Internet-Draft PowerBench February 2024
Pignataro, et al. Expires 16 August 2024 [Page]
Workgroup:
Benchmarking Methodology Working Group
Internet-Draft:
draft-cprjgf-bmwg-powerbench-00
Published:
Intended Status:
Standards Track
Expires:
Authors:
C. Pignataro
NC State University
R. Jacob
ETH Zürich
G. Fioccola
Huawei

Characterization and Benchmarking Methodology for Power in Networking Devices

Abstract

This document defines a standard mechanism to measure, report, and compare power usage of different networking devices and under different network configurations and conditions.

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 https://datatracker.ietf.org/drafts/current/.

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This Internet-Draft will expire on 16 August 2024.

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Table of Contents

1. Introduction

Energy efficiency is becoming increasingly important in the operation of network infrastructure. Network devices are typically always on, but in some cases, they run at very low average utilization rates. Both network utilization and energy consumption of these devices can be improved, and that starts with a normalized characterization. The benchmarking methodology defined here will help operators to get a more accurate idea of the power drawn by their network and will also help vendors to test the energy efficiency of their devices.

There is no standard mechanism to benchmark the power utilization of networking devices like routers or switches. [I-D.manral-bmwg-power-usage] started to analyze the issue. This document defines the mechanism to correctly characterize and benchmark the energy consumption of networking devices to better estimate and compare their power usage.

1.1. Aim and Scope

Benchmarking can be understood to serve two related but different objectives:

The benchmarking methodology outlined in this draft focuses on the first objective. Specifically, it aims to compare the energy efficiency for individual devices (routers and switches belonging to similar device classes). The benchmark aims to showcase the effectiveness of various energy optimization techniques for a given device and load type, with the objective of fostering improvements in the energy efficiency of future generations of devices.

1.2. 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.

2. Terminology

2.1. Total Weighted Capacity of the interfaces

The total weighted capacity of the interfaces (T) is the weighted sum of all interface throughputs.

Definition:

  • T = B1*T1 +...+ Bi*Ti +...+ Bm*Tm

Discussion:

  • Ti is the total capacity of the interfaces for a fixed configuration model and traffic load (the sum of the interface bandwidths)

  • Bi is the weighted multiplier for different traffic levels (note that B1+...+Bj+...+Bm = 1)

  • m is the number of traffic load levels (if it is considered 100%, 30%, 0%; m = 3)

Measurement units:

Issues

  • The traffic loads and the weighted multipliers need to be clearly established a priori.

  • It is unclear if the definition of the Ti's is/should be linked to the traffic load levels. For a given port configuration (which may result in 50% of the total capacity a device can provide), one may be interested in traffic load of e.g., 5% or 10% or the total capacity (not only 50%).

See Also:

2.2. Total Weighted Power

The total weighted power (P) is the weighted sum of all power calculated for different traffic loads.

Definition:

  • P = B1*P1 +...+ Bi*Pi +...+ Bm*Pm

Discussion:

  • Pi is the Power of the equipment in each traffic load level (e.g. 100%, 30%, 0%)

  • Bi is the weighted multiplier for different traffic levels (note that B1+...+Bj+...+Bm = 1)

  • m is the number of traffic load levels (if it is considered 100%, 30%, 0%; m = 3)

Measurement units:

Issues:

  • The traffic loads and the weighted multipliers need to be clearly established a priori.

  • Importantly, the traffic must be forwarded of the correct port! It would be easy to cut power down by dropping all traffic, and we of course do not want that. A tolerance on packet loss and/or forwarding error must be specified somehow. That tolerance could be zero for some benchmark problems, and non-zero for others. Tolerating some errors may be interesting to navigate the design space of energy saving techniques, such as approximate computing/routing.

See Also:

2.3. Energy Efficiency Ratio

Energy Efficiency Ratio (EER) is defined as the throughput forwarded by 1 watt and it is introduced in [ETSI-ES-203-136]. A higher EER corresponds to a better the energy efficiency.

Definition:

  • EER = T/P

Discussion:

  • T is the total weighted sum of all interface throughputs

  • P is the weighted power for different traffic loads

Measurement units:

  • Gbps/Watt.

Issues:

  • The traffic loads and the weighted multipliers need to be clearly established a priori.

See Also:

3. Energy Consumption Benchmarking

The maximum power drawn by a device does not accurately reflect the power under a normal workload. Indeed, the energy consumption of a networking device depends on its configuration, connected transceivers, and traffic load. Relying merely on the maximum rated power can overestimate the total energy of the networking devices.

A network device consists of many components, each of which draws power (for example, it is possible to mention the power consumption of the CPU, data forwarding ASIC, memory, fan, etc.). Therefore, it is important to formulate a consistent benchmarking method for network devices and consider the workload variation and test conditions.

Enforcing controlled conditions on test conditions (e.g., temperature) may be impractical or unfeasible. At this stage it is unclear whether it is more useful for the benchmark to enforce controlled conditions (and if so, which ones) or only specifying how those conditions should be measured and reported.

4. Test Methodology

4.1. Test Setup

The test setup in general is compliant with [RFC2544]. The Device Under Test (DUT) is connected to a Tester and a Power Meter. The Power Meter allows to measure the energy consumption of the device and can be used to measure power under various configurations and conditions. Tests SHOULD be done with bidirectional traffic that better reflects the real environment. The Tester is also a traffic generator that enables changing traffic conditions. It is OPTIONAL to choose a non-equal proportion for upstream and downstream traffic.

        +----------+
+-------|  Tester  |<-------+
| +-----|          |<-----+ |
| |     +----------+      | |
| |                       | |
| |      +--------+       | |
| +----->|        |-------+ |
+------->|  DUT   |---------+
         |        |
         +--------+
             |
             |
        +----------+
        |  Power   |
        |  Meter   |
        +----------+
Figure 1: Test Setup

It is worth mentioning that the DUT also dissipates significant heat. That means that part of the power is used for actual work while the rest is dissipated as heat. This heating can lead to more power drawn by fans/ compressor for cooling the devices. The benchmarking methodology does not measure the power drawn by external cooling infrastructure. The Power Meter only measures the internal energy consumption of the device.

4.2. Traffic and Device Characterization

The traffic load supported by a device affects its energy consumption. Therefore, the benchmark MUST include different traffic loads.

There are different interface types on a network device and the power usage also depends on the kind of connector/transceiver used. The interface type used needs to be specified as well.

In addition, it is necessary to indicate the number of ports used per linecard as well as the aggregate bandwidth that each linecard can accommodate.

The traffic load must specify packet sizes, packet rates, and inter-packet delays, as all may affect the energy consumption of network devices.

5. Reporting Format

Network Device Hardware and Software versions:

For the benchmarking tests, it must be specified.
Number and type of line cards:

For each test the total number of line cards and their types can be varied and must be specified.
Number of enabled ports:

For each test the number of enabled and disabled ports must be specified.
Number of active ports:

For each test the number of active and inactive ports must be specified.
Port settings and interface types:

For each test the port configuration and settings need to be specified.
Port Utilization:

For each test the port utilization of each port must be specified. The actual traffic load can use the information defined in [RFC2544].
Traffic attributes:

For each test they must be specified (e.g., packet size, packet rate, etc.)
CPU load:

For each test it must be specified.
Power measurement:

For each test it must be specified. All power measurements are done in Watts.

6. Benchmarking Tests

6.1. Throughput

Objective:

Procedure:

Reporting format:

6.2. Base Power

Objective:

Procedure:

Reporting format:

Note:

6.3. Energy Consumption with Traffic Load

Objective:

Procedure:

Reporting format:

6.4. Energy Efficiency Ratio

Objective:

Procedure:

Reporting format:

7. Security Considerations

The benchmarking characterization described in this document is constrained to a controlled environment (as a laboratory) and includes controlled stimuli. The network under benchmarking MUST NOT be connected to production networks.

Beyond these, there are no specific security considerations within the scope of this document.

8. Acknowledgements

We wish to thank the authors of [I-D.manral-bmwg-power-usage] for their analysis and start on this topic.

9. References

9.1. Normative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC2544]
Bradner, S. and J. McQuaid, "Benchmarking Methodology for Network Interconnect Devices", RFC 2544, DOI 10.17487/RFC2544, , <https://www.rfc-editor.org/info/rfc2544>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.

9.2. Informative References

[ETSI-ES-203-136]
ETSI, "ETSI ES 203 136: Environmental Engineering (EE); Measurement methods for energy efficiency of router and switch equipment", , <https://www.etsi.org/deliver/etsi_es/203100_203199/203136/01.02.00_50/es_203136v010200m.pdf>.
[I-D.manral-bmwg-power-usage]
Manral, V., Sharma, P., Banerjee, S., and Y. Ping, "Benchmarking Power usage of networking devices", Work in Progress, Internet-Draft, draft-manral-bmwg-power-usage-04, , <https://datatracker.ietf.org/doc/html/draft-manral-bmwg-power-usage-04>.

Authors' Addresses

Carlos Pignataro
North Carolina State University
United States of America
Romain Jacob
ETH Zürich
Switzerland
Giuseppe Fioccola
Huawei
Italy