Defining Network Capacity
RFC 5136
Document | Type | RFC - Informational (February 2008; No errata) | |
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Authors | Joseph Ishac , Phil Chimento | ||
Last updated | 2015-10-14 | ||
Stream | Internent Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Reviews | |||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 5136 (Informational) | |
Action Holders |
(None)
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Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Lars Eggert | ||
Send notices to | (None) |
Network Working Group P. Chimento Request for Comments: 5136 JHU Applied Physics Lab Category: Informational J. Ishac NASA Glenn Research Center February 2008 Defining Network Capacity 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. Abstract Measuring capacity is a task that sounds simple, but in reality can be quite complex. In addition, the lack of a unified nomenclature on this subject makes it increasingly difficult to properly build, test, and use techniques and tools built around these constructs. This document provides definitions for the terms 'Capacity' and 'Available Capacity' related to IP traffic traveling between a source and destination in an IP network. By doing so, we hope to provide a common framework for the discussion and analysis of a diverse set of current and future estimation techniques. Chimento & Ishac Informational [Page 1] RFC 5136 Network Capacity February 2008 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Links and Paths . . . . . . . . . . . . . . . . . . . . . 4 2.2. Definition: Nominal Physical Link Capacity . . . . . . . . 4 2.3. Capacity at the IP Layer . . . . . . . . . . . . . . . . . 5 2.3.1. Definition: IP-layer Bits . . . . . . . . . . . . . . 5 2.3.1.1. Standard or Correctly Formed Packets . . . . . . . 5 2.3.1.2. Type P Packets . . . . . . . . . . . . . . . . . . 6 2.3.2. Definition: IP-type-P Link Capacity . . . . . . . . . 7 2.3.3. Definition: IP-type-P Path Capacity . . . . . . . . . 7 2.3.4. Definition: IP-type-P Link Usage . . . . . . . . . . . 7 2.3.5. Definition: IP-type-P Link Utilization . . . . . . . . 8 2.3.6. Definition: IP-type-P Available Link Capacity . . . . 8 2.3.7. Definition: IP-type-P Available Path Capacity . . . . 8 3. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3.1. Time and Sampling . . . . . . . . . . . . . . . . . . . . 9 3.2. Hardware Duplicates . . . . . . . . . . . . . . . . . . . 9 3.3. Other Potential Factors . . . . . . . . . . . . . . . . . 9 3.4. Common Terminology in Literature . . . . . . . . . . . . . 10 3.5. Comparison to Bulk Transfer Capacity (BTC) . . . . . . . . 10 4. Security Considerations . . . . . . . . . . . . . . . . . . . 11 5. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7.1. Normative References . . . . . . . . . . . . . . . . . . . 12 7.2. Informative References . . . . . . . . . . . . . . . . . . 12 Chimento & Ishac Informational [Page 2] RFC 5136 Network Capacity February 2008 1. Introduction Measuring the capacity of a link or network path is a task that sounds simple, but in reality can be quite complex. Any physical medium requires that information be encoded and, depending on the medium, there are various schemes to convert information into a sequence of signals that are transmitted physically from one location to another. While on some media, the maximum frequency of these signals can be thought of as "capacity", on other media, the signal transmission frequency and the information capacity of the medium (channel) may be quite different. For example, a satellite channel may have a carrier frequency of a few gigahertz, but an information-carrying capacity of only a few hundred kilobits per second. Often similar or identical terms are used to refer to these different applications of capacity, adding to the ambiguity and confusion, and the lack of a unified nomenclature makes it difficult to properly build, test, and use various techniques and tools. We are interested in information-carrying capacity, but even this is not straightforward. Each of the layers, depending on the medium, adds overhead to the task of carrying information. The wired Ethernet uses Manchester coding or 4/5 coding, which cuts down considerably on the "theoretical" capacity. Similarly, RF (radio frequency) communications will often add redundancy to the coding scheme to implement forward error correction because the physicalShow full document text