Network Working Group                                          A. Morton
Internet-Draft                                                 AT&T Labs
Updates: 2330 (if approved)                                    J. Fabini
Intended status: Informational                                   TU Wien
Expires: February 7, 2016                                      N. Elkins
                                                   Inside Products, Inc.
                                                            M. Ackermann
                                      Blue Cross Blue Shield of Michigan
                                                                V. Hegde
                                                          August 6, 2015

   Updates for IPPM's Active Metric Framework: Packets of Type-P and
                        Standard-Formed Packets


   This memo updates the IP Performance Metrics (IPPM) Framework RFC
   2330 with new considerations for measurement methodology and testing.
   The memo updates the definition of standard-formed packets in RFC
   2330 to include IPv6 packets.  It also augments distinguishing
   aspects of packets, referred to as Type-P for test packets in RFC

   Two points (at least) are worthwhile discussing further: extent of
   coverage for 6LO and IPv6 Header Compression, and the continued need
   to define a "minimal standard-formed packet".

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any

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   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 February 7, 2016.

Copyright Notice

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

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   ( in effect on the date of
   publication of this document.  Please review these documents
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Packets of Type-P . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Standard-Formed Packets . . . . . . . . . . . . . . . . . . .   4
   5.  Conclusions . . . . . . . . . . . . . . . . . . . . . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   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].

   The IPPM framework [RFC2330] recognized (in section 13) that many
   aspects of IP packets can influence its processing during transfer
   across the network.

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   In Section 15 of [RFC2330], the notion of a "standard-formed" packet
   is defined.  However, the definition was never updated to include
   IPv6, as the original authors planned.

   In particular, IPv6 Extension Headers and protocols which use IPv6
   header compression are growing in use.  This memo seeks to provide
   the needed updates.

2.  Scope

   The purpose of this memo is to expand the coverage of IPPM metrics to
   include IPv6, and to highlight additional aspects of test packets and
   make them part of the IPPM performance metric framework.

   The scope is to update key sections of [RFC2330], adding
   considerations that will aid the development of new measurement
   methodologies intended for today's IP networks.  Specifically, this
   memo expands the Type-P examples in section 13 of [RFC2330] and
   expands the definition (in section 15 of [RFC2330]) of a standard-
   formed packet to include IPv6 header aspects and other features.

   Other topics in [RFC2330] which might be updated or augmented are
   deferred to future work.  This includes the topics of passive and
   various forms of hybrid active/passive measurements.

3.  Packets of Type-P

   A fundamental property of many Internet metrics is that the measured
   value of the metric depends on characteristics of the IP packet(s)
   used to make the measurement.  Potential influencing factors include
   IP header fields and their values, but also higher-layer protocol
   headers and their values.  Consider an IP-connectivity metric: one
   obtains different results depending on whether one is interested in
   connectivity for packets destined for well-known TCP ports or
   unreserved UDP ports, or those with invalid IPv4 checksums, or those
   with TTL or Hop Limit of 16, for example.  In some circumstances
   these distinctions will result in special treatment of packets in
   intermediate nodes and end systems (for example, if Diffserv
   [RFC2780], ECN [RFC3168], Router Alert, Hop-by-hop extensions
   [RFC7045], or Flow Labels [RFC6437] are used, or in the presence of
   firewalls or RSVP reservations).

   Because of this distinction, we introduce the generic notion of a
   "packet of Type-P", where in some contexts P will be explicitly
   defined (i.e., exactly what type of packet we mean), partially
   defined (e.g., "with a payload of B octets"), or left generic.  Thus
   we may talk about generic IP-Type-P-connectivity or more specific IP-
   port-HTTP-connectivity.  Some metrics and methodologies may be

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   fruitfully defined using generic Type-P definitions which are then
   made specific when performing actual measurements.

   Whenever a metric's value depends on the type of the packets involved
   in the metric, the metric's name will include either a specific type
   or a phrase such as "Type-P".  Thus we will not define an "IP-
   connectivity" metric but instead an "IP-Type-P-connectivity" metric
   and/or perhaps an "IP-port-HTTP-connectivity" metric.  This naming
   convention serves as an important reminder that one must be conscious
   of the exact type of traffic being measured.

   If the information constituting Type-P at the Source is found to have
   changed at the Destination (or at a measurement point between the
   Source and Destination, as in [RFC5644]), then the modified values
   SHOULD be noted and reported with the results.  Some modifications
   occur according to the conditions encountered in transit (such as
   congestion notification) or due to the requirements of segments of
   the Source to Destination path.  For example, the packet length will
   change if IP headers are converted to the alternate version/address
   family, or if optional Extension Headers are added or removed.  Local
   policies in intermediate nodes based on examination of IPv6 Extension
   Headers may affect measurement repeatability.  If intermediate nodes
   follow the recommendations of [RFC7045], repeatability may be
   improved to some degree.

   A closely related note: it would be very useful to know if a given
   Internet component treats equally a class C of different types of
   packets.  If so, then any one of those types of packets can be used
   for subsequent measurement of the component.  This suggests we devise
   a metric or suite of metrics that attempt to determine C.

4.  Standard-Formed Packets

   Unless otherwise stated, all metric definitions that concern IP
   packets include an implicit assumption that the packet is *standard-
   formed*. A packet is standard-formed if it meets all of the following

   +  It includes a valid IP header: see below for version-specific

   +  It is not an IP fragment.

   +  The Source and Destination addresses correspond to the intended
      Source and Destination, including Multicast Destination addresses.

   +  If a transport header is present, it contains a valid checksum and
      other valid fields.

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   For an IPv4 ( [RFC0791] and updates) packet to be standard-formed,
   the following additional criteria are required:

   o  The version field is 4

   o  The Internet Header Length (IHL) value is >= 5; the checksum is

   o  Its total length as given in the IPv4 header corresponds to the
      size of the IPv4 header plus the size of the payload.

   o  Either the packet possesses sufficient TTL to travel from the
      Source to the Destination if the TTL is decremented by one at each
      hop, or it possesses the maximum TTL of 255.

   o  It does not contain IP options unless explicitly noted.

   For an IPv6 ([RFC2460] and updates) packet to be standard-formed, the
   following criteria are required:

   o  The version field is 6.

   o  Its total length corresponds to the size of the IPv6 header (40
      octets) plus the length of the payload (including Extension
      Headers) as given in the IPv6 header.

   o  Either the packet possesses sufficient Hop Count to travel from
      the Source to the Destination if the Hop Count is decremented by
      one at each hop, or it possesses the maximum Hop Count of 255.

   o  Either the packet does not contain IP Extension Headers, or it
      contains the correct number and type of headers as specified in
      the packet, and the headers appear in the standard-conforming
      order (Next Header).

   o  All parameters used in the header and Extension Headers are found
      in the IANA Registry of Internet Protocol Version 6 (IPv6)
      Parameters, partly specified in [RFC7045].

   Compressed IPv6 headers must be compliant with [RFC4494], as updated
   by [RFC6282], in order to be declared "standard-formed".

   The topic of IPv6 Extension Headers brings current controversies into
   focus as noted by [RFC6564] and [RFC7045].  The following additional
   considerations apply when IPv6 Extension Headers are present:

   o  Extension Header inspection: Some intermediate nodes may inspect
      Extension Headers or the entire IPv6 packet while in transit.  In

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      exceptional cases, they may drop the packet or route via a sub-
      optimal path, and measurements may be unreliable or unrepeatable.
      The packet (if it arrives) may be standard-formed, with a
      corresponding Type-P.

   o  Extension Header modification: In Hop-by-Hop headers, some TLV
      encoded options may be permitted to change at intermediate nodes
      while in transit.  The resulting packet may be standard-formed,
      with a corresponding Type-P.

   o  Extension Header insertion or deletion: It is possible that
      Extension Headers could be added to, or removed from the header
      chain.  The resulting packet may be standard-formed, with a
      corresponding Type-P.

   o  A change in packet length (from the corresponding packet observed
      at the Source) or header modification is a significant factor in
      Internet measurement, and requires a new Type-P to be reported.

   We further require that if a packet is described as having a "length
   of B octets", then 0 <= B <= 65535; and if B is the payload length in
   octets, then B <= (65535-IP header size in octets, including any
   Extension Headers).  The jumbograms defined in [RFC2675] are not
   covered by this length analysis.  In practice, the path MTU will
   restrict the length of standard-formed packets that can successfully
   traverse the path.

   So, for example, one might imagine defining an IP connectivity metric
   as "IP-type-P-connectivity for standard-formed packets with the IP
   Diffserv field set to 0", or, more succinctly, "IP-type-
   P-connectivity with the IP Diffserv Field set to 0", since standard-
   formed is already implied by convention.  Changing the contents of a
   field, such as the Diffserv Code Point, ECN bits, or Flow Label may
   have a profound affect on packet handling during transit, but does
   not affect a packet's status as standard-formed.

   A particular type of standard-formed packet often useful to consider
   is the "minimal IP packet from A to B" - this is an IP packet with
   the following properties:

   +  It is standard-formed.

   +  Its data payload is 0 octets.

   +  It contains no options or Extension Headers.

   (Note that we do not define its protocol field, as different values
   may lead to different treatment by the network.)

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   When defining IP metrics we keep in mind that no packet smaller or
   simpler than this can be transmitted over a correctly operating IP

5.  Conclusions

   This memo adds the key considerations for utilizing IPv6 in two
   critical conventions of the IPPM Framework.  It is RECOMMENDED to
   adopt these new considerations in measurements involving IPv6.

6.  Security Considerations

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

   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
   [I-D.ietf-lmap-framework], which covers active and passive

7.  IANA Considerations

   This memo makes no requests of IANA.

8.  Acknowledgements

   The authors thank Brian Carpenter for identifying the lack of IPv6
   coverage in IPPM's Framework, and for listing additional
   distinguishing factors for packets of Type-P.  Both Brian and Fred
   Baker discussed many of the interesting aspects of IPv6 with the co-
   authors, leading to a more solid first draft: thank you both.  Thanks
   to Bill Jouris for an editorial pass through the pre-00 text.

9.  References

9.1.  Normative References

   [RFC0791]  Postel, J., "Internet Protocol", STD 5, RFC 791,
              DOI 10.17487/RFC0791, September 1981,

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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

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

   [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
              December 1998, <>.

   [RFC2675]  Borman, D., Deering, S., and R. Hinden, "IPv6 Jumbograms",
              RFC 2675, DOI 10.17487/RFC2675, August 1999,

   [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,

   [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,

   [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,

   [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,

   [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,

   [RFC5644]  Stephan, E., Liang, L., and A. Morton, "IP Performance
              Metrics (IPPM): Spatial and Multicast", RFC 5644,
              DOI 10.17487/RFC5644, October 2009,

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   [RFC5835]  Morton, A., Ed. and S. Van den Berghe, Ed., "Framework for
              Metric Composition", RFC 5835, DOI 10.17487/RFC5835, April
              2010, <>.

   [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,

   [RFC6437]  Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme,
              "IPv6 Flow Label Specification", RFC 6437,
              DOI 10.17487/RFC6437, November 2011,

   [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,

   [RFC7045]  Carpenter, B. and S. Jiang, "Transmission and Processing
              of IPv6 Extension Headers", RFC 7045,
              DOI 10.17487/RFC7045, December 2013,

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

9.2.  Informative References

              Eardley, P., Morton, A., Bagnulo, M., Burbridge, T.,
              Aitken, P., and A. Akhter, "A framework for Large-Scale
              Measurement of Broadband Performance (LMAP)", draft-ietf-
              lmap-framework-14 (work in progress), April 2015.

Authors' Addresses

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

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

   Joachim Fabini
   TU Wien
   Gusshausstrasse 25/E389
   Vienna  1040

   Phone: +43 1 58801 38813
   Fax:   +43 1 58801 38898

   Nalini Elkins
   Inside Products, Inc.
   Carmel Valley, CA  93924


   Michael S. Ackermann
   Blue Cross Blue Shield of Michigan


   Vinayak Hegde


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