draft-ietf-v6ops-rfc6555bis-04.txt   draft-ietf-v6ops-rfc6555bis-05.txt 
Network D. Schinazi Network D. Schinazi
Internet-Draft T. Pauly Internet-Draft T. Pauly
Obsoletes: 6555 (if approved) Apple Inc. Obsoletes: 6555 (if approved) Apple Inc.
Intended status: Standards Track August 17, 2017 Intended status: Standards Track September 10, 2017
Expires: February 18, 2018 Expires: March 14, 2018
Happy Eyeballs Version 2: Better Connectivity Using Concurrency Happy Eyeballs Version 2: Better Connectivity Using Concurrency
draft-ietf-v6ops-rfc6555bis-04 draft-ietf-v6ops-rfc6555bis-05
Abstract Abstract
Many communication protocols operated over the modern Internet use Many communication protocols operated over the modern Internet use
host names. These often resolve to multiple IP addresses, each of host names. These often resolve to multiple IP addresses, each of
which may have different performance and connectivity which may have different performance and connectivity
characteristics. Since specific addresses or address families (IPv4 characteristics. Since specific addresses or address families (IPv4
or IPv6) may be blocked, broken, or sub-optimal on a network, clients or IPv6) may be blocked, broken, or sub-optimal on a network, clients
that attempt multiple connections in parallel have a higher chance of that attempt multiple connections in parallel have a higher chance of
establishing a connection sooner. This document specifies establishing a connection sooner. This document specifies
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provides an example algorithm. provides an example algorithm.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 18, 2018. This Internet-Draft will expire on March 14, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
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Implementations SHOULD NOT wait for both families of answers to Implementations SHOULD NOT wait for both families of answers to
return before attempting connection establishment. If one query return before attempting connection establishment. If one query
fails to return, or takes significantly longer to return, waiting for fails to return, or takes significantly longer to return, waiting for
the second address family can significantly delay the connection the second address family can significantly delay the connection
establishment of the first one. Therefore, the client SHOULD treat establishment of the first one. Therefore, the client SHOULD treat
DNS resolution as asynchronous. Note that if the platform does not DNS resolution as asynchronous. Note that if the platform does not
offer an asynchronous DNS API, this behavior can be simulated by offer an asynchronous DNS API, this behavior can be simulated by
making two separate synchronous queries on different threads, one per making two separate synchronous queries on different threads, one per
address family. address family.
The RECOMMENDED algorithm proceeds as follows: if the AAAA query The RECOMMENDED algorithm proceeds as follows: if a positive AAAA
returns first, the first IPv6 connection attempt is immediately response (a response with at least one valid AAAA record) is received
started. If the A query returns first due to reordering, the client first, the first IPv6 connection attempt is immediately started. If
a positive A response is received first due to reordering, the client
SHOULD wait for a short time for the AAAA response to ensure SHOULD wait for a short time for the AAAA response to ensure
preference is given to IPv6 (it is common for the AAAA response to preference is given to IPv6 (it is common for the AAAA response to
follow the A response by a few milliseconds). This delay will be follow the A response by a few milliseconds). This delay will be
referred to as the "Resolution Delay". The RECOMMENDED value for the referred to as the "Resolution Delay". The RECOMMENDED value for the
Resolution Delay is 50 milliseconds. If the AAAA response is Resolution Delay is 50 milliseconds. If a positive AAAA response is
received within the Resolution Delay period, the client immediately received within the Resolution Delay period, the client immediately
starts the IPv6 connection attempt. If, at the end of the Resolution starts the IPv6 connection attempt. If a negative AAAA response (no
Delay period, the AAAA response has not been received but the A error, no data) is received within the Resolution Delay period or the
response has been received, the client SHOULD proceed to Sorting AAAA response has not been received by the end of the Resolution
Addresses [Section 4] and staggered connection attempts [Section 5] Delay period, the client SHOULD proceed to Sorting Addresses
using only the IPv4 addresses returned so far. If the AAAA response [Section 4] and staggered connection attempts [Section 5] using any
arrives while these connection attempts are in progress, but before IPv4 addresses returned so far. If the AAAA response arrives while
any connection has been established, then the newly received IPv6 these connection attempts are in progress, but before any connection
addresses are incorporated into the list of available candidate has been established, then the newly received IPv6 addresses are
addresses [Section 6] and the process of connection attempts will incorporated into the list of available candidate addresses
continue with the IPv6 addresses added, until one connection is [Section 6] and the process of connection attempts will continue with
established. the IPv6 addresses added, until one connection is established.
3.1. Handling Multiple DNS Server Addresses 3.1. Handling Multiple DNS Server Addresses
If multiple DNS server addresses are configured for the current If multiple DNS server addresses are configured for the current
network, the client may have the option of sending its DNS queries network, the client may have the option of sending its DNS queries
over IPv4 or IPv6. In keeping with the Happy Eyeballs approach, over IPv4 or IPv6. In keeping with the Happy Eyeballs approach,
queries SHOULD be sent over IPv6 first (note that this is not queries SHOULD be sent over IPv6 first (note that this is not
referring to the sending of AAAA or A queries, but rather the address referring to the sending of AAAA or A queries, but rather the address
of the DNS server itself and IP version used to transport DNS of the DNS server itself and IP version used to transport DNS
messages). If DNS queries sent to the IPv6 address do not receive messages). If DNS queries sent to the IPv6 address do not receive
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12. Acknowledgments 12. Acknowledgments
The authors thank Dan Wing, Andrew Yourtchenko, and everyone else who The authors thank Dan Wing, Andrew Yourtchenko, and everyone else who
worked on the original Happy Eyeballs design [RFC6555], Josh worked on the original Happy Eyeballs design [RFC6555], Josh
Graessley, Stuart Cheshire, and the rest of team at Apple that helped Graessley, Stuart Cheshire, and the rest of team at Apple that helped
implement and instrument this algorithm, and Jason Fesler and Paul implement and instrument this algorithm, and Jason Fesler and Paul
Saab who helped measure and refine this algorithm. The authors would Saab who helped measure and refine this algorithm. The authors would
also like to thank Fred Baker, Nick Chettle, Lorenzo Colitti, Igor also like to thank Fred Baker, Nick Chettle, Lorenzo Colitti, Igor
Gashinsky, Geoff Huston, Jen Linkova, Paul Hoffman, Philip Homburg, Gashinsky, Geoff Huston, Jen Linkova, Paul Hoffman, Philip Homburg,
Erik Nygren, Jordi Palet Martinez, Rui Paulo, Stephen Strowes, Jinmei Warren Kumari, Erik Nygren, Jordi Palet Martinez, Rui Paulo, Stephen
Tatuya, Dave Thaler, Joe Touch and James Woodyatt for their input and Strowes, Jinmei Tatuya, Dave Thaler, Joe Touch and James Woodyatt for
contributions. their input and contributions.
13. References 13. References
13.1. Normative References 13.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU
Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007, Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007,
<https://www.rfc-editor.org/info/rfc4821>. <https://www.rfc-editor.org/info/rfc4821>.
[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X. [RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052, Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
DOI 10.17487/RFC6052, October 2010, <https://www.rfc- DOI 10.17487/RFC6052, October 2010,
editor.org/info/rfc6052>. <https://www.rfc-editor.org/info/rfc6052>.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful [RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6 NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146, Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146,
April 2011, <https://www.rfc-editor.org/info/rfc6146>. April 2011, <https://www.rfc-editor.org/info/rfc6146>.
[RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., and I. van [RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., and I. van
Beijnum, "DNS64: DNS Extensions for Network Address Beijnum, "DNS64: DNS Extensions for Network Address
Translation from IPv6 Clients to IPv4 Servers", RFC 6147, Translation from IPv6 Clients to IPv4 Servers", RFC 6147,
DOI 10.17487/RFC6147, April 2011, <https://www.rfc- DOI 10.17487/RFC6147, April 2011,
editor.org/info/rfc6147>. <https://www.rfc-editor.org/info/rfc6147>.
[RFC6535] Huang, B., Deng, H., and T. Savolainen, "Dual-Stack Hosts [RFC6535] Huang, B., Deng, H., and T. Savolainen, "Dual-Stack Hosts
Using "Bump-in-the-Host" (BIH)", RFC 6535, Using "Bump-in-the-Host" (BIH)", RFC 6535,
DOI 10.17487/RFC6535, February 2012, <https://www.rfc- DOI 10.17487/RFC6535, February 2012,
editor.org/info/rfc6535>. <https://www.rfc-editor.org/info/rfc6535>.
[RFC6555] Wing, D. and A. Yourtchenko, "Happy Eyeballs: Success with [RFC6555] Wing, D. and A. Yourtchenko, "Happy Eyeballs: Success with
Dual-Stack Hosts", RFC 6555, DOI 10.17487/RFC6555, April Dual-Stack Hosts", RFC 6555, DOI 10.17487/RFC6555, April
2012, <https://www.rfc-editor.org/info/rfc6555>. 2012, <https://www.rfc-editor.org/info/rfc6555>.
[RFC6724] Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown, [RFC6724] Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6 "Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012, (IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012,
<https://www.rfc-editor.org/info/rfc6724>. <https://www.rfc-editor.org/info/rfc6724>.
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