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MMUSIC                                                          T. Reddy
Internet-Draft                                                  P. Patil
Intended status: Standards Track                                 D. Wing
Expires: January 12, 2014                                          Cisco
                                                           July 11, 2013


                    Happy Eyeballs Extension for ICE
                draft-reddy-mmusic-ice-happy-eyeballs-01

Abstract

   This document specifies requirements for algorithms that make ICE
   connectivity checks more responsive by reducing delays in dual-stack
   host ICE connectivity checks when there is a path failure for the
   address family preferred by the application or by the operating
   system.  As IPv6 is usually preferred, the procedures in this
   document helps avoid user-noticeable delays when the IPv6 path is
   broken or excessively slow.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 12, 2014.

Copyright Notice

   Copyright (c) 2013 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
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   (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.  Code Components extracted from this document must



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   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Notational Conventions  . . . . . . . . . . . . . . . . . . .   2
   3.  Candidates Priority . . . . . . . . . . . . . . . . . . . . .   2
   4.  Algorithm overview  . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  Processing the Results  . . . . . . . . . . . . . . . . .   5
   5.  Indicating Happy-Eyeballs . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   In situations where there are many IPv6 addresses, ICE [RFC5245] will
   prefer IPv6 candidates [RFC6724] and will attempt connectivity checks
   on all the IPv6 candidates before trying an IPv4 candidate.  If the
   IPv6 path is broken, this fallback to IPv4 can consume a lot of time,
   harming user satisfaction of dual-stack devices.

   This document describes an algorithm that makes ICE connectivity
   checks more responsive to failures of an address family by reordering
   the candidate pairs such that IPv6 and IPv4 candidates get a fair
   chance during connectivity checks.  This document specifies
   requirements for any such algorithm, with the goals that the ICE
   agent need not be inordinately harmed with a simple reordering of the
   candidate pairs.

2.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   This note uses terminology defined in [RFC5245].

3.  Candidates Priority

   A prioritization formula is used by ICE [RFC5245] so that most
   preferred address pairs are tested first, and if a sufficiently good



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   pair is discovered, the tests can be stopped.  With IPv6, addresses
   obtained from local network interfaces, called host candidates, are
   recommended as high-priority ones to be tested first since if they
   work, they provide usually the best path between the two hosts.  The
   ICE specification recommends to use the rules defined in [RFC6724] as
   part of the prioritization formula for IPv6 host candidates and
   [I-D.keranen-mmusic-ice-address-selection] updates the ICE rules on
   how IPv6 host candidates are selected.

   For dual-stack hosts the preference for IPv6 host candidates is
   higher than IPv4 host candidates based on precedence value of IP
   addresses described in [RFC6724].  IPv6 server reflexive candidates
   have higher precedence than IPv4 server reflexive candidate since
   NPTv6 is stateless and transport-agnostic.

   (highest)  IPv6 Host Candidate
              IPv4 Host Candidate
              IPv6 Server Reflexive Candidate
              IPv4 Server Reflexive Candidate
              IPv6 Relayed Transport Candidate
   (lowest)   IPv4 Relayed Transport Candidate

            Figure 1: Candidate Preferences in decreasing order

   By using the technique described in Section 4, if there are both IPv6
   and IPv4 addresses in the check list, and the first 'N' candidates
   are of the same IP address family, then the highest-priority
   candidate pair of the other address family is promoted to position N
   in the check list thus making ICE connectivity checks more responsive
   to failures of an address family.

   Note: The algorithm works even if the administrator changes the
   policy table to prefer IPv4 addresses over IPv6 addresses as defined
   in [RFC6724]

4.  Algorithm overview

   The Happy Eyeballs Extension for ICE algorithm proposes the
   following:

   1.  Indicate support for ICE Happy Eyeballs in the SDP offer if the
       end-point is dual-stack.  The end-point will also include the
       position 'N' at which promotion is to occur.








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   2.  After SDP offer/answer exchange if both end points support ICE
       Happy Extension for ICE algorithm the following steps are
       performed by the ICE agents after computing the candidate pair
       priority, ordering and pruning the pairs (section 5.7.2, 5.7.3 of
       [RFC5245])

       a.  If the first 'N' candidate pairs in the check list are of the
           same IP address family, then the highest-priority candidate
           pair of the other address family is promoted to position 'N'
           in the list.

       b.  Step b is repeated for candidate pairs that are next in the
           check list.  This is continued until all candidate pairs of
           the preferred address family are exhausted.

   The result of these steps is that after every consecutive 'N'
   candidate pairs of the preferred family, a candidate pair of the
   other family is inserted.

   The following figure illustrates the result of the algorithm on
   candidate pairs:

   Before Happy Eyeballs Extension for ICE algorithm :
   ----------------------------------------------------
    (highest)  IPv6 Host Candidate-1 pair
               IPv6 Host Candidate-2 pair
               IPv6 Host Candidate-3 pair
               IPv6 Host Candidate-4 pair
               IPv6 Host Candidate-5 pair
               IPv6 Host Candidate-6 pair
               IPv6 Host Candidate-7 pair
               IPv4 Host Candidate pair
               IPv6 Server Reflexive Candidate  pair
               IPv4 Server Reflexive Candidate pair
               IPv6 Relayed Transport Candidate pair
    (lowest)   IPv4 Relayed Transport Candidate pair


   After Happy Eyeballs Extension for ICE algorithm :
   --------------------------------------------------
    (highest)  IPv6 Host Candidate-1 pair
               IPv6 Host Candidate-2 pair
               IPv6 Host Candidate-3 pair
               IPv4 Host Candidate pair            ---> Promoted pair
               IPv6 Host Candidate-4 pair
               IPv6 Host Candidate-5 pair
               IPv6 Host Candidate-6 pair
               IPv4 Server Reflexive Candidate pair ---> Promoted pair



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               IPv6 Host Candidate-7 pair
               IPv6 Server Reflexive Candidate pair
               IPv6 Relayed Transport Candidate pair
    (lowest)   IPv4 Relayed Transport Candidate pair


4.1.  Processing the Results

   If ICE connectivity checks using an IPv4 candidate is successful then
   ICE Agent will performs as usual "Discovering Peer Reflexive
   Candidates" (Section 7.1.3.2.1 of [RFC5245]), "Constructing a Valid
   Pair" (Section 7.1.3.2.2 of [RFC5245]), "Updating Pair States"
   (Section 7.1.3.2.3 of [RFC5245]), "Updating the Nominated Flag"
   (Section 7.1.3.2.4 of [RFC5245]).

   If ICE connectivity checks using an IPv4 candidate is successful for
   each component of the media stream and connectivity checks using IPv6
   candidates is not yet successful, the ICE endpoint will declare
   victory, conclude ICE for the media stream and start sending media
   using IPv4.  However, it is also possible that ICE endpoint continues
   to perform ICE connectivity checks with IPv6 candidate pairs and if
   checks using higher-priority IPv6 candidate pair is successful then
   media stream can be moved to the IPv6 candidate pair.  Continuing to
   perform connectivity checks can be useful for subsequent connections,
   to optimize which connectivity checks are tried first.  Such
   optimization is out of scope of this document.

   The following diagram shows the behaviour during the connectivity
   check when Alice calls Bob and Agent Alice is the controlling agent
   and uses the aggressive nomination algorithm.  "USE-CAND" implies the
   presence of the USE-CANDIDATE attribute.

    Alice                                                         Bob
     |                                                             |
     | SDP Offer; a=happy-eyeballs:2                               |
     |                              SDP Answer; a=happy-eyeballs:2 |
     |                                                             |
     |  Bind Req USE-CAND                     Bind Req             |
     |  using IPv6                            using IPv6           |
     |------------------>X                X<-----------------------|
     |  Bind Req USE-CAND                     Bind Req             |
     |  using IPv6 after Ta                   using IPv6           |
     |------------------>X                X<-----------------------|
     |                                                             |
   [after connectivity checks for 2 IPv6 addresses, try IPv4]      |
     |                                                             |
     |  Bind Req USE-CAND                                          |
     |  using IPv4                                                 |



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     |------------------------------------------------------------>|
     |                                        Bind Resp            |
     |                                        using IPv4           |
     |<----------------------------------------------------------- |
     |          RTP                                                |
     |============================================================>|
     |                                       Bind Req              |
     |                                       using IPv4            |
     |<------------------------------------------------------------|
     |  Bind Response                                              |
     |  using IPv4                                                 |
     |------------------------------------------------------------>|
     |          RTP                                                |
     |<===========================================================>|

                Figure 2: Happy Eyeballs Extension for ICE

5.  Indicating Happy-Eyeballs

   To indicate that Happy Eyeballs Extension for ICE algorithm defined
   in this document is used, the ICE offerer MUST include ice-options
   attribute with "happy-eyeballs:N" option identifier in the Session
   Description Protocol (SDP) [RFC4566] ICE offer, where N indicates the
   position at which promotion is to occur.  If the ICE offer does not
   include this option tag, the answerer SHOULD NOT utilize the updated
   ICE algorithm defined in this document.  If the offer included the
   option tag and the answerer supports this specification, the answerer
   SHOULD add the same option tag to the response and use the Happy
   Eyeballs Extension for ICE algorithm.  If the ICE answer does not
   contain the option tag, the offerer SHOULD NOT use the updated ICE
   algorithm.  Recommended value for 'N' is 3.  As IPv6 becomes more
   prevalent, the value of 'N' can be increased as desired.

6.  IANA Considerations

   IANA is requested to register "happy-eyeballs" option identifier
   under the "ICE Options" [RFC6336] registry.

   The required registration information is as follows:

   Option identifier: happy-eyeballs

   Contact: Tirumaleswar Reddy, tireddy@cisco.com

   Change control: IETF

   Description: Existence of this option identifier indicates that Happy
   Eyeballs Extension for ICE algorithm is used.



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   Reference: RFCXXXX

   [RFC editor: replace XXXX with the RFC number of this document]

7.  Security Considerations

   STUN connectivity check using MAC computed during key exchanged in
   the signaling channel provides message integrity and data origin
   authentication as described in section 2.5 of [RFC5245] apply to this
   use.

8.  Acknowledgements

   The authors would like to thank Bernard Aboba for his inputs.

9.  References

9.1.  Normative References

   [I-D.keranen-mmusic-ice-address-selection]
              Keraenen, A. and J. Arkko, "Update on Candidate Address
              Selection for Interactive Connectivity Establishment
              (ICE)", draft-keranen-mmusic-ice-address-selection-01
              (work in progress), July 2012.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3484]  Draves, R., "Default Address Selection for Internet
              Protocol version 6 (IPv6)", RFC 3484, February 2003.

   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
              Description Protocol", RFC 4566, July 2006.

   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
              Description Protocol", RFC 4566, July 2006.

   [RFC5245]  Rosenberg, J., "Interactive Connectivity Establishment
              (ICE): A Protocol for Network Address Translator (NAT)
              Traversal for Offer/Answer Protocols", RFC 5245, April
              2010.

   [RFC5389]  Rosenberg, J., Mahy, R., Matthews, P., and D. Wing,
              "Session Traversal Utilities for NAT (STUN)", RFC 5389,
              October 2008.






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   [RFC5766]  Mahy, R., Matthews, P., and J. Rosenberg, "Traversal Using
              Relays around NAT (TURN): Relay Extensions to Session
              Traversal Utilities for NAT (STUN)", RFC 5766, April 2010.

   [RFC6336]  Westerlund, M. and C. Perkins, "IANA Registry for
              Interactive Connectivity Establishment (ICE) Options", RFC
              6336, July 2011.

   [RFC6724]  Thaler, D., Draves, R., Matsumoto, A., and T. Chown,
              "Default Address Selection for Internet Protocol Version 6
              (IPv6)", RFC 6724, September 2012.

9.2.  Informative References

   [RFC2663]  Srisuresh, P. and M. Holdrege, "IP Network Address
              Translator (NAT) Terminology and Considerations", RFC
              2663, August 1999.

Authors' Addresses

   Tirumaleswar Reddy
   Cisco Systems, Inc.
   Cessna Business Park, Varthur Hobli
   Sarjapur Marathalli Outer Ring Road
   Bangalore, Karnataka  560103
   India

   Email: tireddy@cisco.com


   Prashanth Patil
   Cisco Systems, Inc.
   Cessna Business Park, Varthur Hobli
   Sarjapur Marthalli Outer Ring Road
   Bangalore, Karnataka  560103
   India

   Email: praspati@cisco.com


   Dan Wing
   Cisco Systems, Inc.
   170 West Tasman Drive
   San Jose, California  95134
   USA

   Email: dwing@cisco.com




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