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Network Working Group                                        P. Thatcher
Internet-Draft                                                  H. Zhang
Intended status: Standards Track                         T. Brandstetter
Expires: September 22, 2016                                       Google
                                                          March 21, 2016


      ICE Renomination: Dynamically selecting ICE candidate pairs
                   draft-thatcher-ice-renomination-00

Abstract

   This document describes an extension to the Interactive Connectivity
   Establishment (ICE) that enables ICE agents to dynamically change the
   selected candidate pair of the controlled side by allowing the
   controlling side to nominate different candidate pairs over time as
   network conditions change.

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
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   This Internet-Draft will expire on September 22, 2016.

Copyright Notice

   Copyright (c) 2016 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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   publication of this document.  Please review these documents
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   include Simplified BSD License text as described in Section 4.e of




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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Renomination  . . . . . . . . . . . . . . . . . . . . . . . .   2
   4.  "Nomination" attribute  . . . . . . . . . . . . . . . . . . .   3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   3
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   3
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   3

1.  Introduction

   ICE agents are either controlling or controlled.  The controlling ICE
   agent can unilaterally select a given candidate pair at any time.
   But it cannot control what candidate pair the controlled ICE agent
   selects once the controlling ICE agent has nominated a candidate pair
   (with passive nomination) or nominated many candidate pairs (with
   aggressive nomination), with the exception that it may nominate a
   higher priority candidate pair with aggressive nomination.  This
   greatly limits the controlling side's options.

   For example, if an ICE agent selects and nominates a candidate pair
   over a cellular network, and then later connects to a Wi-Fi network
   and trickles ICE candidates for the Wi-Fi network, it may wish to
   select and nominate a candidate pair using Wi-Fi.  If soon thereafter
   the Wi-Fi network disconnects and the ICE agent wishes to select and
   nominate the cellular candidate pair again, it would be unable to do
   with either passive or aggressive nomination.

2.  Terminology

   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].

3.  Renomination

   We define a new ICE option called "renomination".  When renomination
   is signaled, aggressive nomination is disabled, and the controlled
   side follows a rule of "last nomination wins".  This allows the
   controlling side to send nominations for new candidate pairs at any
   time.  The controlling side SHOULD send the new nomination until the
   STUN packet is acked to ensure that the renomination was received.



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   If one side signals "renomination" and the other does not understand
   it, then according to the rules of ICE, aggressive nomination is
   disabled and passive nomination is used, and the controlling side
   MUST NOT send more than one nomination.

4.  "Nomination" attribute

   To deal with out-of-order delivery of nominations, we define a new
   STUN attribute: "nomination" which includes a 24-bit integer in the 3
   least significant bytes of the attribute.

   The controlling side MAY include such an attribute when renominating.
   The controlled side MUST select the nomination with the largest value
   contained in the "nomination" attribute.  Any value included takes
   precedence over the lack of a value.

5.  IANA Considerations

   This specification requests no actions from IANA.

6.  Security Considerations

   TODO

7.  Acknowledgements

   TODO

8.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC5245]  Rosenberg, J., "Interactive Connectivity Establishment
              (ICE): A Protocol for Network Address Translator (NAT)
              Traversal for Offer/Answer Protocols", RFC 5245,
              DOI 10.17487/RFC5245, April 2010,
              <http://www.rfc-editor.org/info/rfc5245>.

Authors' Addresses









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   Peter Thatcher
   Google
   747 6th St S
   Kirkland, WA  98033
   USA

   Email: pthatcher@google.com


   Honghai Zhang
   Google
   747 6th St S
   Kirkland, WA  98033
   USA

   Email: honghaiz@google.com


   Taylor Brandstetter
   Google
   747 6th St S
   Kirkland, WA  98033
   USA

   Email: deadbeef@google.com


























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