wdiff rfc6985.original rfc6985.txt

Network Working Group
Internet Engineering Task Force (IETF) A. Morton
Internet-Draft
Request for Comments: 6985 AT&T Labs
Intended status:
Category: Informational June 3, 2013
Expires: December 5, July 2013
ISSN: 2070-1721

IMIX Genome: Specification of variable packet sizes Variable Packet Sizes
for additional
testing
draft-ietf-bmwg-imix-genome-05 Additional Testing

Abstract

Benchmarking Methodologies 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 a 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". "IMIX"
("Internet Mix"). 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 known, and
the tester may be asked to augment the fixed size fixed-size tests. To address
this need, need and the perpetual goal of specifying repeatable test
conditions, this draft document defines a way to specify the exact
repeating sequence of packet sizes from the usual set of fixed sizes, sizes
and from other forms of mixed size 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 This Memo

This Internet-Draft document is submitted in full conformance with the
provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents not an Internet Standards Track specification; it is
published for informational purposes.

This document is a product of the Internet Engineering Task Force
(IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list It represents the consensus of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a maximum candidate for any level of Internet
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This Internet-Draft will expire on December 5, 2013.
http://www.rfc-editor.org/info/rfc6985.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 ....................................................2
2. Requirements Language ...........................................3
3. Scope and Goals . . . . . . . . . . . . . . . . . . . . . . . 4
3. .................................................3
4. Specification of the IMIX Genome . . . . . . . . . . . . . . . 5
4. ................................4
5. Specification of a Custom IMIX . . . . . . . . . . . . . . . . 7
5. ..................................6
6. Reporting Long or Pseudo-Random Pseudorandom Packet Sequences . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 .................7
6.1. Run-Length Encoding ........................................7
6.2. Table of Proportions .......................................7
6.3. Deterministic Algorithm ....................................7
6.4. Pseudorandom Length Algorithm ..............................8
6.5. Pseudorandom Sequence Algorithm ............................8
7. IANA Security Considerations . . . . . . . . . . . . . . . . . . . . . 9 .........................................8
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 ................................................8
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 ......................................................9
9.1. Normative References . . . . . . . . . . . . . . . . . . . 9 .......................................9
9.2. Informative References . . . . . . . . . . . . . . . . . . 10
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10 .....................................9

1. Introduction

This memo defines a method to unambiguously specify the sequence of
packet sizes used in a load test.

Benchmarking Methodologies 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 bit-processing capacity. Tests
with sizes in-between 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], [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 known, and the tester may be asked
to augment the fixed size 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 packet-size information on private
networks.

To address this need, 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 packet-size
sequence can be replicated if this information is known, 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 result; thus, a standardized specification of sequence is
valuable.

2. Requirements Language

3. 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
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, IMIX -- and certainly no ability to extrapolate
results to other circumstances. circumstances -- even when the mix varies only
slightly from another IMIX.

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 pseudorandom 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]. BMWG
mailing list [IMIXonList]. The goal is to enable customization with
minimal constraints while fostering repeatable testing once the fixed size
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.

4. 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).
and 16000 bytes). Note that the 4 octet 4-octet Ethernet frame check
sequence may fail to detect bit errors in the larger jumbo frames, see [jumbo].

+-------------+--------------------+ frames
[Jumbo1] [Jumbo2].

+--------------+--------------------+
| Size, bytes 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: example, a five packet 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 Packet sizes not defined by RFC 2544 would need to be approximated
by those available in the table.

o The Genome 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 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 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:

+------------------------+--------------------------+---------------+

where testers can specify the IMIX used between any two entities in
the test architecture (and Blade "Blade" is a component in a multi-component multi-
component device chassis).

5. Specification of a Custom IMIX

This section describes how to specify an IMIX with locally-selected locally selected
packet sizes sizes.

The Custom 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 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: example, a five packet five-packet sequence with sizes
aaa=64,aaa=64,aaa=64,ggg=1020,ggg=1020 would be designated:

CUSTOM IMIX - AAAGG

6. Reporting Long or Pseudo-Random Pseudorandom Packet Sequences

When the IMIX-Genome IMIX Genome cannot be used (when the sheer length of the
sequence would make the Genome genome unmanageable), two five options are
possible.
possible, as noted in the following subsections.

6.1. Run-Length Encoding

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): Section 4):

+------------------------------+----------------------+
| Count of Repeating Sequences | Packet Size Packet-Size Sequence |
+------------------------------+----------------------+
| 20 | abcd |
| 5 | ggga |
| 10 | dcba |
+------------------------------+----------------------+

The run-length encoding approach is also applicable to the custom
IMIX as described in section 4 Section 5 (where the single upper-case letter
Genome Codes would be used instead).

6.2. Table of Proportions

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 Other Layers |
+-----------+---------------------+---------------------------+
| 64 | 23 | 82 |
| 128 | 67 | 146 |
| 1000 | 10 | 1018 |
+-----------+---------------------+---------------------------+

Note that the table of proportions also allows non-standard packet
sizes,
sizes but trades the short Genome genome specification and ability to
specify the exact sequence for other flexibilities.

6.3. Deterministic Algorithm

If a deterministic packet size packet-size generation method is used (such as a
monotonic increase by one 1 octet from start value to MTU), then the
generation algorithm SHOULD be reported.

6.4. Pseudorandom Length Algorithm

If a pseudo-random pseudorandom 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 pseudorandom generation algorithms and seeds
SHOULD be reported when used.

6.5. Pseudorandom Sequence Algorithm

Finally, we note another possibility: a pseudo-random pseudorandom sequence
generates an index to the table of packet lengths, and the generation
algorithm SHOULD be reported with the results results, along with the seed
value if used.

7. 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, 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. Device Under Test
(DUT) or System Under Test (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
run-length encoding approach in Section 5. 6.1.

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
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, Agilent, "The Journal of Internet Test Methodologies", 2007.
September 2007, <http://www.ixiacom.com/pdfs/test_plans/
agilent_journal_of_internet_test_methodologies.pdf>.

[IMIXonList]
http://www.ietf.org/mail-archive/web/bmwg/current/
msg00691.html,
IETF Benchmarking Methodology Working Group, "Discussion
on IMIX", 2003. October 2003, <http://www.ietf.org/mail-archive/
web/bmwg/current/msg00691.html>.

[IXIA] http://www.ixiacom.com/library/test_plans/
display?skey=testing_pppox, "Library: Test Plans", 2010. IXIA, "Testing PPPoX and L2TP Broadband Access Devices",
2004, <http://www.ixiacom.com/library/test_plans/
display?skey=testing_pppox>.

[Jumbo1] Dykstra, P., "Gigabit Ethernet Jumbo Frames, and why you
should care", WareOnEarth Communications, Inc., December
1999, <http://sd.wareonearth.com/~phil/jumbo.html>.

[Jumbo2] Mathis, M., "The Ethernet CRC limits packets to about
12 kBytes. (NOT)", Pittsburgh Supercomputing Center,
April 2003,
<http://staff.psc.edu/mathis/MTU/arguments.html#crc>.

[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, Spirent, "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". January 2006, <http://gospirent.com/whitepaper/
IMIX%20Test%20Methodolgy%20Journal.pdf>.

Author's Address

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

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