Internet DRAFT - draft-morton-ippm-2330-stdform-typep
draft-morton-ippm-2330-stdform-typep
Network Working Group A. Morton
Internet-Draft AT&T Labs
Updates: 2330 (if approved) J. Fabini
Intended status: Informational TU Wien
Expires: June 13, 2016 N. Elkins
Inside Products, Inc.
M. Ackermann
Blue Cross Blue Shield of Michigan
V. Hegde
Consultant
December 11, 2015
IP Options and IPv6 Updates for IPPM's Active Metric Framework: Packets
of Type-P and Standard-Formed Packets
draft-morton-ippm-2330-stdform-typep-02
Abstract
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
2330.
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",
"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
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
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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 June 13, 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Packets of Type-P . . . . . . . . . . . . . . . . . . . . . . 3
4. Standard-Formed Packets . . . . . . . . . . . . . . . . . . . 5
5. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.1. Normative References . . . . . . . . . . . . . . . . . . 8
9.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
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 Network Address Translator (NAT) on the path can have unpredictable
impact on latency measurement (in terms of the amount of additional
time added), and possibly other types of measurements. It is not
usually possible to control this impact (as testers may not have any
control of the underlying network or middleboxes). There is a
possibility that stateful NAT will lead to unstable performance for a
flow with specific Type-P, since state needs to be created for the
first packet of a flow, and state may be lost later if the NAT runs
out of resources. However, this scenario does not invalidate the
Type-P for testing. The presence of NAT may mean that the measured
performance of Type-P will change between the source and the
destination. This can cause an issue when attempting to correlate
measurements conducted on segments of the path that include or
exclude the NAT. Thus, it is a factor to be aware of when conducting
measurements.
A closely related note: it would be very useful to know if a given
Internet component (like host, link, or path) 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.
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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
criteria:
+ It includes a valid IP header: see below for version-specific
criteria.
+ 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.
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
correct.
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.
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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
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-
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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.)
When defining IP metrics we keep in mind that no packet smaller or
simpler than this can be transmitted over a correctly operating IP
network.
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 [RFC7594],
which covers active and passive techniques.
7. IANA Considerations
This memo makes no requests of IANA.
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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,
<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>.
[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>.
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[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>.
[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>.
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9.2. Informative References
[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
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/
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/
Nalini Elkins
Inside Products, Inc.
Carmel Valley, CA 93924
USA
Email: nalini.elkins@insidethestack.com
Michael S. Ackermann
Blue Cross Blue Shield of Michigan
Email: mackermann@bcbsm.com
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Vinayak Hegde
Consultant
Brahma Sun City, Wadgaon-Sheri
Pune, Maharashtra 411014
INDIA
Phone: +91 9449834401
Email: vinayakh@gmail.com
URI: http://www.vinayakhegde.com
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