TCP Friendly Rate Control (TFRC): The Small-Packet (SP) Variant
RFC 4828
Document | Type | RFC - Experimental (April 2007; Errata) | |
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Authors | Eddie Kohler , Sally Floyd | ||
Last updated | 2020-01-21 | ||
Stream | Internet Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized with errata bibtex | ||
Reviews | |||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4828 (Experimental) | |
Action Holders |
(None)
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Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Lars Eggert | ||
Send notices to | (None) |
Network Working Group S. Floyd Request for Comments: 4828 ICIR Category: Experimental E. Kohler UCLA April 2007 TCP Friendly Rate Control (TFRC): The Small-Packet (SP) Variant Status of This Memo This memo defines an Experimental Protocol for the Internet community. It does not specify an Internet standard of any kind. Discussion and suggestions for improvement are requested. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This document proposes a mechanism for further experimentation, but not for widespread deployment at this time in the global Internet. TCP-Friendly Rate Control (TFRC) is a congestion control mechanism for unicast flows operating in a best-effort Internet environment (RFC 3448). TFRC was intended for applications that use a fixed packet size, and was designed to be reasonably fair when competing for bandwidth with TCP connections using the same packet size. This document proposes TFRC-SP, a Small-Packet (SP) variant of TFRC, that is designed for applications that send small packets. The design goal for TFRC-SP is to achieve the same bandwidth in bps (bits per second) as a TCP flow using packets of up to 1500 bytes. TFRC-SP enforces a minimum interval of 10 ms between data packets to prevent a single flow from sending small packets arbitrarily frequently. Flows using TFRC-SP compete reasonably fairly with large-packet TCP and TFRC flows in environments where large-packet flows and small- packet flows experience similar packet drop rates. However, in environments where small-packet flows experience lower packet drop rates than large-packet flows (e.g., with Drop-Tail queues in units of bytes), TFRC-SP can receive considerably more than its share of the bandwidth. Floyd & Kohler Experimental [Page 1] RFC 4828 TFRC: The SP Variant April 2007 Table of Contents 1. Introduction ....................................................3 2. Conventions .....................................................5 3. TFRC-SP Congestion Control ......................................5 4. TFRC-SP Discussion ..............................................9 4.1. Response Functions and Throughput Equations ................9 4.2. Accounting for Header Size ................................12 4.3. The TFRC-SP Min Interval ..................................13 4.4. Counting Packet Losses ....................................14 4.5. The Nominal Packet Size ...................................15 4.5.1. Packet Size and Packet Drop Rates ..................15 4.5.2. Fragmentation and the Path MTU .....................17 4.5.3. The Nominal Segment Size and the Path MTU ..........17 4.6. The Loss Interval Length for Short Loss Intervals .........18 5. A Comparison with RFC 3714 .....................................19 6. TFRC-SP with Applications that Modify the Packet Size ..........19 7. Simulations ....................................................20 8. General Discussion .............................................21 9. Security Considerations ........................................22 10. Conclusions ...................................................23 11. Acknowledgements ..............................................24 Appendix A. Related Work on Small-Packet Variants of TFRC .........25 Appendix B. Simulation Results ....................................26 B.1. Simulations with Configured Packet Drop Rates .............26 B.2. Simulations with Configured Byte Drop Rates ...............30 B.3. Packet Dropping Behavior at Routers with Drop-Tail Queues ....................................................32 B.4. Packet Dropping Behavior at Routers with AQM ..............37 Appendix C. Exploring Possible Oscillations in the Loss Event Rate ...........................................................42 Appendix D. A Discussion of Packet Size and Packet Dropping .......43 Normative References ..............................................44 Informative References ............................................44 Floyd & Kohler Experimental [Page 2] RFC 4828 TFRC: The SP Variant April 2007 1. Introduction This document specifies TFRC-SP, an experimental, Small-Packet variant of TCP-friendly Rate Control (TFRC) [RFC3448]. TFRC was designed to be reasonably fair when competing for bandwidthShow full document text