Internet DRAFT - draft-ietf-bmwg-imix-genome
draft-ietf-bmwg-imix-genome
Network Working Group A. Morton
Internet-Draft AT&T Labs
Intended status: Informational June 3, 2013
Expires: December 5, 2013
IMIX Genome: Specification of variable packet sizes for additional
testing
draft-ietf-bmwg-imix-genome-05
Abstract
Benchmarking Methodologies have always relied on test conditions with
constant packet sizes, with the goal of understanding what network
device capability has been tested. Tests with constant packet size
reveal device capabilities but differ significantly from the
conditions encountered in operational deployment, and so additional
tests are sometimes conducted with a mixture of packet sizes, or
"IMIX". The mixture of sizes a networking device will encounter is
highly variable and depends on many factors. An IMIX suited for one
networking device and deployment will not be appropriate for another.
However, the mix of sizes may be known and the tester may be asked to
augment the fixed size tests. To address this need, and the
perpetual goal of specifying repeatable test conditions, this draft
defines a way to specify the exact repeating sequence of packet sizes
from the usual set of fixed sizes, and other forms of mixed size
specification.
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
time. It is inappropriate to use Internet-Drafts as reference
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 5, 2013.
Copyright Notice
Copyright (c) 2013 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Scope and Goals . . . . . . . . . . . . . . . . . . . . . . . 4
3. Specification of the IMIX Genome . . . . . . . . . . . . . . . 5
4. Specification of a Custom IMIX . . . . . . . . . . . . . . . . 7
5. Reporting Long or Pseudo-Random Packet Sequences . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.1. Normative References . . . . . . . . . . . . . . . . . . . 9
9.2. Informative References . . . . . . . . . . . . . . . . . . 10
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10
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1. Introduction
This memo defines a method to unambiguously specify the sequence of
packet sizes used in a load test.
Benchmarking Methodologies [RFC2544] have always relied on test
conditions with constant packet sizes, with the goal of understanding
what network device capability has been tested. Tests with the
smallest size stress the header processing capacity, and tests with
the largest size stress the overall bit processing capacity. Tests
with sizes in-between may determine the transition between these two
capacities.
Streams of constant packet size differ significantly from the
conditions encountered in operational deployment, and so additional
tests are sometimes conducted with a mixture of packet sizes. The
set of sizes used is often called an Internet Mix, or "IMIX"
[Spirent], [IXIA], [Agilent].
The mixture of sizes a networking device will encounter is highly
variable and depends on many factors. An IMIX suited for one
networking device and deployment will not be appropriate for another.
However, the mix of sizes may be known and the tester may be asked to
augment the fixed size tests. The references above cite the original
studies and their methodologies. Similar methods can be used to
determine new size mixes present on a link or network. We note that
the architecture for IP Flow Information Export [RFC5470] provides
one method to gather packet size information on private networks.
To address this need, and the perpetual goal of specifying repeatable
test conditions, this memo proposes a way to specify the exact
repeating sequence of packet sizes from the usual set of fixed sizes:
the IMIX Genome. Other, less exact forms of size specification are
also recommended for extremely complicated or customized size mixes.
We apply the term "genome" to infer that the entire test packet size
sequence can be replicated if this information is known, a parallel
to the information needed for biological replication.
This memo takes the position that it cannot be proven for all
circumstances that the sequence of packet sizes does not affect the
test result, thus a standardized specification of sequence is
valuable.
2. Scope and Goals
This memo defines a method to unambiguously specify the sequence of
packet sizes that have been used in a load test, assuming that a
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relevant mix of sizes is known to the tester and the length of the
repeating sequence is not very long (<100 packets).
The IMIX Genome will allow an exact sequence of packet sizes to be
communicated as a single-line name, resolving the current ambiguity
with results that simply refer to "IMIX". This aspect is critical
because no ability has been demonstrated to extrapolate results from
one IMIX to another IMIX, even when the mix varies only slightly from
another IMIX, and certainly no ability to extrapolate results to
other circumstances.
While documentation of the exact sequence is ideal, the memo also
covers the case where the sequence of sizes is very long or may be
generated by a pseudo-random process.
It is a colossal non-goal to standardize one or more versions of the
IMIX. This topic has been discussed on many occasions on the bmwg-
list[IMIXonList]. The goal is to enable customization with minimal
constraints while fostering repeatable testing once the fixed size
testing is complete. Thus, the requirements presented in this
specification, expressed in [RFC2119] terms, are intended for those
performing/reporting laboratory tests to improve clarity and
repeatability.
3. Specification of the IMIX Genome
The IMIX Genome is specified in the following format:
IMIX - 123456...x
where each number is replaced by the letter corresponding to the size
of the packet at that position in the sequence. The following table
gives the letter encoding for the [RFC2544] standard sizes (64, 128,
256, 512, 1024, 1280, and 1518 bytes) and "jumbo" sizes (2112, 9000,
16000). Note that the 4 octet Ethernet frame check sequence may fail
to detect bit errors in the larger jumbo frames, see [jumbo].
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+-------------+--------------------+
| Size, bytes | Genome Code Letter |
+-------------+--------------------+
| 64 | a |
| 128 | b |
| 256 | c |
| 512 | d |
| 1024 | e |
| 1280 | f |
| 1518 | g |
| 2112 | h |
| 9000 | i |
| 16000 | j |
| MTU | z |
+-------------+--------------------+
For example: a five packet sequence with sizes 64,64,64,1280,1518
would be designated:
IMIX - aaafg
If z (MTU) is used, the tester MUST specify the length of the MTU in
the report.
While this approach allows some flexibility, there are also
constraints.
o Non-RFC2544 packet sizes would need to be approximated by those
available in the table.
o The Genome for very long sequences can become undecipherable by
humans.
Some questions testers must ask and answer when using the IMIX Genome
are:
1. Multiple Source-Destination Address Pairs: is the IMIX sequence
applicable to each pair, across multiple pairs in sets, or across
all pairs?
2. Multiple Tester Ports: is the IMIX sequence applicable to each
port, across multiple ports in sets, or across all ports?
The chosen configuration would be expressed in the following general
form:
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+------------------------+--------------------------+---------------+
| Source Address + Port | Destination Address + | Corresponding |
| AND/OR Blade | Port AND/OR Blade | IMIX |
+------------------------+--------------------------+---------------+
| x.x.x.x Blade2 | y.y.y.y Blade3 | IMIX - aaafg |
+------------------------+--------------------------+---------------+
where testers can specify the IMIX used between any two entities in
the test architecture (and Blade is a component in a multi-component
device chassis).
4. Specification of a Custom IMIX
This section describes how to specify an IMIX with locally-selected
packet sizes
The Custom IMIX is specified in the following format:
CUSTOM IMIX - 123456...x
where each number is replaced by the letter corresponding to the size
of the packet at that position in the sequence. The tester MUST
complete the following table, giving the letter encoding for each
size used, where each set of three lower-case letters would be
replaced by the integer size in octets.
+-------------+--------------------+
| Size, bytes | Custom Code Letter |
+-------------+--------------------+
| aaa | A |
| bbb | B |
| ccc | C |
| ddd | D |
| eee | E |
| fff | F |
| ggg | G |
| etc. | up to Z |
+-------------+--------------------+
For example: a five packet sequence with sizes
aaa=64,aaa=64,aaa=64,ggg=1020,ggg=1020 would be designated:
CUSTOM IMIX - AAAGG
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5. Reporting Long or Pseudo-Random Packet Sequences
When the IMIX-Genome cannot be used (when the sheer length of the
sequence would make the Genome unmanageable), two options are
possible. When a sequence can be decomposed into a series of short
repeating sequences, then a run-length encoding approach MAY be
specified as shown in the table below (using the single lower-case
letter Genome Codes from section 3):
+------------------------------+----------------------+
| Count of Repeating Sequences | Packet Size Sequence |
+------------------------------+----------------------+
| 20 | abcd |
| 5 | ggga |
| 10 | dcba |
+------------------------------+----------------------+
The run-length encoding approach is also applicable to custom IMIX
described in section 4 (where the single upper-case letter Genome
Codes would be used instead).
When the sequence is designed to vary within some proportional
constraints, a table simply giving the proportions of each size MAY
be used instead.
+-----------+---------------------+---------------------------+
| IP Length | Percentage of Total | Length(s) at other layers |
+-----------+---------------------+---------------------------+
| 64 | 23 | 82 |
| 128 | 67 | 146 |
| 1000 | 10 | 1018 |
+-----------+---------------------+---------------------------+
Note that the table of proportions also allows non-standard packet
sizes, but trades the short Genome specification and ability to
specify the exact sequence for other flexibilities.
If a deterministic packet size generation method is used (such as
monotonic increase by one octet from start value to MTU), then the
generation algorithm SHOULD be reported.
If a pseudo-random length generation capability is used, then the
generation algorithm SHOULD be reported with the results along with
the seed value used. We also recognize the opportunity to randomize
inter-packet spacing from a test sender as well as the size, and both
spacing and length pseudo-random generation algorithms and seeds
SHOULD be reported when used.
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Finally, we note another possibility: a pseudo-random sequence
generates an index to the table of packet lengths, and the generation
algorithm SHOULD be reported with the results along with the seed
value if used.
6. Security Considerations
Benchmarking activities as described in this memo are limited to
technology characterization using controlled stimuli in a laboratory
environment, with dedicated address space and the other constraints
[RFC2544].
The benchmarking network topology will be an independent test setup
and MUST NOT be connected to devices that may forward the test
traffic into a production network, or misroute traffic to the test
management network.
Further, benchmarking is performed on a "black-box" basis, relying
solely on measurements observable external to the DUT/SUT.
Special capabilities SHOULD NOT exist in the DUT/SUT specifically for
benchmarking purposes. Any implications for network security arising
from the DUT/SUT SHOULD be identical in the lab and in production
networks.
7. IANA Considerations
This memo makes no requests of IANA, and hopes that IANA will leave
it alone as well.
8. Acknowledgements
Thanks to Sarah Banks, Aamer Akhter, Steve Maxwell, and Scott Bradner
for their reviews and comments. Ilya Varlashkin suggested the run-
length coding approach in Section 5.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2544] Bradner, S. and J. McQuaid, "Benchmarking Methodology for
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Network Interconnect Devices", RFC 2544, March 1999.
9.2. Informative References
[Agilent] http://www.ixiacom.com/pdfs/test_plans/
agilent_journal_of_internet_test_methodologies.pdf, "The
Journal of Internet Test Methodologies", 2007.
[IMIXonList]
http://www.ietf.org/mail-archive/web/bmwg/current/
msg00691.html, "Discussion on IMIX", 2003.
[IXIA] http://www.ixiacom.com/library/test_plans/
display?skey=testing_pppox, "Library: Test Plans", 2010.
[RFC5470] Sadasivan, G., Brownlee, N., Claise, B., and J. Quittek,
"Architecture for IP Flow Information Export", RFC 5470,
March 2009.
[Spirent] http://gospirent.com/whitepaper/
IMIX%20Test%20Methodolgy%20Journal.pdf, "Test Methodology
Journal: IMIX (Internet Mix) Journal", 2006.
[jumbo] http://sd.wareonearth.com/~phil/jumbo.html and
http://staff.psc.edu/mathis/MTU/arguments.html#crc,
"Discussion of Jumbo Packets and FCS Failure".
Author's Address
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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