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MMUSIC                                                          T. Reddy
Internet-Draft                                                  P. Patil
Intended status: Standards Track                                 D. Wing
Expires: April 11, 2014                                            Cisco
                                                        October 08, 2013


                    Happy Eyeballs Extension for ICE
                draft-reddy-mmusic-ice-happy-eyeballs-03

Abstract

   This document describes an algorithm that makes Interactive
   Connectivity Establishment (ICE) connectivity checks more responsive
   by reducing delays in dual-stack host ICE connectivity checks when
   there is a path failure for an address family preferred by the
   application or by the operating system.  As IPv6 is usually preferred
   over IPv4, 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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   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 April 11, 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
   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.  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.  Candidate Priority  . . . . . . . . . . . . . . . . . . . . .   3
   4.  Algorithm overview  . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  Processing the Results  . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

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 causes ICE to
   perform terribly in cases where IPv6 doesn't work, which is still
   very commonplace.  This document recommends an alternative
   prioritization for candidates that improves this situation with a
   goal that the ICE agent not be inordinately harmed by a simple
   reordering of the candidates.

   This document describes an algorithm that makes ICE connectivity
   checks more responsive to failures of an address family by reordering
   the candidates such that IPv6 and IPv4 candidates get a fair chance
   during connectivity checks.  This algorithm change is backward
   compatible with existing implementations, and does not require any
   changes other than to the selection of candidate priority.

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].





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3.  Candidate Priority

   By using the technique described in Section 4, if there are both IPv6
   and IPv4 addresses candidates gathered, and the first 'N' candidates
   are of the same IP address family, then the highest-priority
   candidate of the other address family is promoted to position 'N+1'
   in the check list thus making ICE connectivity checks more responsive
   to failures of an address family.  The algorithm ensures that there
   are no more than a fixed number of candidates of a given IP version
   in a single sequence.

   Even if an administrator changes the policy table to prefer IPv4
   addresses over IPv6 addresses as explained in [RFC6724], the IPv4
   server-reflexive candidates will still have lower priority than IPv6
   host candidates as per the "Recommended Formula" (section 4.1.2.1 of
   [RFC5245]) which is not desired.  The Happy Eyeballs extension for
   ICE algorithm resolves the problem in this scenario as well by
   ensuring that IPv4 server-reflexive candidates are placed before IPv6
   host candidates and thus ordering based on candidate types is no
   longer in effect.

4.  Algorithm overview

   The Happy Eyeballs Extension for ICE algorithm proposes the following
   steps after candidates are prioritized using the formula in section
   4.1.2.1 of [RFC5245]:

   a.  If the first 'N' candidates are of the same IP address family,
       then the highest-priority candidate of the other address family
       is promoted to position 'N+1' in the list.

   b.  Step (a) is repeated for subsequent candidates in the list until
       all candidates of the preferred address family are exhausted.

   The algorithm ensures that a long sequence of candidates belonging to
   the same address family is interleaved with candidates from an
   alternative IP version.

   The following figure illustrates the result of the algorithm on
   candidates:

   Before Happy Eyeballs Extension for ICE algorithm :
   ----------------------------------------------------
    (highest)  IPv6 Host Candidate-1
               IPv6 Host Candidate-2
               IPv6 Host Candidate-3
               IPv6 Host Candidate-4
               IPv6 Host Candidate-5



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               IPv6 Host Candidate-6
               IPv6 Host Candidate-7
               IPv4 Host Candidate
               IPv6 Server Reflexive Candidate
               IPv4 Server Reflexive Candidate
               IPv6 Relayed Transport Candidate
    (lowest)   IPv4 Relayed Transport Candidate


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


4.1.  Processing the Results

   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
   optimizations are 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
     |                                                             |
     |                                                             |
     |  Bind Req USE-CAND                     Bind Req             |



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

                Figure 1: Happy Eyeballs Extension for ICE

5.  IANA Considerations

   None.

6.  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.

7.  Acknowledgements

   Authors would like to thank Bernard Aboba, Martin Thomson, Jonathan
   Lennox, Pal Martinsen for their comments and review.









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8.  References

8.1.  Normative References

   [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.

   [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.

8.2.  Informative 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.

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



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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.
   Bangalore
   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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