absolutes are still a pipe-dream today.

   There are many fundamental metrics already-defined.  But we might
   find that we need new metrics that make interpreting the results
   easier!  The notion of *derived metrics* has been applied
   successfully.  Test streams with a known bias toward a particular
   class of user streams can also be useful basis for performance
   measurement.  Where the fundamental metrics are well-defined, a
   framework to standardize new metrics and active test streams exists
   and been used with success.  Metrics can be defined that immediately
   improve our understanding of the performance presented to users, but
   to understand user satisfaction requires that user opinions are part
   of the development process.

   All users, both knowledgeable and newcomers, need a frame of
   reference to understand what numerical measurements are telling them.
   The clues from the expected measurement range, the results from the
   recent past, or the theoretical maximum value all have their place.
   If users are willing, measurements should help them isolate their

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   current issue to one or more networks and/or components in the user-
   to-X path.

   If we break the problem down by specific communications activities
   and look for specific metrics for each one, it could take a long time
   to complete.  Perhaps a categorization of the performance metrics,
   numeric criteria, and reliability of a "pseudo-dream-pipe" for a set
   of communication activities that have similar needs is a way to move

8.  Security Considerations

   Active metrics and measurements have a long history of security
   considerations.  The security considerations that apply to any active
   measurement of live paths are relevant here.  See [RFC4656] and

   When considering privacy of those involved in measurement or those
   whose traffic is measured, the sensitive information available to
   potential observers is greatly reduced when using active techniques
   which are within this scope of work.  Passive observations of user
   traffic for measurement purposes raise many privacy issues.  We refer
   the reader to the privacy considerations described in the Large Scale
   Measurement of Broadband Performance (LMAP) Framework [RFC7594],
   which covers active and passive techniques.

9.  IANA Considerations

   This memo makes no requests of IANA.

10.  Acknowledgments

   Thanks to all the folks who have worked on performance metric
   development, many of whom are the authors of the references.  Many
   more have provided their insights along the way.  It's rewarding to
   travel with others (even for a short time), and to meet new people on
   the journey.

11.  References

11.1.  References

              Morton, A., Geib, R., and L. Ciavattone, "Metrics and
              Methods for One-way IP Capacity", draft-ietf-ippm-
              capacity-metric-method-12 (work in progress), June 2021.

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   [RFC2330]  Paxson, V., Almes, G., Mahdavi, J., and M. Mathis,
              "Framework for IP Performance Metrics", RFC 2330,
              DOI 10.17487/RFC2330, May 1998,

   [RFC2678]  Mahdavi, J. and V. Paxson, "IPPM Metrics for Measuring
              Connectivity", RFC 2678, DOI 10.17487/RFC2678, September
              1999, <>.

   [RFC2681]  Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip
              Delay Metric for IPPM", RFC 2681, DOI 10.17487/RFC2681,
              September 1999, <>.

   [RFC3393]  Demichelis, C. and P. Chimento, "IP Packet Delay Variation
              Metric for IP Performance Metrics (IPPM)", RFC 3393,
              DOI 10.17487/RFC3393, November 2002,

   [RFC3432]  Raisanen, V., Grotefeld, G., and A. Morton, "Network
              performance measurement with periodic streams", RFC 3432,
              DOI 10.17487/RFC3432, November 2002,

   [RFC4656]  Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
              Zekauskas, "A One-way Active Measurement Protocol
              (OWAMP)", RFC 4656, DOI 10.17487/RFC4656, September 2006,

   [RFC4737]  Morton, A., Ciavattone, L., Ramachandran, G., Shalunov,
              S., and J. Perser, "Packet Reordering Metrics", RFC 4737,
              DOI 10.17487/RFC4737, November 2006,

   [RFC5357]  Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
              Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
              RFC 5357, DOI 10.17487/RFC5357, October 2008,

   [RFC5481]  Morton, A. and B. Claise, "Packet Delay Variation
              Applicability Statement", RFC 5481, DOI 10.17487/RFC5481,
              March 2009, <>.

   [RFC5560]  Uijterwaal, H., "A One-Way Packet Duplication Metric",
              RFC 5560, DOI 10.17487/RFC5560, May 2009,

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   [RFC6076]  Malas, D. and A. Morton, "Basic Telephony SIP End-to-End
              Performance Metrics", RFC 6076, DOI 10.17487/RFC6076,
              January 2011, <>.

   [RFC6390]  Clark, A. and B. Claise, "Guidelines for Considering New
              Performance Metric Development", BCP 170, RFC 6390,
              DOI 10.17487/RFC6390, October 2011,

   [RFC6673]  Morton, A., "Round-Trip Packet Loss Metrics", RFC 6673,
              DOI 10.17487/RFC6673, August 2012,

   [RFC7679]  Almes, G., Kalidindi, S., Zekauskas, M., and A. Morton,
              Ed., "A One-Way Delay Metric for IP Performance Metrics
              (IPPM)", STD 81, RFC 7679, DOI 10.17487/RFC7679, January
              2016, <>.

   [RFC7680]  Almes, G., Kalidindi, S., Zekauskas, M., and A. Morton,
              Ed., "A One-Way Loss Metric for IP Performance Metrics
              (IPPM)", STD 82, RFC 7680, DOI 10.17487/RFC7680, January
              2016, <>.

11.2.  More References

              of-us-know-their-broadband-speed/, "Survey: Just 36% of US
              know their broadband speed (title is incorrect)", June
              2021, <

              favour-broadband-reliability-over-speed/, "Study: UK homes
              favour broadband reliability over speed", June 2021,

   [ForAll]   Morton, A., ""Performance Metrics for All," in IEEE
              Internet Computing, vol. 13, no. 4, pp. 82-86, doi:
              10.1109/MIC.2009.87.", July 2009,

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              "Internet speeds improved in North Africa over last four
              quarters", June 2021,

   [RFC2544]  Bradner, S. and J. McQuaid, "Benchmarking Methodology for
              Network Interconnect Devices", RFC 2544,
              DOI 10.17487/RFC2544, March 1999,

   [RFC3148]  Mathis, M. and M. Allman, "A Framework for Defining
              Empirical Bulk Transfer Capacity Metrics", RFC 3148,
              DOI 10.17487/RFC3148, July 2001,

   [RFC5136]  Chimento, P. and J. Ishac, "Defining Network Capacity",
              RFC 5136, DOI 10.17487/RFC5136, February 2008,

   [RFC7312]  Fabini, J. and A. Morton, "Advanced Stream and Sampling
              Framework for IP Performance Metrics (IPPM)", RFC 7312,
              DOI 10.17487/RFC7312, August 2014,

   [RFC7594]  Eardley, P., Morton, A., Bagnulo, M., Burbridge, T.,
              Aitken, P., and A. Akhter, "A Framework for Large-Scale
              Measurement of Broadband Performance (LMAP)", RFC 7594,
              DOI 10.17487/RFC7594, September 2015,

   [RFC7799]  Morton, A., "Active and Passive Metrics and Methods (with
              Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799,
              May 2016, <>.

   [RFC8337]  Mathis, M. and A. Morton, "Model-Based Metrics for Bulk
              Transport Capacity", RFC 8337, DOI 10.17487/RFC8337, March
              2018, <>.

   [RFC8468]  Morton, A., Fabini, J., Elkins, N., Ackermann, M., and V.
              Hegde, "IPv4, IPv6, and IPv4-IPv6 Coexistence: Updates for
              the IP Performance Metrics (IPPM) Framework", RFC 8468,
              DOI 10.17487/RFC8468, November 2018,

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              Systems, "Internet speed record of 319Tb/s reached", July
              2021, <

   [Y.1540]   Y.1540, I. R., "Internet protocol data communication
              service - IP packet transfer and availability performance
              parameters", December 2019,

Author's Address

   Al Morton
   AT&T Labs
   200 Laurel Avenue South
   Middletown, NJ  07748

   Phone: +1 732 420 1571
   Fax:   +1 732 368 1192

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