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Versions: 00

Network Working Group                                        P. Thatcher
Internet-Draft                                                  H. Zhang
Intended status: Standards Track                         T. Brandstetter
Expires: January 2, 2017                                          Google
                                                            July 1, 2016


  ICE Candidate Removal: Remove ICE candidates when they are no longer
                                useful.
                 draft-thatcher-ice-remove-candidate-00

Abstract

   This document describes an extension to the Interactive Connectivity
   Establishment (ICE) that enables ICE agents to signal the removal of
   ICE candidates to the remote ICE agent to prevent the remote ICE
   agent from wasting resources by attempting to use the ICE candidate.

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 January 2, 2017.

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
   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
   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.  Signaling candidate removal . . . . . . . . . . . . . . . . .   3
   4.  Removing candidates when a removal is signaled  . . . . . . .   3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   3
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   In certain network conditions, ICE agents may find that a local ICE
   candidate is no longer useful and that the remote ICE agent should
   not attempt to use that ICE candidate.

   For example, if an ICE agent is gathering TURN candidates and finds a
   set of better candidates (such as using UDP to the TURN server) than
   candidates already signaled (such as using TCP to the TURN server),
   it may choose to deallocate the worse candidates.  But if it does so,
   the remote ICE agent may waste time and resources attempting to use
   the deallocated TURN candidates.

   Just as trickle-ice optimizes ICE by signaling the addition of an ICE
   candidate, this extension optimizes further by signaling the removal
   of an ICE candidate.

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].

   This specification makes use of all terminology defined by the
   protocol for Interactive Connectivity Establishment in [RFC5245].

   Removal Signal  The messsage signaled between ICE agents that a
      candidate is removed.

   Removed Candidate  An ICE candiate for which a removal signal is
      sent.

   Removing Agent  The ICE agent that sends the removal signal.



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   Receiving Agent  The ICE agent that receives the removal signal.

3.  Signaling candidate removal

   This specification does not define the usage of candidate removal
   with any specific signaling protocol.

   However, it will be noted that any signaling protocol must be able to
   unique identify the Removed Candidates.  For example, a combination
   of the component, ip address, protocol (UDP or TCP), and port would
   unique identify a Removed Candidate.

4.  Removing candidates when a removal is signaled

   When a removal signal, the Receiving Agent MUST NOT pair the Removed
   Candiates with any future candidates gathered by the Receiving Agent.
   The Receiving Agent MAY keep the existing candidate pairs that use
   the Removed Candidates and behave as though the Removed Candidates
   had not been removed for those candidate pairs.

   Why would an Receiving Agent choose not to immediately remove
   existing candidate pairs?  Because the Removing Agent MAY choose to
   keep the Removed Candidate capable of receiving ICE checks and
   sending responses so that any ICE checks already sent by the
   Receiving Agent may continue to work briefly so that media can flow
   as quickly as possible, even if over a candidate pair that will soon
   be discarded.

   Both the Removing Agent and the Receiving Agent SHOULD prioritize
   candidate pairs with a Removed Candidate lower than those without a
   Removed Candidate.

5.  IANA Considerations

   This specification requests no actions from IANA.

6.  Security Considerations

   TODO

7.  Acknowledgements

   TODO








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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

   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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