Metrics for the Evaluation of Congestion Control Mechanisms
RFC 5166
Document | Type |
RFC - Informational
(March 2008; No errata)
Was draft-irtf-tmrg-metrics (tmrg RG)
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Last updated | 2018-12-20 | ||
Stream | IRTF | ||
Formats | plain text pdf htmlized bibtex | ||
Reviews | |||
Stream | IRTF state | (None) | |
Consensus Boilerplate | Unknown | ||
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 5166 (Informational) | |
Telechat date | |||
Responsible AD | Lars Eggert | ||
Send notices to | (None) |
Network Working Group S. Floyd, Ed. Request for Comments: 5166 March 2008 Category: Informational Metrics for the Evaluation of Congestion Control Mechanisms 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. IESG Note This document is not an IETF Internet Standard. It represents the individual opinion(s) of one or more members of the TMRG Research Group of the Internet Research Task Force. It may be considered for standardization by the IETF or adoption as an IRTF Research Group consensus document in the future. Abstract This document discusses the metrics to be considered in an evaluation of new or modified congestion control mechanisms for the Internet. These include metrics for the evaluation of new transport protocols, of proposed modifications to TCP, of application-level congestion control, and of Active Queue Management (AQM) mechanisms in the router. This document is the first in a series of documents aimed at improving the models that we use in the evaluation of transport protocols. This document is a product of the Transport Modeling Research Group (TMRG), and has received detailed feedback from many members of the Research Group (RG). As the document tries to make clear, there is not necessarily a consensus within the research community (or the IETF community, the vendor community, the operations community, or any other community) about the metrics that congestion control mechanisms should be designed to optimize, in terms of trade-offs between throughput and delay, fairness between competing flows, and the like. However, we believe that there is a clear consensus that congestion control mechanisms should be evaluated in terms of trade- offs between a range of metrics, rather than in terms of optimizing for a single metric. Floyd Informational [Page 1] RFC 5166 TMRG, METRICS March 2008 Table of Contents 1. Introduction ....................................................2 2. Metrics .........................................................3 2.1. Throughput, Delay, and Loss Rates ..........................4 2.1.1. Throughput ..........................................5 2.1.2. Delay ...............................................6 2.1.3. Packet Loss Rates ...................................6 2.2. Response Times and Minimizing Oscillations .................7 2.2.1. Response to Changes .................................7 2.2.2. Minimizing Oscillations .............................8 2.3. Fairness and Convergence ...................................9 2.3.1. Metrics for Fairness between Flows .................10 2.3.2. Metrics for Fairness between Flows with Different Resource Requirements ....................10 2.3.3. Comments on Fairness ...............................12 2.4. Robustness for Challenging Environments ...................13 2.5. Robustness to Failures and to Misbehaving Users ...........14 2.6. Deployability .............................................14 2.7. Metrics for Specific Types of Transport ...................15 2.8. User-Based Metrics ........................................15 3. Metrics in the IP Performance Metrics (IPPM) Working Group .....15 4. Comments on Methodology ........................................16 5. Security Considerations ........................................16 6. Acknowledgements ...............................................16 7. Informative References .........................................17 1. Introduction As a step towards improving our methodologies for evaluating congestion control mechanisms, in this document we discuss some of the metrics to be considered. We also consider the relationship between metrics, e.g., the well-known trade-off between throughput and delay. This document doesn't attempt to specify every metric that a study might consider; for example, there are domain-specific metrics that researchers might consider that are over and above the metrics laid out here. We consider metrics for aggregate traffic (taking into account the effect of flows on competing traffic in the network) as well as the heterogeneous goals of different applications or transport protocols (e.g., of high throughput for bulk data transfer, and of low delay for interactive voice or video). Different transport protocols or AQM mechanisms might have goals of optimizing different sets of metrics, with one transport protocol optimized for per-flow throughput and another optimized for robustness over wireless links,Show full document text