Benchmarking Methodology Working Group                         V. Manral
Internet-Draft                                                 P. Sharma
Intended status: Informational                               S. Banerjee
Expires: September 13, 2013                                           HP
                                                                 Y. Ping
                                                                     H3C
                                                          March 12, 2013


             Benchmarking Power usage of networking devices
                    draft-manral-bmwg-power-usage-04

Abstract

   With the rapid growth of networks around the globe there is an ever
   increasing need to improve the energy efficiency of network devices.
   Operators are begining to seek more information of power consumption
   in the network, have no standard mechanism to measure, report and
   compare power usage of different networking equipment under different
   network configuration and conditions.

   This document provides suggestions for measuring power usage of live
   networks under different traffic loads and various switch router
   configuration settings.  It provides a benchmarking suite which can
   be employed for any networking device .

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
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 13, 2013.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   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
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   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 . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Challenges in defining benchmarks  . . . . . . . . . . . . . .  4
   3.  Factors impacting  power consumption . . . . . . . . . . . . .  6
     3.1.  Network Factors affecting power consumption  . . . . . . .  6
     3.2.  Device Factors affecting power consumption . . . . . . . .  6
     3.3.  Traffic Factors affecting power consumption  . . . . . . .  7
   4.  Network Energy Consumption Rate (NECR) . . . . . . . . . . . .  8
   5.  Network Energy Proportionality Index (NEPI)  . . . . . . . . .  9
   6.  Benchmark Details  . . . . . . . . . . . . . . . . . . . . . . 10
   7.  Benchmark Extensions . . . . . . . . . . . . . . . . . . . . . 11
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 13
   10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 15
     11.2. Informative References . . . . . . . . . . . . . . . . . . 15
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16





















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1.  Introduction

   Energy Efficiency is becoming increasingly important in the operation
   of network infrastructure.  Data traffic is exploding at an
   accelerated rate.  Networks provide communication channels that
   facilitate components of the infrastructue to exchange critical
   information and are always on.  On the other hand, a lot of devices
   run at very low average utlization rates.  Various strategies are
   being defined to improve network utilization of these devices and
   thus improve power consumption.

   The first step to obtain a network wide view of energy consumption is
   to start with an individual device view and address different devices
   in the network on a per device basis.  The easiest way to measure the
   power consumption of a device is to use a power meter.  This can be
   used to measure power under a variety of configurations and
   conditions affecting power usage on a networking device.

   Various techniques have been defined for energy management of
   networking devices.  However, there is no common mechanism to
   actually benchmark power utilization of networking devices like
   routers or switches.  This document defines the mechanism to
   correctly characterize and benchmark the power consumption of various
   networking devices so as to be able to correctly estimate and compare
   the power usage of various devices.  This will enable intelligent
   decisions to optimize the power consumption for individual devices
   and the network as a whole.  Benchmarks are also required to compare
   effectiveness of various energy optimization techniques.

   The Network Energy Consumption Rate (NECR) as well as Network Energy
   Proportionality Index (NEPI) of network devices are also defined
   here.

   The procedures/ metrics defined in this document have been used to
   perform live measurement with a variety of networking equipment from
   three large well known vendors.















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2.  Challenges in defining benchmarks

   Using the "Maximum Rated Power" and spec sheets of devices and adding
   the values for all devices are of little use because this value
   provides the maximum power that can consumed by the device, however
   that does not accurately reflect the actual power consumed by the
   device under a normal work load.  Typical energy requirements of a
   networking device are dependent on device configuration and traffic.

   The ratio of the actual power consumed by the device on an average,
   to its maximum rated power varies widely across different device
   families, configurations and traffic conditions.  Thus, relying
   merely on the maximum rated power can grossly overestimate the total
   energy consumed by networking equipment.

   There are a wide variety of networking equipment and finding a
   general benchmark to work across a variety of devices, requires a lot
   of flexibility in benchmarking methodology.  The benchmarking
   workload and test conditions will also depend on the kind of device.
   However, it is important to formualte a consistent framework to
   enable benchmarking across devices for comparison.

   A network device consists of a lot of individual component, each of
   which consume power.  For example, only considering the power
   consumption of the CPU/ data forwarding ASIC we may ignore the power
   consumption of the other components like external memory, fan etc..

   Power instrumentation of a device in a live network involves
   unplugging the device and plugging it into a power meter.  This can
   inturn lead to traffic loss.  Unfortunately, most current equipment
   is not equipped with internal instrumentation to report power usage
   of the device or its components.  It is for this reason the power
   measurement is done on an individual device under varied network
   conditions using a traffic generator.

   The network devices can also dissipate significant heat.  Past
   studies have shown dissipation ratios of 2.5.  Which means if the
   power in is 2.5 Watt, only 1 Watt is used for actual work, the rest
   is disspated as heat.  This heating can lead to more power consumed
   by fan/ compressor for cooling the devices.  Though this methodology
   does not measure the power consumed by external cooling
   infrastructure, it measures the power consumed internally.  The
   internal power consumption is the power drawn by the device as
   measured by the power-meter.  It also (optionally) measures the
   temperature change of the device which can be correlated to the
   amount of external power consumed to cool the device.

   The amount of power used at startup can be more than the average



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   power usage of the device.  This is also measured as part of the test
   methodology.

















































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3.  Factors impacting  power consumption

   The metrics defined here will help operators get a more accurate idea
   of power consumed by network equipment and hence forecast their power
   budget.  These will also help device vendors test and compare the new
   power efficiency enhancements on various devices.

3.1.  Network Factors affecting power consumption

   The first and the most important factor from the network perspective
   which can impact the power consumption is the offered traffic load.
   Power measurements must be performed with different offered traffic
   loads to the network device.

   There are now various kinds of transcivers/ connectors on a network
   device.  For the same bandwidth the power usage of a device depends
   on the kind of connector used.  The connector/ interface type used
   needs to be specified in the benchmark.

   The length of the cable used also defines the amount of power
   consumed by the system.  Benchmarks should specify the cable length
   used.  For example, a 5 meter cable can be used wherever possible.

3.2.  Device Factors affecting power consumption

   Base Chassis Power - typically, higher end network devices come with
   a chassis and linecard slots.  Each slot may have a number of ports.
   For the lower end devices there are no removable card slots.  In both
   these cases the base chassis power consists of processors, fans,
   memory, etc.

   Number and type of line cards - In switches that support inserting
   linecards, there is a limit on the number of ports per linecard as
   well as the aggregate bandwidth that each linecard can accommodate.
   This mechanism allows network operators the flexibility to only plug
   in as many linecards as they need.  For each benchmark the total
   number of line cards and their types plugged into the system needs to
   be varied and specified.

   Number of enabled ports - This term refers to the total number of
   ports on the switch (across all the linecards) that are
   administratively enabled.  When a port is enabled, the network device
   turns on the SerDes and additional electronic circuits required to
   activate the port.  The remaining ports on the switch are explicitly
   disabled using the switch's command line interface.  For each
   benchmark the number of enabled and disabled ports must be specified.

   Number of active ports - This term refers to the total number of



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   ports on the switch (across all the linecards) that are active (with
   cables plugged in).  The remaining ports on the switch are explicitly
   disabled using the switchs command line interface.  For each
   benchmark the number of active and inactive ports must be specified.

   Port settings - Setting this parameter limits the line rate
   forwarding capacity of individual ports.  For instance same port
   maybe configured to 1Gbps, 100Mbps or 10Mbps capacity.  For each
   benchmark the port configuration and settings need to be specified.

   Port Utilization - This term describes the actual traffic flowing
   through a port relative to its specified capacity.  For each
   benchmark the port utilization of each port must be specified.  The
   actual traffic can use the information defined in RFC 2544 [RFC2544].

   TCAM - Network vendors typically implement packet classification in
   hardware.  TCAMs are supported by most vendors as they have very fast
   look-up times.  However, they are are notoriously power-hungry.  The
   size of the TCAM in a switch is widely variable.  The size of the
   TCAM needs to be reported in the benchmark document.  The number of
   used TCAM entries might not significantly affect power consumption.

   Firmware - Vendors periodically release upgraded versions of their
   switch/router firmware.  Different versions of firmware may also
   impact the device power consumption.  The firmware version needs to
   be reported in the benchmark document.  Different firmware versions
   have resulted in different power usage.

3.3.  Traffic Factors affecting power consumption

   Packet Size - Different packet sizes typically do not effect power
   consumption.

   Inter-Packet Delay - time between successive packets may affect power
   usage but we do not measure the effects in detail.

   CPU traffic - Percentage of CPU traffic.  For our benchmarks we can
   assume different values of CPU bound traffic.  The different
   percentage of CPU bound traffic must be specified in the benchmark.












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4.  Network Energy Consumption Rate (NECR)

   To optimize the run time energy usage for different devices, the
   additional energy consumption that will result as a factor of
   additional traffic needs to be known.  The NECR defines the power
   usage increase in MilliWatts per Mbps of data at the physical layer.

   The NECR will depend on the line card, the port and the other factors
   defined earlier.

   For the effective use of the NECR the base power of the chassis, a
   line card and a port needs to be specified when there is no load.
   The measurements must take into consideration power optimization
   techniques when there is no traffic on any port of a line card.





































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5.  Network Energy Proportionality Index (NEPI)

   In the ideal case the power consumed by a device is proportional to
   its offered network load.  The average difference between the
   ideal(I) and the measured (M) power consumption defines the EPI.

   The ideal power is measured by assuming the power consumed by a
   device at 100% traffic load and using that to derive the ideal power
   usage for different traffic loads.

   EPIx = (Mx - Ix)/ Mx * 100

   EPI = EPI1 + EPI2 + .......  EPIn / n

   The EPI is independent of the actualy traffic load.  It can thus be
   used to define the energy efficiency of a networking device.  A value
   of 0 means the power usage is agnostic to traffic and a value of 100
   means that the device has perfect energy proportionality.

   Similarly NEPI can be computed for other configurations and varying
   conditions.  For instance, variating in network power consumption as
   increasing number of ports on the network switch are acitivated.





























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6.  Benchmark Details

   All power measurements are done in MilliWatts, except NECR which is
   done in MilliWatts/ Mbps.















































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7.  Benchmark Extensions

   The benchmark framework must to extensible to incorporate future
   changes in network device architectures.  For instances there is a
   new push towards adaptive management of device components such as
   fanspeed management etc.  Similarly, the benchmark should be
   extensible to include environmental factors such as operational
   temperature etc.











































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8.  Security Considerations

   This document raises no new security issues.
















































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9.  IANA Considerations

   No actions are required from IANA for this informational document.
















































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10.  Acknowledgements

   This document derives a lot of its text and content from "A Power
   Benchmarking Framework for Network Devices" paper and the authors of
   that are duly acknowledged.

   The authors would like to thank Srini Seetharaman -
   srini.seetharaman@telekom.com and Priya Mahadevan
   priya.mahadevan@hp.com for their support with the draft.  The authors
   would like to thank Al Morton - ATT and Robert Peglar- XioTech for
   his careful reading and suggestions on the draft.








































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11.  References

11.1.  Normative References

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

11.2.  Informative References

   [RFC2554]  Bradner, S., "Benchmarking Methodology for Network
              Interconnect Devices", March 1999.








































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Authors' Addresses

   Vishwas Manral
   Hewlett-Packard Co.
   3000 Hanover St.
   Palo Alto, CA  94304
   USA

   Email: vishwas.manral@hp.com


   Puneet Sharma
   Hewlett-Packard Co.
   3000 Hanover St.
   Palo Alto, CA  94304
   USA

   Email: puneet.sharma@hp.com


   Sujata Banerjee
   Hewlett-Packard Co.
   3000 Hanover St.
   Palo Alto, CA  94304
   USA

   Email: sujata.banerjee@hp.com


   Yang Ping
   H3C.
   TBD.
   Bejing, CO  12345
   China

   Email: yangpin@h3c.com















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