Internet DRAFT - draft-morton-ippm-capcity-metric-method
draft-morton-ippm-capcity-metric-method
Network Working Group A. Morton
Internet-Draft AT&T Labs
Updates: ???? (if approved) R. Geib
Intended status: Standards Track Deutsche Telekom
Expires: January 9, 2020 L. Ciavattone
AT&T Labs
July 8, 2019
Metrics and Methods for IP Capacity
draft-morton-ippm-capcity-metric-method-00
Abstract
This memo revisits the problem of Network Capacity metrics first
examined in RFC 5136. The memo specifies a more practical Maximum
IP-layer Capacity metric definition catering for measurement
purposes, and outlines the corresponding methods of measurement.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14[RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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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Drafts is at https://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
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 9, 2020.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Scope and Goals . . . . . . . . . . . . . . . . . . . . . . . 3
3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Metric Definitions . . . . . . . . . . . . . . . . . . . . . 4
4.1. Formal Name . . . . . . . . . . . . . . . . . . . . . . . 4
4.2. Parameters . . . . . . . . . . . . . . . . . . . . . . . 4
4.3. Metric Definitions . . . . . . . . . . . . . . . . . . . 5
4.4. Related Round-Trip Delay and Loss Definitions . . . . . . 7
4.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . 7
4.6. Reporting the Metric . . . . . . . . . . . . . . . . . . 8
5. Method of Measurement . . . . . . . . . . . . . . . . . . . . 8
5.1. Load Rate Adjustment Algorithm (from udpst) . . . . . . . 8
6. Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
10.1. Normative References . . . . . . . . . . . . . . . . . . 10
10.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
The IETF's efforts to define Network and Bulk Transport Capacity have
been chartered and progressed for over twenty years. Over that time,
the performance community has seen development of Informative
definitions in RFC 3148 for Framework for Bulk Transport Capacity
(BTC), RFC 5136 for Network Capacity and Maximum IP-layer Capacity,
and the Experimental metric definitions and methods in [RFC8337],
Model-Based Metrics for BTC.
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This memo recognizes the importance of a definition of a Maximum IP-
layer Capacity Metric at this time, a definition that is both
practical and effective for the performance community's needs,
including Internet users. The metric definition is intended for
Active Methods of Measurement [RFC7799], and a method of measurement
is included here.
The most direct active measurement of IP-layer Capacity would use IP
packets, but in practice a transport header is needed to traverse
address and port translators. UDP offeres the most direct assessment
possibility, and in the [copycat][copycat] measurement study to
investigate whether UDP is viable as a general Internet transport
protocol, the authors found that a high percentage of paths tested
support UDP transport. A number of liaisons have been exchanged on
this topic [ refs to ITU-T SG12, ETSI STQ, BBF liaisons ], discussing
the laboratory and field tests that support the UDP-based approach to
IP-layer Capacity measurement.
This memo also recognizes the many updates to the IP Performance
Metrics Framework [RFC2330] published over twenty years, and makes
use of [RFC7312] for Advanced Stream and Sampling Framework, and RFC
8468 [RFC8468]IPv4, IPv6, and IPv4-IPv6 Coexistence Updates.
NOTE: The text contains Author comments, in brackets [RG: , acm: ]
2. Scope and Goals
The scope of this memo is to define a metric and corresponding method
to unambiguously perform Active measurements of Maximum IP-Layer
Capacity.
The main goal is to harmonize the specified metric and method across
the industry, and this memo is the vehicle through which working
group (and eventually, IETF) consensus will be captured and
communicated to achieve broad agreement, and possibly changes in
other Standards Development Organizations (SDO).
A local goal is provide efficient test procedures where possible, and
to recommend reporting with additional interpretation of the results.
Also, to foster the development of protocol support for this metric
and method of measurement.
3. Motivation
As with any problem that has been worked for many years in various
SDOs without any special attempts at coordination, various solutions
for metrics and methods have emerged.
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There are five factors that have changed (or begun to change) in the
last 5 years, and the presence of any one of them on the path
requires features in the measurement design to account for the
changes:
1. Internet access is no longer the bottleneck for many users
2. Both speed and latency are important to user's satisfaction
3. UDP's growing role in Transport, in areas where TCP once
dominated.
4. Content and applications moving closer to users.
5. Possibly less traffic crossing ISP gateways in future.
4. Metric Definitions
This section sets requirements for the following components to
support the Maximum IP-layer Capacity Metric.
4.1. Formal Name
Type-P-Max-IP-Capacity, or informally called Maximum IP-layer
Capacity.
Note that Type-P depends on the chosen method.
4.2. Parameters
This section lists the REQUIRED input factors to specify a Route
metric.
o Src, the address of a host (such as the globally routable IP
address).
o Dst, the address of a host (such as the globally routable IP
address).
o i, the limit on the number of Hops a specific packet may visit as
it traverses from the host at Src to the host at Dst (such as the
TTL or Hop Limit).
o MaxHops, the maximum value of i used, (i=1,2,3,...MaxHops).
o T, the time at the start of measurement interval
o I, the duration of measurement interval
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o dt, the duration of N equal sub-intervals in I
o Ts, the host time of a transmitted test packet as measured at
MP(Src), meaning Measurement Point at the Source.
o Ta, the host time of a test packet's *arrival* as measured at
MP(Dst), assigned to packets that arrive within a "reasonable"
time (see parameter below).
o Tmax, a maximum waiting time for test packets to arrive at the
destination, set sufficiently long to disambiguate packets with
long delays from packets that are discarded (lost), such that the
distribution of one-way delay is not truncated.
o F, the number of different flows synthesized by the method.
o flow, the stream of packets with the same n-tuple of designated
header fields that (when held constant) result in identical
treatment in a multi-path decision (such as the decision taken in
load balancing). Note: The IPv6 flow label MAY be included in the
flow definition when routers have complied with [RFC6438]
guidelines at the Tunnel End Points (TEP), and the source of the
measurement is a TEP.
o Type-P, the complete description of the packets for which this
assessment applies (including the flow-defining fields). Note
that the UDP transport layer is one requirement specified below.
o PM, a list of fundamental metrics, such as loss, delay, and
reordering, and corresponding Target performance threshold. At
least one fundamental metric and Target performance threshold MUST
be supplied (such as One-way IP Packet Loss [RFC7680] equal to
zero).
4.3. Metric Definitions
This section defines the REQUIRED aspects of the measureable Maximum
IP-layer Capacity metric (unless otherwise indicated) for
measurements between specified Source and Destination hosts:
Define the IP-layer capacity, Maximum_C(T,I,PM), to be the maximum
number of IP-layer bits (including header and data fields) that can
be transmitted from the Src host and correctly received by the Dst
host during one contiguous sub-interval, dt in length, during the
interval [T, T+I], and where the packet count of that single sub-
interval dtn in [T, T+I] indicates the maximum number of IP-layer
bits n0[dtn-1,dtn] which was captured as part of all packet counts n
for all dt in [T, T+I]. The interval dt SHOULD be set to a natural
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number m so that T+I = T + m*dt with dtn - dtn-1 = dt and with 0 < n
<= m. Parameter PM represents the other performance metrics [see
section Related Round-Trip Delay and Loss Definitions below] and
their measurement results for the maximum IP-layer capacity. At
least one target performance threshold MUST be defined. If more than
one target performance threshold is defined, then the sub-interval
with maximum number of bits transmitted MUST meet all the target
performance thresholds.
[RG: this requires more explanation. Do you mean that all results
must hit the target performance level? Or is a one / two / k times
hit out of x trials [T, T+I] a criterium indicating that a target has
been reached? Or do you look for the maximum capacity without packet
loss and queuing or added RTD latency, respectively? acm: I think
I've clarified this in the text above... ]
Mathematically, this definition can be represented as:
max ( n0[dtn-1,dtn] )
[T,T+I]
Maximum_C(T,I,PM) = -------------------------
dt
where:
T T+I
_________________________________________
| | | | | | | | | | |
dtn=0 1 2 3 4 5 6 7 8 9 m=10
Equation for Maximum Capacity
and:
o n0 is the total number of IP-layer header and payload bits that
can be transmitted in Standard Formed packets from the Src host
and correctly received by the Dst host during one contiguous sub-
interval, dt in length, during the interval [T, T+I],
o Maximum _C(T,I,PM) corresponds to the maximum value of n0 measured
in any sub-interval ending at dtn (meaning T + n*dt), divided by
the constant length of all sub-intervals, dt.
o all sub-intervals SHOULD be of equal duration. Choosing dt as
non-overlapping consecutive time intervals allows for a simple
implementation. [RG: a sliding window of dt has its charme too,
why exclude it? acm: seems less practical for real-time feedback.]
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o [acm: I think this is a discussion point, not essential to the
definition] If traffic conditioning applies along a path for which
Maximum _C(T,I,PM) is to be determined, different values for dt
SHOULD be picked and measurements be executed during multiple
intervals [T, T+I]. Any single interval dt SHOULD be chosen so
that is an integer multiple of increasing values k times
serialisation delay of a path MTU at the physical interface speed
where traffic conditioning is expected. This should avoid taking
configured burst tolerance singletons as a valid Maximum
_C(T,I,PM) result.
o The bandwidth of the physical interface of the measurement device
must be higher than that of the interface whose Maximum _C(T,I,PM)
is to be measured.
In this definition, the m sub-intervals can be viewed as trials when
the Src host varies the transmitted packet rate, searching for the
maximum n0 that meets the PM criteria measured at the Dst host in a
test of duration, I. When the transmitted packet rate is held
constant at the Src host, the m sub-intervals may also be viewed as
trials to evaluate the stability of n0 and metric(s) in the PM list
over all dt-length intervals in I.
Measurements according to these definitions SHALL use UDP transport
layer. [RG: don't we need loss free transmission without added
latency as criteria and add that UDP without closed loop flow control
needs to be applied ? acm: I don't think we should require loss-free
transmission, because most networks allow a small loss ratio which
would likely appear to be zero loss in most trials. Methods may use
feedback, let's talk about how to diffentiate from flow-control]
4.4. Related Round-Trip Delay and Loss Definitions
RTD[dtn-1,dtn] is defined as a sample of the [RFC2681] Round-trip
Delay between the Src host and the Dst host over the interval
[T,T+I]. The statistics used to to summarize RTD[dtn-1,dtn] MAY
include the minimum, maximum, and mean.
RTL[dtn-1,dtn] is defined as a sample of the [RFC6673] Round-trip
Loss between the Src host and the Dst host over the interval [T,T+I].
The statistics used to to summarize RTL[dtn-1,dtn] MAY include the
lost packet count and the lost packet ratio.
4.5. Discussion
Depending on the
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4.6. Reporting the Metric
@@@@ not yet addressed,
5. Method of Measurement
This section needs development, based on Annex A of Y.1540.
The duration of a test, I, MUST be constrained in a production
network, since this is an active test method and it will likely cause
congestion on the Src to Dst host path during a test.
Additional Test methods and configurations may be provided in this
section, after review.
5.1. Load Rate Adjustment Algorithm (from udpst)
A table is pre-built defining all the offered load rates that will be
supported (R1 - Rn, in ascending order). Each rate is defined as
datagrams of size S, sent as a burst of count C, every time interval
T. While it is advantageous to use datagrams of as large a size as
possible, it may be prudent to use a slightly smaller maximum that
allows for secondary protocol headers and/or tunneling without
resulting in IP-layer fragmentation.
At the beginning of a test, the sender begins sending at rate R1 and
the receiver starts a feedback timer at interval F (while awaiting
inbound datagrams). As datagrams are received they are checked for
sequence number anomalies (loss, out-of-order, duplication, etc.) and
the delay variation is measured (one-way or round-trip). This
information is accumulated until the feedback timer F expires and a
status feedback message is sent from the receiver back to the sender,
to communicate this information. The accumulated statistics are then
reset by the receiver for the next feedback interval. As feedback
messages are received back at the sender, they are evaluated to
determine how to adjust the current offered load rate (Rx).
If the feedback indicates that there were no sequence number
anomalies AND the delay variation was below the lower threshold, the
offered load rate is increased. If congestion has not been confirmed
up to this point, the offered load rate is increased by more than one
rate (e.g., Rx+10). This allows the offered load to quickly reach a
near-maximum rate. Conversely, if congestion has been previously
confirmed, the offered load rate is only increased by one (Rx+1).
If the feedback indicates that sequence number anomalies were
detected OR the delay variation was above the upper threshold, the
offered load rate is decreased. If congestion has not been confirmed
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up to this point, the offered load rate is decreased by more than one
rate (e.g., Rx-30). This allows the offered load to back off enough
to compensate for the fast initial ramp-up. Conversely, if
congestion has been previously confirmed, the offered load rate is
only decreased by one (Rx-1).
If the feedback indicates that there were no sequence number
anomalies AND the delay variation was above the lower threshold, but
below the upper threshold, the offered load rate is not changed.
This allows time for recent changes in the offered load rate to
stabilize, and the feedback to represent current conditions more
accurately.
Lastly, the method for confirming congestion is that there were
sequence number anomalies OR the delay variation was above the upper
threshold for two consecutive feedback intervals.
6. Reporting
This section needs development...
The following text TO BE REPLACED !!!!
=======================================
The results SHOULD be reported in the format of a table with a row
for each of the tested frame sizes and Number of Flows. There SHOULD
be columns for the frame size with number of flows, and for the
resultant average frame count (or time) for each type of data stream
tested.
The number of tests Averaged for the Benchmark, N, MUST be reported.
The Minimum, Maximum, and Standard Deviation across all complete
tests SHOULD also be reported.
The Corrected DUT Restoration Time SHOULD also be reported, as
applicable.
+-------------------+-------------------+----------------+----------+
| Frame Size, | Max IP-Layer | Min,Ave,StdDev | Time dt, |
| octets + # Flows | Capacity, bps | | Sec |
+-------------------+-------------------+----------------+----------+
| 64,100 | 26000 | 25500,27000,20 | 0.00004 |
+-------------------+-------------------+----------------+----------+
Maximum IP-layer Capacity Results
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Static and configuration parameters:
Number of test repetitions, N
Minimum Step Size (during searches), in frames.
7. Security Considerations
Active metrics and measurements have a long history of security
considerations [add references to LMAP Framework, etc.].
<There are certainly some new ones for Capacity testing>
8. IANA Considerations
This memo makes no requests of IANA.
9. Acknowledgements
Thanks to
10. References
10.1. Normative References
[RFC1242] Bradner, S., "Benchmarking Terminology for Network
Interconnection Devices", RFC 1242, DOI 10.17487/RFC1242,
July 1991, <https://www.rfc-editor.org/info/rfc1242>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://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,
<https://www.rfc-editor.org/info/rfc2330>.
[RFC2544] Bradner, S. and J. McQuaid, "Benchmarking Methodology for
Network Interconnect Devices", RFC 2544,
DOI 10.17487/RFC2544, March 1999,
<https://www.rfc-editor.org/info/rfc2544>.
[RFC2681] Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip
Delay Metric for IPPM", RFC 2681, DOI 10.17487/RFC2681,
September 1999, <https://www.rfc-editor.org/info/rfc2681>.
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[RFC2889] Mandeville, R. and J. Perser, "Benchmarking Methodology
for LAN Switching Devices", RFC 2889,
DOI 10.17487/RFC2889, August 2000,
<https://www.rfc-editor.org/info/rfc2889>.
[RFC5136] Chimento, P. and J. Ishac, "Defining Network Capacity",
RFC 5136, DOI 10.17487/RFC5136, February 2008,
<https://www.rfc-editor.org/info/rfc5136>.
[RFC5180] Popoviciu, C., Hamza, A., Van de Velde, G., and D.
Dugatkin, "IPv6 Benchmarking Methodology for Network
Interconnect Devices", RFC 5180, DOI 10.17487/RFC5180, May
2008, <https://www.rfc-editor.org/info/rfc5180>.
[RFC6201] Asati, R., Pignataro, C., Calabria, F., and C. Olvera,
"Device Reset Characterization", RFC 6201,
DOI 10.17487/RFC6201, March 2011,
<https://www.rfc-editor.org/info/rfc6201>.
[RFC6412] Poretsky, S., Imhoff, B., and K. Michielsen, "Terminology
for Benchmarking Link-State IGP Data-Plane Route
Convergence", RFC 6412, DOI 10.17487/RFC6412, November
2011, <https://www.rfc-editor.org/info/rfc6412>.
[RFC6438] Carpenter, B. and S. Amante, "Using the IPv6 Flow Label
for Equal Cost Multipath Routing and Link Aggregation in
Tunnels", RFC 6438, DOI 10.17487/RFC6438, November 2011,
<https://www.rfc-editor.org/info/rfc6438>.
[RFC6673] Morton, A., "Round-Trip Packet Loss Metrics", RFC 6673,
DOI 10.17487/RFC6673, August 2012,
<https://www.rfc-editor.org/info/rfc6673>.
[RFC6815] Bradner, S., Dubray, K., McQuaid, J., and A. Morton,
"Applicability Statement for RFC 2544: Use on Production
Networks Considered Harmful", RFC 6815,
DOI 10.17487/RFC6815, November 2012,
<https://www.rfc-editor.org/info/rfc6815>.
[RFC6985] Morton, A., "IMIX Genome: Specification of Variable Packet
Sizes for Additional Testing", RFC 6985,
DOI 10.17487/RFC6985, July 2013,
<https://www.rfc-editor.org/info/rfc6985>.
[RFC7312] Fabini, J. and A. Morton, "Advanced Stream and Sampling
Framework for IP Performance Metrics (IPPM)", RFC 7312,
DOI 10.17487/RFC7312, August 2014,
<https://www.rfc-editor.org/info/rfc7312>.
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[RFC7799] Morton, A., "Active and Passive Metrics and Methods (with
Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799,
May 2016, <https://www.rfc-editor.org/info/rfc7799>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8337] Mathis, M. and A. Morton, "Model-Based Metrics for Bulk
Transport Capacity", RFC 8337, DOI 10.17487/RFC8337, March
2018, <https://www.rfc-editor.org/info/rfc8337>.
[RFC8468] Morton, A., Fabini, J., Elkins, N., Ackermann, M., and V.
Hegde, "IPv4, IPv6, and IPv4-IPv6 Coexistence: Updates for
the IP Performance Metrics (IPPM) Framework", RFC 8468,
DOI 10.17487/RFC8468, November 2018,
<https://www.rfc-editor.org/info/rfc8468>.
10.2. Informative References
[copycat] Edleine, K., Kuhlewind, K., Trammell, B., and B. Donnet,
"copycat: Testing Differential Treatment of New Transport
Protocols in the Wild (ANRW '17)", July 2017,
<https://irtf.org/anrw/2017/anrw17-final5.pdf>.
[RFC8239] Avramov, L. and J. Rapp, "Data Center Benchmarking
Methodology", RFC 8239, DOI 10.17487/RFC8239, August 2017,
<https://www.rfc-editor.org/info/rfc8239>.
[TST009] Morton, R. A., "ETSI GS NFV-TST 009 V3.1.1 (2018-10),
"Network Functions Virtualisation (NFV) Release 3;
Testing; Specification of Networking Benchmarks and
Measurement Methods for NFVI"", October 2018,
<https://www.etsi.org/deliver/etsi_gs/NFV-
TST/001_099/009/03.01.01_60/gs_NFV-TST009v030101p.pdf>.
[VSPERF-b2b]
Morton, A., "Back2Back Testing Time Series (from CI)",
June 2017, <https://wiki.opnfv.org/display/vsperf/
Traffic+Generator+Testing#TrafficGeneratorTesting-
AppendixB:Back2BackTestingTimeSeries(fromCI)>.
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[VSPERF-BSLV]
Morton, A. and S. Rao, "Evolution of Repeatability in
Benchmarking: Fraser Plugfest (Summary for IETF BMWG)",
July 2018,
<https://datatracker.ietf.org/meeting/102/materials/
slides-102-bmwg-evolution-of-repeatability-in-
benchmarking-fraser-plugfest-summary-for-ietf-bmwg-00>.
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: acm@research.att.com
Ruediger Geib
Deutsche Telekom
Heinrich Hertz Str. 3-7
Darmstadt 64295
Germany
Phone: +49 6151 5812747
Email: Ruediger.Geib@telekom.de
Len Ciavattone
AT&T Labs
200 Laurel Avenue South
Middletown,, NJ 07748
USA
Email: lencia@att.com
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