Unicast UDP Usage Guidelines for Application Designers
RFC 5405
Document | Type |
RFC - Best Current Practice
(November 2008; No errata)
Obsoleted by RFC 8085
Also known as BCP 145
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Authors | Lars Eggert , Gorry Fairhurst | ||
Last updated | 2015-10-14 | ||
Replaces | draft-eggert-tsvwg-udp-guidelines | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 5405 (Best Current Practice) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Magnus Westerlund | ||
Send notices to | (None) |
Network Working Group L. Eggert Request for Comments: 5405 Nokia BCP: 145 G. Fairhurst Category: Best Current Practice University of Aberdeen November 2008 Unicast UDP Usage Guidelines for Application Designers Status of This Memo This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. Distribution of this memo is unlimited. Copyright Notice Copyright (c) 2008 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract The User Datagram Protocol (UDP) provides a minimal message-passing transport that has no inherent congestion control mechanisms. Because congestion control is critical to the stable operation of the Internet, applications and upper-layer protocols that choose to use UDP as an Internet transport must employ mechanisms to prevent congestion collapse and to establish some degree of fairness with concurrent traffic. This document provides guidelines on the use of UDP for the designers of unicast applications and upper-layer protocols. Congestion control guidelines are a primary focus, but the document also provides guidance on other topics, including message sizes, reliability, checksums, and middlebox traversal. Eggert & Fairhurst Best Current Practice [Page 1] RFC 5405 Unicast UDP Usage Guidelines November 2008 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. UDP Usage Guidelines . . . . . . . . . . . . . . . . . . . . . 5 3.1. Congestion Control Guidelines . . . . . . . . . . . . . . 6 3.2. Message Size Guidelines . . . . . . . . . . . . . . . . . 11 3.3. Reliability Guidelines . . . . . . . . . . . . . . . . . . 12 3.4. Checksum Guidelines . . . . . . . . . . . . . . . . . . . 13 3.5. Middlebox Traversal Guidelines . . . . . . . . . . . . . . 15 3.6. Programming Guidelines . . . . . . . . . . . . . . . . . . 17 3.7. ICMP Guidelines . . . . . . . . . . . . . . . . . . . . . 18 4. Security Considerations . . . . . . . . . . . . . . . . . . . 19 5. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22 7.1. Normative References . . . . . . . . . . . . . . . . . . . 22 7.2. Informative References . . . . . . . . . . . . . . . . . . 23 Eggert & Fairhurst Best Current Practice [Page 2] RFC 5405 Unicast UDP Usage Guidelines November 2008 1. Introduction The User Datagram Protocol (UDP) [RFC0768] provides a minimal, unreliable, best-effort, message-passing transport to applications and upper-layer protocols (both simply called "applications" in the remainder of this document). Compared to other transport protocols, UDP and its UDP-Lite variant [RFC3828] are unique in that they do not establish end-to-end connections between communicating end systems. UDP communication consequently does not incur connection establishment and teardown overheads, and there is minimal associated end system state. Because of these characteristics, UDP can offer a very efficient communication transport to some applications. A second unique characteristic of UDP is that it provides no inherent congestion control mechanisms. On many platforms, applications can send UDP datagrams at the line rate of the link interface, which is often much greater than the available path capacity, and doing so contributes to congestion along the path. [RFC2914] describes the best current practice for congestion control in the Internet. It identifies two major reasons why congestion control mechanisms are critical for the stable operation of the Internet: 1. The prevention of congestion collapse, i.e., a state where an increase in network load results in a decrease in useful work done by the network. 2. The establishment of a degree of fairness, i.e., allowing multiple flows to share the capacity of a path reasonably equitably. Because UDP itself provides no congestion control mechanisms, it isShow full document text