RFC 8305 - Happy Eyeballs Version 2: Better Connectivity Using Concurrency

Document Information

• RFC Number: 8305
• Title: Happy Eyeballs Version 2: Better Connectivity Using Concurrency
• Authors: D. Schinazi, T. Pauly (Apple Inc.)
• Date: December 2017
• Status: Standards Track
• Obsoletes: RFC 6555
• Category: IETF - Standards Track

Abstract

Many communication protocols operating over the modern Internet use hostnames. These often resolve to multiple IP addresses, each of which may have different performance and connectivity characteristics. Since specific addresses or address families (IPv4 or IPv6) may be blocked, broken, or sub-optimal on a network, clients that attempt multiple connections in parallel have a chance of establishing a connection more quickly. This document specifies requirements for algorithms that reduce this user-visible delay and provides an example algorithm, referred to as "Happy Eyeballs". This document obsoletes the original algorithm description in RFC 6555.

Status of This Memo

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841.

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc8305.

Copyright Notice

Copyright (c) 2017 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 (https://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. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

Table of Contents

• 1. Introduction
  • 1.1. Requirements Language
• 2. Overview
• 3. Hostname Resolution Query Handling
  • 3.1. Handling Multiple DNS Server Addresses
• 4. Sorting Addresses
• 5. Connection Attempts
• 6. DNS Answer Changes during Happy Eyeballs Connection Setup
• 7. Supporting IPv6-Only Networks with NAT64 and DNS64
  • 7.1. IPv4 Address Literals
  • 7.2. Hostnames with Broken AAAA Records
  • 7.3. Virtual Private Networks
• 8. Summary of Configurable Values
• 9. Limitations
  • 9.1. Path Maximum Transmission Unit Discovery
  • 9.2. Application Layer
  • 9.3. Hiding Operational Issues
• 10. Security Considerations
• 11. IANA Considerations
• 12. References
  • 12.1. Normative References
  • 12.2. Informative References
• Appendix A. Differences from RFC 6555
• Acknowledgments
• Authors' Addresses