Hash and Stuffing: Overlooked Factors in Network Device Benchmarking
RFC 4814
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RFC - Informational
(March 2007; No errata)
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2015-10-14
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IETF
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RFC 4814 (Informational)
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David Kessens
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Network Working Group D. Newman
Request for Comments: 4814 Network Test
Category: Informational T. Player
Spirent Communications
March 2007
Hash and Stuffing: Overlooked Factors in Network Device Benchmarking
Status of This Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
Test engineers take pains to declare all factors that affect a given
measurement, including intended load, packet length, test duration,
and traffic orientation. However, current benchmarking practice
overlooks two factors that have a profound impact on test results.
First, existing methodologies do not require the reporting of
addresses or other test traffic contents, even though these fields
can affect test results. Second, "stuff" bits and bytes inserted in
test traffic by some link-layer technologies add significant and
variable overhead, which in turn affects test results. This document
describes the effects of these factors; recommends guidelines for
test traffic contents; and offers formulas for determining the
probability of bit- and byte-stuffing in test traffic.
Newman & Player Informational [Page 1]
RFC 4814 Hash and Stuffing March 2007
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. General Considerations . . . . . . . . . . . . . . . . . . . . 4
3.1. Repeatability . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Randomness . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Packet Content Variations . . . . . . . . . . . . . . . . . . 5
4.1. Problem Statement . . . . . . . . . . . . . . . . . . . . 5
4.2. IEEE 802 MAC Addresses . . . . . . . . . . . . . . . . . . 7
4.2.1. Randomized Sets of MAC Addresses . . . . . . . . . . . 8
4.3. MPLS Addressing . . . . . . . . . . . . . . . . . . . . . 9
4.4. Network-layer Addressing . . . . . . . . . . . . . . . . . 9
4.5. Transport-Layer Addressing . . . . . . . . . . . . . . . . 10
4.6. Application-Layer Patterns . . . . . . . . . . . . . . . . 10
5. Control Character Stuffing . . . . . . . . . . . . . . . . . . 11
5.1. Problem Statement . . . . . . . . . . . . . . . . . . . . 11
5.2. PPP Bit-Stuffing . . . . . . . . . . . . . . . . . . . . . 12
5.2.1. Calculating Bit-Stuffing Probability . . . . . . . . . 14
5.2.2. Bit-Stuffing for Finite Strings . . . . . . . . . . . 15
5.2.3. Applied Bit-Stuffing . . . . . . . . . . . . . . . . . 16
5.3. POS Byte-Stuffing . . . . . . . . . . . . . . . . . . . . 16
5.3.1. Nullifying ACCM . . . . . . . . . . . . . . . . . . . 17
5.3.2. Other Stuffed Characters . . . . . . . . . . . . . . . 17
5.3.3. Applied Byte-Stuffing . . . . . . . . . . . . . . . . 17
6. Security Considerations . . . . . . . . . . . . . . . . . . . 18
7. Normative References . . . . . . . . . . . . . . . . . . . . . 19
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 20
Appendix B. Proof of Formula for Finite Bit-Stuffing . . . . . . 20
Appendix C. Explicit Calculation of Bit-Stuffing Overhead for
IPv4 . . . . . . . . . . . . . . . . . . . . . . . . 21
Appendix D. Explicit Calculation of Bit-Stuffing Overhead for
IPv6 . . . . . . . . . . . . . . . . . . . . . . . . 23
Appendix E. Terminology . . . . . . . . . . . . . . . . . . . . . 24
Newman & Player Informational [Page 2]
RFC 4814 Hash and Stuffing March 2007
1. Introduction
Experience in benchmarking networking devices suggests that the
contents of test traffic can have a profound impact on test results.
For example, some devices may forward randomly addressed traffic
without loss, but drop significant numbers of packets when offered
packets containing nonrandom addresses.
Methodologies such as [RFC2544] and [RFC2889] do not require any
declaration of packet contents. These methodologies do require the
declaration of test parameters such as traffic distribution and
traffic orientation, and yet packet contents can have at least as
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