The IESG has approved the following document: - 'UDP Usage Guidelines' (draft-ietf-tsvwg-rfc5405bis-19.txt) as Best Current Practice This document is the product of the Transport Area Working Group. The IESG contact persons are Mirja Kühlewind and Spencer Dawkins. A URL of this Internet Draft is: https://datatracker.ietf.org/doc/draft-ietf-tsvwg-rfc5405bis/ Technical Summary The User Datagram Protocol (UDP) provides a minimal message-passing transport that has no inherent congestion control mechanisms. This document provides guidelines on the use of UDP for the designers of applications, tunnels and other protocols that use UDP. Congestion control guidelines are a primary focus, but the document also provides guidance on other topics, including message sizes, reliability, checksums, middlebox traversal, the use of ECN, DSCPs, and ports. Because congestion control is critical to the stable operation of the Internet, applications and other 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. They may also need to implement additional mechanisms, depending on how they use UDP. Some guidance is also applicable to the design of other protocols (e.g., protocols layered directly on IP or via IP-based tunnels), especially when these protocols do not themselves provide congestion control. This document obsoletes RFC5405 and adds guidelines for multicast UDP usage. Working Group Summary The Transport Area WG (TSVWG) is a collection of people with varied interests that don't individually justify their own working groups. This draft is supported by the portion of the TSVWG working group that is familiar with and interested in UDP and congestion control. The draft has received significant review and critique from a number of WG members and has undergone significant modification as a result. A significant area of expansion over RFC 5405 is the addition of multicast guidelines; this UDP multicast guideline work began in a separate draft that was merged into this draft by the WG so that protocol designers would have one place to look for UDP guidelines. Recent discussion in the WG has focused on issues related to the increasing use of UDP to encapsulate other protocols; an important outcome is the addition of Section 3.6 on Limited Applicability and Controlled Environments where aspects such as equipment robustness and operator traffic management may substitute for protocol features (e.g., checksums, congestion management) that are necessary in unrestricted environments such as the Internet in general. This draft incorporates guidelines based on lessons learned from MPLS/UDP (RFC 7510), GRE/UDP (recent TSVWG WG Last Call) and the routing area encapsulation design team's work (much broader draft in the RTGWG WG). Document Quality In addition to Last Call reviews by Martin Stiemerling (for TSV-ART), Ronald Bonica (for RTG-DIR), Paul Kyzivat (for Gen-ART), Takeshi Takahashi (for SEC-DIR), and Tim Chown (for OPS-DIR), Mark Allman helped to reconcile protocol timer guidelines in this draft (for UDP) with the protocol timer guidelines from TCPM (for TCP). Personnel Document Shepherd: David Black Responsible AD: Spencer Dawkins
