Internet DRAFT - draft-fabini-ippm-2330-time

draft-fabini-ippm-2330-time







Network Working Group                                          J. Fabini
Internet-Draft                                                   TU Wien
Updates: 2330 (if approved)                                    A. Morton
Intended status: Informational                                 AT&T Labs
Expires: April 16, 2016                                 October 14, 2015


        Updates for IPPM's Framework: Timestamping and Use Cases
                     draft-fabini-ippm-2330-time-00

Abstract

   Quality and accuracy of measurements depend on the selection of
   appropriate locations and timers for timestamp acquisition.  This
   memo updates the IP Performance Metrics (IPPM) Framework RFC 2330
   with new considerations on timers, timestamps and time-related
   definitions with particular focus on wireless networks and
   virtualized hosts.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 16, 2016.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.





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   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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Definition and Use of Wire Time . . . . . . . . . . . . . . .   4
     3.1.  Virtualization  . . . . . . . . . . . . . . . . . . . . .   5
   4.  Definition and Use of Host Time . . . . . . . . . . . . . . .   5
     4.1.  Virtualization  . . . . . . . . . . . . . . . . . . . . .   6
   5.  Encryption  . . . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   The IETF IP Performance Metrics (IPPM) working group first created a
   framework for metric development in [RFC2330].  This framework has
   stood the test of time and enabled development of many fundamental
   metrics.  It has been updated in the area of metric composition
   [RFC5835], and in several areas related to active stream measurement
   of modern networks with reactive properties [RFC7312].

   Time is fundamental to measurements.  The IPPM framework [RFC2330]
   includes a comprehensive terminology, definition and discussion of
   time- and clock-related concepts.  But network technology has evolved
   since 1998.  First, host computing performance and software
   complexity have increased while network delays have decreased.  These
   advances enable development of new concepts like host virtualization
   in cloud computing, and network function virtualization.  One side-
   effect of these technologies is that packets spend more and more time
   in software, their propagation through the stack being biased by a
   series of uncertainty factors like buffers, queues and operating
   system scheduling.  Measurements can acquire timestamps in various
   locations within the host's software stack, causing potentially



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   significant variances in timestamp values [MCDC].  This is a
   consequence of just one alternative that the IPPM framework [RFC2330]
   defines for these timestamps: host time.  This memo seeks to update
   this aspect of the IPPM framework by discussing alternatives and
   proposing generic solutions that can be referenced by metric
   definitions.

   Second, the IPPM framework was approved one year before the release
   of the first IEEE 802.11 series standard.  This was a time when the
   data communication landscape was dominated by wired communication
   technologies and wireless data communications were in their infancy.
   This fact originated IPPM definitions like host time or wire time.
   Today, after more than one decade and half, wireless IEEE 802.11
   networks and cellular packet-switched data technologies like High-
   Speed Packet Access (HSPA) and Long Term Evolution (LTE) are
   responsible for an essential part of the worldwide Internet access
   traffic.  This raises the question, how the IPPM framework concept of
   wire time can be mapped to wireless networks.

   This memo revisits and updates time-related IPPM framework [RFC2330]
   definitions like host time and wire time in the light of
   technological advances.

2.  Scope

   The purpose of this memo is to update the IPPM metrics framework
   [RFC2330] with respect to timestamps and virtualization.  Concepts
   like "host time" or "wire time" must be revisited to be applicable
   for wireless networks and virtualized environments.

   The scope is to update key sections of [RFC2330] ...

   Potential Topics (Draft outline for discussion):

   - Fundamentals

   1.  Host Time (further develop the definition as mentioned but not
   defined in RFC2330.  Explain variants, propose examples and
   guidance).  Dedicated subsection and challenge: virtualization.

   2.  Wire Time (rename "Wire Time" to "Medium Time" or "Media Time" to
   account for wireless networks; revisit the definition of "Media
   Arrival Time" and "Media Exit Time" in the light of encryption,
   complex network coding, interleaving etc.  Define how to measure
   media time in wireless networks) Dedicated subsection and challenge:
   virtualization





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   3.  Define new terms wrt timestamps that help to differentiate
   between software delays within a host.  Ideally it should give
   guidance and define terms that allow to differentiate between delays
   (uncertainties) that a) are caused by host load, timer resolution,
   system scheduling, etc. and b) the ones that originate when packets
   wait in drivers because of network access policies or network
   congestion.  A "network (or IP) timestamp" can be useful in
   (virtualized) environments it might make sense to define the term
   "network timestamp" as "tcpdump timestamp of the host instance that
   is located closest to the hardware".  Hypervisor tcpdump timestamps
   should be preferred over VM timestamps.

   4. (optional) Protocol design considerations: (Security vs.
   flexibility): adding timestamps into headers/payload protocol fields
   at driver level (tcpdump equivalent) is difficult/impossible if link
   is protected using SSL/TLS/IPsec.  Meaningful: insert timestamp in
   application space.

   5. (probably not in IPPM) NTP is understood to operate sub-optimally
   for time-transfer to virtual machines (VM) as guest-clients in some
   hosts.  What meachanisms can be employed to improve time accuracy and
   stability when VMs intend to perform time measurement?

3.  Definition and Use of Wire Time

   [RFC2330] defines the following terms related to wire time (defined
   in terms of an Internet host H observing an Internet link L at a
   particular location):

   o  For a given packet P, the 'wire arrival time' of P at H on L is
      the first time T at which any bit of P has appeared at H's
      observational position on L

   o  For a given packet P, the 'wire exit time' of P at H on L is the
      first time T at which all the bits of P have appeared at H's
      observational position on L.

   However, wireless LAN and cellular networks are essential components
   of today's Internet.  This memo proposes to replace the term "wire
   time" by the equivalent term "media time" and provides additional
   guidance for wireless network measurements.

   This definition of media time raises one additional challenge: how
   can "media arrival time" and "media exit time" be defined for
   wireless networks.  Aligning with existing physical-layer standards
   of other standardization organizations like the 3GPP, this memo
   recommends the antenna connector of the Host(?) to be used for
   measuring media time in wireless networks.



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3.1.  Virtualization

   Virtualization adds additional level of uncertainty for timestamps:
   VM application, VM tcpdump, Hypervisor tcpdump.  What about wire time
   for virtual network interfaces?  Should it be bound to the related
   physical interface or to the hypervisor/virtual interface?

   There was some flexibility in the original mention of Host Time.
   Virtualization adds more layers where host timestamps could b e
   applied or derived, and the specification requires its own framework:

           Host
       |'''''''''''|
       |           |
       | |'''''''| |
       | |  UDP  | |  H
       | :-------: |  o
       | |   IP  | |  s
       | :-------: |  t
       | |  Link | |
       | :.......: |  T
       | |  NIC  | |  i
       | `.......' |  m
       |____||_____|  e
            ||
            || Wire Time
            ||
            ::

4.  Definition and Use of Host Time

   Section 3 of [RFC2330] includes an occurrence of the term "host time"
   but does not define it.  Some metric definitions like one-way delay
   in section 3.7.2 of [RFC2679] or round-trip delay in section 2.7 of
   [RFC2681] discuss the consequences of differences between wire time
   and host time.  Common to these metric definitions is the request to
   report errors and uncertainties resulting from the difference between
   host time and wire time.

   However, the evolution of network technology has decreased the
   network delay substantially.  Today, the delay of wireless and wired
   LAN links are in the same order of magnitude as the uncertainty of
   host time, the difference between timestamps at application layer and
   the ones in kernel space being substantial as pointed out in [MCDC]).
   Instead of accepting this uncertainty as an inherent part of
   measurements, this memo recommends to accurately define the location
   within the stack where timestamps are assigned to a packet.




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4.1.  Virtualization

   Virtualization extends the concept of host time beyond earlier
   limits.  For instance packet captures (tcpdump) in virtualized
   environments are possible at VM-level and at hypervisor level.
   Therefore, the definition of "Host Time" spans a broad range of
   timestamps, encompassing anything from timestamps acquired by an
   application running on top of a VM, down to tcpdump timestamps
   acquired within the VM or hypervisor network stack.

                                Host
                            |'''''''''''|
        Host                |           |  V
    |'''''''''''|           | |'''''''| |  i
    |           |           | |  UDP  | |  r
    | |'''''''| |           | :-------: |  t
    | |  UDP  | |  H        | |   IP  | |  u
    | :-------: |  o        | :-------: |  a
    | |   IP  | |  s        | |  Link | |  l
    | :-------: |  t        | :-------: |
    | |  Link | |           | |OverLay| |  M
    | :.......: |  T        | :-------: |*****
    | |  NIC  | |  i        | |FrontEnd |  H
    | `.......' |  m        | :-------: |  Y
    |____||_____|  e        |    I/O    |  P
         ||                 |   Ring    |  E
         || Wire Time       |           |  R
         ||                 | :-------: |  -
         ::                   |BackEnd|    V
                            | :-------: |  i
                            | |Native | |  s
                            | :  NIC  : |  o
                            | |Driver | |  r
                            | :-------: |
                            |___________|
                                   ||
                                   || Wire Time
 Xen VM based on:                  ||
 http://www.cc.gatech.edu/~lingliu/papers/2012/YiRen-CollaborateCom2012.pdf


5.  Encryption

6.  Security Considerations

   The security considerations that apply to any active measurement of
   live paths are relevant here as well.  See [RFC4656] and [RFC5357].




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   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.

7.  IANA Considerations

   This memo makes no requests of IANA.

8.  Acknowledgements

   The authors thank ...

9.  References

9.1.  Normative References

   [RFC0791]  Postel, J., "Internet Protocol", STD 5, RFC 791,
              DOI 10.17487/RFC0791, September 1981,
              <http://www.rfc-editor.org/info/rfc791>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC2330]  Paxson, V., Almes, G., Mahdavi, J., and M. Mathis,
              "Framework for IP Performance Metrics", RFC 2330,
              DOI 10.17487/RFC2330, May 1998,
              <http://www.rfc-editor.org/info/rfc2330>.

   [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
              December 1998, <http://www.rfc-editor.org/info/rfc2460>.

   [RFC2675]  Borman, D., Deering, S., and R. Hinden, "IPv6 Jumbograms",
              RFC 2675, DOI 10.17487/RFC2675, August 1999,
              <http://www.rfc-editor.org/info/rfc2675>.

   [RFC2679]  Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way
              Delay Metric for IPPM", RFC 2679, DOI 10.17487/RFC2679,
              September 1999, <http://www.rfc-editor.org/info/rfc2679>.





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   [RFC2681]  Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip
              Delay Metric for IPPM", RFC 2681, DOI 10.17487/RFC2681,
              September 1999, <http://www.rfc-editor.org/info/rfc2681>.

   [RFC2780]  Bradner, S. and V. Paxson, "IANA Allocation Guidelines For
              Values In the Internet Protocol and Related Headers",
              BCP 37, RFC 2780, DOI 10.17487/RFC2780, March 2000,
              <http://www.rfc-editor.org/info/rfc2780>.

   [RFC3168]  Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
              of Explicit Congestion Notification (ECN) to IP",
              RFC 3168, DOI 10.17487/RFC3168, September 2001,
              <http://www.rfc-editor.org/info/rfc3168>.

   [RFC4494]  Song, JH., Poovendran, R., and J. Lee, "The AES-CMAC-96
              Algorithm and Its Use with IPsec", RFC 4494,
              DOI 10.17487/RFC4494, June 2006,
              <http://www.rfc-editor.org/info/rfc4494>.

   [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,
              <http://www.rfc-editor.org/info/rfc4656>.

   [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,
              <http://www.rfc-editor.org/info/rfc5357>.

   [RFC5644]  Stephan, E., Liang, L., and A. Morton, "IP Performance
              Metrics (IPPM): Spatial and Multicast", RFC 5644,
              DOI 10.17487/RFC5644, October 2009,
              <http://www.rfc-editor.org/info/rfc5644>.

   [RFC5835]  Morton, A., Ed. and S. Van den Berghe, Ed., "Framework for
              Metric Composition", RFC 5835, DOI 10.17487/RFC5835, April
              2010, <http://www.rfc-editor.org/info/rfc5835>.

   [RFC6282]  Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
              Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
              DOI 10.17487/RFC6282, September 2011,
              <http://www.rfc-editor.org/info/rfc6282>.

   [RFC6437]  Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme,
              "IPv6 Flow Label Specification", RFC 6437,
              DOI 10.17487/RFC6437, November 2011,
              <http://www.rfc-editor.org/info/rfc6437>.




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   [RFC6564]  Krishnan, S., Woodyatt, J., Kline, E., Hoagland, J., and
              M. Bhatia, "A Uniform Format for IPv6 Extension Headers",
              RFC 6564, DOI 10.17487/RFC6564, April 2012,
              <http://www.rfc-editor.org/info/rfc6564>.

   [RFC7045]  Carpenter, B. and S. Jiang, "Transmission and Processing
              of IPv6 Extension Headers", RFC 7045,
              DOI 10.17487/RFC7045, December 2013,
              <http://www.rfc-editor.org/info/rfc7045>.

   [RFC7312]  Fabini, J. and A. Morton, "Advanced Stream and Sampling
              Framework for IP Performance Metrics (IPPM)", RFC 7312,
              DOI 10.17487/RFC7312, August 2014,
              <http://www.rfc-editor.org/info/rfc7312>.

9.2.  Informative References

   [MCDC]     Fabini, J. and T. Zseby, "M2M communication delay
              challenges: Application and measurement perspectives",
              IEEE International Instrumentation and Measurement
              Technology Conference (I2MTC 2015) doi:
              10.1109/I2MTC.2015.7151564, May 2015.

   [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,
              <http://www.rfc-editor.org/info/rfc7594>.

Authors' Addresses

   Joachim Fabini
   TU Wien
   Gusshausstrasse 25/E389
   Vienna  1040
   Austria

   Phone: +43 1 58801 38813
   Fax:   +43 1 58801 38898
   Email: Joachim.Fabini@tuwien.ac.at
   URI:   http://www.tc.tuwien.ac.at/about-us/staff/joachim-fabini/










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

   Phone: +1 732 420 1571
   Fax:   +1 732 368 1192
   Email: acmorton@att.com
   URI:   http://home.comcast.net/~acmacm/









































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